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I noticed the engine started lacking overall power during acceleration. Upon removing the air filter I discovered some kind of rodent decided to make its nest in the air filter. It ate through the filter and created shreeds that blocked the air intake. I left the filter off and went for a quick ride around the block and I seemed to have full power. The issue I am seeing now is that following a rev up, the engine wants to stall before returning to idle. Similarly, when parked and the wheel is fully turned to one side such that the power steering motor is still operating, the engine wants to hesitate for a bit.
I believe there is a cylinder leak for multiple reasons. After a few days without driving, it will start, but runs rough for a few seconds; I assume it’s burning off the coolant in the cylinder and there is a sweet smell in the air. The coolant is disappearing over time.
It’s possible there is a head gasket leak but I haven’t needed to top off the oil yet. It could just be very dirty.
I am guessing it’s around 200,00 miles. The odometer went out years ago around 150,000.
I am not a mechanic and lack overall knowledge and terms, but I have a shop with a slew of tools, and feel capable of trying some things.
Wanted to give an update that I ran down to the auto store and used their radiator pressure check kit but didn't see the gauge go down. I'm not certain what this means but the employee acknowledged he smelt "coolant" with me after starting it. Other than almost dying when revved, it drove with no loss of power with the air filter off. I went a head and pick up a replacement filter for the next rodent.
On fuel injected engines an air valve is used to set idle, idle screw doesn't work because there are no "ider Jets"
Ford calls their unit an IAC(idle air control) Valve
You can see yours on the upper intake drivers side, looks like a can on its side
Has a 2 wire connector
These can be cleaned, just pull off the connector and the 2 bolts, spray inside with degreaser or carb cleaner
And let it dry out, the valve can stick a bit when it gets dirty
To see if IAC Valve is working at all
Start cold engine, don't touch gas pedal
RPMs should surge and then settle in at 1,100rpms or so
Computer opens IAC Valve all the way for start up, thats the surge, then computer close it a bit to set cold high idle, as engine warms up idle will start to drop
After 5mins or so warm idle will be set at about 650 on a manual trans vehicle
If IAC Valve and computer are doing this then its working but could be sticking if warm idle stumbles
You can only replace Ford IAC Valve with a Motorcraft or Hitachi IAC Valve, just FYI, other brands cause odd issues in idle
Clean MAF sensor, always once a year, 4.0l OHV hates a dirty MAF sensor, easy to clean
I am sure with rodent debris its dirty
I pulled off the IAC and cleaned it the best I could. I sprayed it inside and out with air intake cleaner. At the same time I also sprayed around and cleaned the intake around the butterfly flap. Once I bolted it back on, the truck will no longer idle and just drops RPMs and dies. It will run by applying a little gas but just suddenly drops off. I didn't do anything "extensive" but here are some before and after pics. Auto store said it would be $200 or so a Motocraft one!
Update: I gave it a good run around the neighborhood up to about 75 @ 4000 rpm and it's idling around 600 or so, but that's after a good warm up. I will let it sit and then check later.
Look at the valve in side and plug in the 2 wire connector, it should have 12volt with key on
Valve should open, only moves 3/8", so not much
Then unplug connector and it should close
Repeat until you decide is working or not working
Unplug connector and try to move valve manually, to make sure its not stuck, then plug it back in to see if it will now move on its own
If you have a volt meter you can test the 2 wire connector, red wire is 12v other color wire is the ground from computer
Should be 11-12v key on
If you have an OHM meter, test IAC terminals, should be low ohms 7-13, if not reverse probes on terminals, there is often a diode inside
Also test OHMs to metal case from each terminal, should be NC(no connection)
Check if parts store has Hitachi brand IAC Valve
Or check wrecking yards, there are not many models of IAC Valves, so many Ford engines used the same model as found on Rangers
I had to run some errands and needed the bed so went for a little drive. It's obvious it's struggling at idle as both the AC "coolness" drops and the volts drop when idle. According to my sensor it's running around 5-600 rpm and it's struggling. When I throttle from 20% (base) to 22% it clears up like a normal idle 6-700 rpm with volts and AC returning to normal. My assumption is that the lower RPM's are not enough to power the alternator and compressor. I noticed another red flag on the drive . The MAF sensor either reads nothing at all or 2.9 - 3.0 at idle. Under load it reads up to the 40-70's but nothing at idle half the time seems bad to me. I may try to give it another good clean. Engine seems to run well under acceleration once I replaced the filter and and cleared out all the debris the rodent left.
I do not have time today but I will take the IAC back off and test it under power to see if it opens as you suggested. I will follow up for sure and thanks for all the help so far!
I let the truck sit for a few days and now it will not start. I let the wife turn the power on and off with the IAC removed but still connected and saw no valve opening. I disconnected the air filter and tried to start it with both the IAC on and off. I'm not sure it will start with the IAC off and disconnected. Any suggestions?
Last edited by Dave-X; Jul 15, 2020 at 05:37 PM.
Reason: Spelling
IAC Valve on or off can't cause a No Start
No spark or no fuel causes a no start
Fuel is the easiest to replace, spray fuel into the engine and try to start it, 50/50 test
If it starts and then dies spark is OK, but engine is not getting fuel from injectors
If it doesn't start then no spark
50/50 instant results
Wanted to give an update. I tested the volts of the IAC connector and saw the 12v as expected. When testing the resistance of the IAC itself I could not get a reading. I connected it again, made sure it had a good connection and let the wife hit the power switch. It looks like it opened just a little, and tries to close a little when turned back off. I wouldn't say its working properly.
I got the it started with the filter and IAC off using some starter fluid. It didn't want to run so I let it die and reconnected the IAC. It started up on it's own and ran much smoother, but again will not idle and dies now. Its start and running on its own right now but can't speak for that tomorrow.
At this point, it almost certain the IAC is faulty. Do you think there is anything else I should confirm before ordering one and does anyone have a good recommendation on where to find a good one, not a cheaply made one?
Found a motorcraft and ordered it but will be a few weeks I think before it arrives. I will update and we can move onto the next step. Thanks for your help so far.
The part came in far faster than I expected so I put it on during lunch and that seems to have fixed the problem. I haven't started the truck since Friday and it started right up without hesitation, it idled around 1100 for awhile until I took it around the block a few times. Once I came back it settled down in the 750-850 range without AC. Not much change turning on the AC. This is with the air filter off and the MAF disconnected. I will connect it all later this evening and give it another run around the block to see how it does. It's obvious there is some maintenance that can be done around the engine. Should I check anything else?
Also, as I mentioned, I have a coolant leak some where so I bought one of those dye kits with the glasses and the UV light. Any tips on using a kit like that?
One last question, would it be safe to spray the engine down with degreaser and give it a good rinse with the hose? I have tiny oil leak but I think it's coming from the oil-pan and not the head gasket. I don't want to ruin anything by getting water into it. I would obviously focus on the engine / block itself and cover anything that looked important.
You just put the dye in a cold engine's cooling system(rad cap opening) and let it spread out thru the cooling system over a few days of driving, then have a look for the trail
You can de-grease and rinse off the engine, do it when engine is cold, if you spray cold water on a warm engine metal will shrink rapidly and can crack, unlikely but..............
You can rinse it off with warm/hot water which helps remove the grease/oil
Not likely to get water in anything important, avoid getting water in fuse box, air filter housing and air tube of course
You can disconnect battery first, just in case you cause a short
Alright, time for some bad news I think. Truck is starting and running good now that I replaced the the IAC. I added some dye, drove around a bit, let it sit for a few hours and before dusk here I took a look around. I couldn't find anything from the top of the engine, looking down the sides or anywhere else. So I decided to crawl under it and saw what looked like oil / coolant mixed running out around one of the oil pan bolts or sides. The coolant is vanishing quite fast and you can really smell it too when it start up because it smells quite sweet, everyone notices.
Doing extensive labor such as replacing a head gasket is beyound me and the cost investment is not worth it. Is there a recommended course of action? Other things I should check? Is this more a sign of drive it as long as I can.
