Recently I've been having some poor gas mileage problems, averaging around 13 MPG. The car appears to be running rich and also recently threw an SES for an EGR problem. I've traced the problem to the EGR valve itself, and will be replacing it this afternoon. I tried applying vacuum to the EGR with my Mityvac while the car was running and the valve would not hold vacuum. With the car off, the valve does hold vacuum. I also tested the EGR solenoid and it appears to be working OK.

In addition to replacing the EGR valve I've cleaned my air filters (SLP CAI) and will also be cleaning the throttle body and MAF prior to firing her back up.

I've done extensive reading and searching about potential problems that can cause this rich condition but I cannot seem to find a clear answer. I am wondering if there is a problem with either the O2 sensors or the IAT sensor. I can successfully connect to the computer with Datamaster, but I have no idea what to look for. Could someone give me some info as to what to look for in Datamaster to troubleshoot the O2 and IAT sensors? Is there anything else I should be looking for in Datamaster?

Would someone look at my logs once I get everything cleaned and reassembled?

Thanks in advance!

Joe

 

I think I know your problem. You deleted your throttle body(!TB).

Ok, heres some things to look for:

1. Check to make sure your coolant temp sensor is indicating correctly. This will cause you to be extremely rich if it malfunctions.

2. Check your long term fuel trims. They should be relatively close to 128. Also make sure there is not a large difference between the banks. They can tell you which side the problem is on. If it is adding a ton of fuel to one side it could mean you have a dead cylinder. Or a vacuum leak. Or a leak in the exhaust.

3. Check the O2 sensors at full operating temperature. They should be jumping around between 0 and .950 millivolts. If they are not indicating or they are stable then you have a problem.

4. Scan for codes.

5. Being since you have headers and exhaust, I would check for burned plug wires or exhaust leaks.

6. Check out Fred and LJ's website

http://para.noid.org/~lj/PCM%20Tutorial/PCMtutorial.htm

http://members.aol.com/InjuneerZZ/ScanMast.htm