Popping In Exhaust

[86Nick]

When At High Spped I Hear A Popping Noise In The Exhaust When Letting Off Of The Throttle Is This Normal?

[Keller]

If letting off the throtle under boost, you may be hearing 'compresor slam' or 'sneeze'. Basically, air backing up against the compressor with nowhere to go.

[JSAautomotive]

What is your setup?? What kind of turbo, intercooler, mods, etc?? Do you have headers or exhaust manifolds?? Theoretically, if you are popping inside the exhaust system on decel, it's usually from a rich running condition and excess air or oxygen in the exhaust causing the excess fuel to ignite in the exhaust system. If you are getting this on a rapid release of the throttle after hitting the car with a heavy load, the backfiring in the exhaust doesn't make sense. Mainly because the Buicks are A-syncronus Sequential fuel systems. In other words. When the ECM sees idle TPS, low MAF readings, but higher RPM's, it will cut off the injectors out sync with the crank sensors input. This system also can pulse the injectors out of sync with the crank sensor too, much like a carburators accelerator pump works independantly of the distributors ignition pulses. I would suspect an air leak into the exhaust on decel. As Keller stated, this "could" be caused by the backing up of air, and that air making into the exhaust system on the overlap portion of the cam.

Lastly.... I had a Buick at the shop one time that had a complaint of backfiring and or bucking between the speeds of 55mph and 70 mph. And the guy would describe that when he got the motor right in between the area of barely accelerating and decelerating, he could make the car do it. We checked everthing when it came to all the computer inputs and outputs, and everything looked fine. When we put a portable secondary ignition scope on the car and looked at the firing lines when the problem happened, we saw alot of turbulence within the cylinders. We then installed a lab scope on the cam and crank sensors and sync'ed off of one of the crank sensors square waves. Then we saw the problem. We saw the cam sensor square wave moving forward and behind the crank sensor square wave it supposed to correspond to. In other words, the 2 signals were phase shifting. And it was all because of the timing chain ready to fall off the engine. Replaced the timing chain, and all was fixed.

[86Nick]

My Car Is All Stock Except For Chip, K&n Filter, Fp Reg, 3" Dp And Hooker Exhaust. The Poping Noise Seem To Start When I Did A Chip Change. At First I Had A Atr Pitbull Chip And Did Not Hear Any Noise.then I Tryed A Kenne Bell That When I First Heard The Noise. The Chip Made The Car Run Really Rich, So I Made Another Change. I Now Have A Red Armstrong Chip And It Runs Damn Good, But The Poiping Is Still There.

[JSAautomotive]

Well.... just like in drag racing. Make only one change at a time. Otherwise you won't know what change did what. I would assume since you noticed the change after changing the stock chip, that putting the stock chip back in would be a place to start. If the problem is still there, then you know it's not the chip causing the problem, and something else just went a rye consiquentially.

When you let off the throttle, is it a quick slam shut release or gradual rolling back off the throttle release? Does it sound like popcorn being popped out the tailpipe, but much louder?? The popcorn sound would indicate an ignition misfire.

[86Nick]

I reinstalled the original chip and no problem with idle was repeated. the chip that was causing it to run with a crap idle was a red armstrong. i guess the calibration is different.

[JSAautomotive]

This is the problem with someone programming a set of fuel and timing tables that is 1/2 way across the country for your car. You can take 2 cars that are set up alike, and both will require a different tune. I'm going to be getting the Maf T Pro, because it seems like the adjustability is there, and it wouldn't require having a stand alone fuel system to have full control over your setup. After buying an LS1 style MAF and a translator, you're almost at the same price as what the Maf T Pro would cost.

[Keller]

If you are having a problem with one of Red's chips, call up and talk to him or one of the other people there. They'll work with you to get it right. Or at least try to.

[JSAautomotive]

Sorry about that Keller. I didn't mean to step on anyones toes here ;)

I'm sure red Armstrong has a great product and is a great tuner. His reputation seems to be pretty strong amongst the Buick people out there. Having personally worked with alot of different fuel systems (Motec, DFI, FAST, etc) prefer taking things into my own hands. You know what they say, "knowledge is power". And I always try to get my friends/customers into understanding the feedback system process and how it works. Gives them the power to understand their own individual situations.

[86Nick]

That's a good idea Keller. How can I get a hold of Red Armstrong and his company? do you have a email or phone number? Other then the popping in the exhaust and idle problem the chip works great.

[Keller]

See our vendors list on the web page. The only means of contacting Red is by phone, during normal business hours.

[kenmosher]

Quad Air Inc.

http://www.gnttype.org/vendors/index.html#Q