1996 LD9 Runnign lean

[erich]

After a list of problems getting a 96 GA with 2.4l running I am still running lean. I am trying to adress the problems and correct before we invest in any crazy modifications that probably will not work.

First off, the engine is a stock 2.4l broken in and has a port matched head. Secrect cams, stock exhaust with new catalytic convertor and stock intake/throttle(for now). I tried to use my DHP generically to read the engines values..but only can read and clear OBDII class 2 codes. BOOO!! I borrowed a Friends Altera Palm program and can get real time o2 values, and temp values. We had 2 year old fuel in this car...i did burn that out have have driven 300 miles with fresh gas and o2 sensors were replaced after that initial old tank.

When starting up i notice no vacuum leaks and very little if any exhaust leaking. At the very first time of running car it did seem to run a little rich.
We initially had problems with getting no cooling fan and O2 sensor values were non existant. First i replaced the front O2 with a Bosch GM oem replacement. I also didn't find any corrosion on plug. The harness side had a crack in the secure latch on the plug..but it seems to be snug enough to get a signal.

After going through some tests we established the PCM may be bad....we were correct. IN went another PCM from a 96 GA 2.4l. After gettnig it all up and running, voila check light went on. The rear o2 sensor i believe it was....we checked that and i swapped in a known good working lightly used.

After getting this all together we were baffled. Damn GM for not putting a port to check fuel pressure..but we took a guess and replaced the nasty fuel regulator. This actually helped...we got faster bank 1 O2 values and the Cat o2 sensor seems to be working as it should. Our values increases slightly but not enough. It looks to be still running lean. Throttle response is actaully nice but sensors are telling me this is not running Stoich.

I have narrowed it down to electrical and fuel issues. Either something is not working correctly OR i actually do need more fuel from a change in fuel injector OR PCM calibration.

Has anyone run into problems with this with the secret cams and a ported head?


I need to invest in a fuel adapter line to test fuel pressure...obviously this would be first on a list of things. Also could be fouled injector? But i would think it would have noticable drivabilty issues. Another thing i have thought about is a fuel filter...i have not changed this yet.