This is a very long post but i m trying to describe it the best that I can, so sorry for the long post lol

A few days ago i was going to work and its running fine, like normal. I was going up a hill and pass a tractor trailer and I notice I have the gas pedal pushed down, but im slowing down. I look at my tach and it shows that my engine is at idle(?!?) and when I push the gas pedal down it does absolutely nothing. After a few times of pushing it down it would stumble and miss and not rev over 1200ish, the it died completely. This all happened in about 3-4seconds. I pulled over and tried starting it about 5 times and it would just crank, not start. I did notice that When the key was in the ON position (engine not running, about to start it) the SES light did not come on at all. No flash or anything, completely off. I popped the hood and got out, and checked connections first. I completely disconnected and reconnected the ESC, est wire, tps, iacv, and all fuel injectors, then walked over to the passengers door and got inside and pressed on the connectors going to the computer. I got back in and tried starting it- started instantly and ran stronger than ever! It ran exceptionally well, I couldnt believe the difference and I dont know how to explain why it ran so much better. It literally felt like it gained 50hp! I was going to work so i didnt have time to check for codes, but I did later and it gave me only 12 and 51..

It did it again going home, i was at a stop and it almost stalled out,idle dropped and it stumbled real bad, then caught and ran normal again.

It did it a third time leaving work the next day. Started up fine, ran normal, died after about 30seconds while driving. I pull over and waited a second, try starting and starts instantly and runs superb again. I must have beat a personal record on my way home! lol As soon as i shut it off it goes back to normal though.

I think that the whole time i have owned the car (8months) what I have come to learn as "normal" performance from the car is really it NOT running right. I think that for whatever reason it runs better after stalling, THAT is how it actually should be running.

Ive noticed that when its cold/warming up it has a miss/stumble around 2k rpms.

When its running "normal" it usually idles in park at 800ish, and around 600-700ish in gear. When its running "RIGHT" it seems to idle in park at a little over 1000 in park, and close to 800 in gear I think. The difference is like comparing a 305 to a 350, its just so much more powerful right after it stalls out. Its even very noticable in the brakes, normally the brakes stop it pretty good, but when its running very well the brakes still stop it, but its noticably harder to stop. It really WANTS to go when its running real strong.

The idle ALWAYS fluctuates, in gear, in park, cold or warm. Sometimes it fluctuates a little sometimes it fluctuates over 100rpms. It literally sounds like its cammed out, loping so much. Its 99% stock, with a stock cam. I have checked my vacuum and i was pulling 17hg (kg?) I beleive. It was a while ago so i dont remember exactly, but i remember it was almost at the most it could be. Maybe it was 19, I really cant remember. It was fluctuating like this for as long as ive had it.

I have replaced the coil, cap and rotor, ESC. I have ohmed my injectors multiple times and they checked out fine. I checked the TPS and its set as .54V. I have a new MAF, I cleaned it and the IACV. The gas tank, fuel pump, fuel filter, strainer, and sending unit are brand new (installed ~8 months ago). I pulled the computer down and it is the 1227165ecm, and i tried the tapping trick. While I was doing it the ses light came on once, but i did it for a while after and it didnt do it again, so im not sure if that was why or not. I dont know much about the computer or the prom.

The problem is so strange and intermittent that its really got me stumped. Im not sure where to start looking. I dont have money to throw at 1000 different parts, I dont believe in throwing parts at a car aimlessly anyways. I would appreciate any help and suggestions, im tired of it stalling out, and i have alot more fun driving it when it is running right! Thanks

 

i love how no one ever responds to things you label as important but 8000 people will view it lol

 

It sounds to me like you need to get some software that allows you to log the data from each run and see what it is doing.

If you cruise the DIY PROM and ECM type forum threads, you ought to find what is needed. If you can't see what the ECM sees, you can't find the weird problem that you're having. You'll need a windows laptop and a cable that fits your ALDL to USB.

Good luck!

 

Can you swap in a different ECM?

Have you checked the ECM connector?

Possibly a bad injector (put a can of cleaner thru the tank, check injectors with a multi-meter)?

 

RRUHL: This is very true lol

KrisW: I dont have a laptop or the cable to do this, I sure wish I did. Can I use a compaq laptop?? Anything else i can try/check?

peterc005: I dont have another ecm, I did unplug it and the connector looks ok. I plugged it back in and it didnt seem to make any difference. I also ran a whole can of seafoam through the tank and split up another can thru the vac lines and intake. I ohmed all the injectors and they all checked out fine.They are the original multechs though, and the car has 106k

What do you think it could be? My computer is failing? A bad sensor(s)? Failing fuel injectors? Any ideas? Any tests I can do?

 

STOP GUESSING and start testing
if your pulling a code #51

DTC - 51 PROM error

DTC - 51 Incorrect MEM-CAL

verify the prom chips not loose or defective, the symptoms indicate a loose or defective electrical connection, or defective sensor or a bad prom chip, loose battery connection or loose or defective electrical ground, you can track that down thru testing, do you have a factory shop manual, and multi meter?
every sensor has a known resistance or voltage range that can be tested, a code reader helps and theres real time laptop software available that can be used to track down or in better versions print out a record of what each sensor sees in real time.

if you don,t your working at a huge disadvantage
http://www.helminc.com/helm/Result.a...elected_media=

 

Grumpyvette, thanks for the reply.

I have a hynes manual, but not a shop manual like that. I do have a multimeter. I have checked my injectors and tps and they're ok, but i havent tested anything else because im not sure what I should even check. Im very unfamiliar with proms, computers in general. I restored an '81TA but yanked the comp controls out of it because i wasnt a fan of them and they were very primitive, i just ran everything vaccum controlled. I checked my ecm and it is the CORRECT ecm for the car, but im not sure how to "test" it, and i dont even know where the prom is or what it looks like. I know its in the computer but nothing more than that. I sure dont know how to test that either (if you can)

It defintetly has all those symtoms, of course on top of the seemingly constant lack of power I am having.

 

the PROM chip is behind the little access panel on the ECM housing. Two little screws and that panel comes off and you can see the chip inside. You might want to just verify that it didn't get knocked loose.

I get my factory service manuals for my firebirds off of eBay for anywhere from 20 bucks to 50 bucks. Used manuals still work fine.

 

Thanks, ill look into that. Are they any better than a haynes manual?

It did something pretty unusual today, when i went out and started it it didnt want to start up, it took a little more cranking than usual but it did start. It idled HORRIBLY, it was idling in park at about 500. I dont know how it was even still running, it sounded like it was just a sliver away from dying out completely. I put it in gear and it stayed at pretty much the same rpms, and surprisingly stayed running. It ran so bad though, but whats weird is once it passed about 1500rpms it ran like normal. Still felt weak but picked up alot of its power back.

I got to work and didnt have much time to mess with it so i did what i normally do and checked the connections and it didnt make any difference. I went to work and 9hrs later i came back out to leave and start it up, ran horrible still. I shut it off and went and unplugged and replugged every injector, unplugged and replugged the est, pushed the esc together tightly, and did the same with the computer. It was dark, but i reached down where the cts and knock sensor are and wiggled some wires around too. I try starting-starts instantly and back to normal;not running superb again, just normal now.

I dont really think its a bad sensor, but im not ruling it out yet. I think its either the computer/prom or a bad connection somewhere.

Any suggestions?

 

A factory manual is the best, It's made specifically for your car by the guys that built it. As for your problem, It sounds like your touching the problem, but your unplugging and plugging so many things at once, you can't pin point the problem plug. IMO

 

There are two approaches to this type of problem.

1. Get a shop manual (yes a real factory-type shop manual) and begin to go through it step by step. A manual may cost a hundred bucks and contains much more information then a Haynes/Chilton book. It will take you through a lot of electrical/electronic testing and troubleshooting. Not everyone is up to this type of work. It takes a lot of patience, mechanical aptitude and thinking as well as a few special tools. If you are this type of person and WANT to learn a lot of new stuff then this will be your best path in the long run. For those people who aren't capable/willing there is option 2.

2. Take it to a reputable repair shop. If you have a good dealer, that would probably be best.

I am not trying to discourage you. The type of problem you are describing sounds a little out of the reach of someone trying to troubleshoot it for you on a forum. You are going to have to get into it and figure it out. As I believe GrumpyV mentioned code 52 indicate PROM (I'm taking his word for it) but just slapping a new one in there may or may not correct your problem. Although the ECMs on these 3gens are simple compared to some of todays cars they are still very complicated and take years to master. I have been doing it for 7-8 years now and still consider myself a newbie. And the ECM (PROM) end of it is just one part of the total system. For example some of the symptoms you are describing could indicate a clogged cat. ???

Having said all that, if you ARE the type of person who is truly capable of troubleshooting/tuning and WANT to do it you may find a yourself a new hobbie that will keep you intertained for many years to come. Maybe even save a few $$ along the way...

 

Antman makes a good point with the clogged cat. My dodge ram had one and i changed everything checked every part over and over, Untill i unbolted the exhaust and it ran perfect. Try unbolting your exhaust. Just a little bit if its the cat clogged it should clear up immediatly once it can breathe. I also had a ford that had a screen on the cat, so pieces would build up on the screen and block flow, but after a shut down, the pieces would fall down and allow flow again. If its not a clogged cat, and you check all of your sensors check the computer. I have seen those go bad before and be very frustrating to trouble shoot, usually its a 45+ step thing that tests everything and after 45+ tests, your manual will say bad computer. See if you can find one online/junkyard with similar features to your car and swap it out. If its an immediate change you know what it is. If it still the same, swap the orignal computer back in and sell the other one online. Oh and another way to check the cat is to unplug the O2 sensor before the cat.

 

Red Rock: I agree with you 100%, but every single time it happens im in a rush, going to work, meeting someone, it never happens when i can stop and try one thing at a time and check for a difference. This time, it was while i was going to work, and while i was leaving, my girlfriend surprised me by showing up to meet me, so i wasnt going to sit there and make her wait while i play around with my car. I think that your also right about me touching the problem, for a while i was thinking my knock sensor is/was the problem but im not sure if thats it. I think whatever it is its something that seems to be fixed when i go and reconnect everything, its just a matter of finding out exactly what it is.

Antman: I do plan to fix it myself, but if i cant I know people that i can take it to and get it fixed, but theyll charge me. Family friend, so i get a discount, but still get charged lol. Id rather fix it myself though of course.I dont really think its a clogged cat, just from when/how it happens. It can happen at any moment, when the engine is warm or cold, at idle or 5000rpm, any time. Also, your car looks just like mine lol

madmax, ill try the o2 sensor trick anyways just to rule it out. When i messed with the sensors and it started running back to normal i didnt touch the o2 sensor though, and it sat for 9+hrs and when i started it the first time it ran horrible again, then after messing with some sensors and the comp it ran better again. Thats part of the reason i wouldnt think its the cat.

Is there any way to test the ecm or prom to make sure theyre ok?

Also, can i use the realtime software to watch what the computer is seeing on a Compaq laptop? Im not sure if its made by microsoft or not, or if the software will be compatable.

Thanks!

 

:YUP:

You stated it had that problem until you pushed on the computer connectors and it ran fine again... Try taking a little electric grease and putting that on your terminals also. It will ensure you get a better electic connection and help keep water and contaminiation out. It doesn't hurt to put in on every electric connector..

 

Thanks, i will do this. Your screen name is ibmtech, do you know if compaq is made by microsoft? Is the software for the realtime compatable with a compaq laptop? It like a 2010 laptop i believe, its fairly new.

Also, your build looks pretty sick! What numbers are you seeing hp/torque? Have you taken it to the strip?

 

Compaqs were not made by Microsoft but that doesn't matter what matters is what version of windows is that compaq running? the Tunerpro software should run on anything newer than windows95 so if that laptop is from 2010 you should be good to go.

 

the fact that the performance changes radically back to running decent occasionally, virtually eliminates the problem being a clogged cat,as that would remain clogged, a bad or shorted injector might be a factor, but symptoms seen to strongly indicate a loose electrical connection or ground on some component or sensor

 

Ok, thats good to know. I will look into getting tunerpro. Im a little unfamiliar with it, just to clarify, with it you can watch in realtime what the computer sees, but you can also tune the car with it right? (Hence TUNERpro)

Grumpyvette, thats what i was thinking, im going to work on it on a little and ill get back with results

 

I am currently in Afghanistan but I can honestly say..
65 mph on Highway
25 mph in School Zone
Strip (NO CLUE!!)
I am planning on doing that once I get back from this lovely sandbox

 

I didn't meant to suggest your problem is a clogged cat. I was just using that as an example of how certian symptoms can lead you down different paths and it's good to have the experiance and/or tools to properly diagnose the problem. If I came across as smug or anything I appologize.

I think you are taking a lot of the right steps to eliminate something simple (like a poor connection) and that is a smart move. I only intended to prepare you that a problem like you are experiancing can get really involved. Back in the mid-80's when comupter controlled cars started coming into repair shops inexperianced mechanics used to do things like un-plug/plug in components, tap on them with the end of a screwdriver etc just to see if there was a response. If there was the part would get replaced to see if that corrected the problem. Not very scientific to say the least and that method probably replaced a lot of good parts. I just didn't want you to go down that road. Better to put your money where it is well spent like having it diagnosed by a reputable shop once you've done the first level of troubleshooting. I wish you best of luck and if I have anything specific to suggest I will certianly chime back in.

 

Have You check fuel presure pressure?

 

Antman: I dont think it came across as rude in anyways, I didnt take it offensive in any way at least. I completely understand what you mean, and I didnt think you meant it in any offensive way. I appreciate the feedback, and although there was no harm/foul I appreciate you apologizing as well. Definetly no hard feelings at all, I actually feel bad there was apparently a misunderstanding lol

IKIK: I have not, but under the circumstances and considering how new all those parts are I really dont think that is the problem though. I will check it, but I really think it seems to be an electronic problem of some sort.



OK: NOW I have really bad news!!!

The car has completely died on me. Just Sh*tted out completely, literally no response at all.

I was leaving my house to go to my grandparents and it started very weak again, and check engine light did come on and stayed on after about 5 seconds. I did not run the codes, unfortunately. I drove to the grocery store first, was there about 20min and went back out, started again and still ran horribly. SES light still on. I shut it off and left the key in the ON position while I went and checked sensors. I walk to the front of the car and the fans are on (P.O hardwired them on like an idiot) and just as im reaching towards the est wire, the fans shut off. I thought my girlfriend had shut it off,but she said she didnt touch it. I looked, keys still in the ON position, but there is NOTHING going on with the car. I shut it completely off, try again, nothing. The lights all work, but when you put it in the on position it literally does nothing, no SES light, no brake light, no seatbelt light, no stereo, absolutely nothing. I also noticed that while the lights all come on and even the interior lights and gauge lights come on, the hazard flashers do not work. The gauges dont do anything, althought the backlights do come on. I checked all the fuses under the dash and they were all ok, but it was dark so i couldnt see anything under the hood to check fusable links. I dont think its a fuse though, if it was it would be a fuse for everything but lights? When you try to start it it does nothing, not even click. I tested the battery (dont think its that anyways, lights are all bright and with these circumstances it just doesnt fit dead battery) and it tested out at over 12v. I did a load test with my multimeter too and it was fine. I have a neighbor with a tow truck, and although it was after 9pm he was kind enough to come pick it up and drop it off at my house.

Can an alternator cause the problems im having? Could it have caused this problem?? I dont think it could, if it was bad it would have drained the battery and my battery would be dead.

Im starting to think its a computer problem, possibly my computer is fried now.

Has anyone ever seen anything like this before? Any ideas of what it should be? Im not really too sure what to even check besides what I already have!

PLEASE HELP, im out of a car now!! I really need to get it fixed asap, and i cant get it to a shop until monday, and id rather fix it myself than pay to get it fixed of course!

Thanks,

 

+1 for the fuel pressure check. Either loaner tool or $25 at HF.

My car was behaving same as yours - intermittent operation. Until it would barely idle and hardly make it around the block then I measured low FP. My car threw no codes, FP had volume per the FSM but low pressure ~ 20psi. Used the pump to empty the tank. Just finished changing the pump yesterday. Works great now.

 

 

I will check fuel pressure as soon as its running again, but right now its not doing anything. I work 9-5 today but after work i will be working on it.

Anything I should check in specific?

Its acting like theres no power to the computer, id like to check for 12v at and leaving the computer. Which wires will I need to get to?

Is there another way to check the computer? How do i test the prom? I havent taken that cover off yet but i will be later today to look at it.

Sorry im asking these questions but i dont have the factory manual yet and i need to get this thing up and moving again. I can borrow my dads truck until monday, but then he'll need it back, and i work monday so ill be out of luck if i dont have the camaro going again.

Thanks again

 

If you pick up a Chilton or Haynes manual there are enough wiring diagrams in there to get you started. If you have a multimeter, too, as you indicated, you now have enough to not only figure out your no crank/no start condition, but you also have enough info to re-wire your fans to work properly. That one is probably just the grounding temperature switch that goes into the engine to turn fans on at higher temps.

I have been having problems with some of my fusible links lately, and some of what you are describing is similar to what I went through as well. You may just need to get under the car and check all the ins and outs down near the starter and see if some of those fusible links are no longer delivering the power required.

 

As Kris said above me, check and double check the fuseable links at the starter and the one near the battery(if your car has it i assume it would). Then check the battery connections, I know you said it has interior light power and other places have power but no start, gages, etc. I had a issue one day where it did something similar. If i remember correctly the CRANK fuse had blown on the fuse box. I would check all of them to see if any are blown or loose...

Reason I say loose is because I have one fuse slot that has had the wire in the back pulled on too hard and now the fuse doesnt always seat correctly. The interesting thing is that it is the ECM power fuse. Every once in a while when i get in to start it i will turn the key and the fuel pump wont do its couple second prime. I know instantly to reach down to where the ECM fuse is and just push it up into the spot and it will make contact and im good to go. You MAY be having a similar issue?

 

start by cleaning both battery cable connections , verify the batterys charged and has 13 volts and doesn,t drop below 12 when you hit the starter,and verifying your alternator puts out about 13.7 -14.9 volts at idle once it starts
pull the trouble codes and buy a FACTORY SHOP MANUAL
a systematic and logical step by step process will locate the cause(s)
you can,t make valid choices without proven and verified facts, guessing is a waste of time and usually money

http://forum.grumpysperformance.com/...op+manual#p383

http://forum.grumpysperformance.com/...nnection#p6369


http://forum.grumpysperformance.com/...nnection#p8575

http://forum.grumpysperformance.com/...nnection#p9217

http://forum.grumpysperformance.com/...nection#p18927

 

Please check for spark if not may be Ignition Control Module.

 

OK, update.

The car is now running. The problem that caused it to not start and leave me stranded in a grocery store parking lot was a broken wire on the starter, turns out it was the positive wire that powers the computer. I fixed it and it started up, the battery was pretty drained (i had left my park lights on a while so the tow truck would be able to find my car) but it started right up. It ran real poorly still though.

After letting it run to charge the battery back up I decided to check the prom since it was still something i had not done. I took the cover off and with it running i pressed down slightly on the prom and it went from idling it about 500 in park and horribly to shooting up to 1000 and running so strong! It was just like when it would stall then run great, it was running that good! It was vibrating the car with that strong V8 thumping around, before it didnt do that. But as soon as i left go it ran poorly again. I did this 3 times and every time it was directly affected and the response was immediate. I turned the car off and pulled the prom out and inspected it and the socket. They both looked fine, didnt see any problems. I put it back in the same way and it still ran horrible. This time when i pushed down it did nothing.

I drove it hoping to see a change and didnt so i stopped and took the prom back out and tried something different; I had put it back in and it "clicked" twice, this time i clicked it in once. What a difference! Ran great again, I was smiling ear to ear with the satisfaction of having all the power back!

Can anyone tell me what way the prom should be installed? Im guessing since its running right its installed correctly but i want to make sure.

I will keep an eye on it and let you all know if its better. Thanks for all the help everyone!

 

I love hearing a success story.

I would at this point start shopping for a reman ECM. Your PROM chip will need to be removed and swapped over to the new one and now you know how to do it.

You might even look for a good used one off of this forum. I get the best prices on TGO and you have the best shot at dealing with people who are helpful rather than shining you on for a sale.

Good luck!

 

I was hanging out at Dyno Don's shop one day and he was having almost the same problem with his GTA. He tried everything but DTC 51 kept popping up. He changed ECMs and the problem went away. He finally just swapped in another Mem-Cal and bingo, that was it. He stated in all his years working on TPIs he'd never seen a Mem-Cal fail intermitantly, it either works or it doesn't. Learn something new everyday.