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Hello, I have a 2000 CVPI (gas 4.6 16v) with 75000 miles, have owned it since almost new with 10000 miles, and have developed an acceleration ping. I do all the maintenance myself, and have run AMSoil 5w-30 since purchase. Regular changes on everything else. I have been using the same 87 octance from primarily the same station for the last 3 years. There are no codes or DTCs present, either stored or in real time. I am leaning towards the MAF sensor, but hate to shotgun an expensive part. I am in Texas and it has been hot recently and the pinging is not as noticeable in the mornings (4am) when I go to work as it is in the afternoon (4pm). Maybe I am sleep-driving? Not sure what else to try before the MAF. I disconnected the MAF and the pinging seems to lighten some. I can generate a MAF failure code with it disconnected. Not sure what else will cause these symptoms. So I guess I need to know if this is the right tree to bark at. Thanks.
Answer -
Hello and thanks for the question...I'll try to help.
I would take a look in to the EGR system more so then the MAF. You'll need to remove the upper plenum all the way down to the EGR and clean out the EGR passages.........they are most likely partially clogged up with carbon, so it won't set a code but will affect exhaust gas flow. The EGR allows exhaust system gas to re-enter the combustion chamber and actually "cools" the cylinder down.
Hope this helps,
Erik
Erik, thanks for the info. I had that same issue on the 1994 CVPI that I had and it was a pain to clean out that small passage in the intake manifold. I looked in the upper plenum through the butterfly valve and did notice some small carbon pieces on the very edge of the EGR valve output port. That port seems to be about 1/2 inch in diameter or maybe a little larger. Would that be enough of a restriction to the flow? The black stuff looks about less than a 1/16 of an inch. Also, what do you recommend for cleaning it. I have MEK, Acetone, ISA, contact cleaner, simple green, etc. Also, I had pulled the 30A fuse for the PCM hoping to reset the adaptive learning, but it did not seem to help. Is there another way besides the battery cable to reset the adaptive learning without losing the memory on the radio? I have also had a hard time starting the last 2 days, when it used to always start on the first try before. If I advance the throttle just slightly it will start and idle. Thanks again, Joel
AnswerHello and thanks for the reply...I'll try to help.
Taking JUST the EGR valve off isn't going to let you get down to where the it needs to be cleaned. The upper air plenum needs to come off as well as the trhottle body. As far as cleaning goes.....use a pick and a rag with carb clean.
For the codes.....since it is an ODBII system a scan tool is needed to reset the check engine light and to make and adaptive strategy changes.
Erik
