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A/F ratio is dropping in boost

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Old Aug 9, 2009 | 10:20 AM
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Default A/F ratio is dropping in boost

This just started yesterday. I only have a narrow band gauge, but when I go into boost the gauge reads in the 100's. It usually goes into the 900's. During normal driving it seems to be in the normal range. My fuel pressure goes up into the 60's, so I don't think it's one of my fuel pumps.
Other things a happening, like when I back up my driveway the truck want's to stall. Everything seems to be in order under the hood so I have no idea what could be the problem.
So what do you guys think could be the problem??
Thanks,
Mike
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Old Aug 9, 2009 | 10:27 AM
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Sounds like something in the tune needs to be adjusted.
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Old Aug 9, 2009 | 10:33 AM
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Is it hard to start after the stall?
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Old Aug 9, 2009 | 10:53 AM
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I have a gauge for that
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Originally Posted by charcoal03silvy
Sounds like something in the tune needs to be adjusted.
Really? Are you sure its not one jet in the carb sticking?

OP, you REALLY need a wideband sensor. Tuning for FI without one is risky and inaccurate.
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Old Aug 9, 2009 | 11:22 AM
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Originally Posted by charcoal03silvy
Sounds like something in the tune needs to be adjusted.
I agree, but I've been running the same tune for over a year. This just started yesterday.

Originally Posted by SincalT/A
Is it hard to start after the stall?
It started right up.

Originally Posted by Atomic
Really? Are you sure its not one jet in the carb sticking?

OP, you REALLY need a wideband sensor. Tuning for FI without one is risky and inaccurate.
I think this will be my next purchase.

Thanks guys. What else do you think?
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Old Aug 9, 2009 | 11:42 AM
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You have an air leak somwhere check piping,clamps,hoses.
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Old Aug 9, 2009 | 12:36 PM
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Are you still running a maf?
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Old Aug 9, 2009 | 03:47 PM
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Originally Posted by SincalT/A
You have an air leak somwhere check piping,clamps,hoses.
I'll have to check all of my connections. If I had a loose connection, wouldn't that make me run rich?

Originally Posted by zippy
Are you still running a maf?
I'm still running a MAF. I hear speed density tuning is a real pain in the *** if you don't tune yourself.

Thanks
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Old Aug 9, 2009 | 03:53 PM
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I bet your maf is cracked letting unmetered air in.It happens around 10 psi or so if the set up is blow through.
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Old Aug 11, 2009 | 01:31 AM
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Sounds like a possible MAF problem. Check to see if the sensor has power. Its either messed up or the ground has come loose off the drivers side head in back. Could be cracked also as stated above.

also check and make sure you havent blown the map sensor off the intake, its only held in by the little grommet so thats a possibility
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