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post #31 of 33 (permalink) Old 10-25-2018, 06:49 PM
 
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Did a fuel pressure test on the inlet line today. Came back at 48psi (3.3bar) at idle. Spec is 55psi (3.8bar) I think or 58psi (4.0bar) if you're running the Audi FPR. Maybe my FPR or pump aren't good.

Wondering if this could be it.... almost certain its a fuelling issue. New Audi 4bar FPR is on its way so will report back!

ps If either the new FPR or replacement ECM don't cure it I'll buy a Chinese STAR, already have the laptop so just need the multiplexer and cables, only slightly more expensive than getting the city Mercedes blokes to scan it apparently =/
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post #32 of 33 (permalink) Old 10-27-2018, 10:48 PM
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I have a 451 that used to do this. It turned out to be the seal between the throttle body and the intake manifold. It had developed a wrinkle in it. Twice. I used Honda Bond on it the last time I put it together, and that solved it. I don't know what the throttle body or seal look like on the 450, but I thought I would mention it. It was aggravating to say the least. My drive home was on a length of road with a 40 mph speed limit that seemed to bring out the misfire at that speed which was right around 2000 rpm. If I recall correctly.
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post #33 of 33 (permalink) Old 11-27-2018, 01:42 AM
 
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Well nothing good to report =/ Chinese STAR arrived and works well, but doesn't really give me any more info that I already had - a misfire on cylinder 2, but only at mid-rpm. No other codes present and all live data etc looks good.

Fuel pressure regulator did nothing, only thing that helps (makes it go away) is unplugging the water temp sensor (which tricks the pcm into giving it more fuel). Put new intake seals all round for good measure

At my wits end now. Wondering if it could be a PCM fault or an invisible vacuum leak in the plastic intake manifold around cylinder 2. I'd like to get a smoke test done for that and then maybe a good 'scope guy to observe pulse width on the injectors.
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