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cobb AP stage 2 too rich? flames?


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Was running stage 2 91ACN SF tune and was shooting big flames mostly 2nd to 3rd upshifts...switched to stage 2 91 acn and same thing. I am running an SPT intake and stock BPV.

 

This normal? Thanks, Nick

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Hmmmm I had this issue when I had an atmosphere venting BOV so I went back to recirc.

You have the ap map from Cobb for their sf intake? If not, it's free to download from their site. I never had a lean/rich issue with this map and an intake. Monitor your AF ratio. Use the gauges in the Ap. make sure it's close to 14.7

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Flame = backfire? Wouldn't I get a CEL for timing issues? I have had occasional CELs for knock sensor and cylinder 2 misfire but they usually occur after a hard launch which doesn't happen often and don't come back after I clear them. I have a brand new knock sensor, wiring harness, and intercooler hose. I'm almost certain that the misfire CELs are from my toasted flywheel and throwout bearing which will be replaced tomorrow.
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Most tuned cars, especially forced induction cars will spit flames with no cats...the cats act as a "flame" arrestor. I have been driving turboed Audi's for 2+ decades and in my earlier years, before the tree huggers made it difficult to run no cats, I ran a number of cars with out cats. I have a '84 Turbo Quattro Coupe with a K27 turbo and big injectors on a MC motor that was tuned in the mid '90's, it also has a 3" turbo back exhaust, no cats, and the amount of fire coming out the back is quite shocking. I will spit flames on every up shift as well as on the over-run....at night it is pretty cool seeing the surrounding area light up because of the flames but I do have to wonder what other people think when they see this.

 

Cheers,

Jim

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Flame = backfire?

 

Close. The flame you are seeing is probably an afterfire (different from a backfire) which is unburnt fuel in your exhaust combusting in your exhuast. I don't think it is a timing issue because I agree that you would be getting CEL codes.

 

The Cobb Stage II map is pretty conservative so I bet you will be running pretty rich. The extra fuel of being rich + no cat is a recipe for afterfires - especially at some load conditions that will almost certainly result in a rich condition (like when you just let off the gas after full boost). I had a stage 3 WRX with no cats and a custom tune and I would get occasional afterfires once the exhaust got hot.

 

So if it is bugging you, the first step would be to get a custom tune which will help you run less rich (either at a Subaru shop or an e-tune from one of the vendors). This will not solve the problem completely though. If you don't want to ever have afterfires you would need to get a DP with a cat. Just remember to make any changes to your set up (DP or ditching the intake) BEFORE you get a tune.

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^yup

 

It's normal with no cat. Even on a good tune you'll get flames sometimes. If you're constantly getting large flames then you're running too rich (which having an aftermarket intake doesn't help with).

 

Either custom tune or go back to stock intake.

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^ thanks for the info! I guess I don't mind it if it's not doing damage. I had heard that you can melt/warp valves when running too rich...

 

Typically adding extra fuel cools things down. Lean = heat. Running so much fuel that you 'wash' the walls can ruin rings.

 

I'm running catless at 16.5 psi, more then your cobb tune and I don't get flames. I suspect something is off.

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this is probably stupid question but...

 

Am I looking at A/F correction 1? 2? learning?...theres a few of them. Then it says "actual" below some of them but that changes depending on rpm. Am I checking on under full load, 3rd gear WOT?

 

 

 

yeah maybe. But if not the cobb intake he should be running lean, unless something else.

 

I agree with you checking his AFRs is the place to start.

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Just learning. You only need to log at idle - they don't change with rpm or anything, it's just the ECU learning to adjust the fuel trims at certain loads. log A, B, C and D (each letter represents a range of engine loads).
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boost leak test using AP?

 

Here is some info on how to boost leak test and other info.

 

http://legacygt.com/forums/showthread.php/checking-general-health-your-engine-and-tune-210369.html

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  • 1 month later...

Not a matter of being rich enough. As you let off the throttle there will always be some small amount of fuel that passing through the engine unburnt.

 

After-fire is probably less likely to happen with direct injection engines as the lag time would be much smaller between injection and ignition - less chance for unburnt fuel to pass through.

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