car backfiring

[_Madman_]

Basically the problem is that under some circumstances car kinda hits back when I let of gas a little. I don't really understand what might be wrong and where to look for the problem.

Last mods that were done to my car is upper IC pipe + BOV, but I cant say that this weird behavior appeared right after mod, nor can I say that it's very common.

I usually notice this backkick when I'm in 3rd and around 3-4k rpm, letting gas off a little.

 

[rc000e]

Did you recirculate the bov? Did the problem start upon install of the new parts? The MAF meters air going into the motor. If the bov isn't recirculated anymore it's going to cause rough performance.

 

[_Madman_]

No, the BOV is recirculated, and works pretty fine, so I doubt it's the problem.

 

[dan2288]

It usually happens when I give it some gas and then get off it, Theres this loud poping coming from the exhaust. What could be causing that ?

 

[xxraptor660xx]

Check your plugs, wires. Is there any smoke? Please be more specific.

 

[dan2288]

yea, i changed my plugs yesterday and it seemed like it ran better for a little. A couple hours later it was doing the same thing. And when i get on the gas, theres black smoke coming from the exhaust...so im probly running rich. Im gonna tune it one of these days...

 

[jcurcillo]

There is a rich condition in the exhaust. The unburned fuel is getting into the exhaust and be burned off causing the pop. It could be your plugs, wires, fuel system, or a number of other things. He is right. Be more specific. Is the car stock?

 

[92dsmtalon]

Im just going to guess he has the BOV vented, causing it to run rich.

 

[jcurcillo]

There you go. When you let off the BOV vents air the ECU thinks is going into the engine. The ECU ads more fuel according to the air intake, but some of the air is vented causing a rich condition.

 

[dan2288]

No, my BOV is recirculated. I think It just needs a good tune because it is running really rich. I see black smoke pouring out of the exhaust when i go WOT. Now i just gotta figure out how to use DSMlink...

 

[zero97tsi]

Has it been tuned at all? With the modifications you have, yes, it does need a good tune. I wouldnt even drive it until it was tuned with the setup you have.

If not only that, check for any boost leaks. Sounds like it could be coming from that as well.

 

[turboglenn]

do you have a logger? could be the TPS not returning to 0%...when you let off teh maps should cut fuel on decel untill around 2k rpms, and even when it's at 1% or so teh map should be fairly low on pulse width.. it could be that the fuel is so lean because of teh no load and the TPS not going fully closed that fuel vapor that's not burning is building up then igniting in the exhaust at once and causing that popping...ever heard a harly with pipes poping really loud when coasting down the RPM's? it's because teh big pipes make the mixture leaner and the pilot crcuit of teh carbs isn't putting enough gas in teh jugs to burn so the vapor builds untill there is enough to light off then it makes a loud POP.. just a thought... when my TPS goes out of adjustment i have my :low load" bars of my maps tunes SO lean that itwill do that... if you're on a stock ECU it would be less likely but still possible.. not saying that this isn100% your issue, but it's something to think about

a lot of times this can be mistaken for a rich condition but most of the time it's ctually lean.... too muhc fuel will burn but when it doen't burn completely it "burrbles" ( best way i can decribe it ) when it's too lean it won't actually burn untill enough builds up then it usually catches fire and pops...

 

[snowborder714]

Is your AFPR set properly to 43.5psi (with the vacuum line off)? Do you have DSMlink set to accomidate your 950cc injectors?

 

[No_Skillz]

How about a proper BLT?

 

[turboglenn]

How about a proper BLT?

bacon, lettuce and tomato?

some of these acronyms confuse me.. what's a BLT?

 

[No_Skillz]

Boost leak test. Although when I say it, I would like a bacon, lettuce, and tomato to go with it.

 

[turboglenn]

oh.. cool thank you.. god the lingo we use in the shop is so different from all teh DSM forum lingo i'm gettign too confused on too much stuff :

we have widgets, whtcha-ma-call-it's, thinga-ma-bobs and doo-hickies

sorry to go OT

 

[turbosax2]

oh.. cool thank you.. god the lingo we use in the shop is so different from all teh DSM forum lingo i'm gettign too confused on too much stuff :

we have widgets, whtcha-ma-call-it's, thinga-ma-bobs and doo-hickies

sorry to go OT

http://www.dsmtuners.com/forums/showthread.php?t=211093

BLT didn't make the list, apparently.

 

[No_Skillz]

That is SO 2006. Get with the times, brother.

 

[blcknspo0ln]

I guess only Chinese people know about BLT's Or maybe it's from FWD-land

 

[Defiant]

Exhaust leak.