924Board.org

CorsePerVita · Joined: 25 Jul 2008 Posts: 1992 Location: Redmond, Oregon

Alright, well, I'm driving the 924 (N/A) to work now pretty regularly and it's got a bit of a quirky idle I need to sort out that is driving me absolutely bonkers.

Sometimes the idle is smooth and where it should be. However, the vast majority of the time, the idle is around 500-600rpm and the car feels like it's going to die, but it doesn't. Drive it around a bit, let it warm up, and sometimes the idle will return to normal. I keep thinking, "what the f***?"

I've replaced vacuum lines and it doesn't seem to affect it. I also thought the idle adjustment screw had no bearing on it but that isn't the case at all. In fact, if you raise the idle, instead of 500-600rpm, it goes up to 650rpm, and then when the idle "returns" to normal, the "normal" idle is higher, say 1200rpm instead of 900 or 1000rpm.

This makes me think it's an aux air valve or something sticking. I'm not entirely sure since I'm not super amazing with CIS. If anyone has any things to check I am happy to start probing and checking sensors because it is driving me NUTS.
_________________
- 1977 Porsche 924 2.0 N/A (Trackday Project)
- 1979 Porsche 924 2.0 N/A (The other daily)
- 1980 Porsche 931 (Daily)
- 1987 Lamborghini Jalpa
- 1999 Ducati 900SS

CorsePerVita · Joined: 25 Jul 2008 Posts: 1992 Location: Redmond, Oregon

Anyone? Bueler?
_________________
- 1977 Porsche 924 2.0 N/A (Trackday Project)
- 1979 Porsche 924 2.0 N/A (The other daily)
- 1980 Porsche 931 (Daily)
- 1987 Lamborghini Jalpa
- 1999 Ducati 900SS

!tom · Posted: Tue Sep 10, 2013 11:51 am Post subject:

I *THINK* i was having similar issues with my decel valve fully connected. It's now in circuit but with the vacuum line connected to atmosphere.
_________________
78 924 NA
5-lug

scriblz7 · Joined: 07 Dec 2008 Posts: 112 Location: kirkland WA.

have you checked the warm and cold fuel pressures you are getting? i had a similar problem, and just needed to adjust the warm up regulator
_________________
Riley
79 924 n/a with gt body
15 VW GTI

scriblz7 · Joined: 07 Dec 2008 Posts: 112 Location: kirkland WA.

have you checked the warm and cold fuel pressures you are getting? i had a similar problem, and just needed to adjust the warm up regulator
_________________
Riley
79 924 n/a with gt body
15 VW GTI

CorsePerVita · Joined: 25 Jul 2008 Posts: 1992 Location: Redmond, Oregon

fiat22turbo · Joined: 18 Jan 2006 Posts: 4040 Location: Portland, OR

Uh, yeah. Yeah you do if you're planning on keeping CIS-equipped cars around (the 931 and 924 daily's for example).
_________________
Stefan
1979 924 Carrera GTS (clone-ish)
1988 944 Turbo S (Silver Rose)

CorsePerVita · Joined: 25 Jul 2008 Posts: 1992 Location: Redmond, Oregon

Any recommendations on CIS testers that people have used, like and are reliable for a reasonable price?
_________________
- 1977 Porsche 924 2.0 N/A (Trackday Project)
- 1979 Porsche 924 2.0 N/A (The other daily)
- 1980 Porsche 931 (Daily)
- 1987 Lamborghini Jalpa
- 1999 Ducati 900SS

fiat22turbo · Joined: 18 Jan 2006 Posts: 4040 Location: Portland, OR

http://forums.pelicanparts.com/porsche-911-technical-forum/179746-diy-cis-tester.html

http://www.924board.org/viewtopic.php?p=350517&sid=3e2c2b277d56b560416417a1628016b3

http://www.tooldiscounter.com/ItemDisplay.cfm?lookup=SAG33800&source=froogle&kw=SAG33800

http://www.ebay.com/itm/Master-Fuel-Injection-Pump-Pressure-Test-Kit-CISE-CIS-Metric-SAE-Free-Shipping-/200885133891
_________________
Stefan
1979 924 Carrera GTS (clone-ish)
1988 944 Turbo S (Silver Rose)

CorsePerVita · Joined: 25 Jul 2008 Posts: 1992 Location: Redmond, Oregon

DIY method seems easy enough. I have an extra CIS system laying around so I can make one from that. Great idea. Thanks man!
_________________
- 1977 Porsche 924 2.0 N/A (Trackday Project)
- 1979 Porsche 924 2.0 N/A (The other daily)
- 1980 Porsche 931 (Daily)
- 1987 Lamborghini Jalpa
- 1999 Ducati 900SS