mrfubs

so the guys whos tuning my truck said im losing like 30hp because my knock sensors are picking up knocks and is retarding my timing so much and i can notice it in the pedal and he seemed to think bad fuel or lack of octane so i just refueled with 93 oct, it seemed to help but when i brake torque it at about like 1700 rpms i can feel the timing get retarted even with running the 93.

what i can tell you is when i put the knock sensors in the block when i rebuilt one sensor was pretty dang rusted but the other one was fine. could these sensors be reading incorrect? the engine sounds awesome no ticks or weird noises sounds health and normal.

last stem would be to disable the knock sensors and the consequences to that is if i actually got bad fuel it could really hurt my engine.

Old Geezer

iTrader: (3)

If he's a "tuner", he should be able to data log it, and get some idea as to where the real issue is. Ask him to post the tune and data log[s].
Did you put the sensors in w/ the correct torque?

mrfubs

No i did not torque them to any spec my guess there around 20 ish ft lbs

Burken01

iTrader: (88)

Torque spec is 15 lbs on knock sensors FYI

sepsis

iTrader: (7)

You said 1 of them is pretty rusty, so it could definitely be faulty.

Change them both, seal the plugs with some RTV, and see how that works.

1FastBrick

iTrader: (16)

If there is corrosion on the knock sensor plug you should replace the Harness as well. It's around $30

I prefer not to splice them. Adding splices or having corrosion on the plug can cause resistance that will affect the sensors reading.

Get OEM knock sensors as well.

My self along with several others have purchased some from local Auto parts stores only to have them fail soon after. Replacing them with OEM ones solved that issue.

The one I purchased had the same markings as the OEM unit. I believe it was repackaged under the auto parts store brand. It only saved me like $10 and I ended up doing the Job twice...

N20zuki

Do it right and replace the knock sensors and harness. Don't turn off knock, its there for a reason.

http://www.1aauto.com/1A/KnockSensor...FQVV4AodmwwAGg

http://www.1aauto.com/1A/KnockSensor...CD00047/409573

truckdoug

iTrader: (25)

rtv the valley plugs & dielectric grease on the connections

1997trans-am

iTrader: (2)

Are you sure it's actual knock, versus false knock (sensor not properly torqued)

Try running some ms109 unleaded fuel in it and see if the knock goes away or not.

mrfubs

the fuel that was in it before was 87 and only 2 weeks old, i ran that down and put in 93 still getting knocks. there was a point where the truck was off and he was getting a reading for a split second from the knock sensors. im convinced they need to be replaced

What are the symtoms of faulty sensors?


70% of total driving time up to 23 degrees is being pulled at times more commonly 15 degrees and is enough to rob be almost half fuel economy and way to much power loss talking some times 50% throttle to get up to 55 mph

mrfubs

Still getting a bunch of knock retard, replaced knock sensors with oem delfi sensors and a new oem harness

I also tested from the pcm plug to the knock sensor pig tail for breaks in wire with ohm meter and all tested good

What else will cause this headache?

gagliano7

What kind of mods do you have? May need to change the sesitivity on the knock sensors in the tune.

mrfubs

Just a cam and ported heads with double valve springs cam is 222/230 ,596 600 111lsa and shorty headers, iv been wondering if theyre picking up the noise from the headers.

In a little bit i will attempt to diagnose if its actual knock or burst knock, im going to Back probe each sensor wire at the pcm with the truck running with a volt meter and hope i dont see voltage of any sort, if i dont then its the burst knock that needs adjustment