I have a 1989 iroc-z with a tpi 305...i bought the car not running with intentions on dropping my built 350 in it...anyway the stock motor was so clean I tried to save it...so i noticed the engine light wouldnt come on when i turned the key forward so i knew it was a computer problem(replaced fuel pump also) I bought a reman NAPA computer(ECM) and the car fired up so I drove it and did a few burnouts...let it sit for a few days...and now the car wont start again and no engine light AGAIN....any ideas? i believe its a ground problem...but what ground? and what would be causing the computers to go bad on a stock car?

 

sounds like a bad prom chip

 

It does sound like a ground issue if the check engine isn't lighting when the key is turned to the accessory position. The ecm grounds the check engine light when the key is turned on . The ground is the ecm's ground on pin d1,d3 and a12. I would think your fuel pump isn't doing the 2 second prime as well. The ecm and sensor grounds are located behind the passenger side cylinder head. You should check for constant 12v at the ecm pin B1 and c16 and with the key on the ecm switched power on pin a6.

 

indications of a bad prom would be a rapidly blinking mil and the engine would run rough in limp home mode.

 

No, there is a much easier way to check for a bad prom first. Turn your key to on position and watch for single fast blink from cel and then it should go solid. That means prom is probably good.

 

:facepalm:

Yes, and if the ECM is functioning, but the PROM is bad the CEL would act EXACTLY as tunedperformanc said it would.

Lack of CEL at all is not an indication of bad PROM, it's an indication of a different problem than a PROM issue, lack of power or ground, or bad hardware.

Honestly, with the amount of time you post in these forums I would have thought that you would have learned a lot more about these systems than your posts lead on.

 

You don't represent a moderator very well. Facepalm? really. If the prom is bad he would most likely have a solid CEL. No blink, and then solid like it should be. The fast blink and then solid light IS how you determine a good prom or not.

 

With a bad prom the CEL could also go solid and stay that way.Also, in some cases the fans would run constantly and the car could ping. It could act like it was stuck in field service mode. Yes, his problem in this case could very well be bad grounds somewhere or a bad connection. Could be the main engine ground too.

 

The facepalm is because of the continued bad information you keep posting.

READ THE FIRST POST There is no CEL being illuminated, none, no solid, no quick flash, nothing, so your post about bad PROM is just so far off the mark.

A bad PROM is so rare, that it is the last thing I look at, unless I get the CEL indication of a bad, or mis-seated PROM.

In this case the first things to check are the connects to and even at the ECM, along with related connectors and connects elsewhere. A good use of a DMM will have this problem licked in no time, without looking at things that are not the issue.

 

It is part of the process of ruling things out. No one asked for YOUR opinion. You are new to this post. So if you can't post politely then YOU should not be a moderator on here. Our site doesn't need people like you on here.

 

READ THIS: We are all trying to help each other on here, not create negative feelings or start arguments.

 

*sigh*

All you do is post incorrect information sending on wild goose chases looking for problems that don't exist.

I do believe information, or "input", that could be construed as an "opinion" was asked for by the OP, as to what his problem may be. Correcting inaccurate information posted by others is part of that.

Just because someone be be within the first few posts does not mean that they are posting correct information.

Please step away from the computer, and I will be able to post less, meaning I won't have to correct what you post so often.

In this case, what you already posted was of ZERO use to the OP, since the CEL was or is not illuminating at all, so your "easier check" is not, and in no way helps the OP.

 

Incorrect information? I know more about thirdgen's than you do. Like I mentioned earlier, you are already about to be reported to the Administrators of the website due to your rude , anally pc comments.

 

Any information I have posted has been correct on this website. In fact, I have had many, many members thank me for my help and thank me for diagnosing their problems over the computer and the phone and knowing what the problem was from the start! Not trying to brag ,but that's just how it is. Sorry, if you feel challenged in any way bud, that is not my intent. You can't always be the one who is right and I apologize if i bruised your ego in any way or challenged your intelligence

 

*sigh*

I'm not the only one that sees your incorrect information.

The sad part is it's drop top roc's thread that you're mucking up with your defending of your incorrect, or misdirecting information.

You can go to JT all you want. Here's his contact info: https://www.thirdgen.org/forums/member.php?u=8676

You can continue to PM me all the threats you want, it's not going to change your habit of posting information that makes people go on wild goose chases looking for problems, or blatantly incorrect information.

You have two members now, tunedperformanc and myself telling you that what you're posting is not helpful and/or incorrect, in this thread alone. There have been many other threads where you've been told you're wrong and you respond in the same manner, with threads and e-**** swinging. I'm not about to stoop to your level of chest beating, all I will do is post the facts about the problem that a solution is being sought for.

I just hope that drop top roc is able to sort out the problem and posts back the results, to help others with a similar issue. The problem being discussed in this thread is an odd one, because it's intermittent, which will also make it harder to find.

Until he posts back with some results there's no reason to continue posting in this thread.

 

So , he told you that he went out on a wild goose chase? Who else went out on "wild goose chase"? I think those are YOUR thoughts , not the person with the car problem. Sure I hope he can figure it out too. Sorry to burst your bubble , but I have been correct in many other posts and have had members tell me how I have been right again with my diagnosis. So, with that being said I will contact the Administrator and you will be banned if you can't communicate effectively with other members. It's that simple.

 

No need to fight about who's correct and who's incorrect. That doesnt help the OP any at all. Just need to learn when to walk away. I'm in agreeance with six shooter. Since the OP replaced the ecm and the engine started and ran, that tells me the prom is just fine. Since it wont start anymore, I would look at the connections at the ecm since this was the only thing he messed with when he replaced the ecm. Probably has a bad pin fit in one of the connectors. Try wiggling the connectors or unplug them and plug them back in at the ecm and try starting again.

 

 

Only thing is a bad prom is also intermittent at times. Also you are correct sometimes the connectors at the ECM connection can come loose and need to be pushed in or wiggled. I have seen that work before. I am not disagreeing with six shooter. I am making him aware of his rude comments.

 

Just because the engine started and ran does not rule anything out. Anything is possible. Remember we are talking about a car here. Any input is helpful and every idea is relevant in that case. For all we know he could have bought another bad ECM, even if he bought it new.anything is possible

 

Any results??? im having similar problems with my camaro