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Mudd
Joined: 27 Aug 2012
Posts: 78
Location: Cincinnati,Ohio
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 Posted: Sun Oct 21, 2012 4:45 am Post subject: Need help |
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I have a 1978 924 with 18000 miles. Starts fine but after 10 minutes of driving and the car warms up the idle goes to 2000 rpm. Also, I am not getting heat. The blower works but the air does not get hot. I am a noob
, but I am trying to learn.
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1978 924
1987 944 |
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Mudd
Joined: 27 Aug 2012
Posts: 78
Location: Cincinnati,Ohio
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| Posted: Mon Oct 29, 2012 12:51 pm Post subject: |
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Any suggestions would be appreciated.
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1978 924
1987 944 |
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Mike924
Joined: 12 Aug 2004
Posts: 2601
Location: IoW UK
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| Posted: Mon Oct 29, 2012 6:22 pm Post subject: |
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Unless you've got documentation to back the mileage up, I'd assume a car showing 18,000 miles on the clock has really done 118,000 miles (at least)...
The idle adjustment is a small screw in the throttle body. With the engine warm, turn the screw in (in your case) to reduce the revs to a more sensible 850 rpm.
If that doesn't work check the integrity of the pipework to the AAV (auxiliary air valve). In fact, do that anyway.
Once you've settled the idle speed, you may encounter starting problems... I suspect a previous owner may have upped the idle speed to cover a problem with starting. A common bodge...
Welcome to the crazy world of CIS injection. Good luck! 
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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 |
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staticsan
Joined: 19 Jan 2009
Posts: 450
Location: Sydney, Australia
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| Posted: Mon Oct 29, 2012 7:52 pm Post subject: |
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A common concern is vacuum leaks. Especially if a previous owner's mechanic raised the idle to help it start. The CIS really doesn't like vacuum leaks because it messes up the airflow meter's metering.
Wade.
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'82 British NA - Which I think I've been very lucky with! |
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pmcaya2
Joined: 24 Nov 2005
Posts: 183
Location: Scio, NY USA
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| Posted: Tue Oct 30, 2012 8:56 am Post subject: |
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Concerning the lack of heat - you might want to see if the lines going to the heater get warm. If they do, its probably a problem with the mechanical control that ducts the warm coolant to the heater core. You didn't say that the car overheats, so I assume that the thermostat's OK.
Caution: replacing a thermostat looks like an easy job, but be prepared to drill and tap the bolt holes after the existing bolts break. This seem to be a problem on these cars. Even after soaking the thermostat housing bolts with penetrating oil, I first broke the bolt heads, then the bolts when I tried vice grips.
P.S. my '82 924 NA has 193,000mi and runs great. |
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scm924s
Joined: 22 Oct 2010
Posts: 264
Location: Gloucester UK
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| Posted: Wed Oct 31, 2012 3:56 am Post subject: Re: Need help |
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| Mudd wrote: | | . The blower works but the air does not get hot. I am a noob. |
Most likely cause is the heater control valve, it is at the back of the intake manifold near the bulkhead. Check it's operation by getting someone to operate the control lever in the cabin whilst watching for valve movement. It is common for the cable to become detached.
_________________
1984 n/a Ruby Red Metallic
1988 924S Guards red- sold
1986 924S Guards Red - sold
1984 n/a Black - sold
1980 n/a Le Mans#1 - sold
1980 n/a Le Mans#2- sold
1977 Martini - sold |
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Mudd
Joined: 27 Aug 2012
Posts: 78
Location: Cincinnati,Ohio
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| Posted: Thu Nov 01, 2012 3:28 am Post subject: |
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Mike924 If you saw this car you would know it only has 18,000 miles, it looks brand new, minus a couple door dings. The PO owned an oil company and bought it new in 1978. It is the Limited Edition model http://transaxle.homeip.net/924/924/LimitedEdition/Index.htm. Also, the title documentation indicates the milage is correct.
Thanks everybody for the things I can check this weekend to hopefully at least get heat into the cabin, it's getting cold here in Cincinnati.
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1978 924
1987 944 |
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Ozzie
Joined: 12 Mar 2005
Posts: 4448
Location: Townsville, Qld. Australia
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| Posted: Thu Nov 01, 2012 7:09 am Post subject: |
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Vacuum leaks, check all your hoses.
Probably find the heater valve is stuck ir disconnected. Its a white and black thing under the coil in the heater hoses.
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Porsche 924 1984 (UK import) NA
Its AUTO and its BLACK
Montego Black on black/red
Engineer of Electro/Mechanical Systems Maintenance |
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Mike924
Joined: 12 Aug 2004
Posts: 2601
Location: IoW UK
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| Posted: Thu Nov 01, 2012 7:07 pm Post subject: |
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| Mudd wrote: | | Mike924 If you saw this car you would know it only has 18,000 miles, it looks brand new, minus a couple door dings. The PO owned an oil company and bought it new in 1978. It is the Limited Edition model http://transaxle.homeip.net/924/924/LimitedEdition/Index.htm. Also, the title documentation indicates the milage is correct. |
That's great! It sounds like you've got a really rare car there (if not the lowest 924 in existence...!)
I wasn't knocking your car; it was just a general warning. Clearly not applicable, in your case...
We need pix, of course...
_________________
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 |
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