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Old 08-07-2013, 11:18 AM   #1
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running rich

my car is running rich at idle and part throttle i did a data log and my maf is reading 290.00 cylces per min what could cause this i tried a new maf and samething
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Old 08-07-2013, 04:41 PM   #2
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my car is running rich at idle and part throttle i did a data log and my maf is reading 290.00 cylces per min what could cause this i tried a new maf and samething
MAF output is not in units of "cycles per min", but rather either counts or voltage where 1024 counts = 5 V. So 290 counts = 1.42 V; or some 150 lb/h of air being ingested. That's enough air to make 17 rwHP or so, which would be enough HP to keep a new-edge GT rolling along at 55 mph on flat ground.

How rich is it running? One thing that can cause what you describe is failing but not yet dead front O2 sensors--how many miles on them/hoe old are they? You can bench test them with a multimeter and a propane torch as described here...
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Steeda UDPs, Ralco flywheel, RAM HDX clutch, 3.73s, 262 rwHP/305 lb-ft.

New ride (7/1/2013) 1998 Mercedes SL500-5.0L 32V VVT 326/347 HP/tq
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Old 08-15-2013, 02:23 PM   #3
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hey sorry i took so long to reply buy i already replaced the 02's and still the same problem runing 10.3 at idle and 11.3 part throttle 10.00 wot my tune guy keeps pulling fuel out and nothing maybe the ecm???
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Old 08-15-2013, 04:43 PM   #4
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hey sorry i took so long to reply buy i already replaced the 02's and still the same problem runing 10.3 at idle and 11.3 part throttle 10.00 wot my tune guy keeps pulling fuel out and nothing maybe the ecm???
WOT operation is pretty much unrelated to the O2 sensors, other than that long term fuel trims are learned in part from the short term trims. You need to look at fuel pressure, the MAF transfer function to make sure it matched your MAF; the high injector slope scalar setting and the values in the Stabilised Open Loop Fuel (SOLF) table in the tune.

Injector pulse width in open loop is "reverse engineered" from the target AFR in the SOLF. The PCM usese what it has been told about the injector "high slope" (lb/h) capacity, air flow from the MAF, fuel pressure (it sort of assumes it is as it has commanded), ECT, IAT and a few other things to calculate the injector pulse width.

If any of these values/assumptions/observations are incorrect then the calculated pulse width will also be incorrect--and the mix will be incorrect...
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SOLD! - 2003 GT, UPR X, FRPP 24lb/h, Magnaflow, PP 70mm TB & plenum, Delta Force tuned,
Steeda UDPs, Ralco flywheel, RAM HDX clutch, 3.73s, 262 rwHP/305 lb-ft.

New ride (7/1/2013) 1998 Mercedes SL500-5.0L 32V VVT 326/347 HP/tq
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