Intermittent stalling, hitting dead-end

[lechnoid]

Ok, my actual SVX has been having intermittent stalling issues for a couple months now. It seems to happen more when ambient temps are higher, but engine temp seems to matter very little. When it happens, sometimes the MIL will flicker on then off, other times it lies dormant.

Without the light being on, I wasn't able to pull any active codes. Took it to the dealer to scan code history and they came up with ECT and MAF codes. I tested both and they are working correctly.

In diagnosing this, I had set up a fuel pressure gauge and a noid light in a way that I could drive and observe both under the stalling condition. Fuel pressure is constantly good, so that ruled out a pump or filter issue. When the car stalls or attempts to stall, I lose the injector pulse completely. This led me to believe that the ECU stopped commanding the injectors on. In many cars, this would point me to either the cam or crank sensor, or both. I have since replaced both crank sensors and the cam sensor with used, known-working ones. My stalling is still occurring.

I have yet to test (likely just replace) the ignition switch. I doubt that's the problem, but it's worth a shot at this point. With 144k on it and not knowing the size of the previous owners' key chains, it probably wouldn't hurt.

Do you guys know of any common wiring issues that could cause this? It's just starting to feel more and more like an electrical issue to me and absolutely HATE testing practically every wire going into the ECU.

[TomsSVX]

It really sounds like a MAF problem. Have you tried replacing it or testing it??

Tom

[lechnoid]

I tested the MAF according to the diagnostic info in AllData and it came up good. The dealership also tested both sensors when I took it in to have the code history pulled and they said both were good as well.

I'd love to try replacing it, but can't seem to locate one within 100 miles of me without buying new from the dealer.

[TomsSVX]

How were you testing it when the problem existed... See, the ECU supplies fuel based upon how much the MAF is reading. So if the MAF signal goes to ****, so does the fuel


Tom

[lechnoid]

Yesterday the check engine light finally came on and stayed on. ECT and MAF codes again. I'm going to spend the $30 and just replace the ECT even though it's still testing out good. The MAF is another story. After an extended time with an oscilloscope hooked up to it, I found that it occasionally drops signal. So it appears that I'm on the path of replacing the MAF. My question now is do I spend the $225 on a new replacement, or do I change over to the Z32 setup now that I'm switching? I'm in the process of searching for info on what all that would need, but am coming up dry so far. What do you guys think?

[TomsSVX]

you can find a used stock MAF for cheap... No reason to spend close to $100 on a used Z32 MAF. Then another couple hundred on ECUtune's software

Tom

[lechnoid]

Off to the parts wanted section....