bp92gsr

Hello all,

I am seeking info regarding how I may go about figuring out why I have bank 1 & 2 knock sensor codes popping up on the display of my c5z. I also have a MAF code popping up but have been told by the previous owner that it has been speed density tuned. Car was built and tuned by Race Proven Motorsports in DE and runs strong but I am hesitant to drive it with these codes on.

Basic list of mods:
416" LSX
TFS 255 cc Gen-X LS3 heads
Callies forged rotating assembly
Dedicated E-85 tune
YSI 8-rib

The knock sensors are located on the side of the block under each header. I've heard that the C5s did occasionally experience issues with their KS harness and sensors at times but mine are no more than 5 years old. We put the car on a lift and held a stethoscope up to the motor in various locations without finding anything significant. Only obvious noise was a squeak coming from the power steering pump pulley area. Everywhere else seemed normal. Our next plan of attack is to turn the key to the on position (powering the sensors) without starting the car and start tapping around to see if the sensors indicate voltage on our tech 2 scanner. Other than that, I'm at a loss and have to assume either the KS harness or the sensors themselves have failed on both banks which, in my opinion, seems unlikely.

Thoughts?

neutron82

maf code has to be set in order to go into speed density so don't worry about that... have you done any data logging to see if there is any knock occuring?... if there is knock under what conditions is it registering?... make sure the knock sensor harnesses aren't melted which is common since they are close to the headers... also check to make sure the exhaust or anything else isn't rubbing on anything that could register false knock

bp92gsr

No data logging as of yet. We do plan to though. So far we hooked up the tech 2 to see if the sensors were recieving voltage as I tapped around each. We had zero indication they were working so we opted to remove both senors from the sides of the block and tried testing them with a multimeter. Neither of which tested good or bad (inaccurate readings on both but they appear to be brand new).

We did notice that both sensors were brand new looking and are the newer generation sensors that are usually in C6 and C7's. They are not the self grounding single wire units that the car came stock with (these are 2 wire set-ups. One white ground and one blue power). Our theory now is that a conversion harness was used to convert the old style harness to work with the new style sensors. Also, we believe, since the driveline recently got removed for clutch work, that the knock sensor harness may be pinched or wedged somewhere causing it to set off codes.

More to come. I went ahead and bought brand new old style single wire sensors just to be ahead of the game if needed but I fully intend to troubleshoot further and hopefully not have to use them.

KnightDriveTV

MAF code has to be set for SD, but I'd think RPM would disable the engine light in HPT, so the light could serve as an alert for arising issues. Leaving it on would take away a safety layer. I'd have to question.

tblu92

Yes in a SD tune you must set the MAF settings in the diagnostics part of the tune file to make them not report Either by maxing some of the tables out or minimizing some of the tables out Plus you need to set all the MAF codes to read NOT REPORTED & NO MILL
Also with some modded applications you also need to "tune out " your knock sensors as they will interpret your nosier engine as having knock when in fact there is none
You can opt to " desensitze" your knock sensors which is a trial and error method or you can simply turn the sensors OFF Depending on your application --- a race only car or a D/D hot rod and the type of fuel you plan on using
Race only apllications tuners will turn the Knock sensors OFF But on a D/D using pump gas it may be best to only desensitize them
In both situations you need to HEAR if you can detect pinging
If you don't hear any then most likely it is FALSE KNOCK due to a nosier engine--Then you can proceed on how to get rid of the timing deducts from false KR
If you are hearing pinging you just have too much timing tuned into your engine

niterydr

What MAF code? There shouldn't be any error codes displayed if it was turned off properly.

bp92gsr

Sorry for just seeing this. The maf code has since been turned off and no CE light now.