At some point, every '88 Fiero ECM will die. The conformal coating shrinks over time and flexes the board, causing components to come off the board and traces to break. The symptoms are NOT predictable, since it depends on what circuits are first affected. The problems can also be intermittent. If the ECM is questionable or original, I think that's a part worth replacing without any further diagnosis.
Originally posted by phonedawgz: Now just because the sticker on the outside says ALWK that doesn't mean the prom inside is an ALWK. Take the cover off and compare the PROM with the chart from the link above.
We drove an hour away to the only auto parts store in NJ that had the ECM in stock.... but it didn't come with the PROM, you had to use your old one. Since I have no clue what's wrong and the ECM has been messed with, I didn't want to use the old PROM.. or anything original at this point so no deal. I went to the local parts store and ordered one that should come with the PROM, be here Tuesday. And just for the hell of it at this point, the PROM reads; JL27C128A/26500 4 SINGAPORE 46
[This message has been edited by DLCLK87GT (edited 04-20-2014).]
27C128 refers to the chip that the program would be loaded on to.
The 3 or 4 letter code refers to the program that GM would load onto the 27C128 chip
So your PROM is only labeled as to the chip but not with the sticker on top of it that designates what program is loaded onto it, it seems.
Generic 27C128 PROM
PROM with label
Most (almost all) replacement ECMs do not come with a PROM. If they didn't ask for your specific make model year engine and transmission then it would not be possible for them to ship you an ECM with the correct PROM in it.
I can burn you a PROM for your ECM if needed.
[This message has been edited by phonedawgz (edited 04-20-2014).]
At some point, every '88 Fiero ECM will die. The conformal coating shrinks over time and flexes the board, causing components to come off the board and traces to break. The symptoms are NOT predictable, since it depends on what circuits are first affected. The problems can also be intermittent. If the ECM is questionable or original, I think that's a part worth replacing without any further diagnosis.
Originally posted by phonedawgz: ALWK refers to the PROM that was originally in the ECM. The ALWK prom wasn't used in a Fiero. Now just because the sticker on the outside says ALWK that doesn't mean the prom inside is an ALWK. Take the cover off and compare the PROM with the chart from the link above.
So with ALWK on it this is the wrong PROM??
quote
Originally posted by phonedawgz: I can burn you a PROM for your ECM if needed.
I might need you to. How much and how long would it take? It's an 88, 2.5 Auto with AC if it matters. There's a local yard that had an 88 but can't remember if it was an auto or 5spd. Maybe I'll go check it out but a new one would be better.
[This message has been edited by DLCLK87GT (edited 04-21-2014).]
BINGO!!! Thanks to everyone for there help and especially phonedawgz for my new PROM; I put in the new ECC/ECM that I ordered from AutoZone with my new prom and it started and ran!!! Granted it's still not right as it wont run without me pushing down on the gas pedal keeping the RPM above 700ish, and it's got a slight skip/pop to it but I suspect that's a sensor or vacuum leak, possibly the IAC needs to be reset again now it's got the right computer/PROM telling it what to do but it's definitely out of the ICU ward and into recovery. Hopefully this weekend I can pull and reset the IAC, quadruple check the vacuum lines and get her running 100%. it was awesome to hear it run without the horrible skip/backfire up the TB and to finally know that the major issue was a bad ECC/PROM and not a timing gear or fubar motor. Thanks again everyone! PAGE LIVES!!!! My wife named it Page
[This message has been edited by DLCLK87GT (edited 04-23-2014).]
A vacuum leak won't cause a speed density (MAP sensor) ECM to go lean . Check your fuel pressure. Suspect fuel delivery even more if it seems to lean out more when the power demands are higher.
Unscrew the IAC. Clean out the IAC hole and make sure nothing is keeping the IAC from moving the pintle. Retract the spring and see if you can easily screw the pintle in. If so screw it in a bit but not enough to bottom it out. Reinstall and see if the ECM can then control the idle.
[This message has been edited by phonedawgz (edited 04-23-2014).]
A vacuum leak won't cause a speed density (MAP sensor) ECM to go lean . Check your fuel pressure. Suspect fuel delivery even more if it seems to lean out more when the power demands are higher.
Unscrew the IAC. Clean out the IAC hole and make sure nothing is keeping the IAC from moving the pintle. Retract the spring and see if you can easily screw the pintle in. If so screw it in a bit but not enough to bottom it out. Reinstall and see if the ECM can then control the idle.
Will do. Need to get a new tubing bender to install the fuel pressure gauge adapter and am also going to replace the CTS, MAP and MAT sensors as they are the only things that aren’t new…..I figure what the hell at this point. Will also pull the IAC and screw the pintle back in. I did this when I rebuilt the TB but when I tried to reset it using the ALDL it didn’t work like it was supposed to. I think the fan turned on instead.
And it reads 10psi when i turn the key on, crank the car it stays at 10, open the bleeder and it drops to 0 while cranking, still no start. One thing that had me thinking last night, if i turn the key on the pump comes on, gauge goes to 10psi, pump stops. If i open the bleeder on the gauge fuel comes out and the pressure drops to 0, but the pump does not cycle back on. With the loss of the fuel/pressure shouldn't the pump try and compensate?
[This message has been edited by DLCLK87GT (edited 05-14-2014).]
And it reads 10psi when i turn the key on, crank the car it stays at 10, open the bleeder and it drops to 0 while cranking, still no start. One thing that had me thinking last night, if i turn the key on the pump comes on, gauge goes to 10psi, pump stops. If i open the bleeder on the gauge fuel comes out and the pressure drops to 0, but the pump does not cycle back on. With the loss of the fuel/pressure shouldn't the pump try and compensate?
Not on most cars as far as I know, I drained a 2003 Grand Prix once at the fuel filter, I had to keep turning the key off and on to use the pump to drain it. In My Formula I had to jumper some connectors to get the pump to keep running to drain the tank via the pump.
[This message has been edited by 2.5 (edited 05-14-2014).]
Originally posted by 2.5: Not on most cars as far as I know,
OK so then if 10psi is good then it's not the fuel pump. The only thing that i can think of that i haven't replaced is the injector, but i don't think that's it. The spray looks good to me but it's possible the PO put the wrong one in. He did put the wrong ECM in.
Do you get a good volume of fuel from the fuel line?
I had a similar issue and my injector in the TB was bad (88 2.5). It wouldn't function, but it looked ok visually (it didn't leak and was putting out some fuel).
Initially I thought it was dumping in too much fuel but after I put in the correct ECM it’s now spraying what I’d expect. But visually it’s hard to say if it’s too much or not enough unless I have another one to compare it to. I guess I can get a new one and see if it helps. What’s another $50 at this point.
I went to the local u-pull it and no injector but still think it's something else. Tonight I pulled the metal fuel lines to make sure they were clear and they are. I blew into the return and heard bubbles in the tank. When I tried to start it tonight the oil gauge that's been pegged since I got it ( actually it's never moved, I thought the needle fell off) flicked down to zero and then pegged again when I cranked it. Bad sending unit or relay? Would this cause the no start/run issue?
for my new PROM; I put in the new ECC/ECM that I ordered from AutoZone with my new prom and it started and ran!!! Granted it's still not right as it wont run without me pushing down on the gas pedal keeping the RPM above 700ish, and it's got a slight skip/pop to it but I suspect that's a sensor or vacuum leak, possibly the IAC needs to be reset again now it's got the right computer/PROM telling it what to do but it's definitely out of the ICU ward and into recovery. Hopefully this weekend I can pull and reset the IAC, quadruple check the vacuum lines and get her running 100%. it was awesome to hear it run without the horrible skip/backfire up the TB and to finally know that the major issue was a bad ECC/PROM and not a timing gear or fubar motor. Thanks again everyone! PAGE LIVES!!!! My wife named it Page 
