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was the car remapped? as the ignition timing will need to be advanced to compensate for the compression changeComment
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very strange.
Fuel pressure changed? See pauls sticky on measuring fuel pressure if you have no gauge.Volcano ABY coupe
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If you drop compression there is less squish for igniting the fuel so you need to start burning it earlier and sometimes less of it too. Like Jamo said you need to remap by advancing ignition and trimming the fuel.UrS6 Stroker + HTA3586 =
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Sounds like a boost leak. Test with compressor. And a remap would be good, but it sounds like a leaky pipe ..Comment
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I am surprised that is *SO* much richer purely because of lower compression - especially as you would expect closed loop lambda operation to adapt accordingly - of course that has its limitations, but I am wondering if fuel pressure is on the high side combined with an air leak... then combine that maybe with a marginal MAF and/or aging lambda probe... the combination of these things might be skewing it out of limits.
It is worth checking that something else hasnt been disturbed when the head was refitted.
Also worth checking air temp and water temp sensors are in spec...
Do you have VAGCOM there ?Paul Nugent
Webmaster http://S2central.net
Administrator http://S2forum.com
1994 S2 Coupe ABY - aka Project Lazarus
2001 A6 allroad 2.5TDi - family tank
2003 S4 Avant 4.2 V8 - daily burble
Purveyor of HomeFries and Exclusive agent for Samco hose kits (S2/RS2)
There are only 10 kinds of people that understand binary - those that do, and those that don't
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yes I know that closed loop operation stops after a certain point... its not a pure rpm threshold on motronic though - are you on motronic or aftermarket ECU ?Paul Nugent
Webmaster http://S2central.net
Administrator http://S2forum.com
1994 S2 Coupe ABY - aka Project Lazarus
2001 A6 allroad 2.5TDi - family tank
2003 S4 Avant 4.2 V8 - daily burble
Purveyor of HomeFries and Exclusive agent for Samco hose kits (S2/RS2)
There are only 10 kinds of people that understand binary - those that do, and those that don'tComment
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Try another maf. If the car is making 400 plus HP then the stock maf seems to drift in calibration before it dies. Mine did this a few times. I'm guessing your not stock power with low compression and moved maf...Comment
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