cvccbum

Hey all. About ready to give up on this car.. I'm running Justin (skinnies) old LT1. 75lbs low imp injectors with boxes, new opti, 2 bar speed density tune, open loop, no knock sensor. my A/F is great but the car just runs like a slug. it has no buckling or anything, just really slow. in my logs the RPMs jump around, like 3500 3550 3600 3500 3650... anyone have any insight?

RealQuick

Have you tried 1 bar at all?

BTW, what happened to the cast manifold kit I sold you?

cvccbum

Thats the kit thats on it, haha. T76 cast manifold.. I may have to try 1 bar just to see how it goes. It just makes no sense on how it runs so horrible. Good A/F low timing but goes no where lol.

RealQuick

That is definitely not Justin's old kit then because I built yours from scratch, plus he had custom log manifolds, and yours uses factory manifolds.

How much timing are you running?

cvccbum

ah, no. It's not Justins old kit. Its a cast manifold kit, but using justins old LT1 bottom end. Also using his injectors and impedance converters. Timing is low. 18-22~. I'm going to try a MAF tune next.

cvccbum

so i've put the 1 bar on there and loaded an N/A tune that was close to mine. scaled the injectors and played with it some to get it running..

just fyi, my knock sensor is not connected and code 43 is turned off (gotta drop kmember and move the vband to get to the sensor).

with this tune, at WOT, 8psi, at 3750rpm my timing is 31 degrees according to datamaster. knock retard 0 and knock count is 1610 (never moves). if i drop the timing to lower (20s) the car runs like complete crap. the car also wont make any more then 4psi at that rpm if the timing is low. the rpms just jump around and it goes no where.

the plugs are gapped to .030, tr6's.

no codes.

anyone have any idea? could the knock sensor put it into a retarded mode yet display high timing?

MikeGyver

Certain knock sensor failures can throw it into a limp mode where it pulls lots of timing (10°) across the board; Ive presonally witnessed this before.

Try pluggin in a knock sensor but dont screw it into the block (electrically ground the sensor though), so the sensor is there but it won't sense anything.

Also sounds like it might be a ignition issue, especially since boost is being limited (or possible even opti signal issue?).

cvccbum

had the dreaded opti code so i replaced it and it went away. car makes great boost with the higher timing so i'm assuming its pulling without displaying it maybe. i guess all I can do is plug in the sensor before going any further