924Board.org

[staticsan]

I thought I'd start a new thread with a more realistic subject line. Basically, my 924 won't idle when hot: it stalls.

Cold start is usually okay: crank crank crank, fire, rpms wobble, dive, rise. Idles at 1500 for about 3 minutes. So the AAV is working just fine. Then the idle rpm starts descending as it warms up. At 1000 it starts stumbling, then they slowly plummet through the floor until it stalls. Now it won't start except with great difficulty: lots of cranking, accelerator floored or pulsing - still very difficult to start.

Once running, though, it drives just fine. Keep the revs above 1000 and everything is just as it should be.

On the advice of a previous thread, I went looking for vacuum leaks. Couldn't find any. The two main pieces of rubber in the air intake pathway are near new, FWIW. As is the O-ring on the idle screw. Talking about the idle-screw: how far out from its stop is it typically? Mine's been at 3 complete turns for ages, then as it's gotten cranky, I've wound it out further. Even at 6 it still won't idle.

The mixture is only very slightly richer than before these trouble started: no more than an eighth of a turn. However, one thing that has changed is that the current and the previous tanks of fuel have not had fuel system cleaner in them (different brands, though). The one before that did, as did the tank two before that. I'm wondering if this is related.

I didn't have time tonight to pull any spark plugs and see if they're okay. Maybe on Thursday night. I was suspecting the spark plug leads because it's usually sounds like one cylinder is missing when it starts for about a minute. And I'm not sure #4 lead is seated properly. Fiddling with that the other night helped it start, but I could be imagining things.

From what I've read about warm start problems, it sounds like the WUR is playing up. It has a "rebuilt" one. Maybe it has died.

What other paths should I be persuing?

Wade.

Edit: update title.
_________________
'82 British NA - Which I think I've been very lucky with!

[Luvmy80-924]

It sounds exactly like mine when my accumulator went bad. Started right up when cold, hard start when warm (When hot)When it did start it felt like it was running on 3cyc for a few seconds until fuel pressure built up. Went to the junkyard found a fresh 79 Rabbit wreck and took the F/P, check valve and accum. (cost me $10.50) threw it on and it purrs like a kitten.
_________________
1980 924 N/A Everyday Driver
1986 930
And now a 1980 931

[Ozzie]

Pull the plugs and clean.
running rich will foul them pretty quick.

get a gastester to set fuel mix.
should be about 1.5% for Oz vehicles.

a new idle screw 'o' ring will change the amount it needs to be screwed in or out so any info from others will not really help.
anyway mine is about 2 1/2 screw out.

Could be a faulty WUR.
_________________
Porsche 924 1984 (UK import) NA
Its AUTO and its BLACK
Montego Black on black/red
Engineer of Electro/Mechanical Systems Maintenance

[staticsan]

Okay, new Fuel Accumulator.

After the hassle with the wheel bearings, I'm going to ask if
this (part from Pelican) will suit. I was surprised it wasn't more expensive, TBH. Or do I need to get this one (part from Pargon) instead? :-/

Wade.
_________________
'82 British NA - Which I think I've been very lucky with!

[!tom]

The one from Paragon. The Pelican part doesn't go on your car anywhere.
_________________
78 924 NA
5-lug

[staticsan]

Thanks, !tom. And the credit card takes another hit... And the postage is atrocious! :-O

(What was that quote I saw? Oh yes: "A Porsche is not just for Christmas. If taken apart carefully, it can provide frustration the whole year long!" )

Wade.
_________________
'82 British NA - Which I think I've been very lucky with!

[RC]

Would check/ replace plugs & leads first, after triple checking for vac leak. NGK or bosch plugs, any good quality leads, just match length at supercrap or repco.

Then check accumulator bleed screw, get underneath and remove screw on bottom. Your car should just have 1, a 40cc unit. Early cars have two 20 cc units and extra plumbing. If fuel drips out it is faulty. Personally would first knock up a basic test gauge or buy the CIS kit to diagnose the fault rather than just throwing money into a wishing well. Your choice but, and would also look around for pricing. Anything but USPS is a rip.
https://www.autohausaz.com/search/product.aspx?sid=lztotp45v4rv0onkwf2bzri0&makeid=800019@Porsche&modelid=1263293@924%20&year=1982&cid=22@Fuel%20%26%20Air%20System&gid=6048@Fuel%20Accumulator
but keep looking if you really need one.
_________________
World`s quickest 924 2L slushbox

[staticsan]

Yeah... I haven't made a purchase; baulked at the USPS charges. Thanks for the info about checking the accumulator without pulling it off.

I've got the CIS test kit. The trick is to get it to the car to measure things when the car is stone cold. I think my Saturday just got filled...

Lead replacement will also be easy; I just have to get to a SCA to buy replacements. The plugs are pretty new; I'll pull them probably tomorrow night to check them.

Wade.
_________________
'82 British NA - Which I think I've been very lucky with!

[!tom]

Personally I can't see how the accumulator has anything to do with idle problems. It's a lot more influential when it comes to starting problems.
_________________
78 924 NA
5-lug

[staticsan]

Okay.

1. Found the accumulator. No fuel drips out of the hole, so the diaphragm isn't broken. Doesn't mean it isn't not working, of course.

2. I found a vacuum leak. The clamp on the vacuum line to the brake booster was loose. This'll probably fix my idle problem.

3. Pulled the leads and plugs. The plugs look good, so the mixture is likely correct. The plugs are NGK and I know they're correct because I remember the research to get them right!

4. I took the leads to the local Repco where they confirmed they were probably not original. They also look undamaged. I later put a meter on them and found they're resistive: the coil lead is 1k4 and the others are higher but proportional to their length. Unfortunately, the internal connector on #3 is broken so I have to repair that before I try starting it.

I'm going to try a proper CIS pressure test, hopefully on Saturday.

Wade.
_________________
'82 British NA - Which I think I've been very lucky with!

[staticsan]

...AND I found another vacuum leak. This time in the elbow in the middle of the airpathway between the meter and the throttle body. The port for the crankcase breather had become detached. Again. Had that problem when I first bought it. My father is going to rummage in his exotic glues and try to fix it. I did look for a replacement but never found one.

Meanwhile, I got the lead for #3 spark plug repaired. Didn't do the CIS pressure test - we ran out of time.

Thanks for putting up with my problems.

Wade.
_________________
'82 British NA - Which I think I've been very lucky with!

[staticsan]

It was a massive vacuum leak all along. Boy do I feel like a massive doofus for not spotting that... The plastic tube in the middle of the airway has had it's port re-glued and re-taped. It now starts and runs even better than I remember it doing when I bought it. Even warm, most of the time.

I took it for a spin in the nearby national park to give the battery a good drink. *sigh* It can do things in corners my Lancer certainly can't. I was reminded all over again why I bought it (and why the lads on that dinky little British car show so love cars that love corners).

Wade, hiding away now I had a lesson in trouble-shooting.
_________________
'82 British NA - Which I think I've been very lucky with!