93 LT1 start up problem
Thread Starter
Cruising
Joined: Dec 2020
Posts: 12
Likes: 0
From: Arizona
93 LT1 start up problem
I have a 40th anniversary that all of a sudden when cold at start up, check engine light comes on the idle fluctuates then settles at high idle for a while then drops to normal check engine goes off and performs fine, like nothing was ever wrong. I replaced the Prom, sent the ECM to SIA electronics and got it reflowered, replaced all sensors, optispark ,tuned, im out of ideas, it did`nt do that before I sent ECM to SIA. anybody have any ideas?
Drifting
Joined: Nov 2018
Posts: 1,798
Likes: 579
From: Mays Landing, NJ
I have a 40th anniversary that all of a sudden when cold at start up, check engine light comes on the idle fluctuates then settles at high idle for a while then drops to normal check engine goes off and performs fine, like nothing was ever wrong. I replaced the Prom, sent the ECM to SIA electronics and got it reflowered, replaced all sensors, optispark ,tuned, im out of ideas, it did`nt do that before I sent ECM to SIA. anybody have any ideas?
You threw a lot of parts at a problem that you never took the time to pull the code(s) that would lead you in the proper direction. Do yourself a favor and pull code(s) now.
Drifting
Joined: Apr 2020
Posts: 1,925
Likes: 610
From: Orange, CA
If it didn't do that before you sent the ECM to SIA, what was it doing that prompted you to send the ECM to SIA?
When you got the ECM back from SIA, did you make sure that the PROM was firmly seated in its slot? There have been reports of PROMs not being fully seated after making it through the mail causing random issues.
When you got the ECM back from SIA, did you make sure that the PROM was firmly seated in its slot? There have been reports of PROMs not being fully seated after making it through the mail causing random issues.
Drifting
Joined: Aug 2019
Posts: 1,338
Likes: 225
Get a good scan tool to find out why that light illuminates. If you can't/don't want to buy one, then go to Autozone, or someone like that, and they'll pull codes for you for free. Without codes or looking at data, you're working blind. And buy the factory repair manual. You'll save in the long run.
