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WIERD ISSUES.......

2K views 15 replies 6 participants last post by  fbilly420 
#1 ·
So I am helping a buddy work on his truck and it is doing some really weird stuff. He has a 2000 super cab 4X4 auto with 157k miles only thing done is a 4" exhaust.
Complains- lack of power and hard to start.
I get to his house and we replace all 8 glow plugs and relay and both batteries. Checked for boost leaks (NONE) only 15-17 psi
Let it sit for 2 days in the cold. Cycle the key wait for the wts light and crank, it romps and dies and does that about 5-6 times. Finally stays running romps for 30 sec to a min.
I plug my scanner in to see what is going on. After the idle smoothes out the scanner shows the RPMs are spiking from about 1k (high idle) to over 10k RPMs. The coolant temp sensor is setting at -40* and spikes to about 236*
Baro reading 12.6 psi and drops to 0. ICP about 800psi and spikes to over 2400 psi.
Only codes are P0541 and P1247

All while idleing nice and smooth no noticable change in idle at all.

:confused:I am at a loss
 
#2 ·
When I read the idle spiking I thought about CPS dying, but after reading everything, it almost sounds like there's something wrong with the PCM. Is there any way you can swap them out to see if that helps?

I'm guessing the AIH has been deleted, since that's what the first code is...

The second one is a turbo low boost code. Well, you already know that it looks like.

I say try a different PCM if you can get your hands on one.
 
#3 ·
well, the -40 coolant temp is default for open circuit for the sensor.

Not sure why it would spike though...

Coolant temp data is not really considered to be a valid parameter through the OBDII on these trucks. That should not effect it much. Oil temp is more important. Any readings for that?

Check your MAP lines before replacing the sensor. They tend to leak and rot over time.

Just curious, when was the last oil change?

As far as the RPM spikes, cant really give you much there, except a bad CPS or PCM.
 
#4 ·
I was thinkng PCM. He has not taken it in for the cps recall and i told him not to. I will try to swap my PCM in and see if that helps.
 
#5 ·
Oil temp had a steady rise as it was running and no spike on that reading. I think it was like 140* when we shut it down.
 
#6 ·
also, Check your MAP lines before replacing the sensor. They tend to leak and rot over time.
The truck has no power because of the MAP readings the PCM is receiving.

Just curious, when was the last oil change?

As far as the RPM spikes, cant really give you much there, except a bad CPS or PCM.

For the hell of it, swap PCMs and see if it makes a difference.
 
#9 ·
OK we swapped the PCM's and no change. Checked wiring and line to map sensor all was ok. Anyone got any other ideas? I am at a loss.
 
#10 ·
when you put the valve covers back on did you tighten the engine harness connecter completely? the one over the drivers side valve cover.. sounds to me like everything is connected the looses connection etc.etc. may also have a 5 volt refrence sensor shorting out. if thats the case try unplugging them one at a time until everthing goes normal.. may not be the issue but just something else to check.


btw i've probably done 75 to 100 cmp recalls with no problems yet ( knock on wood) may as well get it done (to keep ford from continually sending the recall notices) just ask for the old sensor back just to cya in case there is a problem
 
#11 ·
I will have to check that harness connector one more time and will try to unplug one sensor at a time. I am will to give anything a try now.

Thanks for the input.

I will tell him to go do the recall and get the old sensor back.
 
#13 ·
checked the plug on Drivers side valve cover again and it is clean and tight. Didnt have enough time to start unplugging one sensor at a time. Anyone else got any suggestions?
 
#15 ·
Would something with the IPR cause romping and then stalling or is the IPR usually just responsible for hard hot starting?
 
#16 ·
UPDATE

Well figured it out finally. The Alternator had a bad rectifier and he had an auxiliary idle control that was no good. Replaced alternator and took out the idle control and all is well. She runs like a champ and fires right up with no romping.
Thanks for the help guys.
 
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