so i figured since it was nice out and i wasn't doing anything i would load my latest touch ups to my tune. everything goes an normal. i start it up.. it sounds a little weird but as soon as the engine stabilized it was fine. i try to go for a spin to see how things are going and it dies. yet it starts right back up but will only idle for about ten seconds i only made changes to the extended VE map. so i compare it to other tunes to see if i am missing something. load an older tune on it still stalling. its only been a few days since the last time it ran and i have no idea what the hell is wrong with it. i am really starting to hate the car. if its not one thing its another.

IAC???

i thought that at first too but even if you try and keep the rpms up it just bogs out.

clogged fuel filter or filter sock?

i am trying to locate my gauge.

I'd check fp first.

Are you using the same chip and loading different tunes on it? If so, the chip could have went bad. I had a 27sf512 chip go bad on me and acted all screwy even if I reloaded a tune I knew was good. I used a new chip and reloaded a tune I knew would work and it was fine.

lt1's are a little different. i dont have a removable eprom. i may have flashed it 20 times.

Dan, on that same note, I know guys have had problems where the tune loads part way then stops and it screws up the whole ccm and it needs to be sent out for repair. Happened to RickAnthony.

Matthew

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True, a while back this happened.. but it would crank and not start at all.. it was a long time ago but I think it was flashing SYS on the speedo. I sent it I think to the guy from AKM cables, because he could un soldier the chips and install new ones, though he said he communicated fine with it when he got it an loaded a stock tune on it, I've flashed it a couple times since no problem.. I'll probably buy some tuning software like tuner cat this spring since I need to change the speedo for the diff swap I did a while ago, and probably make a few other changes as well..

-=Rick

i have a ecm that failed a flash. that will not run at all. i am going to see if i can send both in for repair. if its getting fuel. madtuner mods them for removable chips which is what i am going to have done.

Keep us posted.

the fuel pressure is fine.. it just shuts off.. no check engine lights.

i tried using the recovery option on jet flash. and i don't know if it did anything or not but i got it to start and was running like complete crap. but it was running.. i had to keep moving the throttle around and it finally started idling on its own. i pulled the intake tube off and sprayed carb cleaner in the iac hole and it is idling again.. although not well. and it stayed on long enough to find out it was running kind of lean.. so i made a new tune and added some fuel to the idle its somewhat back to normal in that aspect but i went to drive it and as soon as you put a load on it it just dies. i don't know whats up with this thing.
it started acting weird a few days before it had this whole issue, after i tried turning the maf back on. i barely got out of my parking lot and i knew i had to go back. so i went to turn around and it stalled. of course. then the battery didn't have enough in it to start it. so i got my other car and jumped it. well when the car start the jumper cable popped off and arced on the nearby metal. and it stalled. so i said hell with it and went back in and switched it to speed density while it was charging up. it still wouldn't run right. so i got it back to the house and went inside with some data from earlier and adjusted the tune. only to come out to run into all this shit. it didn't really run correctly on the way home. i dont know what the hell is going on with it. i am temped to put the stock engine back in it and live with it being slow.

man... this is annoying.

Have you thought about going back to the stock tune, just to make it run? I am wondering if there is a bigger problem... fuel delivery? something... it dies under load. I wonder about the coil and that set of components.

the fuel pressure didn't drop at all. i couldn't even get the clutch out and it fades out. i have to find my spare coil and icm. it is just about the same temp. i could try another tune and want to change the fuel filter just for the hell of it. the thing is i can't really go back to a stock tune with my 42# injectors.

well i put a new napa gold fuel filter on it.. still no changes. pulled the coolant temp connector and it acts the same. of course i am not lucky enough for it to just have a code tell me wtf is wrong with it. i also tested the tps and it was fine. i would have to assume that it a computer issue since it all started after a flash. it was running the best it has yet.

Have you unhooked the battery since changing back to speed density? Is it possible that somewhere in the computer it has some learns stored? I'm not familiar with the LT1's but on mine I have to unhook the battery when I change a chip from closed loop to a full open loop tune.

I have removed battery power.

Are you getting spark when it dies?

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That's a tough one to catch, because is it the lack of spark or did the spark quite because the engine stalled? There are alot of variables with this one..

how did you check the TPS? Did you scope it? it's hard to see a drop out with a volt meter.. just something to consider..

I also wonder if you aren't having an issue with the opti spark, If fuel pressure is good ect.. was it miss fireing when it was idleing? I assume it was since you said it was running rough.. missfires can cause the O2 readings to look high which makes the pcm think it's running lean...

just some thoughts I had.. not sure if they are of any help..
-=Rick

It was not idling properly. it was somewhat lower then commanded. So I don't know if its the iac took a shit along with the pcm or opti. It will fire right back up as if nothing it wrong. The opti isn't wet and is a gm unit with not a whole lot of miles on it. I can't remember when it was replaced last.

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When my CTS was unplugged (bad pigtail) it barely ran. Perhaps you have a bad CTS or pigtail?

i will have to try and get it running to see what i can log if possible with my scan tool. there isn't any damage to the coolant temp sensor connector. it seems to be seated properly. it looks like i need to get my ass in gear and start checking everything

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Totally agree with you. Need to scan.

All I'm saying is that from MY experience, when you (if I) unplugged your (my) CTS and got no difference in the way it ran (badly)...that would tell ME that the CTS was suspect.

Best of luck.

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That's exactly what I would do...look at all numbers IAC, CTS, target AFR/cold , blm/hot, at idle and both cold and at operating temp (if possible). The only drag is scrolling through when using a scan tool.

My car starting running like you describe out of the blue about 2 months ago. The problem wasn't consistent in nature; car wouldn't idle, then it would idle at about 1200 nice and smooth but drove terrible, too rich, too lean, etc... No consistency at all with the symptoms. It ended up being the TPS sensor. The TPS would read normally on datamaster, had a nice sweep of voltage, etc... I was logging it one day and saw the TPS drop to zero voltage for a split second. I replaced the sensor and the car runs great.

I doubt you have the same issue, but it's an easy one to swap out.

I don't know anything about the LT engines, hell I can barely keep my L98 running but if it was running great before the flash wouldn't that kind of indicate that either the flash or the PCM is funky?

well i broke down and sent a pcm to be repaired.. it wont be back till next week. at least i will hopefully be able to narrow things down once i get the pcm back.

Hope that gets you rolling again.

me too. i dont really have a ton of money to put towards it and the pcm repair was more then i was wanting to really spend.

Did you get the PCM back? Did it fix the issue?

Quote: not yet.. i sent it out monday of last week.. idk wtf is taking so long.. i got some money out of my ex girlfriend that she owes me so i can drop a few bucks on the turd if it needs it. too bad it was only a 1/5 of what she owes me.

just got it in the mail. woot

well it runs. i put the last known working tune and it doesn't seem to want to run the same as before. i need to see if i can get it to log some data if at all possible tomorrow. i dont know what is the problem is.

anyone want to buy a vette.

Guess you haven't quite got it worked out.

Atleast it's running now and you can start tracking down the issue(s).

Don't know just guessing, but somehow this sounds like an easy fix you could probably do yourself?
Open up the PCM and take a look if you can find some solder joints they screwed around with.
You'll probably find an EEprom, that looks very similar to our old Eproms. Note, the older once had only one "E", erasable but not electronically.
Replace that sucker and you should be good to go.
On a side note, I would use an IC socket instead of soldering the new EEprom directly onto the circuit board. This way you can replace the EEprom as often as you like.

the repairs i had done to it included upgrading it to a socketed board so i can replace the chips myself instead of having it sent out for repair.

if i were to guess i would say josh is probably right with the tps that or the iac or both or both and something else.. who knows. this thing will be the death of me. i can't get it to progress at all from its current state.

well it is straight back to doing what it was doing the other day. so i am guessing i just spent unneeded money. i did drive it down the street but it quickly started running worse and worse. i know that the tune i put on it ran fine at idle and part throttle before all this so i know it has to be something else now. i can't wait to figure out what the hell it is.

Is the 02 sensor a possiblility? Maybe it fouled when the other tune didn't load right?


Could the battery be just strong enough to crank it but still weak? I've been reading a few posts here and there where guys have had running issues and it ended up being the battery.

Don't know, just throwing some thoughts out there.

the battery starts the car. again and again after it stalls. the bad tune was making it super lean if i remember correctly. and it having the same issue on two different pcms and knowing it ran better before with the tune that is in it i cant see how it would be the tune. it just wont stay running. the only change was unclicking speed density. and going back to speed density its no change. its also locked in open loop so i dont think a 02 would be able to cause it. i am going to pull the icm and have it tested. and i want to test out some other sensors, but i have been doing a bunch of running around and half dont want to know the cost of repairs. even fluctuating the throttle it wont hardly stay running. its been back firing so i can't help but think in the back of my mind that the opti is shitting the bed. its not going super rich or super lean on the wideband. only when getting into the upper heavy throttle which hasn't been adjusted. the more i think about it, it points to the ignition. so who knows.. i just need to test some sensors see what i can find.. hopefully tomorrow is nice out.

It was gorgeous here today.Until about 5:30 when it started to rain. Hopefully you got things figured out.

no. i got too much going on personally to bother with it. if its not one thing its 10 others with it and my life. i am almost at the point where its just not worth it anymore. i may just part it out.

Get it hooked up to a laptop and do some scans, see what's not in spec. You know that's the answer, just try not to get too frustrated with it!

Matthew

its really not even worth it. i dont have the money right now to mess with it.. i shouldn't have spent what i have already in it. i am also sure its going to be something that i cant afford. its been just too much. i mean if i would have gotten to the point where it was drivable after fixing whatever this problem is i could see it. but its just not the case. its been a hassle to get going since i put this engine in it. i should have done some things differently from the start. i let too much get in the way before i finished it and i made some choices that effected me financially and haven't been able to recover. i could go on but i am sure you would rather me spare you the details.

Maybe you should just put the stock engine back in and just drive it. I know you said that you think it's slow that way but it will run right?
Let the modded engine sit on a stand until you can afford to mess with it?

cause that needs stuff too to before it can be dropped in. its money any way i look at it. i robbed some parts off it to get my trans am running again to get rid of it..

Josh, I can understand the money portion and the frustration. But all I'm saying is scan it so you can identify the problem. If it's something silly like a sensor pigtail, that's an easy fix. If it's something more complicated, then make your decision based on that. Don't be hasty - try to enjoy the car!

Matthew