Finally finished the new motor and started the car Tuesday night. A buddy of mine that works at the dealer brought a scan tool out and put on it. First time he turned the key it started right up idled smoothly at 825 RPM and wasn't running rich. Smelled and sounded better than it had since I did the heads and cam last year I didn't drive it cause the brakes were still unhooked awaiting the linelock.
Last night I got the line lock installed and started the car again. It will not Idle, if you take your foot off the gas it dies. <img border="0" title="" alt="[Sad]" src="gr_sad.gif" /> It also is getting rich again which I don't want since the rings are trying to seat. We took another snapshot with the scan tool and after comparing the two it would seem that the biggest difference is in the timeing. On the first night RPM was at 823, TPS at 0% timeing was around 21 or 22. On night two the RPM was at 955, TPS at 3 or 5% and timing at the snapshot was at 29 but just watching it was usually about 30. WTF nothing on the motor was changed from one night to the next. After my buddy asking me twice if I had all the grounds back on correct I remembered reading posts about PCM's craping out during tuning sessions because of a weak battery and mine was weak so we stopped messing with it and charged the battery. I tried to start it again this morning hoping maybe with a stronge battery we would go back to running smooth, but no such luck.
I was worried we crapped out the PCM but my buddy said if that had happend it would give a no communications message but he never got that.
Also on the first night it was throwing missfires all over the place. That didn't concern me to much since all the fuel and everything had been sitting for six months, but on night two it didn't give any missfires, strange.
Anybody got any suggestions? LS1 edit won't be hear for 3 weeks so I don't know if I will be able to do anything till then.

 

Reading the PCM should not effect it, so I doubt you harmed it that way.

Did the TPS increase because your foot was on the gas?

Have you enlarged the TB hole since you put in the heads & cam & extra cubes? you probably need a little extra air.

Did you change the MAF or injectors?

 

Get back on the scanner and make sure you don't have any pending codes. There is a ground cluster on the back of the driver's cyl head (3 to be exact) One of these is for the heated O2's.

Start it up and read your short and long term fuel trims and see what the computer is trying to do.

Yea, ragtop is right, your PCM should be fine but you do want to make sure you've got all your grounds hooked up!

Mark

 

I would also suggest that after you check for error codes, that maybe you should do a PCM reset and then start the engine and take some recordings to see what the PCM is trying to do, like going more rich or lean, etc.

 

There are 2 ground studs if I remember correctly but if they'are all on one it wouldn't make any difference.

Resetting your PCM won't clear out your tuning. O2 readings should be in milli-volts. (Range between 0 and 1 V - PCM ref volage is 450mv)
Personally, I've never seen a neg reading. When you say -3 and +1, could you be referring to your Ltrims?

Mark

 

MTI drilled a 1/4 hole on mine with the T1 cam installed and PCM tuning with LS1 edit..the car idles fine, before it would turn off when put it gear...they went from a small hole going up in increments and trying it out..they got to 1/4 and it idles fine, when put in gear or when ac is turned on...

 

Ragtop the TPS increased because of foot on the gas since it would not idle. TB hole is not enlarged. I thought with aftermarket tuning that wasn't necessary. Although the tuning was done last year when I did the head and cam. Now the car has more cubes and a bigger cam so I may need to do this. What size hole do you drill? Maf is SLP and was done before the tuning. Injectors are still stock for now.
Sparky, all three of the grounds are hooked up unless one slipped off the bolt when I was putting it in. I'll double check to make sure. I can't remember though were all three of those grounded through the same bolt or would that even make a difference.
Doc, wouldn't reseting the PCM wipe out the custom tuning.
One other thing the O2's were reading -3 on one bank and +1 on the other does the negative number mean it's rich or lean on that side.

 

Well two ground studs would explain that extra bolt I have left over <img border="0" title="" alt="[Wink]" src="gr_images/icons/wink.gif" /> but I didn't think it would make a difference.
The -3 and +1 was a percent I believe and it was on the O2's. Keep in mind this was with a dealer scan tool not autotap. My buddy thought the negative number showed a lean condition but I wanted to check since he's a service rep not a technician.
Thanks for the help guy's

 

I reset the PCM the other day and it didn't help so I took the TB off and drilled the hole about 3 sizes bigger. That seemed to have made a difference so I'm going to go a little bigger still unless someone has a reason why I shouldn't.
I also stumbled across an Idle Learn Procedure in the GM service manual. Has anyone ever done this? Should I try that?
Also, AutoTap came in today so I should have some better info in a couple of day's. Still 2 weeks away on LS1 Edit. Just hope I can figure out how to use it. One last question. I know I can't edit my custom tuning, but aside from the poor idle it runs pretty good. Can I save the custom tuning before I reflash the PCM with factory tuning for editing? That way if I can't get it right I'll at least have something to fall back on.