I agree with corey, it would be a shame to fry the new PCM too. Where there's a burning smell, there's usually smoke. In my personal experience, those PCMs stand up well to a lot shorted wires and voltage going to random pins, but you never know.

That bundle of burnt wires by the PCM concerns me. I would track down a pinout of the connectors going to the PCM and whichever of the 3 connectors has the burnt wires see what all connects to it for a general idea of where to start looking.

But before you put more money into parts, I'd make sure all the wiring is good, because shorts in them going to sensors will most likely throw a code saying to replace that sensor when it is probably working fine.

 

2002 4.7 4wd. Hey guys I started a thread the other day on this problem, but now things are ge
tting really complicated.

My engine will stumble and die. The injectors would still pulse after shut down until I turn the key off. At the same time the tach will jump sporadically as well. At the shop the reader only showed a crank position sensor problem, so we replaced it to no avail, but the code disappeared. Then a code showed for the speed sensor.

We were convinced it was the ecm, and that was reinforced by the suggestions here as well.

So I got a programmed one sent from American Computer Exchange overnight, vin# and all. We hooked it up and it ran at idle for an hour just fine. I took it home and the stumbling started again, all the same symptoms.

What do I do now? I'm absolutely stumped. Any help, PLEASE.

 

Well I started a new thread on what happened when I got the new pcm because my smart phone browser couldn't get to these additional pages so I'm on a different phone now.

This is the latest. Put on a new pcm and it sat at idle just fine for about an hour. When I took it home she started stumbling and did again- the smells usually happened when the stumbling occured but none now for some reason.

I'm stumped. I haven't been able to find any burnt wiring at all. I hope I haven't toasted this new pcm.

What tells me the old and new pcm are ok (in retrospect) is that when you leave the d alone for a while then restart she runs fine for a while. It seems as though it doesn't run as long each time because the engine warms up (but normal running temp).

When it does run it idles perfectly.

I'm totally stumped guys.

 

Check wiring around the PCM and also check your O2 sensor wiring and ensure they're doing their job.

 

Well I've moved the three connectors quite a bit and sometimes it shuts off, but that could be coincidental. I think that in the morning I'm going to have to get out my meter and test each pin connector for continuity to the wire by poking through the insulation.

How do I test my o2 sensor?

 

Oh, and why would it be shutting down a lot more several hours after the pcm has been in use? Almost as though whatever is wrong is degrading or the problem is worse when the engine is warmer.

 

Could be a number of things, best thing to do is take it one step at a time, ruled out the PCM and crank sensor. Usually some codes will be thrown like misfires or something, unless it's not having enough time to store a code before it stalls. If you don't have a scanner just do the key trick to pull up the codes and see what you get.

Could also be a simple fuel system/pump or ignition problem.

 

Could he heat expansion if more of your wiring is burnt down the line. Just break out the multimeter and check for any pins connected/shorted to ground or each other although some will be, but a wiring diagram/pinout will help.

Basically if you have melted wires in a bundle, it will melt others around it and all sorts of funny things will happen, the possibilities are endless...almost.

Could also be a fuel delivery problem, when it wants to stall, spray some starter fluid in the intake and see if that fixes the problem, then you can narrow it down to a fuel problem or not.

 

I don't think its fuel, unless its electrically faulting the fuel pump. I'm saying this because the tach jumps around badly when the engine starts failing- and its not in relation to rpms at all.

I guess I'm just going to have to start testing and chasing wires.

You know- now that I think of it- and its a long shot, the left brake lights won't work either (new bulbs and clean contacts)

Man this sucks, bad.

 

Battery or IAC.