breNt*

iTrader: (1)

just got my pcm tuned last week, im currently using a 2002 ls1 pcm on my 99 trans am.. and today when i started it and i was backing out it like wanted to stall on me.. everytime i pressed the gas it wanted to stall.. so i drove it down the road and went to turn around and come back home and when i put it in reverse and gave it the gas it stalled.. so i WOT on my way home and then it started again fine and drove fine.. drove up town like 5 miles just fine then 5 hours later i went to leave and it was doing it again.. this time it just shut off while i was driving.. so i pulled over and kept trying to start it and it wouldn't stay running then finally it ran fine and i drove it like 500 feet and it backfired extremely loud... 1 huge boom.. then stalled again then i waited 5 min and it started up fine and drove it home.. now its sitting in my driveway and i have no idea.. i don't know if it has something to do with the fuel filter, pcm, maf..

--ok got an update, i was gonna push my luck and drive it up to autozone to get the service engine code but now it wont even stay running for 3-4 seconds after i start it.. tried about 10 times now even waiting 15 minutes and checked everything under the hood.. everything is fine all cables, plugs,hoses.. everything.. but now it wont even stay running for longer than 5 seconds tops. it just stalls out after starting.. and im not even pushin the gas. its in park

thanks..

breNt*

iTrader: (1)

now it wont even start.. it cranks but nothing.. just changed the fuel filter and nothin

lt1pwr1

iTrader: (1)

Can you hear the fuel pump prime when you key the car up? What mods do you have that required a tune? Who tuned it and was it mail order or dyno?

breNt*

iTrader: (1)

1. il check tomorrow.
2. i have mac midlengths and slp loudmouth exhaust dumped at the y, mainly needed the speedo recalibrated after getting higher gears.
3. 1badls1 tuned it. mail order.. but idk if the 02 pcm messed with the car seeing how its in 02 and my car is 99.. he has already sent my original pcm back, i should get it anytime(iv been using the 02 one because it worked fine and he sent it prior of me sending mine to him because my car is my daily driver and i couldn't afford going a week without it.)

breNt*

iTrader: (1)

ok i can hear the pump prime but only for like 2 seconds.. i actually unhooked the gas line where the fuel filter is and then turned the key and it shoots out a little gas for like 1 second then stops.. isn't it supposed to be a non stop flow?

Drew24

Instead of checking it there i would check it with a fuel pressure tester you should be around 41-43 Psi. You can rent them at autozone for free. Also will it start now? When you turn the engine over does it try to engage or does it just crank

breNt*

iTrader: (1)

just cranks over and over nothing happens..

Drew24

Check your spark to make sure that its not the coil packs

breNt*

iTrader: (1)

i have no spark.. i tried spark plugs #1 and #2 and nothing.. so where does this leave me now?

Drew24

IMO sounds the the pcm seeing how ever since you got it tuned you had this problem. Was it acting up at all before the tune?

I would have who ever tuned it for you look at it see if something was messed up

breNt*

iTrader: (1)

no this problem just randomly started yesterday. before yesterday the past week iv had this tune its been amazing and i have had 0 problems.. should be getting my original pcm back anytime hopefully tomorrow.. a buddy is comin over tonight with a tech 2 so il just go from here.. any advice is appreciated.. thanks

breNt*

iTrader: (1)

bump anyone? buddy didn't make it last night hopefully tonight.. nor did the pcm come.. sigh.

LS6427

iTrader: (2)

Crank Shaft Position sensor............

Could have fried the PCM. Mine fried because of loose ground wire couple months ago and it completely shut down the drivers side of my engine from firing. Wierd stuff.

I'd take the two tops off the PCM and look to see if any of the pins are fried. I chased all kinds of ideas till I simply took those off and saw some burnt pins. Put in a new PCM and it was perfect again. And I tightened the loose ground wire.

Also, try to crank it while grabs onto the wiring harness coming directly out of the PCM and moving it around. See if it starts or tries to fire. If it does you might have a loose PCM-to-engine block ground wire, or broken totally off. If it breaks all the way off the engine will not fire, but when its loose it'll run crazy like you described it running before it quit.

.

breNt*

iTrader: (1)

iv tried looking for all my grounds and they all seem tight.. also note that for about 1 year now iv been having a major electrical problem.. car goes down to 12.1 volts(tested with fluke 88) while idle.. got new alternator, had everything checked, battery.. everything.. but its been running completely fine never stalled before the other day but just thought id throw that in there..

i just checked all the pins on the pcm they are good. tried wiggling it while my gf trys starting it.. nothing.. even reset the battery, and had her try holding the gas pedal to the floor one of the times, still nothing. its just weird that iv driven 600 miles since i got this 02 pcm and its been perfect then 1 day out of no where its sputtering and acting up..

heres my other thread about the voltage problem that iv been trying to fix for the past year almost haha..

https://ls1tech.com/forums/general-m...e-problem.html

NOTE: my car has NEVER given me any type of stalling/start up problem until just a couple days ago, or 1 week after my new 02 pcm in my 99 ta.

breNt*

iTrader: (1)

ok just got a tech 2 hooked up to my car.. it wouldn't read the pcm.. i didn't even realize it until my buddy left but he had it selected under 1999 trans am ls1.. the pcm is 2002.. would that make it unreadable? the tech 2 did read the BCM though..

LS6427

iTrader: (2)

I can tell you this: A couple months ago when my engine stopped firing on just the drivers side 4 cylinders and was running like ****, misfiring, spitting, bucking, etc.... I had no codes, no SES light and a scanner couldn't pick up anything either. The only thing that was wrong with my car was a loose ground (the pcm to engine ground wire) and my PCM got fried. In my case it was the Crank Shaft Sensor input signal pin that was all black and burnt.

When the PCM has any kind of problem, it seems to quit sending codes, at least mine did. I was lucky and had a pretty badass guy come over that does nothing but electrical/PCM issues and found my problems quick....re-wired the 4 grounds that come out my PCM and screwed it to a new place on the block. Then my PCM read all normal and it started up and ran like new.

I hope not...but your PCM may have gotten fried. Engine won't do anything with a fried PCM.

Did you check your fuses for the PCM under the hood.........

.

breNt*

iTrader: (1)

yeah they were all fine. i have both check engine lights though.. but where does the ground go to the pcm? iv tried finding every single ground on the car and everything seems good, but im sure iv missed 1 or 2..

i can try to follow it but it looks like it just connects to the harness and they are all bundled together so idk..

LS6427

iTrader: (2)

I just learned this from the guy that fixed me up.

Its about 10 inches from the PCM. You will see 4 small wires buried inside that big pack of little wires, they all converge into one wire where they are soldered together....then that one big wire leads to the rear of the block and attaches with a bolt. I think he said behind the head on the passengers side but not sure. He had a mirror tool reaching back looking for mine in that area, the passenger side rear of that head and the back of the block up by the rear of that head.
He couldn't find it, so he just snipped the big wire, spliced a new one in, and attached it to my valley cover bolt.

But he grabbed the whole pack and moved it all back and forth....thats how he found it. His Tech II was blinking and beeping on and off while he would move that harness up by the PCM.

Since you just had that PCM put in...its "almost" certain your problem lies with it or the wiring to/from it.

.

sherm6998

Dont forget to check ALL your fuses. If it is an electrical issue you could have gotten lucky and popped a fuse before frying anything.

breNt*

iTrader: (1)

ok my buddy couldn't make it back over hes been swamped so i just went to oreilys and rented one.. it doesn't read.. so iv been under the car for the past hour trying to find grounds and making sure everything is correct.. iv went through every fuse too..

just doesn't make sense to me

i tried looking for the ground to the pcm and no luck.. i can barley fit my hand behind there..