Hey all,

This post concerns my 1986 LB9 Tuned Port Injection engine, VIN F

Basically, the title of this post says what's up. I've got backfiring going on through the intake and I've just about had it with my camaro. Just whem e and my dad FINALLY get the idle speed set the right way, including adjustment of the TPS voltage, we have a new issue with backfiring pop outta nowhere.

I've owned this car since December 24, 2001. It has NEVER backfired on me before. Now it suddenly just starts. I thought it was the plug wires. So I got brand-new ones and put them on my engine, being careful not to rest them on anything that could damage them while the engine is running. Nope, that solved nothing. I still get backfiring through the intake. And then, my father goes to check out the timing, disconnects the EST and everything, and tries numerous degrees of advance or retard, and nothing changes. Even at 6 degrees top dead center, it still backfires.

It only backfires when I accelerate. Never when I slow down or just idle. I mean, what the heck would cause this thing to just start? I have receipts from the original owner proving that there is a new distributor cap and rotor in the car, and that's not solving anything.

I checked for vacuum leaks. Can't find one. I only found one, leading to the passenger side PCV valve, but I know that wouldn't make it backfire because that hasn't had a hose hooked up to it in a long time and it never backfired before last week.

I can only think that my gutted airboxes may be causing it. Also, my gas cap hisses loudly when the car runs, and really hisses when you unscrew it to take it off, so I think I need a new one of those. But I can't see how that would make it backfire.

Well, if anyone has any info on what the heck is going on, please let me know. I'm about to throw in the towel with this car. And judging by the way this car has been, I can see why so many go import or so many thirdgen owners go tbi or carb. I thought I could learn from a TPI model since fuel injection is the thing now. Boy do I regret that now.

Again, my engine is a 1986 LB9 Tuned Port Injection engine, VIN F.

Kevin

 

How are you checking for vaccum leaks. That is what it sounds like. I don't know if I'm correct or not, but I think the ecm uses the maf readings for timing the injectors and if the maf is off then that timing gets messed up. Mine was doing the same thing and it was a vacuum leak. Car idled great, no surge or buck, rock solid. Hope you get it worked out.