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chaparral2f · Joined: 29 Jan 2011 Posts: 33 Location: southern oregon

I removed the fuel pump rrelay, and installed the jumper as the says, this is so I could check the fuel pump output and pressure. Noticed that there was a buzzing coming from the Frequency valve. (it stopped when I disconected the power from it) I havent checked the pump yet, but will later tonight. Meanwhile I'll replace the oxy senser, and see if that has any effect on the frequency valve. Is there a chance that I may actrually
be closing in on the not running problem?
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If you're gonna be stupid, you gotta be tough.
1980 Porsche 924
1997 GMC Jimmy (DD)
1984 300zx Tube chassis, Jag suspension, 400hp sbc

Grenadiers · Posted: Sat Feb 12, 2011 9:53 am Post subject:

Need more historical info on the non-start problem. Got fuel at the injectors? Got spark at the sparkies? Distributor aligned correctly, makes a difference on 1980 models? Start at all cold or hot? Sparkies really really wet? Try spare brand new fuel pump relay?
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'83 944 Track car.
'88 924S Track car.
'89 944 Turbo
2004 Winnebago Vectra monster RV
2012 Jeep Wrangler
2014 Kia Soul
2001 Ford F350 powerstroke

chaparral2f · Joined: 29 Jan 2011 Posts: 33 Location: southern oregon

Car ran when I got it but had dead cyl.
Pulled head and did valve job replaced 2 valves.
Ran compression (170 178 173 180)
Installed new timing belt (crank, flywheel and cam marks exactly on)
Installed new plugs
Checked wires, rotor, coil and cap.
Checked vacuum lines for leaks (replaced lines.)
Replaced AAV
Checked thermo time switch, and cold start valve (no leak and good spra TTS @4sec duration)
Tested injectors, replaced all 4 (new)
Replaced injector lines
Removed WUV, cleaned and tested electrics
Checked and centered air metering plate
Removed and checked frequency valve and solonoid
Installed CST override
Replaced fuel pump relay
_________________
If you're gonna be stupid, you gotta be tough.
1980 Porsche 924
1997 GMC Jimmy (DD)
1984 300zx Tube chassis, Jag suspension, 400hp sbc

Rasta Monsta · Joined: 12 Jul 2006 Posts: 11733 Location: PacNW

Likelihood of FV causing no run condition = ZERO.
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Toofah King Bad

WeiBe (1987 924S 2.5t) - 931 S3

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

IIRC the idle switch on the throttle body should disable the O2 system and frequency valve during start and low rpm operations. Might try unplugging it.

Didn't see anything about ignition timing. When my 80 924 NA sat for a year, I had to retard ( turn CW) the timing by about 10 degrees for its initial start up.

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

Smoothie · Posted: Sun Feb 13, 2011 2:58 am Post subject:

Plug the fv back in, and disconnect the o2 sensor.
With o2 sensor unplugged, the lambda system defaults to a 50:50 duty cycle.
-Then the a:f mix can be checked/set correctly. (After control and system pressures have been verified with a CIS fuel pressure tester.)
The lambda system is operational (aka- in "closed-loop" mode) at idle, and at steady part-throttle - but only after warm-up, which I found to take roughly 5-10 mins. depending on temperature.
Changes in throttle position cause it to go into "open-loop" (with 50:50 duty cycle) briefly, then it's back to closed-loop if the throttle remains steady (at either idle or part-throttle).
-And of course it's always in open-loop 50:50 while the o2 senor is unplugged.
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"..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