Members CamarosPost pictures and information about your Third Gen Sport Coupe, Berlinetta, LT, RS, Z28, and IROC-Z28 Camaros!
Welcome to ThirdGen.org!
Welcome to ThirdGen.org.
You are currently viewing our forum as a guest, which gives you limited access to view most discussions and access our other features. By joining our community, at no cost, you will have access to post topics, communicate privately with other members (PM), respond to polls, upload content and access many other special features. Registration is free, fast and simple, join the ThirdGen.org community today!
My 350 TPI motor cranks & idles & runs great cold . After about 5 minutes the motor starts running very rich . Changed the temperture sensor with no change . All sensors check out OK with scan tool . Have replaced everything but the sensor under the plentum . New ECM , Temp. sensor,Map sensor & TPS . It has a Ron Francis Harness using a 90 Camaro ECM & Ron Francis prom . Car has been running fine for 15 years
& just started this problem .
Any help would be welcomed .
It even idles fine when it goes into this rich mode . It's like a carb. loading up at
2000 to 3000 RPM's. Cut it off & let it cool down for about 10 minutes & it runs fine til temp. starts to increase . It has had
a 180 deg. thermastat form day one . This in my 88 SS Monte
Carlo . I have the same system in my 34 Ford .
Last edited by Chris Aiken; 10-16-2009 at 08:03 AM.
I would think it should throw a code if that is the case.
The temp sensor that you changed -- is it for the gauge or the ECM? The one that feeds the gauge won't have an effect on how the engine runs. There is another one that feeds the ECM, and it may be the one you haven't changed.
If it tests good, are you testing it cold? My hunch is that the sensor tests OK when cold, which is why the car runs OK, but apparently is not working properly and that is why you are having this problem. Could that be the one that is under the plenum? I am not sure where the ECM temp sensor is located; I just know that there is one.
It's for the ECM in front of intake . It's a 87 Camaro TPI .
I've been fooling TPI motors for 10 to 15 years & this one has me stumped . Everything has been repalced but the sensor under the plentum .
Last edited by Chris Aiken; 10-16-2009 at 08:20 AM.
I had a similar problem with my son's MPFI V6 Firebird. First, I mistakenly changed the wrong temp sensor. Then, I changed the right one. No help. Finally, I looked for (and found) a bad wiring harness ground. When I fixed that, it cured the problem.
What bothers me about your situation is that you aren't getting any codes. At the risk of sounding like Johnny Cochrane, I would expect the O2 sensor to pitch a bitch if you are running rich.
Here is a thought: suppose you have an injector (or maybe a fuel pressure regulator) with a hairline crack that only affects performance when it heats up and expands?
It did this once before & it was the cold start coolent sensor in the front of the intake . I used teflon pipe dope because it has to be grounded from the treads to
work properly . Thanks for your replys .
