924Board.org

Magnus K

Hi!

My 924 NA hesitates when i hit the gaspedal hard and fast. This is worse when the engine is cold but it can be felt even if the engine is warm.

Just another thing with these engines or can I do something about it?

Regards
Magnus
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Another curious Swede...

Asleep in Sweden, Europe, when you US guys are awake...

5150 · Posted: Wed Jul 21, 2004 4:56 pm Post subject:

Timing slightly out perhaps? Can't say that I've noticed any hesitation from mine, though i can't say i've jumped on the pedal quick either..
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Mars Red '78 Euro 924 n/a
http://www.cardomain.com/id/5150_uk

Graphite? Grey Metallic '85 (late model) 944 2.5

There are two kinds of pedestrians: the quick and the dead.

Magnus K · Posted: Wed Jul 21, 2004 5:25 pm Post subject:

OK, I'll try to adjust the timing first, to see if that will cure it.

My 924 got a "slight" problem with timing adjustment though... It seems like the timing marks on the "big metal thingey at the end of the motor just before the clutch" (my English word just took a holiday there, sorry

) is non-existing. Maybe that the PO has mounted the thingey with the timing marks the wrong way, cause I couldn't see any marks when I was looking the last time...

Thanks for the tips anyway!

Magnus
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Another curious Swede...

Asleep in Sweden, Europe, when you US guys are awake...

5150 · Posted: Wed Jul 21, 2004 6:06 pm Post subject:

Flywheel

I borrowed a timing strobe for mine, spent ages trying to use the thing but the marks are damned impossible to see in there... in the end I just kept adjusting things a little and running her until she ran smooth.

I usually have a hell of a time getting the gap set correctly on the contact breaker/points too, seems to be a fine line between the perfect gap and one where she runs rough.
_________________
Mars Red '78 Euro 924 n/a
http://www.cardomain.com/id/5150_uk

Graphite? Grey Metallic '85 (late model) 944 2.5

There are two kinds of pedestrians: the quick and the dead.

Magnus K · Posted: Wed Jul 21, 2004 8:06 pm Post subject:

wdb · Joined: 02 Nov 2002 Posts: 2024

a hesitation when you give it gs can be caused by a rich mixture , too much gas chokes the motor .

Magnus K · Posted: Wed Jul 21, 2004 9:48 pm Post subject:

wdb - OK, can that be adjusted by turning the CO adjustment screw?

/Magnus
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Another curious Swede...

Asleep in Sweden, Europe, when you US guys are awake...

D Hook · Joined: 02 Nov 2002 Posts: 3158 Location: Omaha, NE

Is this a new occurence or has it always been this way?

I'd check for air leaks on the boots and check the fuel pressures before adjusting the CO screw. There's alot of different things that can cause what you describe and sometimes changing the CO only masks the real problem. Do you have access to a CIS pressure tester by chance? Testing and eliminating the fuel pressure system as the problem saves alot of money and time and can sometimes pinpoint the problem for you. Let us know what you find.

Magnus K · Posted: Wed Jul 21, 2004 11:42 pm Post subject:

New quirk or always = I don´t know. I bought the ca in November last year and it spent all winter on 4 jack stands while I rebuilt the floor pan. Air leaks and other things related to aging components is a probability here...

CIS tester = something to measure fuel pressure in the fuel distributer = K-Jetronic unit? Nope, sorry. Maybe later I can install some gauges in the system but not right know.

I think I see what you mean by "saving a lot of money and time". The time I got but no money... I'll try setting the timing first and take it from there.

Thanks!
Magnus
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Another curious Swede...

Asleep in Sweden, Europe, when you US guys are awake...

Chrenan · Joined: 15 Jan 2003 Posts: 3903 Location: Canada

Magnus,

So basically the guys have narrowed it down to one of 2 things, the timing is off or the fuel mixture is too rich. Here's a few tips for both issues as I've had similar problems in the past with my car.

Before you use the timing light, turn the motor by hand using the nut on the oil pump pulley while looking at the flywheel. When you see a number or marking on the flywheel stop turning the motor and clean the number or marking (a timing mark). I use carb cleaner and a rag to wipe the timing mark clean. Then put a dot of white paint beside the timing mark. Now when you use the timing light gun, the timing marks will really stand out.

There is a cheap test to check if your mixture is rich. Let your car warm up, then while it idles, put your hand in front of the exhaust. If you see small black/brown specks accumulate on your hand (un-burned fuel), it could be the sign of a rich mixture. Anyway, I wouldn't just turn the CO screw to adjust the mixture without finding out why it is rich in the first place. Have you changed the Oxygen Sensor lately (if your car has one)? Past 30,000 km the Oxygen Sensor will start to fail and the mixture will richen. Also, is your frequency valve working? It is my understanding that if it fails, it fails in the open position, which richens the mixture. If you've ever heard one of these little devices in action, you'll know if your isn't working, they make an annoying high pitched buzzing sound when they are working.

Hope that helps,

Chrenan
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1987 951 - M193 Version for Japan

Magnus K · Posted: Thu Jul 22, 2004 9:11 pm Post subject:

Chrenan, thanks!

CO sensor - No, ny car doesn't one of those.

Frequency valve? What is that and where should it be located? And what function does it serve?

Regards
Magnus
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Another curious Swede...

Asleep in Sweden, Europe, when you US guys are awake...

Chrenan · Joined: 15 Jan 2003 Posts: 3903 Location: Canada

If you have no Oxygen Sensor, then you have no frequency valve, they work together. That's good, it eliminates that as a possible source for a rich running condition. Your car is from before 1980? What year?
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1987 951 - M193 Version for Japan

Porchenewbe · Joined: 04 Jun 2004 Posts: 30 Location: stoke on trent

Just had MOT on my car, passed with no prob's, but theMOT dude turned down the CO screw to weaken the mixture, was running like yours by the sounds of things! so i had the engine dyno tuned and it sorted the problem right out, sorting mixture and timing gave me 11 bhp, making a total of 131 bhp. So thats what i recommend, car runs sooo much better. Sweet!!

Hope that helps.

john
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Riding a steep learning curve about all that is 924.

My first porsche ... I'm only 19..But loving it (except the insurance) ... quite some car.

Magnus K · Posted: Fri Jul 23, 2004 7:30 pm Post subject:

Chrenan · Joined: 15 Jan 2003 Posts: 3903 Location: Canada