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Discussion Starter · #1 ·
i have a 1989 900 turbo 4 door with an 1988 LH 2.2 ecu conversion. Recently every once and a while when i shift and then boost i blow out smoke. the car seems so bog down and then power comes back strong. other times the car is fine and is not a problem. Anybody have any advice. heres what i have
stock block and head
t-3 super 60
9000 FMIC
3.0 bar FPR
stock turbo injectors
2.5 inch exhaust
TurboXS blow off valve venting into atmosphere

one more thing, this problem just started gettin worse the last few weeks.

sorry for the length.
Pete
 

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well it depends on what color smoke that youre blowing, but looking at your mods list, i'm willing to venture a guess that it is this one
TurboXS blow off valve venting into atmosphere
what happens when you put an atmospheric bov on a car with an amm is that extra air youre venting confuses the ecu and makes it run rich between shifts since it is still assuming that its in the system and it adds extra fuel to compensate for the extra air that it thinks you still have in your engine (confused yet?) this would also explain why youre getting a decrease in power after shifting. what i would suggest is that you try to either vent your BOV back into the intake track (downstream of the amm) if you can, or just try swapping the stock bosch valve back in temporarily. I've got 5 bucks on the BOV being the problem :wink:

Oh and by the way, since youre in Connecticut, you should come to my meet next weekend here in NY, get some real HP figures for that beast :) .

Paul
 

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Discussion Starter · #4 ·
the car had been running fine, just recently it has begun to do this bogging. i have been runnin the BOV for a bout 2 years now and never had a problem until now
 

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Why'd ya go to LH 2.2?

AFFECT ON AIR/FUEL RATIO

"Something to keep in mind here while we are on the subject of dumping air from the inlet system, whether it be for the purpose of boost control or for the more usual function of maintaining compressor rpm and avoiding compressor damage when the throttle is closed at boost, is what effect this will have on the air/fuel ratio. If fuelling is metered according to inputs from a speed density MAP sensor based system, dumping air back to the atmosphere will not alter the A/F ratio. However, in any system employing some kind of air-flow meter, remember that once air flows through that meter it has been accounted for. Fuel delivery will then be calculated by the ECU, based primarily on the signal received from that source. Therefore, any time air is released to the atmosphere fuelling will go rich."
 

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Discussion Starter · #6 ·
i went to LH 2.2 because it is much easier to tune. exampels, the tuneable air mass meter, the ability to get rid of fuel cut. as for my problem i found out saturday at the VT 100, it was a bad spark plug on cyl. # 2.
 

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PaulH said:
well it depends on what color smoke that youre blowing, but looking at your mods list, i'm willing to venture a guess that it is this one
TurboXS blow off valve venting into atmosphere
what happens when you put an atmospheric bov on a car with an amm is that extra air youre venting confuses the ecu and makes it run rich between shifts
While this is true of many dump valves on AMM cars, dual piston ones like the Forge DV004 are designed to prevent it from happening. I've been using one for 2 weeks now and no signs of running rich or stalling between shifts.
 
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