LT1 backfires when left in sunlight
Thread Starter
Instructor
Joined: Jan 2010
Posts: 106
Likes: 0
From: Coral Springs Florida
My 92 LT1 does not have a maf . It does have a map sensor that I never changed in the 12 years that I've owned the car. What does the map sensor do to the engine good or bad ? Finally the engine seems to be running great now afraid to make any changes. My mpg dropped after I installed 22 lb fuel injectors from FIC. Maybe the old OEM injectors were plugged up or maybe it does have something to do with having an old map sensor and new injectors
Instructor
Joined: Sep 2004
Posts: 208
Likes: 1
From: Lawrenceville GA
Chill
Speaking from experience, I have done this...Put a bag of ice on the ecm just b4 you try to start it when its hot, like midday. Give it a minute or 2. If it starts right up its the ecm. Buy a rebuilt one then send yours in for a resolder. It sounds stupid, but cooling the ecm on a hot day will either prove or disprove. Ya only have a bag of ice to lose
Thread Starter
Instructor
Joined: Jan 2010
Posts: 106
Likes: 0
From: Coral Springs Florida
Thanks Jispr but after I replaced the ICM and coil the problem seemed to go away. If the back firing comes back I will definitely try the bag of ice. Where did you have your ECM rebuilt at?
Instructor
Joined: Nov 2009
Posts: 164
Likes: 2
From: Spring Texas
Your MAP sensor tells the computer what the atomospheric pressure is behind the TB. As the TB opens that pressure increases and the computer changes the air/fuel ration and gets correction from the O2 sensors. To do a complete rebuild replace the MAP sensor, the O2 sensors, the EGR valve. The problem with our diagnostics is slight failure of these components does not yield DTC's but the system operation deteriates. I would change the MAP , then maybe the EGR and last the O2 sensors. Do Not use anything other than A C Delco parts! Borg Warner Division replacements are designed for a broad spectrum of applications and collectively they vary the set points the PCM was designed for. At one point I had to pull all BWD parts and replace them with ACD parts. What kind of shape is your digital temperature sensor mounted on water pump. This temperature along with the outside temp set the base line for the computer. Even in Houston my temp summer or winter runs at 200 to 204 degrees with a 190 thermastat.
Hope this helps.
Hope this helps.
Instructor
Joined: Sep 2004
Posts: 208
Likes: 1
From: Lawrenceville GA
There are a lot of places that have remanned ecms now. NAPA, Autozoneetc. I had to go through Zip Corvette 3 times before whoever they used got it right. I just went thru 3 weeks of "no start" till I rechecked the fuses
and found 3 that looked good but were bad, ecm, coil, and fan. Now I'm
On the road again.
Glad you found your problem.
