Rich Running Causes
10-28-2010, 04:32 PM
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Rich Running Causes
Running so rich that it stalls at idle in about 15 seconds. I can keep it running with accelerator but I can smell the gas in the exhaust . LH is a recent rebuild so I suspect something else. WOT switch is not closing but not a cause for rich. Temp. Sensor and MAF have right resistance values. Any suggestions to check appreciated. Extensive maintenance on front of engine but I can't find any broken wires.
10-28-2010, 05:35 PM
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1. Vacuum leak on top end; had to seek outside help with a smoker to find it (that's what he said anyway.) I had replaced everything on top and in valley. 2 Also the cat had been gutted.
10-28-2010, 05:41 PM
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Pull the small vacuum lines on both fuel pressure dampeners and the fuel pressure regulator. Check for any trace of fuel in each of the lines. Any trace of fuel means that the leaking unit must be replaced.
10-28-2010, 05:58 PM
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Thanks Wally,
I think I can smell gas on the front dampener but it is very faint and maybe wishful thinking. How strong should the odor be and would it be better to play contortionest and get my nose to the dampener ?
I think I can smell gas on the front dampener but it is very faint and maybe wishful thinking. How strong should the odor be and would it be better to play contortionest and get my nose to the dampener ?
10-28-2010, 06:22 PM
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I started it up to try for fresh gas smell and amazingly it didn't die because I hadn't hooked up the MAF. I guess that means my MAF is toast even though element resistance is OK. How can MAF failure cause rich mixture ?
10-28-2010, 07:04 PM
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You have proved your MAF has failed. THis is a not uncommon problem, due to a Bosch design fault. The output stage can go into thermal runaway. THis causes the over - rich mixture. I always correct this design fault on all my rebuilds (Bosch corrected later MAFs for this problem)
The resistance check will check out OK, even if the MAF is toast, like yours. Louie Ott in OR stocks my MAF rebuilds.
http://www.performance928.com/cgi-bi...pass_parent=0/
The resistance check will check out OK, even if the MAF is toast, like yours. Louie Ott in OR stocks my MAF rebuilds.
http://www.performance928.com/cgi-bi...pass_parent=0/
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10-28-2010, 09:22 PM
#8
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You have proved your MAF has failed. THis is a not uncommon problem, due to a Bosch design fault. The output stage can go into thermal runaway. THis causes the over - rich mixture. I always correct this design fault on all my rebuilds (Bosch corrected later MAFs for this problem)
The resistance check will check out OK, even if the MAF is toast, like yours. Louie Ott in OR stocks my MAF rebuilds.
http://www.performance928.com/cgi-bi...pass_parent=0/
The resistance check will check out OK, even if the MAF is toast, like yours. Louie Ott in OR stocks my MAF rebuilds.
http://www.performance928.com/cgi-bi...pass_parent=0/
10-29-2010, 05:26 AM
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http://www.jdsporsche.com/sharktunerfaq.html
