TheLlamaGod

my car has 2.5" exhaust with testpipe and no muffler. i get backfire when i shift usually and sometimes on decel in gear. my narrowband sometimes shows no lights when i let go of the throttle and it doesnt backfire. sometimes it has a few lights on though and thats when it backfires. based on the research ive done, i was thinking this was the TPS. at first i thought the backfire was normal but it now im not sure.

am i right or could it be something else?
TIA

CDH-CTT

I have 2.5" exhaust with a Magnaflow and sometimes it backfires too when Im at WOT going through the gears( my narrowband is 3 green deep)....Any chips or anything else you have done to cause it to
over fuel??

Carl

TheLlamaGod

i got chips from lindsey racing for stock exhaust

Adam Poland

Mine backfires and shoots a flame about 3 feet out of the exhaust at WOT banging through the gears. I have LR's 4" exhaust with the Magnaflow race muffler. I also get pops when decellerating. My wideband reads good when this happens though. Does your car stumble when under heavy acceleration?

TheLlamaGod

my car seems to be driving fine. pulls hard at WOT. im just confused why the gauge sometimes shows that im using fuel at times while decelerating in gear. i watched it alot yesterday and even was rich a few times decelerating in gear and it popped like crazy

Adam Poland

Hmm...I can't say I have heard of that one. Have you checked the gauge wiring? Also, I know that on my friends 06 Pontiac GTO, his wideband doesnt read right because of backpressure issues. You can put your foot over one of the exhaust outlets and it will start to read. You could be experiencing the same thing, but I doubt it with a 2.5" exhaust on a turbo car. It could also possibly be unburned fuel floating around in the exhaust passing over the sensor and giving you a rich reading. I dont know if that could do it or not, just throwing ideas out there for you. As long as your car isn't surging under decel or going more lean than you're comfortable with, I wouldn't lose any sleep over it...but thats just me.

TheLlamaGod

so is the TPS not at all in question?

CDH-CTT

No TPS should be fine....you can check the switch point by hand(a really quick way to check and adjust) move the thottle blade cable attachment point by hand and listen for the "Click" that when TPS hits the "first" switch and WOT should be the "second" if I'm not mistaken....
My Narrowband looks like it "turns off" on decel too, but thats a Narrow for you....

Carl

Adam Poland

I agree. Eliminate tps as an issue. And I think the fact that Carl's narrowband does the same thing, I'd just not worry about it.

TheLlamaGod

alright. im installing a wideband hopefully soon. still trying to figure out where to put it and all the wiring details but hopefully that will let me know some more about whats going on

TheLlamaGod

oh i forgot to add that sometimes my car dies on startup unless i give it gas when its warmish usually. also it idles very low at times. thought these could be related? idk im still learning. haha

Adam Poland

I have the Innovate wideband you get from LR. They have a write up on how to install it under the "tech garage" link. It will be the WBO2 Location link under that. This should be a pretty universal location, so you still have your different wideband company options. As for your car dying on startup, does it have the ISV (idle stabilizer valve)? My car doesnt, and will sometimes even die when coasting up to a stop sign.

TheLlamaGod

the bung was already in the testpipe that i bought, but thx. im not to sure what the ISV looks like. ill have to figure that out i guess. do they come with them and then people take them off? or why would you not have one?

Adam Poland

The ISV will be a valve underneath your intake manifold. It is shaped like an upside down "T", with vacuum hoses coming off of either side of the valve. It will have an electrical connection at the top. They are not necessary to make the car run, but a must if you want smooth idle. I would definitely keep it if your car is a street car. When doing a cold start up without one, you have to move the gas pedal to give it some fuel until it warms up, even then your car will sound like it has a nasty cam at idle, or at least mine does. The only reason I don't have one anymore, is because my car has my old race cars engine in it now, where an ISV really isn't necessary. But now that it is back in the street car, I'm dying to have it back.

TheLlamaGod

is that what the venturi delete kit does?