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Forced Induction Junkie
 
WERK I's Avatar
 
Join Date: Jan 2003
Location: Wisconsin
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Correct. You have no Lambda controls in your '82.
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Dave
'85 930 Factory Special Wishes Flachbau
Werk I Zuffenhausen 3.3l/330BHP Engine with Sonderwunsch Cams, FabSpeed Headers, Kokeln IC, Twin Plugged Electromotive Crankfire, Tial Wastegate(0.8 Bar), K27 Hybrid Turbo, Ruf Twin-tip Muffler, Fikse FM-5's 8&10x17, 8:41 R&P
Old 07-05-2007, 06:40 AM
  Pelican Parts Catalog | Tech Articles | Promos & Specials    Reply With Quote #21 (permalink)
Crotchety Old Bastard
 
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As Dave stated the idle mixture screw should be adjusted only after the fuel pressure has been verified as in spec. I assume sense you are having no cold start issues that your cold presure is in spec.
The idle mixture screw only adjusts the CO at idle when the engine is fully warm. Sense you are seeing an oscillating idle when warm it is logical that this might be the issue.

Once you get a feel for how all this works and some CO and fuel presure data gathering experience you can adjust the idle mixture by ear. On my engine I turn it rich until it begins to oscillate and then back it off a tick. That gets me real close to 3% CO. All engine are a little different, you will find where that "sweet spot" is in yours as well.
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RarlyL8 Motorsports / M&K Exhaust - 911/930 Exhaust Systems, Turbos, TiAL, CIS Mods/Rebuilds
'78 911SC Widebody, 930 engine, 915 Tranny, K27, SC Cams, RL8 Headers & GT3 Muffler. 350whp @ 0.75bar
Brian B. (256)536-9977 Service@MKExhaust Brian@RarlyL8
Old 07-05-2007, 08:56 AM
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Well, this is all just bumming me out. I just got back from another test drive and this is a very intermittant problem.

I drove the car around until the oil temp got up to 180 - 185. The car ran perfect. With the motor fully hot, idle was smooth as could be, 800 rpm at every stop, it would not vary or faulter. Finally after about 1/2 hour of stop and go driving at operating temp, I pulled up to a stop sign and the idle dropped to 200 rpm, then up to 1,200 rpm ( up and down within a few seconds ) then it died. It did it once more as I pulled in my drive. I sat in front of the garage and it was at a smooth 800 rpm. I let it idle for about 5 minutes blipping the throttle now and then.... but it remained a perfect idle.


If this was a mixture problem, I am wondering why it would run perfect 90% of the time? Seems to me there is some valve or regulator sticking or intermittantly failing on me rather than a constant such as a bad mixture... don't you think?
You guys are the experts, but I am trying to logically think this out from my past experience.

Here are some other details;

I did pull a few plugs and they are dark, but not sooty... so yes it is on the rich side at idle.

Whenever I blip the throttle, there is a clicking sound from the motor, but I am not sure where it's coming from?

The car quietly pops and burbles trailing throttle (while shifting gears)... is that normal?

For whatever it's worth, I tried about 50 times to get the car to die by pushing the clutch in and coasting while under way, but it always settled down to a nice 800 rpm idle. It only seems to die when I am stopping or turning.

At any rate, thanks for your suggestions, I am learning a lot about the fuel system so it's all good. ... intermittant problems are the hardest to figure out sometimes.
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82 Porsche 930 Euro, black, 31K miles.
Factory stock other than k27 turbo, B&B headers, GHL exhaust, Tial F40, 1 bar wastegate, MSD 6A ignition, 8" and 9" Fuch upgrade, H4 Xenon headlamps and a 930S steering wheel.
Old 07-05-2007, 12:31 PM
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Metal Guru
 
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Maxx,
The best guy on the board to talk to about this is John Walker. Shoot him a PM and get his opinion. He's never steered me wrong.
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Paul B.
'91 964 Turbo
Port matched, SC cams, K27/K29 turbo, Roush Performance custom headers w/Tial MV-S dual wastegates, Rarlyl8 muffler, LWFW, GT2 clutch & PP, BL wur, factory RS shifter, RS mounts, FVD timing mod, Big Reds, - 210 lb
Old 07-05-2007, 01:25 PM
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Crotchety Old Bastard
 
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The clicking sound is likely your BOV. The BOV is stock correct?

Idle oscillation is typically reproduceable under similar environmental conditions. What you are describing is a bit radical. If the mixture is close enough to correct that it idles smooth 90% of the time you should be able to calm it the other 10% by braking with the clutch out until the engine is pulled down to <1500rpm. From what you are describing I'll bet that won't work, so something else is at play.
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RarlyL8 Motorsports / M&K Exhaust - 911/930 Exhaust Systems, Turbos, TiAL, CIS Mods/Rebuilds
'78 911SC Widebody, 930 engine, 915 Tranny, K27, SC Cams, RL8 Headers & GT3 Muffler. 350whp @ 0.75bar
Brian B. (256)536-9977 Service@MKExhaust Brian@RarlyL8
Old 07-05-2007, 01:58 PM
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Quote:
Originally posted by RarlyL8
The clicking sound is likely your BOV. The BOV is stock correct?

Idle oscillation is typically reproduceable under similar environmental conditions. What you are describing is a bit radical. If the mixture is close enough to correct that it idles smooth 90% of the time you should be able to calm it the other 10% by braking with the clutch out until the engine is pulled down to <1500rpm. From what you are describing I'll bet that won't work, so something else is at play.
I'm not sure if the BOV is stock or not.

I'm going to do some more troubleshooting and see if I can get some kind of pattern when the idle goes unstable, then report back.

I'll check out the WUR mod as well and see what that's all about.

Thanks.
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82 Porsche 930 Euro, black, 31K miles.
Factory stock other than k27 turbo, B&B headers, GHL exhaust, Tial F40, 1 bar wastegate, MSD 6A ignition, 8" and 9" Fuch upgrade, H4 Xenon headlamps and a 930S steering wheel.
Old 07-06-2007, 03:31 AM
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Gotta be a vacuum leak.....
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1986 930 RUF equipped
Old 07-06-2007, 03:35 AM
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Hello!

First of all, if your BOV is clunking, replace it's gaskets.
Here is how to do it:
Changing 930 dump-gaskets, pictures galore

It will do wonders for idle quality. Second, while re-installing everything back, triple check all hoses for leakage and tighten. Third, make sure your metering plate is centered and not binding.

If that doesn't help, check CIS pressures. If they are allright, do a run with WBO2.
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Thank you for your time,
Old 07-06-2007, 08:19 AM
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Thumbs up

Quote:
Originally posted by beepbeep
Hello!

First of all, if your BOV is clunking, replace it's gaskets.
Here is how to do it:
Changing 930 dump-gaskets, pictures galore

It will do wonders for idle quality. Second, while re-installing everything back, triple check all hoses for leakage and tighten. Third, make sure your metering plate is centered and not binding.

If that doesn't help, check CIS pressures. If they are allright, do a run with WBO2.
Good step by step! Thanks.
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82 Porsche 930 Euro, black, 31K miles.
Factory stock other than k27 turbo, B&B headers, GHL exhaust, Tial F40, 1 bar wastegate, MSD 6A ignition, 8" and 9" Fuch upgrade, H4 Xenon headlamps and a 930S steering wheel.
Old 07-08-2007, 11:45 AM
  Pelican Parts Catalog | Tech Articles | Promos & Specials    Reply With Quote #29 (permalink)
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