i recently had my 93 LT1 supercharged with a paxton charger 6-8 lb boost....my car is automatic.....when i get on the gas at about 4700-5000 RPM my car stutters and wont accellerate until i let off the gas.....it isnt hitting the rev limit cuz it isnt bouncing....it seems as though when it gets to that RPM range it is lacking something....gas for example..........i was told that i may need to upgrade or replace my stock fuel pump because it isnt putting out enough gas at a constant rate since it is under so much more pressure form the charger.......i didnt upgrade my injectors b/c the kit came with 3 extra injectors that function so i have 11 injectors going ......BASICALLY any ideas what may cause that stutter at 5000 RPM....Thanks

 

Have you gapped your plugs down to .035? I had a little bit of probably what you'd call stutter till I changed the gap when I was at peak boost on my turbo at high RPM. While I was at it, I tossed in some cooler plugs (Autolite 104s???). This totally fixed my problem.

 

hmm ur saying i may need different SPARK PLUGS huh.....im not familiar with gap sizes and what that means...but if i need a .035 gap....well, what is the stock gap.....like, ur saying i need less or more of a gap...and a gap between what and what?...also, what you mean by cooler plugs? ha to many questions? thank you

Gio

 

The label under your hood will list your stock spark plug gap (the distance the little spark has to travel to go from the little puck in the plug to the hooked piece of metal over it. It probably is .050. Going to .035 shrinks the gap.

Apparently, on forced induction motors, it's common for "spark blow out" to occur if the gap is too large. I don't know the theory behind why this happens, but the smaller gap cures the problem.

A 1 step cooler spark plug will allow the plug to dissipate heat a little better. Since these engines have such high compression, their biggest problem will be knock retard at high RPM. A cooler plug should theoretically reduce the chance of this?

Plugs are really cheap. It's the effort of putting them in that costs the money (or the sore back and scratched up hands/arms). So see what plug your tuner recommends if you're going to go to the trouble to pull them out and re-gap them.

 

ok i gotcha - well i can get the plugs installed for free...just like my charger was installed for free.....my friend goes to an autoschool after his high school classes and they used my car as a demo car for them to work on.....so if i buy the plugs then i can get it done b/c yes, i nko on these cras a tune up is a pain in the ***....thanks for your suggestions though - appreciate it

 

Do you have an MSD ignition Box like a 6a or 6AL?
If not, get one. I have heard of many guys at that boost level without and MSD box that have this problem. After they get the MSD box it solves the problem (probably do to the stronger spark energy).

Hope that helps,
Claude

 

Don't over look the basics like "weak" valve spring pressure.

 

You took the words right out of my mouth...

I had the exact same problem until I got a new set of valve springs, then the problem just went away

 

Hadn't heard of that. Wouldn't that typically be related to a cam change or higher rev limit? Or is that something caused by adding boost?