LS1 Running Too Rich - Pontiac GTO Forum
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post #1 of 29 (permalink) Old 07-06-2005, 09:55 AM Thread Starter
 
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LS1 Running Too Rich

I've started to notice that the inside of my exhaust pipes and the arse-end of my car have become very sooty as of late...this, along with the noticable drop-off in fuel economy (at least 1 to 1.5mpg average) point to my LS1 running way too rich. I had suspected it before the transmission failure, but it is obviously much worse now... while it was in for the warranty problem, the dealership performed a fuel system maintenance (cleaning the fuel rails and changing at least one of the fuel filters as to partially recompensate me for their first-time screwup.

What is weird is that with the Accel Blue flat air filter (essentially a European K&N filter) and JHP/HSV MAF tube I added ~10-12k miles back, the car should be getting more air. I haven't popped off the airbox cover yet (I will shortly), but there's no way the filter is dirty enough to restrict airflow this soon. Even assuming that the EEPROM computer did not properly adjust to these new additions, shouldn't the car be running leaner? Can an intake leak somewhere cause weird airflow problems that actually restrict airflow?

So-- I'm looking for suggestions. Should I buy a programmer and lean it out myself (ka-ching), or drag it back to the dealership and tell them to recal the EEPROM since I suspect their fuel service knocked the mixture further out of whack?
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post #2 of 29 (permalink) Old 07-06-2005, 10:49 AM
 
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If you're still under warranty, I'd just take it back to the dealership and see what they say/do. Maybe they can at least tell you exactly what will be happening... it sounds like the cheaper option than dishing some of your money to take care of it yourself. Even if you're not under warranty I'd take it to them and just see what they say is wrong.
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post #3 of 29 (permalink) Old 07-06-2005, 11:06 AM
 
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From what I've read, even just a CAI will cause it to run rich.

I won't know until I get the car tuned. Finally, got a good tuner close by.

We got Houston Goat Herd dyno day Saturday and got 17 signed up. These are all '04 and '05 GTO's. Some modded, most near stock.

I've decided on a tuner rather than experimenting with edit myself.
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post #4 of 29 (permalink) Old 07-06-2005, 12:01 PM Thread Starter
 
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I've disconnectected the negative terminal of the battery to allow the PCM to reset itself...we'll see what that does.

It just seems counterintuitive to me that a CAI setup would make the car run richer...oh well.
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post #5 of 29 (permalink) Old 07-06-2005, 01:14 PM
 
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This is where we're going. https://www.horsepowerengineering.com/shop/

This subject, tuning, mods all for the day's event. I'm curious to HPE's answer.
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post #6 of 29 (permalink) Old 07-06-2005, 01:29 PM Thread Starter
 
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Houston's a bit far. If I can't figure it out, I may take it to these guys.

http://www.tuningtechnologies.com/index.html
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post #7 of 29 (permalink) Old 07-06-2005, 02:06 PM
 
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Quote:
Originally Posted by westell
This is where we're going. https://www.horsepowerengineering.com/shop/

This subject, tuning, mods all for the day's event. I'm curious to HPE's answer.
You said your tuning 05 GTO's? I thought that software wasnt available yet for the 05?
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post #8 of 29 (permalink) Old 07-06-2005, 03:06 PM
 
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Quote:
Originally Posted by Groucho
I've disconnectected the negative terminal of the battery to allow the PCM to reset itself...we'll see what that does.

It just seems counterintuitive to me that a CAI setup would make the car run richer...oh well.
The computer senses that you have leaned out from the intake. It's answer is to throw all the fuel it can at the situation. That ends up leaving you on the rich side.
I know you hate them, but I had the same situation with my Z28. I spent $485 for a dyno tune and picked up 1-2 tenths in the 1/4 mile and my mileage went from 26-27 hwy to 29-30 hwy. It also improved some driveability issues.
With how much you drive the dyno tune is the way to go. I would not do it till you are done modifying the car though, as it will need to be reset each time you add something to the car. Also if you go to the dealer you will need to let them know not to reflash your computer. You will have basically voided any emissions warranty you have too.
Your best bet for tuning is to find somebody that specializes in the LS1. That means you are going to have to go where the mullet-heads with the F-bodies go. Sorry to share that piece of bad news with you, but anything less and you will be disapointed. Check out GM High Tech Performance magazine to see if they have any tuners listed in your area. That's how I found Stropes Speed Shop in Washington, PA, near Pittsburgh, they weren't cheap but definately the best.
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post #9 of 29 (permalink) Old 07-06-2005, 05:26 PM Thread Starter
 
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Quote:
Originally Posted by fergyflyer
The computer senses that you have leaned out from the intake. It's answer is to throw all the fuel it can at the situation. That ends up leaving you on the rich side.
I know you hate them, but I had the same situation with my Z28. I spent $485 for a dyno tune and picked up 1-2 tenths in the 1/4 mile and my mileage went from 26-27 hwy to 29-30 hwy. It also improved some driveability issues.
With how much you drive the dyno tune is the way to go. I would not do it till you are done modifying the car though, as it will need to be reset each time you add something to the car. Also if you go to the dealer you will need to let them know not to reflash your computer. You will have basically voided any emissions warranty you have too.
Your best bet for tuning is to find somebody that specializes in the LS1. That means you are going to have to go where the mullet-heads with the F-bodies go. Sorry to share that piece of bad news with you, but anything less and you will be disapointed. Check out GM High Tech Performance magazine to see if they have any tuners listed in your area. That's how I found Stropes Speed Shop in Washington, PA, near Pittsburgh, they weren't cheap but definately the best.
LOL!

I can suck it up. I think I have a Def Leppard t-shirt somewhere...if I hack a wig just right I'll fit right in.



I'm done modding the engine. She's a daily driver, after all. Is there a cheaper way than buying LS1 Edit or a Superchips flasher to "store" a tune, should it need to be reflashed back to factory settings?

I've hooked the battery back up and drove it around the block. Felt pretty good....but I haven't noticed a performance drop off to begin with...
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post #10 of 29 (permalink) Old 07-06-2005, 11:45 PM Thread Starter
 
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Looks like the computer reset has done the trick. I tried to keep the drive "typical," which essentially means a 80 mph cruise over the 4100' mountain on the 115 mile drive home.

The soot build-up on my clean "test patch" looked clean when I got home.

The end result: 76mph average speed, 22.5 mpg...a 3 mpg gain. I burned a gallon less of gas than on the way to work. That may not sound like much, but if this holds true it'll save ~$5.50 a day in gas...

Gonna keep a close eye on it.
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