Poor Mileage!
#16
Pitch the NGK's and put AC Delco 41-993 plugs in it with a gap of .060"
While you're at it, use AC Delco cap & rotor too. (yes, it does make a difference) Have you checked camshaft retard? Spec is zero degrees, plus or minus 2 degrees at 2,000 rpm. It has a direct affect on ignition timing and makes a huge difference in gas mileage if it's off too far. It will not turn the SES light on until it's off ~27 degrees or more.
The spacer on the downstream oxygen sensor will not keep the light off. When the PCM runs the monitor for the converter, it switches fuel mixture full rich then full lean. Then the PCM watches how long it takes for the sensor to report the change in fuel mixture. If it takes too long, the light comes on. If it reports too rapidly, the converter isn't working, (or gutted) and the light comes on. If the converter is working properly, sensor voltage should remain steady, (around .4 volts) at a steady cruising speed. The monitor does not run continuously, a certain set of parameters must be performed before the monitor will run and complete the test. If they are not duplicated precisely, the monitor will not complete the test. Performing step 7 of the General Motors Driving Cycle will force the monitor to run and complete the test.
While you're at it, use AC Delco cap & rotor too. (yes, it does make a difference) Have you checked camshaft retard? Spec is zero degrees, plus or minus 2 degrees at 2,000 rpm. It has a direct affect on ignition timing and makes a huge difference in gas mileage if it's off too far. It will not turn the SES light on until it's off ~27 degrees or more.
The spacer on the downstream oxygen sensor will not keep the light off. When the PCM runs the monitor for the converter, it switches fuel mixture full rich then full lean. Then the PCM watches how long it takes for the sensor to report the change in fuel mixture. If it takes too long, the light comes on. If it reports too rapidly, the converter isn't working, (or gutted) and the light comes on. If the converter is working properly, sensor voltage should remain steady, (around .4 volts) at a steady cruising speed. The monitor does not run continuously, a certain set of parameters must be performed before the monitor will run and complete the test. If they are not duplicated precisely, the monitor will not complete the test. Performing step 7 of the General Motors Driving Cycle will force the monitor to run and complete the test.
Last edited by Captain Hook; 10-19-2012 at 09:09 PM.
#17
I doubt my brand of plugs will effect it. I can regap if neccessary. However I do not feel the need to replace them, they're brand new and do their job. I run NGK's in everything and never have issues.
I can tell you for a fact that it does indeed keep the light off as far as daily driving goes. I had a steady light for months and I put the spacer on and it has been off since. Whether or not it gives the PCM the correct information is a different story, but it isn't throwing a code for anything. Does performing the test do anything for me other than turning the light on, if the spacer doesn't stop it?
The 4x4 is not engaged. Just to clear that up.
I will look into the cam retard, but I won't be able to check and/or reset the cam retard for at least a few more days.
Thanks again for the help everyone! I appreciate it.
I can tell you for a fact that it does indeed keep the light off as far as daily driving goes. I had a steady light for months and I put the spacer on and it has been off since. Whether or not it gives the PCM the correct information is a different story, but it isn't throwing a code for anything. Does performing the test do anything for me other than turning the light on, if the spacer doesn't stop it?
The 4x4 is not engaged. Just to clear that up.
I will look into the cam retard, but I won't be able to check and/or reset the cam retard for at least a few more days.
Thanks again for the help everyone! I appreciate it.
#18
I can tell you for a fact that it does indeed keep the light off as far as daily driving goes. I had a steady light for months and I put the spacer on and it has been off since. Whether or not it gives the PCM the correct information is a different story, but it isn't throwing a code for anything..
Step 7 must be followed exactly as explained before the monitor will run and complete the test. If it is not followed exactly, the monitor will abort and will not run again until it is followed correctly, then it will complete the test. During daily driving, it's entirely possible for the monitor not to run and complete for months, or more. If you live in a State that requires emission testing, it will fail immediately if the monitor is incomplete.
#20
The downstream O2 sensor has absolutely no affect on engine performance. Its sole purpose is to monitor the efficiency of the catalytic converter. The only way it would pose a problem is if you need to pass an emission test. Some states require it before license plates are issued.