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gumba's Avatar
 
Join Date: Dec 2001
Posts: 3,962
strange a/f ratios

Everything has been running fine until recently. A few weeks back I noticed the motor went way rich, 9.5-10:1 under acceleration (1/2 throttle) getting on the freeway. When I backed off it would go back down to 12-12.5 at cruising speeds. Recently, after the motor warms up, at idle the motor goes way lean, 16:1. When I start driving it goes back down to 12-13:1. It's not the gauge/sender because the motor is reacting to both conditions.
WUR pressure is 38 psi when warm.
This is a modified 3.3 motor, cis, wur, Electromotive xdi single plug. I have another WUR I can swap in but thought I'd check here first.
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Harold
'79 930/DP935
'68 VW 3.3 Turbo Crewcab
Old 07-01-2019, 03:17 PM
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T77911S's Avatar
 
Join Date: Oct 2006
Location: MYR S.C.
Posts: 11,863
you have an air leak on the pressure side.

the turbo blows air OUT requiring more air in thru the AFM making it run richer

then sucks air in at idle making it lean
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Old 07-02-2019, 02:46 AM
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That was it.
Thanks
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Harold
'79 930/DP935
'68 VW 3.3 Turbo Crewcab
Old 07-03-2019, 03:46 PM
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