brent95ta

Alright guys, my car has not been running the greatest lately, it has been stumbling at lower rpm and not pulling as hard as it used to in the upper rpm. After reading some threads on here i unplugged the maf. This instantly changed the way the car ran, runs amazing now actually. I took some data logs with the MAF plugged in and with it unplugged. Both of them show a code 48 MAF error. One of my questions is even with the maf plugged in, wouldn't the computer kick over to speed density mode with a maf error? Secondly i am getting a CONSTANT 5.0 degrees of knock retard at WOT i have no exhaust leaks and i run 91 octane (most octane i can get around here) I am going to try to put some octane booster in and try it again. Any one have any ideas on the knock? Lastly, is there any way to test the MAF? i am going to try to clean it with contact cleaner after work and see if it makes a difference.

93redBirdMan

Do you have an LT4 knock module? OR did Ion possibly desensitize the LT1 knock module you have? If not, that needs to be done, because you've got aftermarket roller rockers which create more noise than stock. The knock sensor picks up that noise as knock and retards the timing...

brent95ta

I emailed Ion before i posted to see if my knock sensor was de-sensitized. I will post results when i find out

Injuneer

First you need to make sure the MAF sensor is getting 12V power. Key on, read the voltage between the pink wire and the black/white wire, should be 12V.

Then with the engine running, harness connected, put a frequency meter across the yellow signal wire and the black/white wire. Should be putting out a signal in the range of 2,400-2,800Hz. At WOT, max RPM you should see about 9,000Hz.

brent95ta

Alright, there is 12V at the sensor, and the MAF is putting out 3.3KHz @ 800 rpm, i could not test the max range but i blipped the throttle a few times to probably about half and saw about 6KHz

brent95ta

Ion did de-sensitize the knock sensor and set the max knock retard to 5.0 degrees, so that explains a lot. Does anyone have any other sources of false knock? I am going to pick up a bottle of octane booster to see if that helps out my problems.