swap help

[N.W. LT1 T/A]

Hi, Problems with my LT1 Swapped 87 T/A.

1) Computer wont communicate with snap-on dia tool.
2) if i give it gas slowly, no problem, but when I get on it it stumblels and kills power until i let off the throttle.
3) after 10 sec. of running its really hot and the plugs are white. help . thanks

[Ghettogmc23]

1.What year is the motor/ harness? Your scan tool might not work due to being the wrong year setup.
2. Hard to diagnose without engine data. Do you run a maf? Any mods to the motor?
3. Sounds like the wrong heat range for the plugs, although it may be running lean causing high cylinder temps. If its lean it could also explain issue #2

off topic I noticed your new here. Welcome! I did a transplant too so I can relate to your frustrations lol.

[N.W. LT1 T/A]

1.What year is the motor/ harness? Your scan tool might not work due to being the wrong year setup.
2. Hard to diagnose without engine data. Do you run a maf? Any mods to the motor?
3. Sounds like the wrong heat range for the plugs, although it may be running lean causing high cylinder temps. If its lean it could also explain issue #2

off topic I noticed your new here. Welcome! I did a transplant too so I can relate to your frustrations lol. I have a 87 t/a with a 97 lt1 running a 94-95 computer. the harness was made by street and preformance in AR. PCM'S for less setup the computer. plugs ar ngk tr55 set at .050 gap. been tring to solve this for quite awhile ....

[Ghettogmc23]

Ok. Not too sure on the scanner but I doubt it'll work with that pcm, it's mainly an OBD1 system. You can try this as a scanner http://ltxtech.com/forums/showthread.php?22725-New-Free-OBD1-LT1-Scan-tool although you will need a cable for it and a laptop
whats your fuel pressure? The plugs sound right but they shouldn't be getting that hot. Are they all doing it or just a few?

It sucks your having issues, however at the same time I'm intrigued to find out the answer...

[popo8]

sounds like a serious lean condition to me. do a fuel preasure test on the car.... bet ur not anywhere near where u need to be...esp under load.


Larry (Popo8) Co-owner
LTXtech.com

[Ghettogmc23]

I already said that Popo! Jeez takin my thunder! Lol.
I actually just thought of something though. What motor was in the car before this? If it was anything other than tpi the factory pump will not flow enough. Tbi ran 25psi max and carb runs max 13ish. The pumps weren't ever designed to handle much over that. The LTX runs 40psi so if the old motor was tbi or carb then that explains the issue (maybe).

[Jloshotz]

Beat me to it, if it's running a stock 87 pump only, it won't see 40 psi. Subscribing :)