I am just curious if a boost leak can cause a misfire. I receantly took my car to a local autocross. Was running great up and on the autocross course(:eek2: :eek2: ). Anyway, on our trip home I was getting on highway and hit 2nd, car misfired extremely bad at exactly 5k, and felt like a wall or rev limit. Exhaust was belowing all kinds of backfire and just sounded awful and wouldnt pull. 4 and 5th gear would boost fine no misfire what so ever. 1st and 2nd do it real bad. I was boosting about 14psi. Also in 3rd the boost would kinda go up and down, felt like my bov leaking, but that wouldnt cause this massive misfire, been down that road before. Any input on this would be greatly appreciated. I for now may see if me fixing around the plug wires helped any, and may check plug gaps. I may get some new tune up stuff if problem persists. Thanks all.

if you have a leak in the piping after the MAFS you will run rich and possibly misfire

Well, I checked plugs today and wires. I re-gapped the plugs down a little bit. I took car out and same problem. It revs to about 5k, and then spits and hesitates for a bit then clears up and keeps revving. It is still like a wall when it starts spitting. I think I will do a pressure test tommor, must be a big leak for this to happen like this. If no boost leaks, what could it be?

If no boost leaks, what could it be?

Worn plugs.

Worn plugs.


These plugs have less then 1000 miles on them. Weird thing is car was running like a champ all weekend long and during the autox. This all started on the way back home from autox. That is why I thinking a boost leak, maybe ripped a coupler or wore a hole in one. Dunno, will look at it soon.

well, just one possibility; it could certainly be something else. For reference though, in the NHRA, they change the plugs after EVERY run. But in your case, I would just slap in a set of new copper plugs as they're cheap and easy to do, and could potentially fix your prob.

Good point.

Okay guys, please give me an opinion. So far today I put in another set of plugs, old ones but worked great when I took them out. I put in a brand new set of wires, and a new rotor. The old rotor was actually cracked, but still nothing different. I will put in a brand new set of plugs tommor and check for a boost leak. Could my stock coil be crapping out on me? The car starts breaking up at 5k rpms every time I roll on gas. It backfires like crazy and then clears up and revs higher. It wont break up if I keep on shifting into next gears and keep gassing it. It is soo weird. I hope I can figure this one out. Thanks.

Could my jwt ecu be any way related to this problem. I had the ecu in car for about a year with absolutly no problems at all. I dont think so but wanted to ask.

Could my jwt ecu be any way related to this problem. I had the ecu in car for about a year with absolutly no problems at all. I dont think so but wanted to ask.

I highly doubt it; you haven't done anything to upset the ecu. It sounds ignition related to me.

i have heard of the camshaft position sensor causing this, and also boost leaks.

i have heard of the camshaft position sensor causing this, and also boost leaks.

spray the connections with tb cleaner for leaks.. what bov u running?:cool:

spray the connections with tb cleaner for leaks.. what bov u running?:cool:

Where exactly is the camshaft sensor? This is b13 highport de. I am running a greddy type S bov. It is working great, as I know when it leaks what happens, been down that road before. Never caused this problem before.

Good news ladies and gents. Got the fucker working. It has to be 1 of 2 things I did today. I went and filled the tank with some gas as it was low. Very unlikely this was the problem *** the damn gas light wasn't even on yet. And the other thing I did was turn my manuel boost controller down a lot. I think that was the whole problem, my cheap ass mbc doesnt work real well turned up high. I think it would spike very high then come crashing down then go back up, and within all that going on it would shoot a crap load of fuel in there and studder backfire, then clear up again. So thanks to all that helped. At least I got a new set of wires and a new uncracked rotor. Boost awaits, later.