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Engine Knocking under boost.

natethegreat

natethegreat

New member
The cars top swapped with the stock pulley. I've also had the car tuned for the top swap. Anywho, put a new supercharger on last night, drove it around for a bit and seemed to drive fine. Went into boost nicely. I didn't have a knock meter up because i wasn't going to romp on it too hard. Well accidentally downshifted to 1st at 6 grand. I let off right away but after that the car would buck. Well turns out it knocks whenever its in boost. Any thoughts on what could cause this? Anything that could get knocked loose in the bay that would cause it to knock only under boost? Thanks.
 


why do you guys touch the shiftier after its in Drive? dont down shift these cars, its not good for the tranny. or your engine in this case.

my guess is you broke something when you hit 6,000 rpm.
 
Stock gtp map sensor off a 97 i think. A local guy a few years ago when i did it, and no, i think it was the stock gtp tune with some fueling/timing changed to account for the higher compression.
 


Oh...so this swap was done awhile ago? Only thing different is blower? So, it was running fine just until you drop shifted into 1st? No KR prior to this?
 
It said it had some kr sometimes but it was never was never a lot. I took the belt off and it's still doing it. 2500/3000 rpms and starts popping, and bucking, it will kind of get out it downshift and be fine then do it again at those rpms. In just barely on the peddle enough to accelerate.
 


if you have not done a tune up, it maybe over due. new wires too, cause they might break when you pull them off the plugs.

im runing 104 copper plugs gapped to 0.50 in my top swap. it seems to like em.
 


well put some new plugs in and took it out. I can now drive it somewhat normally. I did some pulls from a stop at max 75% throttle and only 3ish pounds of boost and it seemed to run well. There was on spike of about 8* of knock but it was just split second. It also seemed like if i started at 30-40mph itd knock more but was alot less severe. Not sure i guess. Either way ill put a fuel filter in and see how that ends up.
 
Only reason I was saying fuel filter is because when mine was plugged my car would just fall flat on its face.

Sent from A Galaxy Far Far Away
 
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