Any luck with the further testing? Since the CTS didn’t solve your issues, which I’m still really surprised it didn’t, I don’t want to see you spend any more money until you positively identify the problem. As for my truck, my BRAND NEW DELPHI FUEL PUMP dumped on me last night. I was on the highway and coming out of an interchange under power when suddenly the pump went to hell. It was still running but ONLY supplying enough fuel to idle the engine. I JUST changed it when I was fixing the head so it had LESS THAN 200 miles on it! The old pump had started to whine so I figured it would be a good thing to change it so it didn’t fail on me. Well, the new pump was whining from the get go so I thought maybe it was normal for it to whine. NOPE. When it heats up, it stops making pressure! I let it cool and it runs normally until it heats back up again. So, I was able to nurse it home. Dropped the tank again, broke a fuel line clip so I had to have a buddy run me to The Zone to get a new clip, and now I’m about to go reinstall the tank. An 80¢ clip held me up! So, if YOU are experiencing what I am right now, I would DEFINITELY monitor the fuel pressure WHILE IT IS ACTING UP. This is the THIRD fuel pump I have had that was faulty in 2 months, NOT all on my truck. 2 of them were on a 2007 Jeep Liberty that was a customer vehicle. They replaced the pump with an Amazon pump that lasted 2 days. I got a Spectra Premium pump (the ONLY one I had available) for her that was faulty out of the box and wouldn’t make more than 8psi. Put another Amazon pump in it and it fixed the problem after 6 hours of troubleshooting 😡. Now this one on my truck. All three were different brands and all three came from different suppliers. Looks like China is making them all in the same factory and slapping different brand names on them and selling them to different vendors. This country REALLY needs to bring our manufacturing back home! I’m getting REALLY tired of doing warranty work and extra labor for things because I simply cannot get my hands on a quality-made part! I got my Delphi pump from Rock Auto. I thought maybe I could avoid issues by buying the brand name part from them rather than “Ultra Power” or some other off-brand junk. Boy was I wrong. Now I have to try to get my tank back in with 10 gallons of fuel in it! I am SO pi$$ed off right now! The ENTIRE reason I changed the pump in the first place was to AVOID a failure like this! I was TRYING to do the right thing and be PROACTIVE! I’m ALWAYS the one that gets **** on!

So, if your symptoms sound ANYTHING like this, I would go straight to that fuel pump because they are similar pumps. When it **** out on me, I was accelerating off of an interchange ramp under power when suddenly I lost ALL power. The engine was still running but had NO power. Then it started bucking at about 1/2 second intervals where it would get fuel and lose fuel. I pulled over, the engine continued to idle. I revved it a couple times, seemed normal, so I started going again. At about 50mph, the same thing happened. I pulled over again, this time the engine died. I grabbed my small scanner and looked for codes. Nothing other than stupid emissions codes. Got the engine to idle and rev again so I merged back on to the highway with my hazards on. Couldn’t get over 35mph. I exited the highway and circled back home. At one point I was not able to go faster than 13mph. BARELY nursed it home. I got it home thinking maybe it was the TPS or the MAF. So, I hooked up my scanner and looked at all the live data. I noticed I could hear the whine changing pitch while I was testing everything. My MAF signals and TPS signals were PERFECT. The fuel pump simply could NOT supply the pressure needed to open the throttle. I let it cool for about an hour and was able to make it to the parts store to buy another pump. I let it cool again at the parts store before I came home. It made the round trip to the parts store with no issues. That is a classic failure of a fuel pump that is heat related. If the fuel pressure regulator would have been the issue, heat would not have affected it. It would have been a total failure because the spring would have been broken, the piston or diaphragm failed or torn, etc. and heat has nothing to do with that. The FPR on the 2000 is in the tank. It’s not under the hood like older models. There is no return line from the engine. The pressure line for the FPR is actually off the inlet of the fuel filter. There appear to be 2 inlets but one is the inlet from the pump and one is the outlet to the FPR. Then there is the outlet on the other end to the engine. Typical EPA BS to put a returnless fuel system on modern cars. It’s a pain in the a$$. There was NOTHING wrong with the old system where the FPR was on the fuel rail and it returned the excess fuel to the tank. But no, the EPA has to be a bunch of a$$holes and say that it’s an opportunity for fuel to leak. At least it’s not that other system from Ford that has a fuel rail pressure sensor and a fuel pump driver module that cycles the pump on and off or varies the voltage to the pump to maintain pressure. The models with the chip in the key use that system because that’s how the PATS (Passive Anti-Theft System) disables the vehicle. It allows SOME fuel pressure but NOT enough to run the engine. The first time I ran across a PATS failure I thought the fuel pump had failed, thought the timing chain had jumped, and thought all sorts of other things happened. The PATS in the instrument cluster fried both itself and the PCM. Replaced both and reprogrammed the keys to fix the problem. Anyway, I’m rambling now, if your truck is doing what mine did last night, your fuel pump is highly suspect.

 

Nah I haven’t been back to the truck yet. Currently dealing with some personal life stuff.

When I had my fuel pressure gauge on the truck, the pressure was normal when I got the engine to act up. I was very surprised but yeah, no change in pressure when it started to misfire. My hunch is something timing related, and it only happens when the truck is hot (especially in very hot weather). My fuel tank has been full this entire time, I made sure of that to prevent any overheating of the fuel pump. Hopefully that precaution actually helped lol.

 

I must remind you of one thing, pressure and volume are completely separate. It MAY produce enough volume to maintain pressure at idle but NOT supply enough volume to maintain pressure when the throttle is opened. So, you DID see some pressure drop at idle. How far does it drop when you rev the engine?

Generally speaking, if there is a timing belt issue, it will tend to smooth out when RPM is increased. Not saying that’s always the case, it’s just a general rule. I do really wish I was closer to you so I could see the truck myself.

On a side note, I got the fuel pump done and, guess what, the new GOOD pump is SILENT. So, that old pump was bad right from the start. If you can hear your pump whining, that’s a sign of an issue. I had a moment when I thought the pump was supposed to whine since a brand new Delphi was whining. Well, it really WAS NOT supposed to whine and that was an indication of an issue, just as I thought with my original pump. I could never hear my old pump until a couple months ago. Again, that’s the reason I changed it. Then the faulty pump had me second guessing myself. Well, I was right in the first place.

I have heard that China has been pulling some shady ****. They have been doing a couple things. One, they have been taking QC rejects that the contracting company has been sending back to them and selling them themselves instead of scrapping or repairing them. They’ll sell a lot of QC rejects to vendors hoping they don’t catch the discrepancy of the origin. Second, they have been stealing our trademarks, logos, brand names, etc, producing FAKE versions of the genuine parts, and, again, selling them to vendors as if they are real, quality parts. I imagine something like that happened with at least my truck’s pump. It really seems more than ever I can only trust parts that come from my commercial Advance Auto Parts account. At least I know those parts have been verified to come from a reputable supplier. The pump I put in this time was a CarQuest branded pump. That usually IS the name brand part with a different logo on it. There is NOT a difference in quality. And my CarQuest parts have a LIFETIME warranty on them. RockAuto is DEFINITELY going to be compensating me on this one. My business lost $1,400 in gross revenue today since I was unable to make it to the jobs I had scheduled. Those customers lost their confidence in me and found other people to do the work for them. Those customers are now lost and I cannot recover them. How much future money have I lost from them from future jobs and their friends/family? All because they couldn’t verify the source of the parts they sell. And what about my personal labor to replace the pump? They don’t know nor do they even care what their carelessness costs their business customers. They are going to hear it from me.

 

KOEO fuel pressure holds at about 40psi. Running at idle, 30psi. Opening the throttle jumps the pressure up to 40 for a second and it snaps right back to about 30-35.

That’s lame about those failing fuel pumps…mine is silent thankfully. This is why I prefer my older vehicles (72 F250) with carbs and mechanical pumps.

 

Ah, the old mechanical pump. Those are like old faithful. And when they do fail because the diaphragm wore out or the spring broke, they were right on the side of the block and took about 10 minutes to change. Electric pumps are just a pain in the a$$. They’re in the tank for one so they can stay cool, they have to supply 8 times the pressure which is why they get hotter, the automakers didn’t use their brain at first and still haven’t on some vehicles and make you drop the tank. What do most people do if think they are running out of fuel? THEY FILL THE TANK UP! How much fun is it to drop a fuel tank that has an extra 150 pounds of fuel sloshing around in it? IT MAKE YOU WANT TO LIGHT IT ON FIRE AND ROAST MARSHMALLOWS! The good thing is that it’s not TOO hard to drop the tank on these trucks. It still sucks but it’s not as bad as say a new Cadillac CTS. On those, you HAVE to drop the entire rear SUBFRAME with ALL of the SUSPENSION hooked to it! I refuse to do it. Even if you have a lift, you have to have a forklift under the subframe to lower it out of the vehicle, then you have to have at least 2 under-lift jack stands under the front subframe to keep the car from tipping forward on the lift when you remove the weight of the rear subframe. Then you can FINALLY get to the bolts that hold the fuel tank straps. They put the Fuel Pressure Regulator IN the tank just like the later Rangers but it’s made of PLASTIC and it fails ALL THE TIME. That’s typical GM BS for you though. They do things on purpose to force you to bring the car back to them and they can charge $160 an hour for labor and 15 hours to change the fuel pump module! But people KEEP buying their JUNK! GM to me stands for Garbage Motors!

 

Oh, and I discovered another thing at least with the later models. If the CTS fails, it will get conflicting signals from the 2 sensors and it will run like poo. If you disconnect the failed sensor, it will run off the other sensor normally. So, what may be going on with your truck is that the gauge sensor has failed and is giving the PCM conflicting signals and throwing everything off. Try disconnecting the other sensor and see what happens. It may run rough or die for a few seconds immediately after you disconnect it, but it will figure it out and throw a code so it starts reading the other sensor.

 

Well, replaced the IAT. By the looks of it, I was hoping it was the problem. Alas, it still happens. It’s harder to get it to act up in cooler weather though. But I think I’ve pinpointed the issue to the EGR.

I disconnected the vacuum line, plugged the line, and hooked up my vacuum pump to the EGR valve. Opened it a little with a small amount of vacuum, and an identical misfire started to happen. Opened a little more, gave it some throttle, and it did exactly what happens any other time it has acted up. So I think the valve is opening when it shouldn't, or it’s getting stuck now and then. Just weird how it only happens when the engine gets hot. Maybe the EGR position sensor is at fault?

I don’t know exactly how that system operates on these engines, but I got that code (34) that says the EGR system failed the self test, and more specifically, it says the EGR did not respond. Meaning the computer system can't detect whether or not the valve is open. If the fuel & timing systems don’t know the EGR valve is open, maybe they aren’t compensating enough when it finally opens (under load, cruising rpm, and when cylinder temps are high). Meaning my A/F ratio will be too lean. Causing a misfire. Thoughts? Seems plausible to me. Wondering if a block-off sandwich-plate would “solve” this issue. At least enough for my dad to putt around.

Oh, and it passed the dollar bill exhaust test. Never gets sucked in.

Here’s the IAT comparison though. Gross.

 

It’s actually RICH with the EGR valve opening either uncommanded or open without the PCM knowing it’s open. When exhaust gasses enter the intake system, there is less than 100% fresh air in the manifold meaning less oxygen and therefore if you put the same amount of fuel in, it won’t have enough oxygen to burn all of the fuel. Like I told you about my dad’s Volvo when the vacuum lines to the EGR control valve were reversed, manifold vacuum was pulling the valve open and allowing vacuum to get to the EGR and opening the EGR valve at idle. That was causing the intake to get filled with exhaust gasses when the manifold was under vacuum and basically causing the engine to run on exhaust gasses rather than air at idle. Obviously that’s just not going to work out too well, lol.

Now, in your case, why that is ONLY happening when both the engine AND the air temperature were hot is a head scratcher. Does it do the same thing if you just unhook the EGR vacuum line and plug it? Yes, I understand you’re going to get a code for incorrect flow or whatever, but it might tell you if it’s a problem with the EGR valve itself or if it’s a problem with what is putting vacuum to the valve to open it. On the later OBD-II Rangers, there is a control valve over by the coils that the computer opens and closes either putting vacuum to the EGR valve or cutting the vacuum off to the EGR valve. Not sure exactly how the OBD-I system works. EPA regulations and system configuration changed between 1989 and 2000. On the OBD-II cars, there is also a differential pressure sensor that hooks to the manifold and to the EGR tube to see what kind of flow the EGR is doing. The whole reason my EGR is blocked off is because the EGR tube went Swiss cheese on the previous owner and the hose nipple on the EGR tube broke off so they pinched off the tube at the manifold but left the damn tube and valve connected like retards. That was a HELL of a vacuum leak! When the computer commanded the EGR open, it was just sucking in air. They pinched the end of the tube off as well not even clueing in that the tube was still going to suck air through the holes in the tube. I now have a slight exhaust leak due to the pinch off on the exhaust manifold not being 100% sealed. Why they couldn’t just go get an AN style block off cap and install it on the manifold is beyond me. It’s after the upstream sensor so it’s not causing an erroneous reading from the oxygen sensor so, at this point in time, I really could care less about the slight clicking coming from the leak! I’m getting ready to redo the entire exhaust system anyway and I’m going to have the EGR and downstream sensor removed from the PCM since I’m going to also be installing Bo-Port’s stage 1.5 N/A Ranger street cam and I’ll have the PCM tuned to take full advantage of the exhaust, intake, and cam. I’m looking at around 40 more horsepower at the wheels with that untuned so I would say 45-50 more with the tune and probably switching it to premium fuel and advancing the ignition significantly. But back to your truck.

Take the wire loom off the vacuum lines and trace the vacuum line from the EGR valve itself back to its source. It will NOT go directly to the manifold. There MUST be something controlling it elsewhere. The problem may not be the EGR valve itself. There is a probably an electrical connection to the EGR valve and that is a transducer that tells the PCM the position of the valve. Yeah, that may be faulty but I would start elsewhere because if there is a problem with the control valve, then it’s going to cause the EGR to not respond. You should be able to find out if there is a change in resistance of the EGR valve position sensor by hooking up your vacuum pump and your multimeter to the pins of the sensor. Open the valve with the vacuum pump and see if any electrical values change. Obviously the valve is physically opening if you can get the engine to change the way it’s running by applying vacuum with your pump. If you don’t see anything change, then the sensor is bad. If you do see a change, the EGR valve itself is fine. Then hook up your vacuum pump to the vacuum line and just use it as a gauge. See if you’re getting manifold vacuum at that line when the engine is idling when it’s hot. If it is, then there is an issue with the control valve. Did someone possibly reverse the vacuum lines to the control valve? The control valve itself may have a torn diaphragm and it’s only acting up when it gets hot enough to expand and allow vacuum through when it shouldn’t.

And holy nastiness with that IAT sensor. YUCK. Is that after the valve cover breather port? That looks like you’re getting oil and blow by gasses into the intake from the valve cover/crankcase breather. Maybe install some sort of air/oil separator in that hose to prevent that nastiness again. Your engine should at least run better in general by changing that disgusting sensor, lol.

I am also happy to hear it passed the dollar bill test. That was a NIGHTMARE for me to deal with. That’s not something I would wish on ANY fellow Ranger owner, especially at the severity of mine. I simply cannot believe how much better this truck runs with that issue fixed. I drive this truck with PRIDE now. Almost anyone else would have junked this truck over that. I just gave it a new lease on life. New head, new and upgraded rear end to the 8.8”, fixed the A/C, fixed the fuel pump, and new CTS. Ive jumped 10MPG in this truck. Now onto the suspension next. Once I get the suspension done, I’ll do the exhaust, build my own intake because every intake I have seen for this truck was designed by someone who completely does not understand how airflow works (I’ll explain in greater detail if you want to know) and that INCLUDES K&N, get my cam, and have the PCM tuned. Then it’s new wheels and tires. I’ll probably go get a couple tires from Pick-N-Pull for now since my front tires are destroyed on the inside from the worn out upper ball joints. I don’t want to spend money on brand new tires when I’ll be getting new wheels and tires within the year. I’m going to go wider to a 275/60-15 on a 15x8 rim with a -18mm offset to bring almost all of that 50mm extra width outward and I’m going to install 2” fender flares to cover the rust until I find a decent body guy to fix my bed wheel arches, cab corners, and front fenders. The previous owner paid some low-rate body guy a year ago to fix the rust but all he did was weld new metal over top of the rusted metal, throw some Bondo on it, and paint it. The rust spread to the new metal because he did NOTHING to remove the rust that was pre-existing nor did he add any corrosion protection to the inside of the new metal. Rust/Corrosion is CANCER. It spreads to anything it touches. I used to share a shop and rent with this guy, he screwed a couple of my customers, and I cut ties with him. I’ve seen what he does. He does things for small corner lots just to sell cars and doesn’t care about longevity. He has known my father for 15+ years, KNOWING that my father was buying this truck, and he still did his half-a$$ job on it. My dad bought the truck for me and then I purchased it from him. My dad was trying to do something nice for me, didn’t think someone that was a friend of a friend would screw him, and they took advantage of him. When I swapped the head, I CONFIRMED they were aware of the misfire and that they sold the truck to make it someone else’s problem without disclosing the problem. I found that ONLY the plugs on cylinder 1 had been changed (I originally thought all 8 were new because it had new plug wires), along with new CTS’s (cheap ones that already failed), new fuel filter, new coil packs, and the removal of all of the emissions controls on the truck for them to try to fix the misfire. I understand that my dad was trying to help me and surprise me but he should have let me go over the truck before the purchase because someone installed lowering shackles in the rear to level the truck, that caused the spring to not be able to flex like it should, and it destroyed the leaf spring and shackle bushings. The correct way to level a truck is to LIFT the front, NOT lower the rear! Now I inherited all of the problems with the truck and I wasn’t able to get more than $300 trade in value for it so I got stuck fixing all of it. Oh well. At least now I can say it’s truly my truck. I swapped instrument clusters on it today to add the tachometer and I even swapped my original odometer into the new cluster so my mileage is showing correctly. Plus I got a good condenser for the A/C from the salvage yard and restored the A/C since the condenser cracked on me due to corrosion behind the brackets that hold the lines when I took the lines off during the head swap. I am a MOBILE mechanic, I’m out in the heat, rarely any shade, and I had nowhere to take a break and cool down. I fixed that problem REALLY fast, lol. But I added LED backlights to the cluster and climate control a while back. Today I put LED’s in the new cluster from my old one and added them to the turn indicators, high beam indicator, and check engine light. I have some more LED’s for the indicators on the way so I can swap them all. Here are a couple pictures of the LED backlighting. The first one is the new cluster with LED’s as of today (check engine light due to EGR flow and catalyst efficiency, that’s what the unreadable bright yellow light is with an LED in the CEL, lmao) and the second is the whole dash with the old cluster:





Eventually I will be getting the cruise control system, under hood accessory/dash harness, and power window/lock systems from a junkyard truck. I wasn’t lucky enough to have them pre-wired so I’ll have to add every last bit of it. I’m not sure if there was a power mirror option or not. If there was, I will be adding it! It’s an XLT so I want it to have all of the options and I’m not going to do that cheesy aftermarket **** that looks terrible when it’s installed. The window box that covers the window crank pin is hideous and looks like trash. I’m going to take the time and do it right by installing the factory parts. Yes, it will be more involved and take more time, but the end result will be much better.

Well, sorry for the novel about my truck, hopefully I’ve been able to help with your diagnostics and I’m sure you will get it figured out one of these days! Unfortunately it’s really hard to check things when I’m 2,000+ miles away from you. I may have been able to identify the EGR issue simply by hearing the truck in person. I’ve heard what that sounds like on other cars. Keep me posted on the progress and any findings so I can try to help you through the process.

 

Ah I see. My brain said “more air” and I thought “lean!” But you’re right it’s not going to be oxygen & nitrogen like fresh air. So, rich then. It’s just weird then that I don’t have black smoke out the tail pipe, it must just barely be too rich.

I’ll get back to the truck as soon as I can but it turns out my dad won’t legally be allowed to park it anywhere where he’s going. So I have to drive him 3hrs at the crack of dawn tomorrow. But I won’t be able to just leave the truck unfixed, so you know I’ll be back to it lol. Going to check the vacuum lines with a fine tooth comb and inspect the position sensor and all that. Unplugging the vacuum to the EGR valve is a good test, I should have thought of that last time. Was just already tired from work and wanted to go home lol. I’ll be back to it soon enough.

Your truck sounds like it’s coming along nicely, thanks for sharing. Definitely a much different looking dash than these old 80s trucks lol. Don’t you wish you could just do all those upgrades right now! Lol my cars are always one “month off of work” away from being complete projects.

 

Oh, same here. Luckily me being a business owner doesn’t jeopardize me losing my job, but the rear end swap, fuel pump replacement, and head swap was a 1 1/2 week project since I had other things I was doing at the same time. My dad just had hip replacement surgery so he’s not quite as mobile as he’d like to be and I have to help him with a lot of his everyday tasks. But yes, I totally understand. What I’m probably going to do is when I grab the harnesses out of the junkyard for the cruise, PDL, PW, and PM systems, I’m actually going to split the loom open on the junkyard truck and just take the wires I need rather than taking the entire harness. I doubt I will find ONE truck with ALL FOUR packages so I am probably going to have to get everything from a few different trucks. All of those harnesses may be a little different so it would be a nightmare trying to combine them all. I’m just going to split the harnesses and take ONLY the wiring I need, then I can split my harnesses, add the wires to them, and then rewrap them. I’m a HUGE fan of making something look like it came from the factory like that

 

Any new findings? Getting curious, lol

 

Nah just haven’t been back to it. It’s not at my house and all of my days off are taken up by big tasks. The truck being one of them. Just this week though I got a flat on my way back from the 3hr trip south. That through a wrench into my scheduled plans. Plus I’m changing jobs soon and work is unnecessarily stressful lol. Currently jumping ship at a real cluster of a shop. I’ll get back to it eventually, sorry to keep you waiting lol.

 

What the hell is this?



Forgot about checking the MAP sensor. This is in-line to it from the intake manifold. Some sort of check valve? Part number brings up nothing. Going to replace the badly-deteriorating rubber hoses for the MAP sensor. It’s all dangling right above the exhaust manifold and I’m theorizing that the hoses heat up and with their crumbliness they might be opening up, creating a leak. Poor placement of the sensor if you ask me.

 

Opened that thing up. It’s completely empty. My guess is it’s some sort of vacuum-regulating tank, maybe it stabilizes the vacuum input to the MAP sensor. Debated bypassing it entirely with a single hose but my theories made it sound valuable lol, so I sealed it shut with JB Weld and reinstalled it with brand new hoses. Letting it sit, and the next time I get to it I’ll giver a whirl.

 

On the OBD-II trucks, there is the Differential Pressure Sensor for the EGR in that location on a bracket supported by the cylinder 4 exhaust manifold bolts. The EGR tube has 2 hose nipples on it and there are 2 hoses going to that sensor off the EGR tube. The same setup was on the 2000 Mustang 3.8L V6’s and I’m sure on other models as well. Those hose nipples break off ALL the damn time and the EGR tube itself goes Swiss Cheese which creates a HELL of a vacuum leak when the EGR valve is open. Instead of it sucking in exhaust gasses, it’s now sucking in air. That’s another terrible design and why I have my EGR valve removed and a block off plate installed. Stupid EPA Bull$h!t. Luckily I live in Ohio and I don’t have to fix dumb **** like that. I’m going to have my PCM reflashed to remove the EGR and rear O2 sensor so I can run cat-less without a MIL. The previous owner pinched off the EGR tube at the manifold and also pinched off the end of the EGR tube itself. All they did was bend it back and forth to kink it and then work harden it until it broke off. But they were too stupid to see the 3/4” rust holes in the EGR tube! They also plugged the vacuum line to the EVAP system but I fixed that. I believe this was their attempt at chasing down the misfire that I fixed with the replacement cylinder head. Modern FI engines really don’t need EGR or catalysts if the PCM is programmed properly and the engine has a hot enough cam that it can actually breathe. If you mix the air/fuel ratio properly and let the engine burn the fuel efficiently, it doesn’t need all the other **** to clean up the exhaust gasses. They are clean to begin with! I understand on a carbureted engine that doesn’t adapt to changing atmospheric conditions. But a FI engine does! Just another excuse for the damn government to tax us and waste money on “research”. Emission control devices create their own necessity. They suffocate the engine to the point where they burn unclean and then need the emissions controls to clean up everything. But are you sure you have a MAP sensor? Is that a speed-density setup or a MAF setup?

 

Oh I totally get you. When I was younger I thought that the EGR system made a lot of sense, cooling down cylinder temperatures and burning I burned fuel from the exhaust. But I’ve grown to dislike it for its problems more than appreciate it for its benefits lol. More often than not I find myself thinking, “if this crap wasn’t here I wouldn’t be having this issue in the first place.” It’s just become annoying lol. None of my hondas have their original EGR systems. Thankfully my ‘72 F250 predates that crap.

But yeah, definitely a MAP sensor. No MAF sensor for sure.

 

Ok, then it’s a speed-density system. Still that really wouldn’t affect things only when the engine and ambient temperature are hot. You would be having issues across the board. I think you were onto something when you pulled vacuum on the EGR and recreated the same running issue. We’re you able to determine when and how much vacuum the control valve was giving the EGR? Did you try unhooking the vacuum line from the EGR valve and plugging it?

 

Finally figured out something solid.

Was testing things to no avail, finally just starting poking things and yanking on hoses/wires. Started to see that a specific bunch of wires moving causes the stumble. Would have found it much sooner but it’s been buried & ziptied underneath/behind the intake manifold.

I now have it pinpointed to what I believe to be the crank angle sensor wiring. Looks to me like someone has jank-wired it together. See pictures below. The connector is glued shut. 2 wires in, one wire out. The single wire leads to the harness that goes to the timing cover - that’s where I assume this has to do with the crank angle sensor. One of the two wires on the other side of the connector has zero insulation.

Any time I move the harness with key on engine off, I can hear some sort of electrical hardware turning on and off, over by the fuse box. Reminds me of a fuel pump priming the system when you turn the key without starting the engine. On/runs for a few seconds, then off. Don’t know what it is thats making the sound but obviously it’s cutting out with movement of the harness.

I need to fix this wiring, but with how sketchy this wiring harness is, I don’t know how it’s supposed to look, or what these wires are. The one next to the bare wire is black like a ground, but it’s obviously smushed in with something providing power.

So that’s where I’m at now, I suppose. Got any leads as far as good wiring diagram resources for these trucks? To answer your question, I tried plugging the EGR control vacuum line with no difference, so for now I’ve ruled it out. Especially now with this harness issue.



Located on drivers side, under intake and by the brake booster. Glued shut.

Two wires into one pin??

This goes into a harness loom that goes to the front of the engine, behind the timing cover

 

It’s definitely the crank position sensor wiring. But the small connector pictured isn’t actually causing the issue. It’s the larger one next to it. Seems like any jostling of that connector causes a stumble and easily kills the engine. I don’t know how this thing was running as well as it has been. All I’ve done is remove one ziptie holding the harness to the intake and now the truck can’t stay running more than a minute.

Checked the local junkyard for a potential replacement with no luck. I have to figure out how to repair or replace this bad connection. I’m only 80% sure it’s the connector itself, as any movement about a foot in either direction of the harness kills the engine. Any suppliers out there with harness replacements?

 

Is that the CRANK position sensor or the CAM position sensor that goes to the oil pump? If it goes to the oil pump, that is the cause of your erratic ignition pickup code. It APPEARS from your pictures that the bare wire IS supposed to be there, but the insulation has deteriorated over the years and now corrosion has set in. Have you tried to pull the bare wire out of the whole mess and see what happens? If the truck runs better with the bare wire pulled out, then it’s not supposed to be there. If it won’t run at all, it IS supposed to be there. My guess is that it IS supposed to be there but has been damaged and gotten corroded.

The way I would repair that is to get a BLUE FEMALE spade disconnect, a RED MALE spade disconnect (BOTH THE FULLY INSULATED TYPE), and some heat shrink. Take the TWO wires on the one side, cut them off evenly, and re-strip about 3/8” of insulation. Twist the strands of wire to keep them from unraveling, then hold the two wires so they cross at a 90° angle and twist them together. Slide a piece of heat shrink over the wires that is big enough to fit over the crimp end of the BLUE terminal. Then, slide the BLUE terminal over the twisted wires and CRIMP. Pull the heat shrink up over the end of the terminal and shrink it with a lighter taking care not to burn anything. Take the other SINGLE wire, strip 1/4” of insulation, twist the strands, slide a piece of heat shrink over it, slide the RED terminal onto the wire and CRIMP, then move the heat shrink up over the end and shrink it. Now connect the BLUE to the RED. The repair is DONE.

 

From what I saw at the junkyards, it’s definitely the crank position sensor. Harness with the same two connectors goes right down to it.

I’ll more than likely do the repair you described, but the biggest problem seems to be in the large Grey 4 pin connector for the CKP sensor itself. If I so much as touch it with the truck running the engine will stumble and die. Trying to see if I can replace it but the junkyard trucks didn’t have much.

 

Try here:

https://www.bmotorsports.com/shop/pr...oducts_id/3258

go through the menu to the left and see if you can find the right connector. There’s no real way to search so you’ll just have to scroll through ALL of the 4-pin connectors until you see it. Also, is this it?

https://www.autozone.com/engine-mana...u221/68788_0_0

That is the sensor side, I’ll bet the first place has BOTH of the connectors for the truck side.

 

Couldn’t find the harness side of it on that first website but thanks for the resource. Yes that’s it on the autozone link. I found what I need on rockauto, out of stock. Used the part number to find it through a Google search, here it is on Amazon. 1-3 weeks out lol.



I found a newer looking CKP sensor at the junkyard and grabbed the connector off of it. Found a plug from another ranger that fits it, not sure it was originally for the CKP sensor but it fits the plug. Basically I have a “used” replacement I might try installing. Just weird to me that a solid connector would have such a bad connection, so I want to look more into the condition of the rest of the harness on my truck, I might find something else loose or frayed.

 

The 4-pin connector looks like it’s the same as a 4-wire oxygen sensor but the little indexing tang may be different. You CAN use an oxygen sensor connector and just file off the tang so it fits universally. Most replacement oxygen sensors come without the tang because they are used in different applications where the tang is in different locations. Just go to the junkyard and find ANY Ford with the round 4-pin oxygen sensor connector and cut off BOTH sides to make sure you get the right one. Hell, you can even re-wire the CKP sensor as long as you are mindful of the pin locations of each wire. And for that matter, you can even get ANY 4-pin connector from ANY car as long as you get both sides and match the pins to the right wires. Make SURE you use the WEATHERPROOF butt connectors!

 

Did I never follow up on this? Damn I could have sworn I came back with some closure on the matter. Ended up replacing the plug connector for the CKP sensor. Ran like a dream after that, no issues. Was a nice truck, wish he kept it, but it was only a means of transportation for one trip and after that he needed fuel economy from something else. Oh well, someone out there has a nice truck!