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Old 04-07-2011, 03:27 PM   #1
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Default Fluctuating idle and overfuelling

I registered here today to see if you guys can give me any help and advice on my problems.

I bought the car with the Greddy kit already fitted, though it was missing the Vortech FMU which i have now fitted. This has now made it overfuel quite badly. I read somewhere about retarding the timing to 6degrees before top dead centre on turbos? Does this sound right and whats my best way to do this? Moving the cam angle sensor?

The second problem is the idle. It fluctuates real bad between 500 and 1200rpm, sometimes dropping so low that it stalls. This is pretty annoying when pulling up to junctions!!! I've tried adjusting the idle adjust screw, but all this does is move the fluctuations higher in the rev range! Where should i be looking first?

Many thanks in advance!

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Old 04-07-2011, 04:03 PM   #2
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Adding the FMU should have zero effect on the fueling out of boost; It is completely transparent under vacuum.

What color are your injectors?

idle could be a number of things, I'd start with vacuum line routing, however that wouldn't cause osciliation per say. Can you provide good pictures of your engine bay?
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Old 04-07-2011, 04:21 PM   #3
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could be caused by a vacuum leak, causing unstable idle, make sure all vacuum lines are hooked up properly
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Old 04-07-2011, 04:33 PM   #4
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by vacuum line rotuing I meant vacuum leak
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Old 04-07-2011, 05:55 PM   #5
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Thanks for the replies!! I have a few pictures of the engine bay from different angles that i'll stick up below. Is there an easy way to check the vacuum pipes, or is it just a case of working my way through them all and taking them off checking them individually?
With regards the overfuelling, it only seems to be in boost that it does it, but the bangs that came from the exhaust were really loud, not just the usual popping/banging on overrrun? It didnt do it before the FMU was fitted, which made me think it could be the cause?
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Old 06-06-2011, 01:48 AM   #6
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Ive got the same problem. I have a 1990 with a turbo as well. Deff not as clean of a set up as yours though! mine was working fine for a whole day I drove, next day i got the same problem that you describe, car wont idle, just stalls, fuel pressure is way too high. I think my problem is in my fuel pressure regulator, when i adjust I see no difference. So im going to take it apart and see if maybe the diaphram inside isnt broken or stuck. If it was my fuel/vacuum lines, the car would have problems from the start...?
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Old 06-06-2011, 08:21 AM   #7
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when were you measuring the fuel pressure? when where you adjusting the AFPR?
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Old 06-06-2011, 11:12 AM   #8
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I have a fuel pressure gauge set up at the outlet of the fuel rail. And I tried to do the adjustments at the fuel pressure regulator.
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Old 06-06-2011, 11:25 AM   #9
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so between the AFPR and OEM FPR?
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Old 06-06-2011, 11:31 AM   #10
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yes...(I think so)
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Old 06-06-2011, 11:35 AM   #11
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that's not the proper place to measure rail pressure, it needs to be on the feed line before the fuel rail.
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