[2016SDSS]

Has anyone who has done the lt4 supercharger swap had issues with part throttle pinging? Like 1/4-1/3 throttle I get a pretty nasty rattle. Shows up on the logs, WOT and deep into the throttle it’s cleared up. It’s just that trying to merge or pass without hammering it down i see like 4-7lbs of boost and it rates pretty good. I’m running my bypass valve off of vacuum. Lt1 injectors and pump. Lt4 in tank pump. Dual nozzle alky control kit.

[95 imp]

Sounds like you might be going lean mid band. What do the O2's say when you're knocking?

The KS clear up at WOT? Or is it knocking there too and it's just not audible?

[2016SDSS]

Logs show its clean at wot. AFR hangs at 14.3-14.6 on my gauge at part throttle. If I stand on it a little harder it dips down into the 12 range

[95 imp]

Cruising might be ok. Under load... it looks lean to me.

[KingLT1]

how much timing advance does it show in that area where it's knocking?

[2016SDSS]

It shows about 16-18 degrees as I roll into the throttle and the knock comes in. It’s generally when I am just rolling into the throttle

[KingLT1]

It sounds like you might need to fatten it up in the transition area into boost of the maf. Is it entering PE mode in the knock area?

You should see afr drop to 13.1 soon as you start to see 1-2psi and then quickly drop to commanded PE AFR by 6-7 psi. If it's still around stoich and you are seeing 7psi, then it's too lean on the hit.

I just fixed a similar issue on my brothers H/C 2300 C7Z. It was lean on entry into PE mode which caused knock around 4400rpm and then recover. I had to add fuel in that area then it was fine.

[2016SDSS]

It’s not going into power enrichment it’s not even seeing that many rpms. The boost spikes pretty quick and it leans out. I have to stab the throttle pretty good to get it into PE and then no issues.

[Joshinator99]

Originally Posted by 2016SDSS

It’s not going into power enrichment it’s not even seeing that many rpms. The boost spikes pretty quick and it leans out. I have to stab the throttle pretty good to get it into PE and then no issues.

You can bring PE on earlier. Sounds like that would solve your problem.

[KingLT1]

Originally Posted by 2016SDSS

It’s not going into power enrichment it’s not even seeing that many rpms. The boost spikes pretty quick and it leans out. I have to stab the throttle pretty good to get it into PE and then no issues.

Agreed with Josh. The LT4 blower gets into boost really quick so you need to change how fast the engine can enter PE mode. That is likely your problem.

[2016SDSS]

Sounds good. Thanks for the feedback folks

[biker2k]

what does the car feel like when its happening
I'm trying to track down a part throttle cruising issue
i have and edlebrock 2300 and not sure if my problem is tuning related or something else like a vacuum leak or electrical

[2016SDSS]

Car feels fine. I just happened to be between songs on the radio and heard the God awful rattle as I got on the interstate.

[biker2k]

mine is different its like sometimes coming from cruising to light throttle car like struggles and then its like almost like a slip then a bang car sounds very blatty when its in struggling mode, its only coming off of cruise back to part throttle. thing is this issue was so much worse before car got tuned.. that the only reason i think there is a chance its correctable in the tune... i have been checking vacuum lines and im not sure the evap canister line isn't leaking.... but know I've gone through 8 million different scenarios in my head and now im driving myself crazy....

plugs look good, wires look good and have been swapped out....
i also have a very choppy cold idle after car comes off fast idle till it warms up then idles rock solid..