924Board.org

[Wiz-PORSCHE-924]

My friend has an 81 924 and is having a problem hopefully u guys can help.
Problem is ...

The car starts idles fine but lacks power when gas is given unless someone stands at the motor and lifts up the small plate under the fuel distributor. What could be bad ? The fuel pressure is good .
_________________
1987 Porsche 944
1978 Porsche 924
1992 Mercedes-Benz 190E
1988 Saab 900 (RIP)

[Martijnus]

could be an air leak.

that plate you mention regulates fuel pressure by the amount of air flow (which pushes the plate up, and the lever on which it is connected).

So either the counter balance weight is gone (unlikely ), or not all the air going in the engine passes past the plate (which means there's a leak beyond the fuel distributor thing).

could be lots of other things, because it's clear that it doesn't get enough fuel.
Could be the injectors, could be the fuel distributor, could be the filter...
_________________
"Rule: Turbo's make torque, and torque makes fun." (C. Bell)

924 "50-jahre", 1981.
MSII/extra, LPG, ITB's, 5lug.
To be turbo'ed in a while.
Killed her at the Nurburgring, Porscheless at the moment

[Ozzie]

To add to this- the air flow is the air going into the throttle body ie vacuum.

Any leaks in the air induction or vacuum lines reduces the vacuum needed to lift the air plate.
_________________
Porsche 924 1984 (UK import) NA
Its AUTO and its BLACK
Montego Black on black/red
Engineer of Electro/Mechanical Systems Maintenance

[Martijnus]

[datatrain]

I'd be taking a serious look at the rubber boots on the plate and manifold end. Could be cracked. And yes it's vacuum on the top of the plate to lift it. The flow is the result of the pressure differential.
_________________
'78 924 NA with Collector plate
33 year old car, with me for 21 yrs
Mint '92 318i BMW
Near mint '98 Buick LeSabre
VE7HFR

[Wiz-PORSCHE-924]

I have updated information on this.

**Pressure Readings**

Cold- 25lbs 1.7 BAR

Warm- 65lbs 4.5 BAR

Valve Closed 75 lbs 5.0 BAR

RPM loss is above 3,000 RPM

The Warm-up regulator is new
_________________
1987 Porsche 944
1978 Porsche 924
1992 Mercedes-Benz 190E
1988 Saab 900 (RIP)

[Ozzie]

Not having a vacuum guage connected I cant tell you if the pressure is +ve or -ve at the throttle body.

I can tell you it is less than normal atmospheric when the engine is running hence it sucks the air in past the plate. The resultant flow/mass of air lifts the plate.

Press down on the pedal, opens the TB, allows more flow.
Any vacuum hose leaks will affect this.
_________________
Porsche 924 1984 (UK import) NA
Its AUTO and its BLACK
Montego Black on black/red
Engineer of Electro/Mechanical Systems Maintenance

[924RACR]

OK, the pressure readings are good to see, as well as to confirm that the WUR is new.

So, back to some basics - have you checked flow pattern on the injectors? Also, has the fuel filter been replaced? Is the flow direction correct (though more commonly a problem on turbos)?
_________________
Vaughan Scott
Webmeister
'79 924 #77 SCCA H Prod racecar
'82 931 Plat. Silver
#25 Hidari Firefly P2 sports prototype

[Wiz-PORSCHE-924]

Ok All the rubber is good and no cracks. Now he said he advanced the timing slightly and said it made it a little better but the problem is stil there.
_________________
1987 Porsche 944
1978 Porsche 924
1992 Mercedes-Benz 190E
1988 Saab 900 (RIP)

[924RACR]

Hmmm... so what is he running for timing, and has anyone set the mixture?? Or idle?

If you lift the plate and it runs better, that means it's running lean. For an NA - Turbo would be the other way round (as the plate drops, not raises, in the airflow).
_________________
Vaughan Scott
Webmeister
'79 924 #77 SCCA H Prod racecar
'82 931 Plat. Silver
#25 Hidari Firefly P2 sports prototype