924Board.org

[keefer]

I have a '79 924 that won't idle for more thanmaybe 2 minutes,even after its been run a few minutes .It seems to run okay at higher engine speeds,but won't idle unless I advance the ign.timing drastically(about 40 degrees BTC).Am I wrong to think this indicates a weak spark,or lean mixture?I'vegone thru basically everything in the Haynes manual(twice),searched for vacuum leaks,my first guess,tried blocking the warmup reg/hot start feed line on top of the fuel dist.with an inline valve.etc.but still no change.I don't know the fuel pressure,but today I tried raising the airflow plate thru the airfilter box to richen the mixture,and it slowed the engine down,so now I'm lost.Any ideas? I hate calling it the "evil Krautmobile",but itjust seems so fitting so far.

[Guest]

Have you checked the timing....it may have jumped a tooth on the belt? How long ago has the belt been changed. Oil leaks near the belt can cause it to strecth and allow the timing to jump. It is a place to look.

[keefer]

yeah,I checked that.The only time Idrove it any distance since I got it in the summer of 2000 was last spring ,a 7 mile trip to town,and it seemed to surge a little.When I got home,the exhaust manifold was glowing,which also leads me to think its some sort of weak spark/mjxture problem causing poor combustion,but I can't locatethe problem.It was bodged a bit by the previous owner,I think,since the head was torqued down to about 170-180ft.-lbs,so maybe he also played around with the fuel mixture adjustment or something.Does anyone know of any ballpark settings for mixture strength?I don't want to mess with that unless absolutely necessary,but it might be worth trying as a last resort.This is probably my punishment for buying a Porsche with an automatic trans.,but it was cheap,and I figured "how bad could it be?".FOOL!

[D Hook]

Check the two rubber boots from the fuel distributor to the intake. I thought mine were okay when I was chasing a vaccum leak and found out they were both cracked around the necks where the clamps go. I couldn't see the cracks but once they were replaced by the mechanic I took it to w/new ones, the symptoms you describe went away.

YMMV

[keefer]

Thanks,as a matter of fact,I just yesterday discovered the boot at the fuel dist. end was stretched at the flange area.Its "seating" on the dist. body is obscured by the hose clamp,so it may have been sucking air all this time.I'll have to seaal it with silicone seal (temporarily) and see if it helps.I've had the boot off umpteen times though;it seems like I should've got it right at least once.Luckily,there's a 924 in the local junkyard ( a '77)with an intake ass'y. on it.If that doesn't do it ,I'll have to go thru everything again ;I've probably missed something.

[Joes924]

Dont get to discouraged when the bugs are out the 924 its a good running reliable car.

I was stumped or boggled by the same situation I replaced fuel injectors ,feul distrib. and warm up regulator,and fuel lines,
fuel filter.

If your not getting air it could be contaminates getting into the injectors.

This was what was my prob. it semmed the tank was rusted and I took it out and resealed it if your filler neck is all rusty as mine was this could be the culprit. I would go to the junk yard and buy up the injectorsand the rest of the parts I mentioned and switch out the injectors
try cleaning them buy sticking the end of a wd-40 sprayer tube into the injector.

Your rob could be as simple as a clogged injector.



[ This Message was edited by: Joes924 on 2001-11-25 05:17 ]

[larso]

Could be something like;
-your distrib cap is off by one quarter turn
-spark plug wires mixed up on cap
-ignition distributor is bad, or it isn't the right one (from another year of 924)
-mixture is off

[larso]

also the vacuum advance (mounted on the distrib) could be wacked, or a plugged hose...

[keefer]

Okay,it isn't the intake boot,I sealed the edge w/silicone,no difference.One thing I should've mentioned in my first post is that once the engine stalls,itwill not re-start,no how ,no way.I tried extra ground straps,felt around for hot components(incl.fuel pump,distrib.,ign.module,etc.),checked compression.Also,when I said it takes 40ish degrees advance,I was estimating with a timing light aimed onthe flywheel.There aren't different flywheels are there?Like maybe its a flywheel from a different year,and doesn't correspond to the actual crank position?Just speculating,though I did find actual TDC once to check cam timing.Stumped as always and appreciative of help,keith

[numbers]

Let's see. The last time you drove it the exhaust manifold was glowing red. That usually indicates a blocked exhaust. Now, when you start it, it idles for a few minutes and then dies and will not restart. Well if your exhaust is plugged, the car will idle until the back pressure builds up, and then die. It won't start until the back pressure bleeds off. I vote for plugged exhaust.

[keefer]

Yeah,I tried that too,since I had a Chrysler that did the same thing once ,but the exhaust is open,including the cat.converter.Does anyone know of any non-compatible components(such as distributors ign.modules,etc.)that wouldn't work with the rest of the '79 components?I've onlyhad the car since June of 2000;I don't know what the previous owner might have done to it.Still open to ideas,Keith

[eturbo924]

Have you checked the injector o-rings? These can harden and cause issues. Though yours sounds more serious than that. Spray some water over the injectors while the car is running (for the 2 minutes). If there is a change in the running condition... then replace the o-rings. Can also use WD-40 but there is a fire hazzard ...

It sounds like you are loosing vacuum to me, but you said you have checked all the boots... so let me think about this some more.

Have you checked the fuel mixture? What do the spark plugs look like... the deposits? Do they indicate lean or rich condition? Try advancing the cam one notch. My car was doing almost the same thing and it turned out my cam was off a bit and the fuel mixture needed to be adjusted.

Eric

[keefer]

Okay,I pulled the plugs again,and they still look okay,no fouling and no serious looking problems(though my plug-reading skills aren't the best,probably).One thing I finally checked,though,is the wiring to the alternator;I'd wondered for a while if maybe it wasn't putting out enough current due to the exhaust "overheating".Sure enough,the smaller wire's insulation was pretty much all melted.Also,the wiring manual shows 2 2.5(sq.mm.?) wires going to the alt.,I only have the one,in addition to the 10mm output wire.I'm wondering,could this limit the ignition current enough to give a weak spark,or am I grasping at straws? I'm speculating that the richer cold-start mixture would burn even witha weak spark,the richer mixture at part throttle would burn,but the leaner idle mixture would have trouble.Also,the battery wouldn't go dead all the time because the car doesn't stay running long enought to kill it,and the plugs don't foul because the car is stalling at a lean mixture strength .Plausible?Either way I'll be replacing the wire(s),does your alt. have 1 or 2 wires?Hopeful,Keith

[eturbo924]

Could be the wires. I also had wire issues that let the car start and run real poor. Then not start at all. I do not rememeber how many wires go to or from the alternator, but I think it was one large and one small... but it has been almost a year since I was dealing with that issue. Replace the wires and route them away from the header if you can. Also you can purchase some insulating blankets to cover the wires and starter and such. Can't rememeber the companies name at the moment, but I purchased their header wrap. So far so good with that.

Let me know if the wires are the cure

[keefer]

Okay,I finally got around to re-wiring the alternator,and it didn't help at all,but I think I know how to fix it now.Just one small question ,do I have to have a Catholic priest to exorcise the demons from the car,or will an Episcopalian minister be okay? Actually,even worse than a demonically possessed car,I'm going to have to try replacing the f.i. unit,though I think I'll get a fair price at the local junkyard.Does anyone know of a rebuilding service for them,preferably on the East Coast?