Yesterday, I drove my car home from work like any other day. I did notice it was running a little hot (just above the mid-line), but it was 95+ out, so I didn't think much of it. about 2 blocks from home the engine started sputtering and surging and the car would barely move unless I revved the engine.

I got the car home by coasting in neutral. Pulled into the garage and let it cool for about 2 hours. Came back out, checked fluids and looked for leaks, etc. Started the car, same problem. Rough and surging idle. There was no SES ligt on, so it was a little confusing. At this point I got out the laptop and attempted to run Freescan on it. I could not connect to the PCM. I tried reattaching the cable and still nothing. I also tried PCMRead just to make sure. I pulled the PCM fuse, but that did not help.

Basically, I cannot even connect to the PCM to see if anything is wrong. Just wondering if you guys think it's a bad PCM somehow and if there's a better way of resetting it. I've always just pulled the fuse when programming, but do I need to disconnect the battery to be sure? I will be trying that regardless when I get home today, but I'm looking for input.

Thanks.

 

Probably a coincidence. Do you have cats on the car? How old is your opti?

 

I am having trouble scanning my car right now too, but its because it keeps blowing the 10 amp PCM IGN fuse... your fuse was ok right?

 

Same problem after disconnecting the battery. It started up normal enough this morning, but after about a block, resumed the sputtering/surging. No, the cat is no longer on the car. Running a MAC off-road pipe. Never had any issues. The Opti is about 2 years old. And yes, I do suspect the Opti (don't we all), but it seems to be more of a fuel issue to me. Though I really don't have any kind of basis for that.

Unfortunately, I don't have the equipment at my place to do any real testing. All of my upgrades are done in my dad's garage where all the real tools are . Unfortunately, that garage is about 35-40min. away and the car barely makes it 2 blocks. It's in the dealership right now, so we'll see what they say. Depending on what they say and their willingness to even touch the car, I may just get it fixed there.

I was at a loss since I could not pull a code from it, so I thought I'd let them take a crack at it.

And yes, to be thorough, I pulled both PCM fuses.

 

Well, the dealer could not read the PCM either. So that pretty much seals it. I'll be looking for another PCM. Still not sure how that would just go bad, yet allow the car to start and run.

I welcome any other suggestions.

 

Have you run through all the engine bay wiring? Cleaned the grounds? Any strange instrument readings? Checked for arcing on the ignition at night? Hooked up a fuel pressure gauge for testing? I'm not a big fan of buying parts to just throw at the car.... do some more testing.

Jonota

 

I'm sure if I connected that PCM to my harness, it would communicate just fine. Check wiring/grounds.

 

As always, know that the ALDL port is powered on the same circuit as the cigarette lighter. Check that circuit and the fuse in the side panel if you are not getting any response with a scan tool.

 

Apparently, leaving the battery disconnected for an extended period of time was the fix for the PCM. I can now read and write to the PCM again. The problem has been diagnosed as a dead Opti (big surprise, eh?)... Yes, the Opti that has less than 20k miles on it and is 2 years old as of last week. This will be Opti #4 for the car.

Thanks for all the suggestions guys. I'm wishing it was the PCM now, much easier and cheaper to fix.

 

Four opti-spark distributors would make me want to find out what is killing them because it would seem it's just a matter of time again. When you take these apart do you see an unusual amount of corrosion? If not, I would be looking upstream for a component that is spiking current to the low side.

Do you happen to have an aftermarket spark enhancing ignition box?

 

I had same exact problem heres what it is on the passenger side by by firewall the wires to pcm are touching the headers they are burnt spent 180 dollars rewiring at dealership the wires and relocating betting money on it.....

 

I'm sure this will be a big help to the OP who solved his problem two posts and 2.5 years before you posted...