XRno1

I tried posting this in the tuning section, and didn't get any response. I also tried searching and didn't find anything that seemed to fit my problem exactly. So, I will try this here...

I just installed Pacesetter LT headers, a Pacesetter ORY, and a TSP lid last weekend. I already had a magnaflow cat back. Other than that the car is stock. It seemed to be running fine up till today. Today, about halfway through a 140 mile trip, it started making a popping sound under hard acceleration in 1st gear back at the rear of the car. Any idea what could be causing this?

Also, I think the car has always done this, but it idles at 800 rpm or so until you start rolling. At that time it will go up to around 1400 and won't come down until you stop again. Is this normal? Thanks for your help.

SSickLS1

iTrader: (2)

As far as your popping noise, does it happen between shifts or as soon as you let off the throttle? If so, it could just be raw fuel backfire. On the rolling rpms question your right it is natural. I just put on some hookers and the difference between idle speeds seems much more pronounced but still ok. Like me you could probably use a dyno tune.

XRno1

Actually it happens right when you really stomp on the throttle, and it seems to be originating somewhere in the left rear of the car. As you continue to hold the pedal down and the RPM's rise, it will stop. It seems to be happening in the lower RPM range in either 1st or 2nd gear. The car is still pulling hard when it occurs, so I don't think it's missing. I'm just concerned that it's a sign that the car is too lean and that I'm going to burn the motor up. Thanks for your help.

mcgodx

About your idling thing, my truck does that too. I think a lot of cars idle higher while moving, I'm not sure why though. Except with me it idles at 700, then when I'm moving it idles at 1200.

01SOMm6

iTrader: (4)

How many Miles on your car? When its making the popping sound does it feel low on power or feel like its bucking on you. Mine did something similiar and it was a bad coil pack.

camaro75racer

iTrader: (1)

01SOMM6 has given a good starting point...could definitely be ignition related. The next thing to check would be weak valve springs, you could be getting some valve float. Also a worn cam or cam bearings will cause this.
PS....forgot to mention fueling....check for sudden drops in fuel pressure or failing injector.

XRno1

Well, the car has 24,000 miles on it. I got it when it had 18,000 on it, and I have not been that rough on it (in my opinion). The person who owned it before me was an older gentleman, so I doubt he thrashed it either, although anything is possible. I just put the headers on a week ago and this problem developed since then, so I doubt that anything would have changed dramatically as far as the valvetrain in that time. I would more think it's something related to tuning, or the way my Magnaflow Catback, Pacesetter LTs, and Pacesetter ORY and interacting with each other.

ChocoTaco369

bah, sounds like rasp to me. my car does it when it shifts at hard throttle (4500rpms and greater). even with the SLP dual/dual it still happens. it's likely from the pairing of the uneven firing order of the engine, a less than perfect Y-pipe merge and the big dent in the pacesetter Y-pipe. the fact that you have an ORY greatly enhances the volume. the best thing you can do to get rid of it is:

-scrap the pacesetter y pipe for a TSP y-pipe (there is no dent in the TSP y pipe) or get one custom fabricated with a good merge.

-run cats

FlashLCD33

iTrader: (8)

I'm interested in how good the car sounds, because that's the exhaust I want to run


If it doesn't feel like you're missing at all it could very well just be the exhaust starting to open up a litlte bit more after some use. If you feel a little missing or bucking I'd check out ignition, probably a plug or wire.

Vz28

iTrader: (1)

Not sure if this answers the question, but I've had the magnaflow catback on my '02 z28 (stock headers/y-pipe) for almost a year now, and it has slowly gotten louder and deeper on hard acceleration, with more backfiring/popping on up-shifts of the m6 as it's broken in -- sounds great IMO, still relatively quiet during cruise. Popping is especially noticable when the motor is not quite up to full-temp yet.