Exhaust popping on down shifts????

rio95 · Sep 5, 2004

About two months ago, my car just started to pop and occasionally backfire when i down shift. It does it on very small ones even. If I'm slowing down in gear above 2k and i'm giving no gas it just starts to pop. It sounds horrible. What would cause this (timing???)??? It did this with my flowmasters for about 3 weeks, then I got a bassani cat-back and i'm still stuck with it. It didn't do this at the beginning of the year.

Any idea's??? I'm embarrassed driving it.

thanks

nmcgrawj · Sep 6, 2004

Could it be just a thing with h-pipes? Thats what i would think.....thats until someone with an X or prochamber chimes in and says they hhave the same problem.

My flows with an offroad H do the same thing. It used to do it A LOT when my timing was wayyy off when i first bought the car. But now it only happends every now and then....

Rootus · Sep 6, 2004

That's a rich condition (or timing, which is another version of the same thing). I've never gotten it at all, with any exhaust combination ... I kinda wish I got a *little* bit of it. I must be a redneck...

Dave

95five-0 · Sep 6, 2004

mine does it when I rev the engine in neutral but doesn;t just driving around. Did start intill I put my x pipe on.

TrueBlue95GT · Sep 6, 2004

Check your timing, fuel pressure, and check for any exhaust leaks.

RIO5.0 · Sep 6, 2004

Thats an H for ya.... Always hated that....Bring it up to 3500 in 3rd and let off it...she's gonna sound off bigtime....mine was wicked if i was coming up thru the gears and had to let off it real quick...it would also do it running up thru the gears, taching it right up...i also had my timing at base of 10 then, it would ping otherwise..
Thats what i refer to as the "Dukes of Hazzard" sound...
I dumped my H for that very reason....

nmcgrawj...Have never heard this from my Prochamber....

final5-0 · Sep 6, 2004

I'm with Dave on this one and I seen my wide band confirm it.

Later
Grady

TheDamned · Sep 6, 2004

mine always backfire and I love it lol
sounds like an harley

rio95 · Sep 6, 2004

obviously an h-pipe is going to have a raw sound, but nothing like this. I may be able to check my air/fuel out next weekend and the last time I checked my timing, it was at 12. I do have an exhaust leak too, so that doesn't make the sound any better either. One of my friends has longtubes with an x and his car started to do the same thing as mine, but not as bad.

Any suggestions on what to have the timing, air/fuel at???

TrueBlue95GT · Sep 7, 2004

Well exhaust leaks will make that popping noise louder, due to oxygen being mixed with the unburnt gas and igniting. aka small backfires.

rio95 · Sep 8, 2004

i got the codes pulled on my car today and I came up with this.

176, 189, 132 or 133(can't remember)

This pretty much means that the left o2 sensor is saying my car is lean and the right is saying rich, which doesn't make much sense. I am going to try new o2 tomorrow probably and possibly get the leak fixed too. I'm hoping this will help or completely take care of it.

gcomfx.com · Sep 8, 2004

rio95 said:
i got the codes pulled on my car today and I came up with this.

176, 189, 132 or 133(can't remember)

This pretty much means that the left o2 sensor is saying my car is lean and the right is saying rich, which doesn't make much sense. I am going to try new o2 tomorrow probably and possibly get the leak fixed too. I'm hoping this will help or completely take care of it.

Makes sense if your left header is leaking and getting air into it.

Mine backfired A LOT when I had my high flow cats put on. I never knew why until I removed my Smog pump. The tubing going to the cats had been poorly transferred from the stock cats to the new ones. They filled the tubing with a lot of weld and it only had a small pea size opening left. I cut off that tube and the popping instantly stopped. It did make a funny noise til I plugged it though.

I must be a redneck too... cause I miss it. My g/f does too. We used to scare people all the time. Drive down hills in low gear and listen to it rumble. Last summer we went to Branson (tons of hills) and our hotel was by a miniature golf course. I could build a little speed, then drop it in 2nd and it would make one big POW.... then rumble, rumble, rumble..... one "golfer" knocked their ball into the water by the pirate ship. It was great!

1105 · Sep 8, 2004

Didnt read all of the posts but if you dont have any exhaust leaks and its still poping, take off your smog pump... My car was doing the same thing, took off my smog pump and hasnt poped since. My guess would be its your smog pump

rio95 · Sep 8, 2004

The smog crap is already off.

chrismillion · Sep 8, 2004

rio95 said:
The smog crap is already off.

i don't know what excatly you mean about the smog crap, but mine was doing that until i took my converters off. i liked the sound personaly.

Joe 5.0 · Sep 8, 2004

I thought it had to do with the baffled muffler design of flowmasters? Mine will pop (not backfire at all, ever) if I run it to redline and let off without shifting out of gear, or if I downshift into gear and let it coast down. I have a o/r h-pipe & 2 chamber flows.

ChromeYellow94 · Sep 8, 2004

Yeah....we'll put in my o2's out of my cobra in the car tommorrow and see if that fixes the problem. I don't need them anymore cuz my car is tuned in open loop (thank god).

If that fixes the problem than that would explain why the car didn't trap what it should have....too rich...

rio95 · Sep 14, 2004

update:

It ended up being an exhaust leak. I knew for a while that I had a "little leak" and didn't realize that it was a "huge" leak that was so loud I couldn't really tell where the popping was coming from while driving. A few days ago, we popped my hood and revved it up and could easily tell it was leaking from the driver side manifold collector. I got it all tightened up and all is well.

thanks

gcomfx.com · Sep 14, 2004

LOL - so the drivers side is the left side right? With the lean condition in the codes? Or was I 100% arse backwards on my guess?

Killer95Stang · Sep 15, 2004

hmm.. I guess I should fix the exhaust leak on mine as well... I know I'm not a redneck, but I love the sound as well..

Exhaust popping on down shifts????

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