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Lizard · Posted: Mon May 16, 2005 10:56 am Post subject: CIS questions

does anyone have a suggestion as to why the fuel metering plate wouldnt raise when the throttle is opened,
the car idles fine,but as soon as you rev it the metering plate lifts only a slight amount and then stops,
moving the plate with my hand and it runs great,
I have also swapped the WUR, but I dont have my CIS pressure guage at the moment to be able to test it,

also the metering plate feels fine it is smooth with no catches up and down.

any suggestions as to what could cause that?
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3 928s,

Paul · Posted: Mon May 16, 2005 11:58 am Post subject:

This can be caused by a vacuum leak, but in your case, I doubt it's the problem.

endwrench · Joined: 07 Dec 2002 Posts: 1631 Location: Victor, Montana

High Fuel pressure from a stuck WUR or clogged return line would cause your problem.

Todd

Lizard · Posted: Mon May 16, 2005 2:41 pm Post subject:

hmm, well when I pulled off the old WUR I did notice abit of a lack of fuel on the smalleer half of the port, thanx guys I will check it out first thing tomorrow.
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3 928s,

Lizard · Posted: Tue May 17, 2005 5:17 am Post subject:

well I took off the return line off the dizzy, and fuel is coming out of the WUR return line, and I blew in the return line just with my lungs and I could hear the air getting all the way to the tank,
I also did inspect the WUR and it appears to be fine, and there is no crap in it,
my vacuum is around 15in hg at idle, which is abit low, but my timing is set to 6 deg btc at idle, and I am getting proper timing advance,
and as soon as I hold the trottle open abit to raise the RPMs the vacuum goes upto 20in hg and stays right there, any other thoughts as to what could cause this?

TIA
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3 928s,

dpw928 · Joined: 02 Nov 2002 Posts: 1860 Location: owasso, ok 74055

Lizard,

Have you checked the plate to make sure it is centered inside the housing? Also, it should rest at the narrowest point of the housing.

Dennis
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81 931 5 sp
78 928 5 sp Silver
78 928 AT Euro Black

Lizard · Posted: Tue May 17, 2005 11:34 am Post subject:

it does look fairly centered and have never had any issues before this with that, and it was resting fairly low in the housing but that was before I had adjusted the air fuel mix, so I will check the plate, but what would cause it to sit too low?
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3 928s,

dpw928 · Joined: 02 Nov 2002 Posts: 1860 Location: owasso, ok 74055

Haven't taken a 924 plenum apart but on the 928 there is a dowel pin that is set to stop it at center. This can be tapped in or pulled out to adjust the level. If overly adjusted the pin can loosed and allow the plate to settle.

Dennis
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81 931 5 sp
78 928 5 sp Silver
78 928 AT Euro Black

Lizard · Posted: Tue May 17, 2005 12:04 pm Post subject:

ok thanx dennis I will take that off and check it
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3 928s,

augidog · Joined: 03 Mar 2003 Posts: 1360 Location: New Jersey

I've read that a vacuum leak at the intake manifold may cause the pvc line to act as a vacuum pulling toward the engine.
Just a shot.
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1978 924 95 mile daily driver.
Audi TB/POR174M/High Flow Cat/2.25" exhaust
I knew that positive thinking thing wouldn't work.

Lizard · Posted: Tue May 17, 2005 12:07 pm Post subject:

dont quiet follow your statement there augidog, but I have just resealed the intake and the ONLY accessories off it are the vacuum advance to the distributor, and the brake booster,
there is NOTHING else on the car.
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3 928s,

Lizard · Posted: Tue May 17, 2005 2:21 pm Post subject:

Dennis I could kiss you at the moment

yet again you know the CIS system too well

I adjusted the metering plate to sit flat, it was sitting too far down and it fixed the issue, I guess that it was sitting down too far and threw off the fuel curve enough, that would explain a few things, I stil need to tweek the fuel mix though,
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3 928s,

MunkPuppy · Posted: Wed May 18, 2005 8:19 am Post subject:

dpw928 · Joined: 02 Nov 2002 Posts: 1860 Location: owasso, ok 74055

Just glad I am down here in Oklahoma.

Dennis
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81 931 5 sp
78 928 5 sp Silver
78 928 AT Euro Black

Joes924Racer · Posted: Wed May 18, 2005 10:36 am Post subject:

Nice work..yahoo
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1979 porsche 924 Na
1980 porsche Turbo 931GT Replica
Have u ever driven a turbo.