TransAm2k4

After about a year of work i finally finished my car but i definitly have a problem with my car because there is a miss after 5400 rpm and it really hard to get the car to 6k rpm and my limiter programed by MadZ28 is 6900. The opti went new right before working on it last year and since i have moved the car less than 200 miles.

TransAm2k4

The Dyno guy cut the graph at 5400 but you could see that after 90 mph on the first one.

TransAm2k4

I will go ahead and change plugs because i useded them for a little while a bit rich but i don't think that only plugs will make me lose about 100 rwhp. What else could it be

TransAm2k4

TTT i couldn't find this thread for a while.So any opinions on the graph

1racerdude

Valve springs?? Fuel Pump??

TobyZ28

My Higher RPM miss was a bad Coil

TransAm2k4

Fuel Pump might be, Then i would have to check Fuel Press up there right?!?!? About the opti and/or Coil There both are virtually new. Opti i installed a new one right before H/C Swap (might have damaged while sitting on the shop how do i check if it works properly) and the Coil was installed about 500 miles before that from Crane Cams its the one that comes with the HI-6 kit.

WS Sick

Yep attach a fuel gage and watch it as the RPMs climb. If it drops below 40-38 PSI it is in dire need of changing. If it dosent go below 42 or so its strong.

lovescamaros25

It sounds like you might be encountering engine ping(aka.spark knock).Do you run 93 octane?I have encountered a similiar problem when running low octane fuel or running on empty to much.lol.Id also check the fuel injectors,and replace the fuel filter to see if that solves your problem.

TobyZ28

Has this started since the new coil went in? It very well may not be the coil but don't rule it out! Reason is that I was in the same boat as you, i replaced my stock coil with an aftermarket one and decided to "rule out" my coil for my high rpm miss... It ended up the new coil was arcing.. as soon as I replaced it with a new stocker from GM it ran beautifully again.

Is your new coil coated in rubber all around like the stock one? The aftermarket coil i had bought wasnt coated and i'm thinking perhaps thats why it was prone to arcing...


I would definatly check your fuel pressure. Tape a guage to your windshield and watch the PSI at WOT when the stutter happens. It should clearly drop a good bit below 40ish PSI. If it does drop into the 30's replace the filter and check again. If that doesnt fix it its your fuel pump

TransAm2k4

I ran on 93 + 1/2 blended with Octane booster i forgot the name but it was the one that says 25hp on the laberl (BS) anyway i guess i can check for the Filter which is worth about $5.

The coil does have rubber on the outside but it was working good before the H/C swap. Although before i bent the valve there was a little miss in the high RPM which i didn't know what it was. But it was on the 6k zone not 5400. If it's fuel pump i guess i will just have to upgrade to a 255

TransAm2k4

In about 2 weeks or so i will be able to check the car with a Datamaster to see what wrong and i will post it here.