Kevin91Z

iTrader: (1)

At the track yesterday, I was getting 6 degrees of knock retard after shifting to third and fourth gear. I was running 103 octane and total advance was 33 degrees. There's no way that is real knock, so it has to be false knock. Is there something I can do in the chip to combat this?

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1991 Camaro Z28
5.7L 5-Speed (originally 305)
317 RWHP, 418 RWTQ
13.23 @ 107.62 MPH
Southern California
Member: SoCal 3rd Gen F-Bodies
Member: SoCal F-Bodies
-=ICON Motorsports=-

Kevin91Z

iTrader: (1)

No ideas?

fast_broker

iTrader: (1)

Disconnect the knock sensor while at the track.

Sarkee

(I've gotten "false" knock counts while shifting at redline; something to do with "overrun")...

fast_broker

iTrader: (1)

I believe that the tranny shift just causes inherent vibrations that trigger the knock sensor, especially if you have a vette servo and/or a shift kit... That's why I don't use it when racing. I actually have a dash switch to disconnect it FAST, if I need to.

sparks383iroc

I took my car out on Sunday for a little test session with my EASE scan tool. Whenever I was at WOT and made a 3 to 4 shift (auto tranny) I would get a knock count of 114 and it would pull out timing. All during the run and other shift points, I would get zero knock counts. At first I thought it was tranny related, but I'm not sure since it didn't happen with the other shifts.

Doesn't help any, but I'm curious like you on what is going on.

Sparks a flyin'

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1989 L98 IROCZ, Bored .030 over,400 Crank,Dart PRO 1 Heads 200cc intake,ZZ3/ZZ4 Cam,Crane 1.6 RR,Edelbrock 3860 Hiflo TPI Manifold, AS&M LTRs, Edelbrock 58MM TB, Ported Plenum, TCI Reverse Pat Man Valve Body, SVO 24# injectors,TCI Streetfight Stall Converter, 3.23 Gears on Auburn Pro Posi, Some Suspension Mods

Kevin91Z

iTrader: (1)

I dont have a Vette Servo or a shift-kit, I've got a manual trans.

If I disconnect the knock sensor, wont I get a Code 43? I have before... But it'd be an idea to try next time.

Grumpy

Airflow allows lags rpm. In the VE computations there is some filtering which even worsens this.

A few patchs that use BKR at various VSS values would ignore the *shift* problem. It's not a false knock by any means. Just one that's hard to work around.

What most folks totally forget about is what is really going on during a shift. Your goiing from just above max HP to max TQ. max TQ is where the BMFC is best, so it's kinda lean there. But remember the AF is begining delayed slightly.

While not your problem since we're talking about shifts. The same thing is for converters. The looser the converter, the faster is get away from max TQ, and back to max HP AFR. So too tight of converter can be a real problem other then just at launch.

You (them)(others) need to remember there is stall speed and flash speed on comverters, and the flash speed is what determines how you recover from a shift. BTW, most converter guys just stare into the heavens when you wanna get to the nitty gritty about converters.

Also explains why you can't get a decent converter for less then $800US.

DM91RS

Mine knocks when I rev it with the clutch in. Guess the knock sensor is too sensitive?

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91 RS 5.0 TBI....LT4 cam....Edelbrock headers....3"Dynomax exhaust....5spd.... 3.08.....Ultimate tbi....afpr...

fast_broker

iTrader: (1)

I can say it ten times but just disconnect the knock sensor at the block...

You will not get errors. Just no retard on knock, so be careful!!!!!!!!!!!!!!

Grumpy

trouble is then you have to tune for the lousiest gas you might run into. If you mean at the track then you should be real good reading plugs before thinking of this.
Why not put the time in and figure things out?.

Kevin91Z

iTrader: (1)

Grumpy, I'm not sure if I understand your first post. Are you saying this happens because the air/fuel ratio is different between where I shift and where the RPM is after I shift? That is true, because I have to lean it out at upper RPMs with the 24lbs injectors. Do you think I should richen it up a little at 3600-4000 RPMs where the RPMs fall back to after a shift?

I'm also not powershifting, I'm sure the computer gets really confused going from full-power, to off the gas, to shifting, to full-power again.