Hello I'm new here would gratefully like some help here is the the problem my 95 Z28 starts to back fire at 4500 rpms got a hypertech programmer and moved the limit to 6500 and still get back firing new spark plug wires and I'm running ngk plugs in not sure about the optispark need help on what the problem is any advice would help thanks

 

I'm at a loss about what it is that you moved to 6500???

Anyway, more details are needed

example: all stock

egr/air deleted, long tube headers installed

aftermarket cam installed and now it has issues etc etc

 

Ok sorry I reset the rev limiter to 6500 with the programmer and it has a hot cam long tube headers egr removed ported heads and when I get on it it starts to back fire about 4500

 

did it start doing this all at once or is it gradually getting worse? did you replace the plug wires before or after the problem started?

 

Craby it's an engine swap I got the car on cl and the engine on cl to I just got it running it runs fine I just can't floor it cuz it starts to back fire at around 4500 and the spark plug wires are new got them on ebay not name brand some 10.4 mm $40 dollar ones

 

was it always an LT1 car or was it a sixer?

When you swapped the engine, what year is the engine and did you use the old ECU or the one from the "new" engine?

full disclosure is needed please. No nugget of info is too small

 

so its been going on from the engine swap? before and after plug wire swap? did you look inside the opti or transfer the one off old engine?

 

Backfire: popping out the intake.
Afterfire: popping out the exhaust.
Since the term backfire is often misused, which one do you have? There are different causes for each.

 

hmm, to add a little levity, and it is April 1st........

Afterfire........that's what I'm now going to call it. And about different causes, my wife swears that I don't need a reason and afterfire still happens.

I blame her cooking.

 

craby this is a new engine I got on cl I've only had these wires on there I want to know if it's the cheap wires or the optispark and I haven't checked the optispark