crazyd

Posting to this forum as this is an engine you guys know much better than the Fiero guys would, it's a speed-density 350 TPI running a '92 8262 ECM. I built it 20 years ago and it's been sitting for about the last 10 years, and I've been trying to get it running properly again. It's not reporting any codes at the ECM, just flashing 12's. I know that generally points to an ignition problem. It starts up immediately, but has a rough idle and is sluggish to rev. It's drivable but is cantankerous at best, with backfires. I've recently put new cats in it and it just has bullet mufflers that shouldn't clog.

First step - Replaced all injectors
Second step - drained fuel tank and refreshed with 5 gallons of premium
Third step - replaced distributor cap
Fourth step - new plug wires
Fifth step - look for vacuum leaks with propane torch. Replaced a few aged hoses around the cruise control, but no apparent leaks.

Have a replacement rotor for the distributor, but the original wasn't coming off and I didn't want to make it worse trying to force it, so I cleaned it up with some emery cloth and stuck with it for now.

I remember checking the plugs a few years ago and they were OK. NGK R's.

None of these fixes made any difference and the issue persists. I recorded a short video so you guys can see & hear what it's doing.


I didn't consider the ICM as a high probability because it wouldn't run at all if it had a problem.

Suggestions for next steps welcome.

crazyd

Additional info I forgot to mention on the fuel side, there is a new fuel filter, and there is a pressure gage on the fuel rail that shows the pump primes to about 42psi with the regulator vac line on, goes to about 48psi with it off (running), so I think that's good fuel pressure & regulator. I have a Snap-On scan tool that I can use to do live readings, but I don't know if I can do logs at this point due to cabling/connector issues.

???

iTrader: (5)

does that intake have a egr valve? I had one stick open forever ago and it ran rough.


what intake is that? it seems to idle OK, does it just not Rev? can you watch the fuel pressure while revving it?

byond that, maybe check the timing bypass isn't unplugged? what computer is in and how's it tuned.

crazyd

No EGR. S&P Ram-Port intake. Not idling OK at all, jumping back & forth between 800-900rpm. Timing bypass is not enabled. 8262 ECM custom-tuned in 2004.

???

iTrader: (5)

I had to Google that ecm number. seems it's a newer Rev of what is normally a 7730 ecm. so should be a standard $8D map tune in it.

is the check engine light wired up correctly? I'm asking cause I'm guessing it's not a stock harness in there. if so, there's a way to check that the ecm is in "limp" home mode. it's been forever and my memory is bad. so you may want to search it. but if you click the key to on but don't start it, the fans kick on high and the check engine light doesn't so something, I don't remember what. maybe go out after it's check? the ecm isn't reading the tune off the chip and it is running off a very base map. but mine would actually idle and stay running even with bigger injectors.
​​​​​​I believe in this mode a scanner also can't connect to see live data either. which I should ask, do you have a scanner. if it's not in limp, data might help to know why it's running badly.

you may want to start a thread over in the DFI/ECM sub forum. might get more eyes on your post over there.

crazyd

Correct, 8262 is newer 7730 with $8D map. Check engine light is wired up correctly and is indicating properly. Painless wiring harness FYI. ECM is not in limp-home mode. I have a Snap-on MT2500 scanner.

crazyd

New video from scanner. Looks like it doesn't want to go into closed loop for some reason.