2004 SLE just turns off at random

[sdxp787]

I have read through many of the topics similar to this one. My 2004 Bonneville , 95k miles, will just shut off.. I still have electrical power. I mean, this happens at 70 mph. It just turns off. The tack still reads around 200-300 rpm, but the motor is definitely dead. I just have to stop and restart it. Sometimes it is hard to start, other times, not so hard. It happened 3 times in a 30 minute period. No misfires, just dies. It has to be electrical, but what? I suspect power to the ICM is getting interrupted, but where do I start in determining which wires are power supply wires? Anyone have a wiring schematic of the ignition system?

As always, thanks in advance for your help.

[AJT2004]

First try disconnecting the MAF sensor and see if that helps.

[sdxp787]

First try disconnecting the MAF sensor and see if that helps.

How will the car run with this disconnected? Can I run it at highway speeds?

[nos4blood70]

Try the MAF, but wonky tach readings and shutting off with difficult restarts usually point to the crank position sensor.

[sdxp787]

Some new info. I thought the car was dying ,but it is actually dieseling. Then it dies
Hard to restart. Has new maf sensor. Fuel pressure seems low. About 37 psi with key on and about 42 running
FPR is not leaking back through vacuum tube
Suggestion s

[redfury]

Replace the fuel filter first, see if you can get some pressure back. However, I doubt fuel pressure is the problem. Your symptoms indicate something that is changing the moment you have the problem. Low fuel pressure would be a problem throughout the operation of the vehicle and wouldn't be a random problem unless the fuel pump itself was cutting out. On a restart, how does the tach act...does it show rpms indicative of cranking or is it jumpy. Have you tried to pull any codes yet....the CEL won't illuminate unless it's a problem with something that will affect emissions normally. You might have a pending code that can illuminate the conditions that cause this to happen.

[sdxp787]

The tachometer indicates the speed at which the motor is cranking over. I have a code reader but there are no codes

[AJT2004]

Why do think the engine is dieseling (which is not a common problem with fuel injection engines)? How's your UIM and are you noticing a slight loss of coolant?

[sdxp787]

Replaced the LIM few months ago. Riesling is my best description of what is happening. It diesels until I shut the key off. It will do this at 70mph or 10mph. I have found that it does it more common it when I start to accelerate after slowing down. I can also make it diesel sitting still. I just habe to rev it a few times, nothing outrageous, just.rev it to 2000 and it will act up.

[AJT2004]

Did this problem start after you replaced the LIM? Hopefully you replaced the UIM at the same time. Although you said the MAF is new, trying running with it disconnected.

[sdxp787]

Yes, upper and lower were replaced. Happened about 2 months after
I have disconnected maf and it still happens

[96 SSEi]

I would check the battery cables just for fun.

your scan tool, does it pull live data?

you can drive and see if you can recreate the issue while documenting fuel trims, ect, map,tp and maf readings. see if you find something funky

as stated above, fuel filter and pump can be inspected - it may cause your issue and not set a dtc.

[sdxp787]

Car runs great when cold, no issues
Takes about 30 minutes to act up
It's a cheap scam tool. No live data. Battery cables are tihht and clean. What should the fuel.pressure be? $

[AJT2004]

Heat can cause intermittent electrical problems including the ICM. Also, how are the ignition wires?

[sdxp787]

Wires and plugs, look newer. To get it to restart, I have to cycle the key a few times, I assume this helps to increase fuel pressure. Is gonna replace the duel.filter today and look into the fuel pump. Still would like to know fuel.pressure spec
I will try to video the "dieseling"

[sdxp787]

So the plate that the ignition control module sits on was corroded. So I cleaned up that plate and then used some Dielectric grease on it. Is that the right thing to do? I am going to go test drive it for a little bit and see if it leaves me stranded

[96 SSEi]

that plate is the ICM that feeds the coils - yes, grease is good - go for your test ride and maybe get a buddy to follow - just in case

[sdxp787]

It didn't help...

[AJT2004]

the ICM maybe bad. It would be great if you could swap in a good one to see if that helps. Alternatively, IM harofreak00 or go to his website (http://www.bonnevillesunlimited.com/) if he has one available.

[dougtoth]

I had a similar problem with my 2001SLE.
We tried everything from fuel pump to MAF and could not get it right.
The car would run great when it was cold and die when it got up to operating temperature.(but not all the time)
When the car cooled down it would start up and run great till it got hot again.(again not all the time)
It was really frustrating because you could not trust the car and to make matters worse it was the car my wife drove.
This situation went on for about 4-8 months.
Most of the time it was great and then all of a sudden it would stall.(she almost had an accident because of this)
I figured that it was not the ICM as it was replaced with a new unit.(Standard brand)
I even replaced that unit with another new one.(Delphi brand)
After reading various comments on this website I went with an OEM unit from Andrew of Bonnevilles Unlimited.
As it turned out I was getting defective brand new ICM'S.
It has been 2 years now with no problems.(knock on wood)
I have since found out that most electrical parts for the Bonneville that you buy are garbage from China.
I do not know if this is your problem but it might be something to check out.