924Board.org

[RobertN]

Hi guys. MOT soon. Checked my CO with Gunston gas analyser 4.8! Seems high I believe 4.5 is a pass. Can anyone advise how to successfully reduce it or adjust it please?
Thanks.
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Robert.
Porsche 924 N/A 1984.
Electrical Engineering Sales to Control panel builders.

[leadfoot]

there is a 3mm allen key fitting on the top of the fuel dissy that will adust fuel settings, only adjust with the car off... and only adjust in very small increments, i.e . 12'o'clock to 2'o'clock position, clockwise richens, counter clockwise leans... you may also need to adjust the idle bypass screw on the throttle to get it idle at the right rpm...
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1981 ROW 924 Turbo -
carbon fiber GT mish mash
LS1 conversion in progress...

[Fasteddie313]

[scm924s]

Adjust with the car running and up to temperature, and remove the allen key between adjustments, it's weight will affect it!

about 2.5% is better
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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

[RobertN]

Thanks guys. Wasn't sure what to adjust and how. I understand the " metering arm" moves when you Rev, so removing the Allen key each time prevents possible damage. The CO was around 3.2 for about 3-4 mins and then it started to climb.
I'll try the adjustment with caution
_________________
Robert.
Porsche 924 N/A 1984.
Electrical Engineering Sales to Control panel builders.

[leadfoot]

http://www.924board.org/viewtopic.php?t=21689
and other sources also state not to asjust in operation, ymmv though
_________________
1981 ROW 924 Turbo -
carbon fiber GT mish mash
LS1 conversion in progress...

[RobertN]

Hi guys. Passed car test "mot" today. CO I got to 1.2 with gunson tester, the test centre level was 1.3 and HC was 191. Nice one. Got her home after a few runs, but she is running very rough so I pulled plugs and they are white/ brown. Replaced them with NGK bpr7es Had to do the mixture adjustment again on fuel dissy, to get her smoothing out, took a while! Weird as she ran well all morning before test, but just after the test this started. Would the idle screw on intake be moving or the 3mm adjuster move during a few runs?? Starting to get paranoid.
_________________
Robert.
Porsche 924 N/A 1984.
Electrical Engineering Sales to Control panel builders.

[ideola]

I've never had an issue with adjusting the fuel mixture while the car is running (idling). But you *must* remove the Allen key and re-plug the access hole between adjustments, firstly so you don't damage anything with the key still in (which frankly seems a bit unlikely), but moreso because an open access hole is a vacuum leak that will bias the adjustment.

And plus one on the Gunson. I have one and like it, although it's not quite as accurate as a wideband O2 setup. Plenty sufficient for getting the idle and mixture "close enough", especially for those of you unlucky enough to live in areas requiring MOT / emission testing.
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erstwhile owner of just about every 924 variant ever made

[RobertN]

Cheers bud. I probably had her a bit weak on the mixture front as the plugs appeared to be burnt, brown and quite white! Done again and turned the adjuster with my trusty 3mm Allen key clockwise and she smoothed out and I'm quite happy with the idle and running. Will get a proper tune up and timing tune soon.
Yes you are right I remived the Allen key and plugged the opening each time I adjusted and revved just in case the lifting arm jammed or stuck!!
_________________
Robert.
Porsche 924 N/A 1984.
Electrical Engineering Sales to Control panel builders.