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GP924
Joined: 16 Jan 2006
Posts: 34
Location: Grants Pass, OR
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 Posted: Sun Apr 22, 2007 10:21 am Post subject: Fouling plugs and rough idle, help |
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I am only a backyard mechanic so please be patient with me (I only get to work on this project occassionaly as well).
Anyway, I bought this car about a year ago. It had set for 8 years without running and in the first six months I had to go through a lot just to make sure it was worth working on (see my previous posts). But now I am stumped and really need some insight from those with the expertise.
The car is constantly fouling plugs since I got is running, Runs pretty good until the plugs foul out. I am wondering if the actions I have taken to get it running may be part of the problem. As you may well have guessed the grounds and electrical are a mess from the PO working on it and it setting so long. I had to bypass the fuel pump relay and installed a switch on the dash to turn on the fuel pumps. I also removed the accumulator because it leaked. I am constantly having things work and then quit working and am pretty sure it is due to the bad grounding under the dash (cleaned/replaced all of the connectors in the trunk).
Anyway, can it be that I have done more harm than good in my efforts to get it going? Possibly is it fouling plugs because the relay is not managing the fuel pump and it runs constantly?
Let me know your thoughts.
Thanks in advance for all of your assistance, I really appreciate it and am looking forward to enjoying my 'soon to be daily driver'.
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Paul
Joined: 02 Nov 2002
Posts: 9491
Location: Southeast Wisconsin
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| Posted: Sun Apr 22, 2007 10:52 am Post subject: |
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A missing accumulator and fuel pump relay will not make the car run rich.
Time to get your system and control pressures checked.
_________________
White 87 924S "Ghost"
Silver 98 986 3.6l 320 HP "Frank N Stein"
White 01 986 "Christine"
Polar Silver 02 996TT. "Turbo"
Owned and repaired 924s since 1977
Porsche: It's not driving, it's therapy. |
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Smoothie
Joined: 01 Jan 2003
Posts: 8032
Location: DE (the one near MD, PA, NJ)
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| Posted: Sun Apr 22, 2007 2:15 pm Post subject: Re: Fouling plugs and rough idle, help |
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| GP924 wrote: | | Possibly is it fouling plugs because the relay is not managing the fuel pump and it runs constantly? |
No. In CIS fuel injection, the pumps (and the injectors) run continuosly. Actually, fuel pumps in all cars run continuosly. The unusual thing about CIS is that the injectors spray all the time, unlike MFI that uses electronic fuel injectors and opens-closes the injectors in time with engine speed. Either way - CIS or MFI, carbs too, keep the fuel pumps running contstantly. All fuel injected cars use a pressure regulator and just return excess fuel back to the tank. One of the things a check of the pressures will tell you is if that pressure ("system" aka-"primary" pressure) is correct. The control pressure check will tell you if the control pressure regulator (aka- "WUR" for warm-up regulator) is functioning properly. A too-low control pressure will cause more fuel to flow to the injectors and give you an overly rich mixture. The opposite, high control pressure would cause it to run lean.
_________________
"..it's made in Germany. You know the Germans always make good stuff."
'82 924T, US version, dark green metallic, 5 speed Audi 016G gearbox |
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GP924
Joined: 16 Jan 2006
Posts: 34
Location: Grants Pass, OR
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| Posted: Tue Apr 24, 2007 1:02 pm Post subject: |
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Thanks guys. I really appreciate the feedback. I was loosing my confidence, luckily my wife is real supportive and won't let me give up (she's a keeper). So I will backup and work through the fuel pressures and keeping work from there. I will update this thread as I make progress and will see how I do.
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