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Discussion Starter #1
Only mods to the car is a CAI. The dyno sheet pretty much says it all. Anyone run across a car going so rich from such a basic mod? I'm stumped, thinking of pulling the screen to see how much it helps.

 

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Resident 10-second Priest
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What did your tuner say? Sniffer or bung O2 sensor? The hp/tq curves look fine.

You might pull a plug on each side and see if it's actually running rich. They'll be coated with black soot if so.

So my initial guess is something wrong with the sensor.

Padre
 

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Discussion Starter #3
PadreGTO said:
What did your tuner say? Sniffer or bung O2 sensor? The hp/tq curves look fine.

You might pull a plug on each side and see if it's actually running rich. They'll be coated with black soot if so.

So my initial guess is something wrong with the sensor.

Padre
It's the sniffer you see on most Dynojets. The car hasn't been tuned, really don't want to pay for a tune until I have a few more mods on the car. I'm sure it's running that rich. It was a dyno day and all the cars running that day were where they should be (or at least in acceptable range) except mine.

We made two passes with nearly identical HP/Torque curve and same A/F ratio. The numbers are STD (so they appear slightly higher) as his temp/humidity sensor was off and throwing SAE numbers off.

Thanks,
Jeff
 

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I hate you
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With my factory tune (at 3.6k miles) when we ran it on the dyno..that thing was PIG RICH. All thru the pull it read 10.0 and stayed there. They said that I was probably even richer...but the machine stops at 10.0

I had a AEM Brute Force AI on when it was done..oh..and no mufflers.

They said they have seen GTOs running rich..but they were surprised on how rich mine was.
 

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I'm not suprised. Stock, the rear end of my '06 QSM is coated with black soot after driving it for a few days to a week. I want a tune not only because it should be tuned right but to keep my car clean! lol
 

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Well heres the issue most of the time. Being once you add an aftermarket CAI you are adding more air. The factory airbox is cooler, and has air flowing nicely. The second your MAF gets wind of alot more air pumping in, it decides to drop more fuel to compensate for the air. When you get your car tuned you can fix that. Its just the computers way to compensate for the extra airflow that your engine is getting.
 

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Not to mention the fact the GM has these things running rich from the factory already!
 

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Flash99 said:
Well heres the issue most of the time. Being once you add an aftermarket CAI you are adding more air. The factory airbox is cooler, and has air flowing nicely. The second your MAF gets wind of alot more air pumping in, it decides to drop more fuel to compensate for the air. When you get your car tuned you can fix that. Its just the computers way to compensate for the extra airflow that your engine is getting.
If only that were the case. If there is any additional mass air flow it will be negligible on a stock car. What is really happening is the air flow characteristics of the CAI kit are crap (when entering the MAF) compared to the stock setup and are causing skewed MAF readings.

The MAF needs to be recalibrated.

Tim
 

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Discussion Starter #10
Tim05GTO said:
If only that were the case. If there is any additional mass air flow it will be negligible on a stock car. What is really happening is the air flow characteristics of the CAI kit are crap (when entering the MAF) compared to the stock setup and are causing skewed MAF readings.

The MAF needs to be recalibrated.

Tim
I think it might/could be vise versa. Seems like from the responses everyone's CAI has had very rich results (regardless of design or make) and even one totally stock car had the terrible A/F ratio. Doesn't sound like there's a good answer other then tune it out.

Jeff
 

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If you think the CAI is causing the car to run rich the best thing to do would be to throw the stock air box back on. Do not compound the problem by doing even more mods like taking the screen off the MAF. The best thing you could do is to get the car tuned though.
 

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Flash99 said:
Well heres the issue most of the time. Being once you add an aftermarket CAI you are adding more air. The factory airbox is cooler, and has air flowing nicely. The second your MAF gets wind of alot more air pumping in, it decides to drop more fuel to compensate for the air. When you get your car tuned you can fix that. Its just the computers way to compensate for the extra airflow that your engine is getting.

+1 Had the same problem and getting it tuned worked for me.
 

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tuner needs to check his O2 sensor probe and make sure it isn't clogged or dirty. then he needs to re-tune the car.
 

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JeffP said:
I think it might/could be vise versa. Seems like from the responses everyone's CAI has had very rich results (regardless of design or make) and even one totally stock car had the terrible A/F ratio. Doesn't sound like there's a good answer other then tune it out.

Jeff
Ok here is one for ya... let's say the CAI kits remove any pressure drops that might exist with the stock intake/filter assembly. In theory if you reduce pressure drops you will have an increase in mass air flow rates. So then lets for arguments sake say we achieve 15 FWHP with the new CAI kit (all else being equal). A 15 FWHP increase on a 400 HP car is 3.75% increase. All else being equal you would have to have had a 3.75% increase in mass air flow and fuel. This is at WOT... full load. Now at low flow rates (idle/part throttle) you will not have pressure drops you would see at WOT. In other words... stock or CAI.. they should be almost identical when the air flow demands are low. So why would a 3.75% increase in mass air flow cause such a huge change in AFR at WOT unless there was also a substantial increase in compensation (ie. LTrims) at the lower flow rates or very inaccurate metering at WOT. Well we know that at low flow rates the stock box will not be inadequate.

The only thing that is going to drop the AFR that hard (outside of COTs kicking in) at WOT is the MAF not being able to meter correctly because of different flow characteristics going into it - either LTrims are going artificially high at low flow rates or the MAF reads higher than is actually coming in at WOT.

The point here is that the MAF needs to be recalibrated to correct for the new flow characteristics... not because you are now flowing a ton more air... you aren't!

Tim
 
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