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Hp tuners ls1 knock retard problem

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Hi all,

I'm tuning an ls1/l98 it's a l98 engine, going into a ls1 original chassis, the owner is keeping the 4l60e on the car, hence using the ls1 gen 3 PCM. It is using a Lingenfelter converter box.

The car is turbo, running a 2 bar map sensor, has been set to run in speed density. it is all working perfectly fine and the tuning has been no problem so far. Though I'm having a persistent full throttle knock retard issue with some sort of false knock.

We are using the ls1 resonant style knock sensors that have been lathed down and cut to the right thread to fit into the l98 knock sensor location.

I have just about turned the knock sensors down the their minimum sensitivity and it is still happening. The car isn't knocking as confirmed with knock ears.

Each time I flash in a new map, The car will do 1 Full throttle run without pulling timing, then the second time I put the foot down it pulls timing. I can't understand why.

Does anyone have some insight into this?? I have attached a Log so you can see what I mean. At 2:05 you can see the 1st pull, no knock retard. the second and third pulls at 3:38 and 3:50 it pulls max knock retard. This is consistent, 1st pull after a new reflash, no knock retard, every pull after it pulls the max amount.

Cheers, Tom

Attached Files

Can you get your hands on a second knock monitor system? Such as a Plex knock monitor system? Also have you tried pulling timing to see if it goes away? Another thing to try is maybe changing the knock sensors to different ones to see if it's still happening? Just throwing ideas out.

Also it's quite odd that the first run after a cool down and it's not knocking (what i mean is that the sensors don't trip and pull timing) and the rest are after that. Maybe it's a firmware issue? Or knock that's generated by heat or something?

One thing that I wish HP tuners would add is the ability to read the actual knock voltage like on some of the mopar stuff. I always find that helpful because some motors are louder than others but the knock signal will always be linear with RPM. I have tuned some GM vehicles where I have desensitized a knock sensors to values that make you raise an eyebrow. I am actually considering getting the Plex unit