Seeking some LT1 PCM advice
Thread Starter
Member
iTrader: (2)
Joined: Nov 2009
Posts: 436
Likes: 1
From: Hubert, NC
Car: 83 Z28
Engine: F-body LT1 swap
Transmission: T-56 swap
Axle/Gears: 10 bolt w/ 28 spl posi, 4.10, disks
Seeking some LT1 PCM advice
I had this posted in the LTx forum, but it didnt generate any steam.
Background is I swapped a 96 F-body LT1/T56 into my 83 camaro. I had the PCM programmed to remove VATS, EGR, Rear o2's, etc. The car runs great, no codes, no CEL, but it smells fat and is consuming more gas then I think it should be. And no, I am not ******* it out. 93 is not cheap. Please read the below and issue advice how you see fit.
I spoke to the place I sent my PCM to and they said that they only deleted the emissions stuff and VATS. They didnt touch the programming.
I hooked up a scan tool to it to look at the data stream and found several things of concern.
-1st: The coolant temp gauge reads about 160* or less when warmed up and both fans running all the time. This seems to go along with my manual hose temp readings when warm which are about 155ish. The PCM however is seeing temps 180* plus at the same time. There is over a 20* disparity between the gauge and the PCM. Where is the fault in this? Is this a PCM coolant temp sensor or a gauge/sender problem?
-2nd: The car runs fat as stated. It actually smells less rich in open loop. It has new o2's and they seem kinda lazy compared to o2's I have graphed in the past. They are also staying on the high side and bouncing from about .300v to .850v even when revving to 2000 rpm for about 30 seconds (plenty enough time for them to warm up, speed up, and switch from one extreme to another).
-3rd: The car is subtracting fuel on both the long term fuel trim and the short term fuel trim. (Still smells really fat when warm)
-4th: The PCM is still commanding both fans to be on at 180* and the car will not get any cooler since the T-stat is closing up. I am running a 160* stat in it and when I replaced it I pulled a 160* stat out.
-Is there a chance that the previous owner of this drivetrain and PCM had this thing mail order tuned or something?
-Should I get another PCM and have it tuned? (I cant have the car down, it is my DD)
-Should I save up and get the software and learn to tune my OBDII PCM?
-Should I ditch the 96 PCM and get a 94 - 95 PCM, or by the time I swap will the cost savings not be worth it?
Thanks in advance,
Scott
Background is I swapped a 96 F-body LT1/T56 into my 83 camaro. I had the PCM programmed to remove VATS, EGR, Rear o2's, etc. The car runs great, no codes, no CEL, but it smells fat and is consuming more gas then I think it should be. And no, I am not ******* it out. 93 is not cheap. Please read the below and issue advice how you see fit.
I spoke to the place I sent my PCM to and they said that they only deleted the emissions stuff and VATS. They didnt touch the programming.
I hooked up a scan tool to it to look at the data stream and found several things of concern.
-1st: The coolant temp gauge reads about 160* or less when warmed up and both fans running all the time. This seems to go along with my manual hose temp readings when warm which are about 155ish. The PCM however is seeing temps 180* plus at the same time. There is over a 20* disparity between the gauge and the PCM. Where is the fault in this? Is this a PCM coolant temp sensor or a gauge/sender problem?
-2nd: The car runs fat as stated. It actually smells less rich in open loop. It has new o2's and they seem kinda lazy compared to o2's I have graphed in the past. They are also staying on the high side and bouncing from about .300v to .850v even when revving to 2000 rpm for about 30 seconds (plenty enough time for them to warm up, speed up, and switch from one extreme to another).
-3rd: The car is subtracting fuel on both the long term fuel trim and the short term fuel trim. (Still smells really fat when warm)
-4th: The PCM is still commanding both fans to be on at 180* and the car will not get any cooler since the T-stat is closing up. I am running a 160* stat in it and when I replaced it I pulled a 160* stat out.
-Is there a chance that the previous owner of this drivetrain and PCM had this thing mail order tuned or something?
-Should I get another PCM and have it tuned? (I cant have the car down, it is my DD)
-Should I save up and get the software and learn to tune my OBDII PCM?
-Should I ditch the 96 PCM and get a 94 - 95 PCM, or by the time I swap will the cost savings not be worth it?
Thanks in advance,
Scott
Thread
Thread Starter
Forum
Replies
Last Post
HoosierinWA
Tech / General Engine
5
Oct 7, 2015 10:15 AM
