924Board.org

DebbOR · Joined: 26 Sep 2006 Posts: 6 Location: Forest Grove Oregon

Hi. I am a new member here. Over this past week end I aquired a '79 924, 5 speed. Mechanically it runs good, except for 1 thing, it has a hard idle when first started, once warmed up it runs fine. The cold start valve was replaced by the PO, and I am wondering if it is the auxillary air regulator that could be causing the troubles. Any ideas, help, suggestions will be greatly apperciated.

Thanks,
Deb

Rasta Monsta · Joined: 12 Jul 2006 Posts: 11733 Location: PacNW

Deb, welcome to the board! If you haven't considered the Oregon chapter of PCA yet, I recommend that.

What is the history of the car? I would start with plugs, wires, cap & rotor, and see if your problem improves. I would also run exclusively Chevron gas, my 79 was very fussy about fuel, and ran as you describe on any other type...and maybe an extra bottle of Techron in each of the first few tanks as well. If you still have a rough idle after these steps, check back.

Rasta

PS, Oh yeah, check all rubber intake boots, and replace if hard/brittle.
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Toofah King Bad

WeiBe (1987 924S 2.5t) - 931 S3

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

I would look for a vacuum leak, also test the Auxiliary Air Valve and replace if required.
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1987 951 - M193 Version for Japan

koolkarateguy · Posted: Tue Sep 26, 2006 11:14 am Post subject:

I was having the same problems as you. I cleaned the auxiliary air regulator and made sure it was working, put fresh plugs in the car (big improvement on the top end)and air filter. But what made the most difference as far as starting goes was when I cleaned the throttle body. I used almost a full can of throttle body cleaner. It was really carboned and gummed up. After that I increased the idle and now it usually starts on the first turn of the key, idles smooth and doesn't sputter and hesitate when it's cold. Hope this helps .

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1979 N/A 924

Charlane · Joined: 25 Jul 2005 Posts: 50 Location: San Antonio, TX

Oh, that K Jetronics system takes some getting used to! I had a hard time initially because there has to be vacuum for the ignition to 'open fire'. So, if your boot over the air flow sensor is cracked, or if there is any excess air leaking into this vacuum, easy starting will be at a minimum. Check all your boots and hoses and replace these if there is any question~!
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Electra is Here......

One 1980 924 Turbo
One 1990 KZ1000P (CHPS) Motorcycle
One 1984 244 Turbo Volvo (B21FT) (I installed this engine myself)
One 1977 240D Mercedes Benz
One 1970 Chevy Impala

John Brown · Joined: 07 Nov 2002 Posts: 903 Location: Leesburg VA

DebbOR · Joined: 26 Sep 2006 Posts: 6 Location: Forest Grove Oregon

Thanks for all the replies. Yes, when I first start the car, it idles rough, and the RPMs are low, and only when the engine is cold. Once it is warmed up it runs fine.
I have also checked for vacuum leaks and have found none.The PO had replaced the plugs & rotor. The wires will need to be replaced in the future. As far as gas goes, the PO said he had just filled it with gas from 76..premium,and I *only* use gas from Chevon.
Again thanks!

Rasta Monsta · Joined: 12 Jul 2006 Posts: 11733 Location: PacNW

John-

Thanks for the 'vote of confidence!'

rasta

P.S. The 'good ideas' come from this. . .with my old 79, I found that any tuning issues had exaggerated effects when the car was cold!
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Toofah King Bad

WeiBe (1987 924S 2.5t) - 931 S3