ok I just about give up

[megadeth]

I have checked the wires at the icm there clean and had icm tested all was good starting to lean towards o2 or pcm just hate to throw more money at it if it doesnt fix prob.

 

[Naasau]

I may have missed it in your list, but did you check to make sure that your Crankshaft Position Sensor was still working?

 

[megadeth]

Replaced crankshaft sensor not long ago .

 

[megadeth]

Just noticed tonight that at idle my voltage jumps around till I hit the gas wonder if bad alternator could cause rough idle..

 

[Birdy]

Not likely. The idle is probably causing the voltage to jump around.

 

[megadeth]

Didnt think about that guess it would

 

[Naasau]

Someone mentioned something about a dealer PCM update, can you get your PCM dealer tested/reflashed?

 

[megadeth]

Local deall said cant flash a 91 . Found some bad spots on batt cables replacing them today see what happens

 

[Naasau]

SitRep?

Also, have you pulled and checked the ground wires that lead off of the PCM and the ground off of the ICM? I know it's a long shot, but without any codes... it could be anything. Since it is running rough (consistently?), it might be a calibration error of some variety. I would go with replacing the O2 sensors just because.

Also, have you checked continuity from the pins on the MAF plug to the PCM, or where ever those wires go first? It could be that you're getting a bad signal from a good sensor, and that is throwing your comp out of whack.

 

[Derek Greenwood]

Make sure the vac line to the air filter box go to the correct side.

 

[Nedwreck]

Did we have a thread on this recently? This truck is 5-spd? The idle is low as well as rough?
(just trying remember is all)

My father had a Escort that did this sort of thing.. I think he ended up bumping the idle speed up with the throttle body adjustment. That's not the way things are "supposed" to work, and I consider it a band-aid - but it worked...

At this point, I'm betting you've inspected the connectors on the idle air controller and stuff, yes?

Replaced your PCV lately?

I agree with the post that said to pull off vac. lines on the manifold stub one at a time and plug the port on the manifold, to ensure no leaks on a vacuum line or device.
(I've seen power brake boosters leak on occasion, it's worth trying?)

Does your A/C work? the problem go away with it on? (higher idle)
(on my truck, the idle is higher with the AC switch on - whether the AC compressor actually starts or not)

I curious what it's gotta take too....

 

[megadeth]

Ok replaced ecu and idle the same . So with everything being new now .what can it be. No vac leak gauge shows steady 20 psi at idle. I dont even know what to look at now. Its all new. Anyone had same issue and find solution? Thanks

 

[Naasau]

Well, yes and no; I'm bugged by the fact that you have rough idle issues and have replaced so many parts but there is no computer codes thrown. It almost sounds like your timing advance (controlled by the Engine Diagnostic Monitoring Signal) is stuck in a test mode.

There is a small grey box attached to one of the wires leading out from the ICM. From what I gather, this SPOUT jumper allows for disabling the computer control advance logic so that the Crank Position Center can be set (Just like removing the vacuum advance on a carburated engine). On the other side of the coin, having the SPOUT signal not working means that at idle the engine will run relatively OK but as it speeds up, the spark arrives too late and the power suffers (if it doesn't quit all together). I would check and see if there is continuity across this little plug critter, and go ahead and pull it out while the engine is running and see if anything changes.

Also, I posted a link to some pertinent sections of the Factory Service Manual on this thread, and it tells the story of my quest to solve my slightly different engine woes. http://www.rmftc.com/forums/showthread.php?t=7287

I'm sure that we can find and kill this issue, eventually. Good hunting.

 

[Dre]

have you replaced CPS (camshaft position sensor)? did you check the synchronizer at that time? synchronizer is what runs off the camshaft and sends signal to the sensor - gear on the synchronizer might be worn down.

 

[megadeth]

I will check wires spout conectors were good . How were u able to find elec shirt just wiggle wires around. I am hunting for bad wire now.
Dre my year has no camshaft sensor just crankshsft and its new to. I could almost call this a 2011 model with all the new parts lol

 

[Dre]

now I see what you drive... sorry - just trying to help.

With all the new parts I'm pretty sure you don't even know where to go now to solve this issue but you need to keep trying - fix might be very simple.

good luck!

 

[megadeth]

Wiggeled every wire no changes at all no bad looking wires . Scanned again no codes . I am ready to lose my mind what little I have left...lol I replaced o2 twice in last 2 years could I have got two bad o2 sensors? I have not replaced the icm yet but had it tested at advanced and it was good.so now what.

 

[shawn294]

seafoam it!!!

 

[Dre]

IMO it's gremlins

I don' think O2 sensors are bad... it's either fuel delivery or bad spark.

injectors?

 

[Elgatoprerunner]

Did you replace the idle control motor?
How long have you had the rough idle?
Are you sure the firing order is correct?