1994 Ford Ranger misfire and hesitation - really need help - Ranger-Forums - The Ultimate Ford Ranger Resource


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Old 03-09-2012
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Icon5 1994 Ford Ranger misfire and hesitation - really need help

I posted about this problem some time ago, i received a lot of useful advices but i am still dealing with the same issue, even though i did replace a lot of parts and i did a lot of testing. I feel really stuck!! I've sunk a lot of money into this old truck buying new/used parts, swapping one part for another and i still have the same problem with very little improvement. Here is the latest.... i would appreciate any feedback, advices, tips, etc.

I have a 1994 Mazda B4000 truck which is essentially a Ford Ranger with 4.0L V6 and 5-speed M/T, 2WD. Truck has 101k miles. California edition (emission)

Here is the problem:
My truck feels as if it’s misfiring/hesitating and shaking/vibrating during acceleration and it feels underpowered. Almost as if I am in the wrong gear at a low speed. Also, quite often, while I am accelerating and I press on the gas harder, I can hear/feel some sort of loud “detonations” (for lack of better word) happening somewhere under the hood, in addition to feeling the lack of power. It sounds like “knocks” inside the engine or inside the exhaust. It's hard to describe but it is very obvious inside the truck and i am sure people outside can also hear it. If i am gentle with the acceleration - the detonations/knocks are not happening.

The problem seems to be more obvious when the truck is warm. Only sometimes, even though for only a short time, it just starts to run fine without any issues and then all of a sudden the misfires and lack of power are back. Feels like something is making a bad contact and as soon as it makes a good connection – the truck is back to normal.

** Currently, the OBD scanner shows NO error codes in the system. I used to have code 216 for a long time but I just fixed it a week ago with a new Camshaft sensor. **

Here is what I have done/checked and replaced so far with no results:

- New spark plugs (autolite) -2nd set because one plug was cracked from the new set I installed 3 months ago.
- New generic brand spark plug cables (2-mo old)
- New coil pack (2-mo old). I tried with a used one before from a junk yard – got same behavior.
- New crankshaft sensor (I was getting “CID error“ code – OBD 216 for a looong time but truck drove fine)
- New camshaft sensor (this fixed the OBD 216 code finally but it did not fix the misfire/detonations/lack of power)
- Newer fuel filter (2-3k miles old)
- Newer air filter
- Cleaned MAF sensor with MAF sensor cleaner twice – made no difference at all
- Ran SeaFoam cleaner thru intake – lots of smoke out of exhaust but made no difference
- New injectors – installed 6 rebuilt OEM injectors and new intake manifold gaskets – made no difference at all
- New CAT converters installed a month ago – made no difference
- I measured the fuel pressure using a pressure gauge and it showed pretty much everything in spec. A bit border line low, but within spec.
- I tested for spark at each plug, using a $10 spark plug tester and I got spark on all 6-cyl @ idle.
- Truck starts easily - every time. No need for excessive cranking.
- My idle seems to be very stable and healthy at all times. If i rev the engine RPM in "neutral", there are no issues or hesitation!!
- ** The misfire/hesitation starts to happen once I start accelerating, especially between 2nd to 3rd and 3rd to 4th gear, etc. Sometimes i even hear the detonations/shaking leaving from a stop light. **
- After driving the truck for awhile, when I stop at a light, I can feel the engine idling fine but vibrating/shaking more than it used to. Occasionally - it will become smooth and then start shaking again. Feels like a cylinder may be off...on...off.
- Something interesting: last week, after I replaced the Camshaft sensor (it required removing of the intake, fuel rail, etc to get to it) I took the truck for a test drive and for the first 5-7 minutes of driving it drove 95% fine!!! There was very little engine vibration under acceleration but I did not feel any misfiring, any detonations or lack of power. The truck was much smoothers and quicker. Took it on the freeway, accelerated to 75-80mph with almost no issue (slight vibration under load)…drove for 1-2 minutes in 5th gear fine, …. I Stepped on the gas to take it to 85mph and I started to feel the hesitation again. I felt and heard a few very obvious “detonations” under the hood too when pressing the gas. The truck went back to the old behavior. :( My hope that the new Camshaft sensor fixed everything disappeared. The problem must be somewhere else and I don’t know where to look. Something did fix it for a few minutes. Not sure what.

Like i said - i am really stuck!!! Not sure where to look next.

Sorry for making this so long. If you can give me any pointers or ideas, I will be very thankful.
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Old 03-09-2012
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I bet it is the distributor.
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Old 03-10-2012
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Quote:
Originally Posted by <TX>TORKiT View Post
I bet it is the distributor.
What "distributor" are you referring to?
All 6 spark plugs are connected to a coil pack. I tried two different coil packs, one new and one used and they did NOT make any difference.

I do not see any other distributor.
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Old 03-10-2012
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there is no deistibuter.

how does your coolant look? also your oil? any of them milky looking?

something you touched when doing the cam sensor is causing it, if it stopped right after you put everything back together. if its only when warm, its clearly expansion of an item.

id start with this list, simple and easy to rule out problem areas. do these when the engine is warm, right after shutting it off since your problem is heat related.

spray the coil pack, (engine running) and each plug wire down to the block with some water, and watch for any arching. replace them it the arch

try the cigar trick. light a cigar, take a mouth full and (with engine off) blow into the brake booster line. keep doing this untill you see smoke coming out the intake. this is a great way to check for a bad intake gasket. look for any smoke coming out around the upper intake and the block.

try a tank of high octane fuel. sometimes the brand of gas you use can do numbers to an engine.

from what your describing, it could also be an exhaust leak from around the headers, since its only when warm. it wouldnt as much explain the lack of power (well a little) but i would explain the noise.

you could have a blown headgasket, or a cracked one. explains loss of power and noise.

my only other thought is the throttle position sensor. (pretty sure you have one) if this is reading wrong, it will throw the whole system off.

Let me know what you find.
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Old 03-10-2012
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Here are some comments/results in line, in red color:

how does your coolant look? also your oil? any of them milky looking?

Coolant and oil, visually look normal. No greasy stuff floating in the coolant from what i can see. However, i should mention that occasionally, i add coolant to the expansion tank. I do not see any leaks! Radiator and hoses are new. The truck is not driven often, mostly sits on the driveway and i do not see any coolant leaks under it. I have an oil leak and PS fluid leak, but no coolant. Yet, my coolant expansion tank seems to "loose" some of the coolant.

something you touched when doing the cam sensor is causing it, if it stopped right after you put everything back together.

It's either that, or while the battery was disconnected for so long, the computer got fully reset and it was running all good (for few minutes) until it got bad signal from a defective sensor? Not sure if this theory makes any sense though, since i have no error codes in the OBD scanner. It shows "111" on both - engine off test and engine running test.

if its only when warm, its clearly expansion of an item.

I drove it again last night, it was cold and only 1 minute after i started it, it was showing all the symptoms again - hesitation, shaking, lost of power and detonations under normal acceleration. So i guess - cold or warm - it is acting up.

id start with this list, simple and easy to rule out problem areas. do these when the engine is warm, right after shutting it off since your problem is heat related.

spray the coil pack, (engine running) and each plug wire down to the block with some water, and watch for any arching. replace them it the arch

Did this last night in the dark. NO arches, no sparks, nothing. Coil pack, cables, areas around spark plugs - all got sprayed wet and i did not see a single arch.

try the cigar trick. light a cigar, take a mouth full and (with engine off) blow into the brake booster line. keep doing this untill you see smoke coming out the intake. this is a great way to check for a bad intake gasket. look for any smoke coming out around the upper intake and the block.

I do not have any cigars at the moment but i will get some. I tried something else....i sprayed carb cleaner everywhere where i could have vacuum leak. I used a whole can while truck was running at idle and i could not trigger any change in idle. If this test is reliable, i should not have any vacuum leaks, correct?

try a tank of high octane fuel. sometimes the brand of gas you use can do numbers to an engine.

I've tried three or four different brands of gas, all reputable, both 87 and 89. I used few different kinds of injector cleaners too ...and none of this made any difference.

from what your describing, it could also be an exhaust leak from around the headers, since its only when warm. it wouldnt as much explain the lack of power (well a little) but i would explain the noise.

Other than visual check, what else can i do to confirm that there is an exhaust leak? The truck is a bit louder now, after i replaced the cats...but this did not change the behavior much. I had all the problems and noises and detonations before i touched the cats. I replaced the cats because i thought that they are clogged and they were causing the detonations. I was wrong.

you could have a blown head gasket, or a cracked one. explains loss of power and noise.

This is where i hope you are wrong but you may be right. I am starting to get the same feeling. What other tests can i do to confirm that it is not my head gaskets? Will a cylinder compression test be any help? Anything else i can do? Keep in mind that the engine has no issues at idle, i can rev as high as i push it in neutral, once it is up to speed, it can keep up well....60-70 even 80mph (getting there is the problem) ... i do not see any excessive smoke out of the tailpipe .... and generally, once the RPM are above 3,000 range....the hesitation/misfire is pretty much gone. Will all this happen if i had bad head gasket??


my only other thought is the throttle position sensor. (pretty sure you have one) if this is reading wrong, it will throw the whole system off.

I am almost sure that i swapped that one with a used one at some point, but it did not make any difference and i put the original back on. Not 100% sure. IS there a way to test this sensor?

What do you think about the fuel pump? Given everything i've listed so far, should i suspect it? My idle is good, truck starts well every time and the problem is there only during acceleration/uphill? Can this be a dying fuel pump?
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Old 03-12-2012
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Icon10 Update - FIxed!!!

Wow!!! I am VERY happy to report that the problem was fixed.

I replaced the spark plugs again and i put new Bosch ignition cables. The 'old' plugs were less than 6 months old with less than 2k miles on them. They were Autolite Platinums. The 'old' cables were some generic cheap brand, but also only 2-3 months old.

I installed brand new, properly gapped NGK Platinums and new cables.... and miracle - now the truck runs like new. Smooth and fast. No hesitation at all. I drove it for 20-30 miles.... in the city, on the freeway, under load, gently, fast - it just runs and runs the way it is supposed to do. I am 100% sure that whatever the problem was - it was related to the spark plugs or the cables or both. I can't really explain to myself what was wrong with the 'old' parts given that they were pretty much new too. I would never find out, i guess.

I had hesitation issues before i replaced the original plugs/cables and i know that the problems did not start when i installed those Autolites. MY original coil pack had one of the 6 connectors kind of burned out/damaged, so when i replaced it, this was when i put the new Autolites and cables. Since I still had the hesitation, i moved to fixing other stuff and sensors, ruling out the plugs. Looks like i was wrong the whole time.

Either way - problem fixed! :) Hopefully it won't return ever again.
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Old 04-01-2012
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I have similar problems to this I guess I could change my plugs again?! The thing is I changed my plugs and wires 2 years ago. My parents and I had taken the truck to a place to get it tuned up and supposedly they were changing out the plugs. Well low and behold I found out that the the plugs had never been changed! The gaps were huge! It's surprising it ran at all, but it ran just fine until a couple of years ago when it finally started acting up.
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Old 04-02-2012
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Did you check for codes again after replacing the sensor that seemed to fix the problem, but didn't? I'm not second guessing you. I'm trying to make sure where we are now. Thanks.
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Old 08-25-2016
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Icon7 Troubleshooting Misfire - Solved! Check the CAT!

Hi Everyone. I know this is an old thread but I've been digging everywhere I could to try to troubleshoot my 2011 Ranger XL for the last 2 months. I thought I'd pass what I found on my Ranger after 2 months of torture.

As mentioned in the original post, my Ranger was running really rough, had lost all of what little power it started with, and basically was drinking gas like I've never seen. It was throwing no codes, and I started with the basics... plugs/wires/octaine treatment/fuel injector cleaner/ignition col.. all which only slightly improved the issue. My trans was shifting hard, and go to the point where it would not even shift unless I took my foot off gas and let it drop to below 2000rpm (which was fun trying to get on highways)

After reading everything I could find on the misfiring subject online, I cleaned (then replaced) the MAF, TPS and Airfilter. Even a overpriced and worthless fuel injector cleaning by Jiffy Lube, it just kept getting worse and worse. I bought a fuel pressure gauge and was getting 60+ PSI so the gas pump was working.

I called then stopped by my local muffler shop and asked them if they thought it was a CAT, and they said if it wasn't throwing a code, then it was probably OK. So I kept looking and looking, reading everything about how the whole system worked. So I replaced the plugs again and did another couple tanks of Shell 93 octane to see if it would shake out.

So a couple of days ago it got to where the it would not get over 40 MPH, and forget about trying to climb a hill. So in frustration I took it to my local muffler shop and had them check it to see if it was clogged. Boom. 80% blockage in the 1st CAT.

I've had CATs go bad before on my 2005 Dodge 1500, and it gave me the codes and I could get around it by unplugging the O2 sensors, so I totally ignored the symptoms and kept thinking it was spark or fuel.

Hope someone can find some of their troubleshooting in my tale, and next time I'm checking the CAT first!

Dave

p.s. The thing runs like it is brand new with all the new parts, go I guess in the long run I came out OK.
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