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[serzas]

Hi, please help me to set up correct air-fuel ratio on my S1. Got to the point where this should be done, but there is something different, then described in how-to, or I'm looking wrong place.

I believe under this bolt should be something to "adjust clockwise", but I couldn't find how to do it - this is just a hole, ending with a lever connected to the "plate" on the right...



why do I think I need adjusting ratio? because afr gauge on idle is showing very lean (LED on the bottom of the scale), and it goes to nothing at all, when revving
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Porsche 931 1980 widebody CS / no, stock again
ex Porsche 944 1984 turbo look
ex Porsche 924 1982
ex Porsche 924 1978

[ideola]

CLOCKWISE to enrich, COUNTER- (ANTI-) CLOCKWISE to enlean. So it sounds like you need to enrich quite a bit. Don't forget that fuel mixture and idle speed settings are directly related...that is, once you enrich, the motor will start to race at idle, and you may need to turn the idle screw in quite a bit to get things to settle out. Also, be absolutely certain you have no vac leaks, as that can greatly affect the air mixture...
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erstwhile owner of just about every 924 variant ever made

[serzas]

yep, but what size hexagon I should use? Because I tryed a little one, it simply pushes the lever down, and the bigger one does the same... I thought that there is nothing to "turn" at all, when my tools simply dropped on that lever.

at least, this is the correct "hole", as I understand from your answer, thanks
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Porsche 931 1980 widebody CS / no, stock again
ex Porsche 944 1984 turbo look
ex Porsche 924 1982
ex Porsche 924 1978

[ideola]

Standard 3mm Alan key. I use a T-handle. You can do it with a long 90 degree angle Alan key, but the T-handles are much easier to operate and adjust carefully.
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erstwhile owner of just about every 924 variant ever made

[Rasta Monsta]

[serzas]

Rasta, I totally agree, but just want to "workaround" this problem, having it rich all the way up, and then see if I'm getting at least lean readings while revving now it's hard to see any progress checking everyting else, when f.e. fixing 1 vacuum leak is still not showing any positive result on gauge...
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Porsche 931 1980 widebody CS / no, stock again
ex Porsche 944 1984 turbo look
ex Porsche 924 1982
ex Porsche 924 1978

[serzas]

yep, found the correct hexagon!

now the question is this - is it possible, that when turning hexagon CLOCKWISE engine RPM drops? BUT AFR gauge readings increase, now indicating normal. when revving, it still goes down to lean.

couldn;t get to "rich" while adjusting, because rpm drops too much and engine stalks... hadn't simple screw driver in my pocket to adjust idle

When turning hexagon ANTI-Clockwise, engine gets to higher RPM, but AFR readings goes to lean, and if I even touch the accelerator, fails to get more rpm, and starts to backfire.

but according to ideola, I should get completelly oposite results - when enriching, engine should race, isn't it?
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Porsche 931 1980 widebody CS / no, stock again
ex Porsche 944 1984 turbo look
ex Porsche 924 1982
ex Porsche 924 1978

[ideola]

I think you should stop with the adjustments for now. The first thing you should do is pull ALL FOUR injectors, put them in a glass jar, jumper the fuel pump relay, and then check the spray pattern and flow rate of each injector. If you have injectors that are spraying at different rates, you could have a couple of cylinders that are bogging down from too rich, and a couple that are going lean. Your AFR gauge isn't going to give you this view, as it's measuring the aggregate oxygen content after it's been collected from the four exhaust ports.

This problem can be caused by either failing injectors, or by faulty ports on the fuel distributor. This is easy to isolate by switching the injectors: if the problem follows the injector, the injector is bad; otherwise, the fuel distributor is at fault.

Once you've eliminated those two things as potential problems, you should then conduct a proper CIS test as Rasta suggested.
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erstwhile owner of just about every 924 variant ever made

[Carrera RSR]

I remember it as

Lefty - leany
Righty - richy

If leaning off always back off too far and adjust to right/rich. Only a 1/4 turn makes a huge difference in the mixture so don't over do it.

Any adjustments needs to be compensated with the idle adjustment screw. You may need to drive it to put load on the engine to get a true reading on the AFR gauge. Revving it just doesn't work for me.

My idle is circa 15, cruise is circa 14.5 and WOT is too rich at high 10's to 11.5. The fuel curve on CIS turbos will always be a 'safe' rich without any external intervention.
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1980 931 - forged pistons, Piper cam, K27/26 3257 6.10 hybrid turbo, 951 FMIC, custom intake, Mittelmotor dizzy & cam pulley, H&S exhaust, GAZ Gold, Fuch'ed, Quaife
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