924Board.org

[ajm0924]

Hello! First off, I would like to introduce myself to the discussion board... My name is Adam, and I am a 20yo guy from Pittsburgh, Pennsylvania that recently acquired a 1980 924 at an auction for $450.00. The car had sat in a garage for about 8 years, and is in excellent physical condition. It is black on black and has 61,000 miles. All options work except the passenger window, and the a/c needs recharged. Since the day I purchased the car though, I have had a cold start problem. I have learned a large deal about these cars and the Bosch fuel injection system, but am by far still in the dark about this problem... therefore, I ask for any help or suggestions that may be up for offer. I have not had time to sort through the entire discussion board, and appologize if I have missed anything on this topic...

Upon initial cold start, the car fires immediately, only 2-3 rotations of the starter. It then revs to normal idle speed for mearly a few seconds, and completely dies. The next time I crank the car, It fires immediately, runs slightly longer, and eventually dies. It usually takes 3-4 tries to get the car to stay running, and even after that, it will run roughly at low rpms for about a minute. If you try to give it gas at this time, it bogs and sometimes stalls. After a minute or so, it smooths out to the suggested 900 rpms, as if someone had flipped a switch. The car will then run perfectly through all rpm ranges, and idle smoothly. It will restart and run flawlessly until it cools down once again.

I have checked many of the suggested problem areas, but am still in the dark... I have...
Replaced both fuel filters
Checked the operation of both fuel pumps
Replaced all vacuum lines in the engine compartment
Tested the operation/spray of the cold start valve
Changed the WUR, and tested it's ohm reading, etc
Changed the oxygen sensor (though not usually related to cold start)
and the car has new plugs, wires, 93 octane fuel, etc...
Any tests I had performed functioned properly as to my haynes/chiltons manuals...

I would love to put a little effort and any money necessary into this car, but I have not put money into it for fear that I may not get it to run properly...

Any help would be greatly appreciated, and I am more than happy to assist anyone as best I can! Thanks!
_________________
-Adam

1980 924... Drive a Porsche- Have a 4gasm!

[Ozzie]

The fact that it starts straight up says the cold start valve is fine.
Normally I'd say its the WUR.
You may have bought a dud WUR? Did you get new or reco or used?
_________________
Porsche 924 1984 (UK import) NA
Its AUTO and its BLACK
Montego Black on black/red
Engineer of Electro/Mechanical Systems Maintenance

[Mike924]

Hi, Adam, welcome to the board.

As Ozzie says, it sounds like it could be WUR related. Even if the WUR checks out electrically, the valve can get rusted and stick.

Also what state are your injectors in after having sat for so long? Try running some injector cleaner through the system.
_________________
1985 Porsche 924 'Lux', Kalahari Beige (my ex)
1993 Porsche 968 Coupe, Midnight Blue, 6 spd

'There is no substitute for a little grease under your fingernails.' - Chrenan, 924board.org

[Eturbo924]

One thing I did not see that you checked or replaced... The Aux air valve.

This is the strange looking silver valve that supplies your engine with more air durring cold start up and idle. If this has failed and is not working properly the engine will not get the proper amount of air when starting from cold. Once the engine is warmed up it be fine. If the valve is stuck closed then this could very well be your problem.

So I would check that. It is easy. Take the intake boot off. And the vac hose off the back. Shine a light into one end and look into the other. If you can not see the light clearly.. then the valve is closed. If it is closed and the engine is cold... there is your problem.

It should be open when the engine is cold and once 12 volts run across it and heats the unit... the valve closes.

Here is a good site to explain how it works.

http://www.firstfives.org/faq/aux_air_valve/aux_air_valve.html

Hope this helps

Eric
eturbo924@yahoo.com
www.geocities.com/eturbo924
_________________
1982 924
1992 968
2003 C4S
Parts Parts Parts and More parts.
E-mail me for parts you need!
Drive Fast!

[Chrenan]

I also have a 1980 N/A, I second the suggestion to check the AAV, sounds like it could be stuck closed. Luckily it is a fairly cheap part, I think it was $70 when I bought one, although it has been a while the price may have changed.

I'm curious that you said you replaced both fuel filters. Where is the second fuel filter. Stock the 1980 came with one in the driver's side front of the engine bay, beside the fuel distribution unit. Where is the second one on your car?
_________________
1987 951 - M193 Version for Japan

[Mike924]

It's been my experience that new CIS part prices have taken a leap upwards in the last couple of years.

One thing that makes me think that it's not the AAV is that Adam said the engine bogs down when the throttle is opened. The engine doesn't care whether it gets its air via the throttle or AAV, so this would imply that it's not the AAV...

Another thing: it's summer. The outside temp would need to be pretty low for the engine not to run at all on a closed AAV.
_________________
1985 Porsche 924 'Lux', Kalahari Beige (my ex)
1993 Porsche 968 Coupe, Midnight Blue, 6 spd

'There is no substitute for a little grease under your fingernails.' - Chrenan, 924board.org

[ajm0924]

Lol... you've really got me thinking now... The WUR that I bought was used from a salvage yard.. it very well could possibly be bad, even though the voltage end checks out ok. As Mike said, I could still be getting a good voltage reading even if the moving parts inside are stuck, which may make for part of my problem.. Believe it or not, Advance Auto Parts actually had new WUR's for about $80, but they only have a few left in their warehouse. When it comes to the injectors, I was looking to replace them anyway... I tried running Lucas cleaner through it, which helped the idle once warm, but didn't effect the start up. Ironically, in the box of parts that came wit the car, are 4 new injectors. I want to replace them, but the old ones seem nearly impossible to remove, and I am afraid of breaking them.
The aux air valve is another thing that has me stumped. I pulled it off a few times when it was about 60*F or so outside, and it was mostly open. Once the car ran for a few minutes, I pulled it off, and it was completely closed. I know that it has power to the unit, but I assume there may be some problem as to how long it takes to close!? The car is definately temperature sensitive though, starting quicker in warmer weather, and almost not at all in the winter, but I'm not sure how much the aux air valve would control the start up on 80+ degree days? Once again though, I don't know too much about the temperatures the valve opens and closes at.
When it comes to the fuel filters, I do in fact have two. I've been told that other years had two, but normally not 80's. I have the classic engine compartment filter near the fuel distributor, but I have another near the tank in the back, shortly after the fuel pump on the main line. It is slightly smaller than the one in the engine compartment. For all I know, the dual filters might even be restricting the fuel flow even though both are new?

I'm definately going to try to get my hands on a new WUR first off, then see what's still happening. It may even be to my advantage to take off the secondary fuel filter?, but I'll consider that for a last resort. Thanks again guys, I'm sure we'll figure this out yet!
_________________
-Adam

1980 924... Drive a Porsche- Have a 4gasm!

[Mike924]

$80 is a brilliant price for a new WUR! (I paid the UK equivalent of $195 for one two years ago!)

At 80°F the AAV will have next to no effect at all. On my car you only notice the effect on idle speed below about 5°C (~40°F).

As for the injectors, they're really quite easy to remove. They just pull straight out. Some board members have resorted to levering them out with a claw hammer, but this seems a bit drastic to me. I've only ever pulled mine out by hand. Requires a bit of effort, but not difficult.

I can't help you on the fuel filter question. Early cars had a filter/damper on the inlet to the main pump, but you seem to suggest yours is after the pump. Are you sure you're not confusing it with the accumulator? If not, it would seem a non-standard fitment.
_________________
1985 Porsche 924 'Lux', Kalahari Beige (my ex)
1993 Porsche 968 Coupe, Midnight Blue, 6 spd

'There is no substitute for a little grease under your fingernails.' - Chrenan, 924board.org

[D Hook]

My '80 has a small inline fuel filter at the back of the car right after the main pump and before the accumulators, IIRC. Not sure if it's factory or not.
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'80 924 n/a SOLD

[seanski44]

As Mike said, the injectors will just pull out, but may leave the seal (rubber doughnut) behind in the head - best to take this out before reinserting the injector, lube it with a bit petrol before slipping it back onto the injector then popping the whole lot back into the head. and watch those fuel lines
_________________
1998 BMW Z3 2.8 arctic silver & red

1981 168HP 931 S2 blue/tan leather - SOLD
1985 121HP 924 2.0l na modded - SOLD!
1992 968 lux SOLD
1989 944 2.7 lux SOLD

[StienbargerR]

you said you got your WUR from a wrecker? I would put my money on the WUR. You should by a new one, or get a reconditioned one. I think a used one that isnt rebuilt is bad news.

Ryan
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1978 924 NA
-250lb lowering springs, Euro Pistons

[Tiny]

A claw hammer works very well for popping the injectors out of their seating. As seanski said...just be careful not to damage anything.
Good luck,
Tiny
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*****1981 - 924 - Auto - London, UK******

[!tom]

The problem could be a crack in the intake boot. When the car is cold and the throttle is opened, air could be entering the intake after the air metering plate, causing it to go overly lean. The car will be more sensitive to running lean when it is cold than after it has had a chance to warm up.

Make sure there is no possible way for any air to enter the engine except by passing over the air metering plate.
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78 924 NA
5-lug