924Board.org

doomer77 · Joined: 10 Jan 2006 Posts: 266 Location: Huskvarna, Sweden

well, i pretty much said it in the title. whenever i drive my car around for a while, enough time for the temp gauge to reach middle the car has a tendency to threaten to stall whenever the rpms drop below 900 (lights flash on, oil pressure warning light comes on), normally it does this at around 500 rpms. as a result of this starting in 2nd gear when the engine is warm becomes difficult.

what could be the reason that the car is acting this way only when hot?

erik
_________________
Why drink and drive when you can smoke and fly?
Carpe diem. and if that doesnt work; get drunk!

1980 924 n/a - engine swap begun
1989 Volvo 480ES

chris24 · Posted: Wed Mar 01, 2006 4:35 am Post subject:

My revs are set at 950rpm when warm as per recommendations. maybe you could adjust that slightly...but your problem sounds a bit different to that.

I don't understand why your revs would drop below 900 if it idles at 900?

Vince Ponz · Joined: 02 Nov 2002 Posts: 3581 Location: Florida

I think your fuel pump is overheating and stalling. It happened to me last year as I was trying to cross the GW Bridge and it stalled. Cooled off and ran another 200 yards and died. This was in busy Friday night at rush hour.

vince
_________________
"Never let them see you sweat"
77.5 924 modified track car
79 931 Euro stock
88 924S SE
87 911 Targa stock

chris24 · Posted: Wed Mar 01, 2006 9:10 am Post subject:

We need some clarity doomer! It doesn't sound like your fuel pump to me, but we need some more info as I may have read your question wrong.
Are you actually trying to drive your car at 500rpm (e.g. when going along slowly in a queue) or are the revs just dropping when you let the engine idle? Can you hear your fuel pump change note? Mine's a high pitched whirry pump that you can hear at 900 rpm. (Been like that for thousands of miles.)
_________________
1983 - 924 (185K miles) - not mint
1985 - 924 (148K miles) - mint
1990 - 944S2 cab (52K miles)

jpab924 · Posted: Wed Mar 01, 2006 2:05 pm Post subject:

Check your basics first. Timing, and idle speed....do this with the engine warm. See what you got and go from there...

doomer77 · Joined: 10 Jan 2006 Posts: 266 Location: Huskvarna, Sweden

it idles at 900 when cold, then slowly moves up to 1200 when warm. the thing is not that the car actually stalls, it just threatens to stall, the lights flash on and the engine goes shaky for a moment, it can be avioded by just giving it more gas. but still its a nuissance and i want to solve it if possible.

i can hear my fuel pump if i turn on the electric ignition only, then its a whirring noise, however i never hear it when the engine is running.
_________________
Why drink and drive when you can smoke and fly?
Carpe diem. and if that doesnt work; get drunk!

1980 924 n/a - engine swap begun
1989 Volvo 480ES

Mike924 · Joined: 12 Aug 2004 Posts: 2601 Location: IoW UK

timstar92404 · Joined: 22 Sep 2004 Posts: 2075 Location: richmond BC

according to haynes the wur very rarely become inoperational. I have proplems with hot / cold starts as well I think could be my aav.

when its really cold the car starts but but it doesn't want to rev when I step on the gas and feels like it wants to shut off... when the engine sits after hot now I have to crank it for 10-30 mins sometimes to get it to start this is when it sits for 1-4 hours guessing after 6+ hours it starts easily.
_________________
78 924 sold.
85.5 944

Mike924 · Joined: 12 Aug 2004 Posts: 2601 Location: IoW UK

doomer77 · Joined: 10 Jan 2006 Posts: 266 Location: Huskvarna, Sweden

lighten up, tim is only trying ot help

latetly it has had a reluctance to start when hot, yesterday it took about 5 minutes of cranking before it caught, today it started after only 10 seconds of cranking. but this might have to something with the injector cleaner i just poured into the tank?

lets have a vote here,

who thinks its the AAV and WUR causing this?

and who thinks its the fuel pump on its way out?
_________________
Why drink and drive when you can smoke and fly?
Carpe diem. and if that doesnt work; get drunk!

1980 924 n/a - engine swap begun
1989 Volvo 480ES

Belgian924t · Joined: 07 Jan 2006 Posts: 104 Location: Belgium

First to Tim: I thought you had sold your 924 or you were going to stop attacking this board?????

Then: Eric, go for basics: check all hoses, earthcables, sparkplugs, ignitiontiming, fuelpressure....

Start simple, then go further

_________________
'79 931 with Carrera GT look
'86 944 turbo (sold)
'88 944 turbo S (sold)
'85 911 Carrera 3,2 (to be restored)
'80 911 SC "SOLD"
http://www.cardomain.com/ride/2224272

doomer77 · Joined: 10 Jan 2006 Posts: 266 Location: Huskvarna, Sweden

will do man!
_________________
Why drink and drive when you can smoke and fly?
Carpe diem. and if that doesnt work; get drunk!

1980 924 n/a - engine swap begun
1989 Volvo 480ES

chris24 · Posted: Thu Mar 02, 2006 7:18 am Post subject:

You say your car revs at 900 then 1200 when warm. Usually it is the other way round as Mike said, the AAV effectively holding the throttle open a bit more at first and the WUR keeping the mixture a bit richer while the engie is cold. When these are turned off the engine revs usually drop a bit (e.g. to 950) and the engine runs happily.

I'm still not clear...maybe I'm being a pedant...but you said that the revs drop to 500 and the oil light comes on. When is this? Does this happen when the engine is ticking over? Are you driving along in 1st or 2nd at 500rpm? When it goes down to 500 from 900, how long does it stay there for? Does it bounce back and forth?

Tim, to back Mike up...the WURs do go wrong/get disconnected etc etc. Don't believe everything in Haynes...

_________________
1983 - 924 (185K miles) - not mint
1985 - 924 (148K miles) - mint
1990 - 944S2 cab (52K miles)

924er · Posted: Thu Mar 02, 2006 11:25 am Post subject:

my idle acts up when its warm too. the idle bounces up and down but i just think i have a minor vacuum leak.
_________________
80' Porsche 924 NA - Slower then a S L O W
86' Porsche 951- New toy

Mike924 · Joined: 12 Aug 2004 Posts: 2601 Location: IoW UK

Firstly: sorry, Tim, if I sounded a bit too harsh - I've done it again...

Secondly: Chris, thanks for backing me up.

Thirdly: 924er - Yes, your problem sounds like a vacuum leak.

Now back to Doomer's problem. I think we need a few more details here. Your car idles at 1200 when warm. This is a little fast - it should be somewhere between 900 - 1000 (depending on the electrical load on the alternator).

Does it always run at this speed when warm or just when it first warms up? If it's always fast, you need to tweak the idle screw in a bit. If you do this, it might not like idling when cold, given that it only runs at 900 rpm cold. It might be that the AAV is stuck and the idle speed has been adjusted to compensate.

You seem to have a problem starting from low revs; you say it tries to stall below 500 rpm. This isn't really surprising as the idle speed is nearly 1000; the engine can't really be expected to produce torque at half its idle speed. Is it simply your driving style? What about giving it more revs before bringing the clutch up?
_________________
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