(copy and paste from a chat with buddy)

Hey all, new guy here,
My beast of the night is a 1988 IROC-Z, stock L98.

This problem just started yesterday.


ok, so at wot around 4500 rpm ( in 2nd ) the car starts to...-slightly- break up or feel like it, then at wot in 3rd around 3500 you can feel it breking up....( I think it gets worse when holding wot, ill do a back road test again today... )

---first gear its all fine---

-thanks guys, need to get this fixed before me and my buddy put a king of the hill tpi on it.

; P

 

Welcome aboard thirdgen.org.

First thoughts are fuel delivery (fuel pump or fuel filter, or both), or ignition (spark plugs, spark plug wires, distributor cap, rotor, coil, etc.).

 

Check fuel pressure, at idle and throughout rpm range, you are gonna have to look up specs, as I cannot remember where it should be , 48-52psi seems right, but I'd double check that. If low, I'd do like James says, fuel filter, then the pump next.....

 

afternoon all,

updates:

car seams to be doing a tad bit better now...mabye alil faster than what it was just a week ago...mabye this cold air plus the new 180 stat? ^_^
did a freeway pull and the problem started happening around 4K in third, also 2nd mabye ALL fine as well.....my buddy will look at this evening.

-Also I had a full tune up (everything, the mech was a geard head as well and got me a discount ^_^)

this was 12/x/2008 so....I shouldnt need another 1...hmmm-

--wheir was I?....dont remember.

---Guess thatll be all for this up date

----Pat

P.S. cant wait for th weather to turn around and my other buddy to get done with that BIG TPI!!!

 

wheres da pics..........

 

what pics?

 

Put a fuel pressure gauge on your shrader valve, tape it to the windshield and check the FP under load

Or tape a friend to the hood and stick the gauge in his mouth so it faces you.

 

i wont tell anyone who you are.... i had a similar problem it was bad plug wires fine at idle but under a load started misfiring. check for stray arcs under the hood at night

 

ok, mabye im confused.....

Any ways my buddy put it on a scan tool and he said it was fine, but when I did another back roads test and the problem is still their in 3rd....

 

Did a bunch of runs and its still doing it...like a back fire or something, 2nd gear wot around 4500 and in nearly all of third...he will look at it when were both free.......DANG IT!!!