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Compression test done.. Just too rich!?!? Were is the screw?

 
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sparky  



Joined: 27 Nov 2002
Posts: 772
Location: Malta

PostPosted: Tue Oct 05, 2004 4:53 am    Post subject: Compression test done.. Just too rich!?!? Were is the screw? Reply with quote

Hi Guys,
I did a compression test on the car and #1 was at 159 #2 was at 152 #3 was at 150 and #4 was at 152.. this all seems about right doesnt it?

Now that i know its not the head im sure there is a mixture problem cause the plugs were all black and i get a cloud of black smoke out of the exhaust.. is it possible its just a mixture setting? I have never adjusted the mixture on the car as the whole fuel system is new and was wondering were the mixture screw is and if anyone has a pic of were it is..

Thanks a million..
SparkY
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emoore924  



Joined: 13 Apr 2004
Posts: 2801

PostPosted: Tue Oct 05, 2004 5:03 am    Post subject: Reply with quote

Sounds like it might be too rich. Black smoke is usually indicates unburnt fuel. (gray is burning oil, white is steam)

The adjustment screw is accessed through a small port in the top of the fuel distributor and you adjust with a long allen wrench tool. Be a little careful though. You really mucking up the mixture if you don't do it right. Personally, I've always just left it alone and let my mechanic mess with it. However, yours might be so out of adjustment that playing with it might make sense in your case. If nothing else, you might get it good enough to drive to a shop with an emissions tester.

I don't know the CO and HC spec offhand but I do have the factory manual. It is in there somewhere I'm sure. Just LMK if you want me to look it up (come to think of it, it might be on a sticker on the underside of the hood...) Anyway, you probably want to take it to someone who has an emissions sniffer so they can set the mixture properly. I don't know if you can "set it by ear" so to speak and get it to run well and with decent consumption.
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Lizard  



Joined: 03 Nov 2002
Posts: 9364
Location: Abbotsford BC. Canada

PostPosted: Tue Oct 05, 2004 7:56 am    Post subject: Reply with quote

I would not recommend messing with the mixture yourself, you can play with the mix and make it worse, or cause starting issues, take it to someone with a gas sniffer and have them adjust it with the sniffer hooked up.
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sparky  



Joined: 27 Nov 2002
Posts: 772
Location: Malta

PostPosted: Tue Oct 05, 2004 8:10 am    Post subject: Reply with quote

would it be safe to adjust it a little bit to make it run better as now it hardly reverse's up the driveway.. could i make it a little leaner safely?
am i right in thinking to lean it a bit i have to turn the screw anti-clockwise?

Thanks
SparkY
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When the checkered flag drops... The Bull$hit Stops

1976 Euro 924 (The 945) - Full 951 Brakes/Suspension

1998 Boxster with goodies
2002 3.0 Xtype 4wd sport
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Diesel  



Joined: 03 Nov 2002
Posts: 1061
Location: Ellington,CT

PostPosted: Tue Oct 05, 2004 8:38 am    Post subject: Reply with quote

Hey Sparky, I guess I'm shit out of luck on that door sill sticker huh? Remember me?
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Joes924Racer  



Joined: 03 Nov 2002
Posts: 11964
Location: Oregon, Denver Colorado native!

PostPosted: Tue Nov 09, 2004 12:10 pm    Post subject: Reply with quote

Sure you can lean it up just take out the rubber plug and turn the screw
its a small allen type head on the screw..

about one eighth of an inch at a time start the car let it idle and rev the engine a couple times repeat the whole procedure a few times to get it
leaned out it should start to rev up faster as it gets lean youll know youve gone to far when it falters when you try and rev it up.
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Vince Ponz  



Joined: 02 Nov 2002
Posts: 3581
Location: Florida

PostPosted: Tue Nov 09, 2004 10:42 pm    Post subject: Reply with quote

Sparky, first send Diesel the door sill. Second I will be going to Sicily in the spring and may make a side trip to Malta.
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924RACR  



Joined: 29 Jul 2001
Posts: 8334
Location: Royal Oak, MI, USA

PostPosted: Tue Nov 09, 2004 11:12 pm    Post subject: Reply with quote

Agreed, 3mm long-handle allen wrench in the top of the distributor. It's much easier to set mixture on the earlier cars since there's no O2 sensor feedback loop messing with you. I do it all the time on my racecar, by ear; you just set it for good throttle response. Better to be too rich than too lean, but if you've got decent octane on a fairly stock motor, and your ignition timing is set properly (and vacuum advance working correctly), you won't likely have any problems. I would recommend an incremental adjustment of about 10-15 degrees at a time. Smaller than that you won't notice the difference in performance. Play with it till it feels good.
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Joes924Racer  



Joined: 03 Nov 2002
Posts: 11964
Location: Oregon, Denver Colorado native!

PostPosted: Wed Nov 10, 2004 3:07 pm    Post subject: Reply with quote

Throttle response is what youll notice and the other thing that

tells you if your still to rich is little backfires when you let off the gas.
get those 2 things to work for you and you should be runnin pretty good.
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