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Old May 8, 2012 | 11:31 AM
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Default Supercharged ls2

I HAVE AN LS2 WITH A TVS-2300 SUPERCHARGER. IT PUTS OUT ABOUT 500 RWHP. MY PROBLEM IS THAT NO ONE WANTS TO DRIVE BEHIND ME ON RUNS. THE FUME SMELL OF GAS IS BAD.
I WAS TOLD THAT I SHOULD GET A HOTTER PLUGS, WIRES AND ALSO A DOUBLE SPARK IGNITION. I AM RUNNING THE SAME PLUGS THAT CAME WITH IT.
HAS ANYONE DONE THIS TO THEIR MOD AND HAD SUCCESS? IF SO WHAT MAKE OF PLUGS/IGNITION SYSTEM ARE YOU USING.
ALSO, UNLIKE THOSE WHO SAY THEIR GAS MILEAGE IS THE SAME OR BETTER, I SAY SHOW ME ....
MAYBE, I'M NOT BURNING THE GAS PROPERLY AND THATS WHY MY GAS MILEAGE IS POOR.

I'M INTERESTED IN GETTING YOUR OPINION. THANKS
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Old May 8, 2012 | 11:59 AM
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If anything, you need a cooler plug, not a hotter one. You can use the AC 41-104 as that is the plug used in the LS9.

Your car is stock as long as you don't put your foot in it and demand boost. If you drive calmly to speed, set the cruise control on 75, you should get the same gas mileage that you got BEFORE the supercharger was installed. The only "load" you are pushing extra is the SC belt pulley.

If you have strong gas smell, you might want to consider someone to double check your A/F with a wideband O2 sensor. It may need a simple adjustment to get your car performing properly.

Elmer

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FYI, Typing in all CAPS on the internet, signifies that you are "yelling".
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Old May 8, 2012 | 12:13 PM
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Thanks Elmer,

What you are saying about the gas m ileage while cruising should be correct. It's not .... I tried that on runs. I do realize that when I get into it my mileage will suffer.
Interesting what you said about the cold plug vs hot. Since you have a supercharger did you change your plugs?
I also agree that an A/F wideband os sensor will help.

Thanks for the info ..... (sorry about the caps)
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Old May 8, 2012 | 12:19 PM
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Originally Posted by rocky7corv
Thanks Elmer,

What you are saying about the gas m ileage while cruising should be correct. It's not .... I tried that on runs. I do realize that when I get into it my mileage will suffer.
Interesting what you said about the cold plug vs hot. Since you have a supercharger did you change your plugs?
I also agree that an A/F wideband os sensor will help.

Thanks for the info ..... (sorry about the caps)

Yes, I've changed the plugs to the AC 41-104s and the car runs great. I get a high 27 MPG cruising at 80. If your gas mileage is not in the 27 range, get that thing back to a tuner and figure out the issue. Some tuners will suggest that you run TR6 plugs but they can cause issues in the Corvette. If your car will run them, then they are cheaper to use but they can give a DIC message of Service Charging System as they are nickel cored and need more voltage at idle to fire. The Iridium plug I recommended does not cause that issue. The AC 41-104/TR6 plugs are cooler plugs than stock by 1 level.

Elmer

Last edited by eboggs_jkvl; May 8, 2012 at 12:23 PM.
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Old May 8, 2012 | 12:37 PM
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Thanks again Elmer,

If I change out the plugs ... do I need to have turned again? Also, did you ever hear about the double spark ignition?

I think I can't go wrong by putting in the plugs you recommend (AC 41-104s) As my father use to say "Columbus took a chance"
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Old May 8, 2012 | 12:45 PM
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You mentioned that you are using the stock plugs? What are they gapped? You need to be .040 or smaller. The TR6 plug is pre-gapped at .039 The AC plug is .040


If changing the plugs fixes your mileage, then no, to the tune but I really think you need to check a few things. If you have the stock plug and it is gapped real tight, then the plugs will not function correctly, You should not go more that .010 in any direction from the stock plug gap.

Last edited by eboggs_jkvl; May 8, 2012 at 12:48 PM.
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Old May 8, 2012 | 12:49 PM
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Rocky, does your car have catalytic converters? If not, then you'll just have to learn to live with the smell. Also, have your tuner go in and do some part-throttle logging and tuning to see where he can clean it up a bit. It will never go completely away, but good tuning goes far in making it more livable.
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Old May 8, 2012 | 12:59 PM
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I am running high flow cats .... I had my tune done at England Green about a year and a half ago. I always seem to have this problem. But like Elmer mentioned, he get 27 mpg when cruising and not into it. I get only about 23.5 doing the same thing. I realize I have bigger injectors from stock and I didn't expect to get the same mileage.

To reply to Elmer, I don't presently know what the gap is on my plugs. However, if I have to pull the plugs I think it will be best just to replace them.

Thanks TNT for your input .... I'll let you both know how I make out.
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Old May 8, 2012 | 01:16 PM
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The bigger injectors don't affect the gas mileage. They simply shoot less gas into the cylinder to keep your fuel at 14.7:1 fuel ratio. I have 62 pound injectors in my Vette. It has 550 RWHP. It gets 27+ MPG when cruising. The bigger injectors only come in to play when you are under boost and need more gas to keep from going lean. You can have 90# injectors and still get 27MPG.

BTW, A6 or M6?

Elmer
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Old May 8, 2012 | 01:58 PM
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M6 .... Makes sense what you said about the injectors. I have to look at my dyno ... If I recall I believe the fuel ratio was 12.6 ... something like that. I'll have to check when I get home. Could that have soemthing to do with it ...?
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Old May 8, 2012 | 02:15 PM
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I found a copy of my dyno ..... the boost was 7.698 psi and the AFR 11.65 A/F
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Old May 8, 2012 | 03:05 PM
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Originally Posted by rocky7corv
I found a copy of my dyno ..... the boost was 7.698 psi and the AFR 11.65 A/F

Those are the figures for the WOT run that measured A/F while you were under boost. It is 11.65 and rich. That is what it should be when you are under boost. Mine under boost is 11.93. When you lift and cruise, the A/F should drop back to 14.7:1 and give you the higher gas mileage. What you need to do is make sure you are getting the 14.7:1 from your ECM. Get it on the dyno with a wide band and see.


Elmer
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Old May 8, 2012 | 04:42 PM
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Sounds like a tune issue running too rich.
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Old May 9, 2012 | 02:03 AM
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I'd also add a catch can if you don't already have one. My car has no cats and it made a huge difference with the smell.
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Old May 9, 2012 | 03:28 AM
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In low throttle or cruise scenarios the car should be running in closed loop which means your fuel trims will auto adjust the car to 14.7:1 AFR. At that point mileage should not be affected, plus it sounds like your larger injectors are at least setup pretty well with the 11.6:1 AFR, this is pretty close to what my car runs at full boost.

Bad or old plugs could be a source of the bad mileage. I recently installed TR-6 plugs ($2 each) and they have been good for over 3k miles already without the service charging system warning coming on even once.

For the smell, I'm guessing it's the high flow cats. I've heard of some that do very little for reducing emissions/smells.
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Old May 9, 2012 | 09:40 AM
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Originally Posted by ashanson
In low throttle or cruise scenarios the car should be running in closed loop which means your fuel trims will auto adjust the car to 14.7:1 AFR. At that point mileage should not be affected, plus it sounds like your larger injectors are at least setup pretty well with the 11.6:1 AFR, this is pretty close to what my car runs at full boost.

Bad or old plugs could be a source of the bad mileage. I recently installed TR-6 plugs ($2 each) and they have been good for over 3k miles already without the service charging system warning coming on even once.

For the smell, I'm guessing it's the high flow cats. I've heard of some that do very little for reducing emissions/smells.
Just like running catless.
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Old May 9, 2012 | 09:56 AM
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Originally Posted by ashanson
In low throttle or cruise scenarios the car should be running in closed loop which means your fuel trims will auto adjust the car to 14.7:1 AFR. At that point mileage should not be affected, plus it sounds like your larger injectors are at least setup pretty well with the 11.6:1 AFR, this is pretty close to what my car runs at full boost.

Bad or old plugs could be a source of the bad mileage. I recently installed TR-6 plugs ($2 each) and they have been good for over 3k miles already without the service charging system warning coming on even once.

For the smell, I'm guessing it's the high flow cats. I've heard of some that do very little for reducing emissions/smells.



Originally Posted by TNTC4VETTE
Just like running catless.

They are for looks in case there is a visual inspection.


Elmer
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