Rich or lean?
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Burning Brakes
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Rich or lean?
OK C5 science guys.....Would a rich or lean condition cause popping or gurgling on deceleration? I suspect a rich condition. I'm at 7,000 feet which could trend to the rich side. Just trying to figure out whether a "Tune" could correct that condition or if I really need to change exhaust to get rid of the popping? Borla S Cat Back.
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Put an x-pipe on the car and I would bet the vast majority of the popping will disappear. It sure did on the ‘00 I had.
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From: Cape Coral, Florida
When I had changed out my OEM exhaust to Borla Stingers I had that "popping" I think you're talking about...installed an X pipe and that basically got rid of it !!
Burning Brakes
Joined: Feb 2006
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From: Stafford Virginia
If it’s on the stock tune still it should be set rich. From what I’ve read GM sent them from the factory with a rich tune for safety reasons. This would cover the car being sent to all different altitude and temperature environments it would be sold and used in and avoid a potentially lean condition. I suspect yours is that way too.
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OK C5 science guys.....Would a rich or lean condition cause popping or gurgling on deceleration? I suspect a rich condition. I'm at 7,000 feet which could trend to the rich side. Just trying to figure out whether a "Tune" could correct that condition or if I really need to change exhaust to get rid of the popping? Borla S Cat Back.
Bill aka ET
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Joined: Sep 2013
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From: Cape Coral, Florida
OK C5 science guys.....Would a rich or lean condition cause popping or gurgling on deceleration? I suspect a rich condition. I'm at 7,000 feet which could trend to the rich side. Just trying to figure out whether a "Tune" could correct that condition or if I really need to change exhaust to get rid of the popping? Borla S Cat Back.
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OK C5 science guys.....Would a rich or lean condition cause popping or gurgling on deceleration? I suspect a rich condition. I'm at 7,000 feet which could trend to the rich side. Just trying to figure out whether a "Tune" could correct that condition or if I really need to change exhaust to get rid of the popping? Borla S Cat Back.
Aftermarket high flow exhausts cause popping and gurgling because they allow unburned fuel in your exhaust to burn because they allow more oxygen to get pulled into your exhaust system. An X-pipe will reduce it.
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Burning Brakes
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Thanks for all the replies, I really appreciate all the ideas. The odd thing is, I called Borla and asked about the X-Pipe and they said it would make it worse???? I may try doing a tune, but that's kinda expensive. The popping and gurgling isn't the end of the world, but I'd rather not have it.
Burning Brakes
Joined: Feb 2006
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From: Stafford Virginia
Why not share your opinion so we can all learn something? I learn quite a bit from your experiences. I’m sure others would too.
Former Vendor
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From: Lookin over Hoover Dam
Are you positive the car doesn't have a tune on it?
Elevation changes will be compensated by the MAF+VE table and the short term/longterm fuel trims based upon O2 narrowband data on closed loop (car warmed and running normally), so decel richness would be avoided, especially given the fact the injectors shut off on decel. There is a DCFO (decel fuel cutoff) entry map that combines with the Baro tables to initiate entry into the DFCO...once the injectors are off, the popping would quit immediately (motor would just be cycling air vs pops=combustion)
Are you running a lower octane fuel by chance? Any codes? Could be possible your car, if truly stock, isn't going into DFCO, which could mean a variety of things visible in a scan. If you scan it actively, once you let off, injector pulse widths go off when DFCO comes on.
Elevation changes will be compensated by the MAF+VE table and the short term/longterm fuel trims based upon O2 narrowband data on closed loop (car warmed and running normally), so decel richness would be avoided, especially given the fact the injectors shut off on decel. There is a DCFO (decel fuel cutoff) entry map that combines with the Baro tables to initiate entry into the DFCO...once the injectors are off, the popping would quit immediately (motor would just be cycling air vs pops=combustion)
Are you running a lower octane fuel by chance? Any codes? Could be possible your car, if truly stock, isn't going into DFCO, which could mean a variety of things visible in a scan. If you scan it actively, once you let off, injector pulse widths go off when DFCO comes on.
Pro
Joined: Jun 2015
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From: Georgia
It sounds like your engine is running too rich due to you extremely high elevation. I would have thought your engine computer would automatically adjust the fuel flow to compensate for this, but if unburned fuel is entering your hot exhaust, maybe the heat inside the system is causing it to ignite and cause the popping (backfiring).
Pro
Joined: Dec 2017
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From: Carol Stream (Chicago suburbs) IL
I almost always hear an off throttle burble ('01 manual, stock exhaust); which I assumed was completely normal. Normal or not, I like it. I'm at 760' above sea level.
Last edited by wdcraig; Apr 23, 2019 at 08:18 PM.
Thread Starter
Burning Brakes
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K.I.T.T.- My car is a 2000 FRC. It was completely stock under the hood, and everywhere else on the car, when I got it a year ago. So, I doubt there was ever a tune on the car. I run 91 octane Shell premium gas, no codes.... just popping and gurgling on deceleration. Only thing I have done under the hood is plugs, wires, and dual filter intake. What ever you just said in your post is Greek to me, but I'm assuming in laymans terms you are suggesting to get a tune???? Probably not something I can find on every street corner in Flagstaff... 
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From: Lookin over Hoover Dam
Well, keep in mind, a "tune" is a simple as sending the PCM away for 150 bucks and getting it back...talking on your basic level tune here, nothing extensive. Does your 1-4 skip shift activate?