vicki711

I have a 95 z28, I had a fill rebuild done a yr ago .I had a lt4 hot cam kit replaced all ignition components installed headers and remobed the a.i.r pump. I also have the ecm flashed for the cam swap. Since igot it running ive had an issue with it ideling funny loading up if sitting at idle and once in awhile backfires through the intake . I notice Im still running the lt1 knock module..was curious if it coild be my knock module reading tje extra noise from the cam upgrade or if I may possibly have a map sensor issue?

Injuneer

Did you install full roller rockers with the LT4 HOT cam? If so, they may be causing knock retard. The LT4 knock module specifically addresses this problem. Unfortunately, they are becoming impossible to obtain.

Best thing to do is download a free copy of Scan9495 scanning/data logging software, get the required 16-pin ALDL cable and collect data on the sensors and PCM parameters, to allow a search for the problem. It will tell you if knock retard is a problem (although that won't cause popping through the intake).

See the "sticky" post about Scan9495 software at the top of the "Computer Diagnostics...." forum. I can help you interpret the data you collect. Unfortunately there doesn't seem to be too many people around any more that will take the time to do this. So sometimes I get a bit backed up with data logs to review.

But we do have the author of Scan9495 (GaryDoug) on this site, and he is always ready to answer questions regarding the software, installing it and using it, plus reviewing the data.

vicki711

I did install a full rocker kit with the cam...I was told by amohe person I , ay need a knock , odule and like u said there abiut impossible to find...im also lookimg into he scan software as well .will keep posted on my findings