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mgatlag · Joined: 02 Aug 2007 Posts: 647 Location: Avon, IN

I've noticed some black stuff coming out of the tailpipe and leaving a nice little spray on the drive when I let the car sit and idle. Does this mean my engine is running too rich? I'm gonna check the plugs and see how they look...
_________________
Michael
'77 1/2 924 N/A- 5 speed Audi box
'04 Ford Taurus - gone!!
'92 Jeep Cherokee Laredo - gone!!

Porsche... better than tea with Miss McGill
(Slap Shot)

Paul · Posted: Sun Nov 18, 2007 5:40 am Post subject:

How's your gas mileage?
_________________
White 87 924S "Ghost"
Silver 98 986 3.6l 320 HP "Frank N Stein"
White 01 986 "Christine"
Polar Silver 02 996TT. "Turbo"
Owned and repaired 924s since 1977
Porsche: It's not driving, it's therapy.

mgatlag · Joined: 02 Aug 2007 Posts: 647 Location: Avon, IN

I don't think it's very good, why?
_________________
Michael
'77 1/2 924 N/A- 5 speed Audi box
'04 Ford Taurus - gone!!
'92 Jeep Cherokee Laredo - gone!!

Porsche... better than tea with Miss McGill
(Slap Shot)

Paul · Posted: Sun Nov 18, 2007 7:19 am Post subject:

If you are running rich, your mileage will be lower than a car running correctly.
_________________
White 87 924S "Ghost"
Silver 98 986 3.6l 320 HP "Frank N Stein"
White 01 986 "Christine"
Polar Silver 02 996TT. "Turbo"
Owned and repaired 924s since 1977
Porsche: It's not driving, it's therapy.

joecitizennn · Joined: 12 Sep 2005 Posts: 2096 Location: no mans land

that black "stuff" is unburned fuel. So your car needs a tune up and is wasting gas.
_________________
87 924s
88 924SE gone
447 hp cgt clone
87 924S gone
84 944 sold
83 944 sold
89 turbo S LSD, ABS etc
86 951 white rocket
85 944 sport everything.
84 944 sold.
87 944 sold

mgatlag · Joined: 02 Aug 2007 Posts: 647 Location: Avon, IN

what kinds of starting areas would you suggest? This rebuilt engine now has about 2500 miles on it. New injectors, warm up regulator, spark plugs and cables were done when I put the engine in. I do notice a tapping in the head area, maybe the valves need adjusting?
_________________
Michael
'77 1/2 924 N/A- 5 speed Audi box
'04 Ford Taurus - gone!!
'92 Jeep Cherokee Laredo - gone!!

Porsche... better than tea with Miss McGill
(Slap Shot)

Meneer aard · Joined: 27 Jan 2006 Posts: 73 Location: Netherlands

You can adjust the valves. Check also the CO level, it should be arround 2 / 2,5 % (a euro 924 runs great on that value).

Good luck!
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Porsche 924 Euro 1977

mgatlag · Joined: 02 Aug 2007 Posts: 647 Location: Avon, IN

I've heard of people checking the CO2 levels, but how do you do it and are there any special tools that I may need?
And are there any special tips on adjusting the valves? It's been a while since I've done it and I've only done Hondas and Mazdas before.
Is there anyting else I should be checking on the tune-up? Other than the normal plugs, wires, fuel filter?
I've also been wanting to do a CIS test but don't know how to do that either...
_________________
Michael
'77 1/2 924 N/A- 5 speed Audi box
'04 Ford Taurus - gone!!
'92 Jeep Cherokee Laredo - gone!!

Porsche... better than tea with Miss McGill
(Slap Shot)

johnathan1 · Joined: 08 Oct 2007 Posts: 308 Location: Downey, Ca

It could very easily be condensation inside the exhaust piping washing away carbon deposits, then blowing them out onto the ground...

Unless you KNOW it's oil that's coming out, I wouldn't worry about it too too much...

Also, do you have a catalytic converter?
_________________
-1977 924, 4-Spd...Gone
-1987 Toyota Supra Turbo, Pearl White, BPU, 300RWHP @ 10psi.
-1989 Mercedes-Benz 300SEL

WARNING: MAY CONTAIN TRACES OF AUDI OR VW!

mgatlag · Joined: 02 Aug 2007 Posts: 647 Location: Avon, IN

no, the cat has been removed, there is a resonator there though. The stock exhaust manifold has been replaced with an upgraded header.
_________________
Michael
'77 1/2 924 N/A- 5 speed Audi box
'04 Ford Taurus - gone!!
'92 Jeep Cherokee Laredo - gone!!

Porsche... better than tea with Miss McGill
(Slap Shot)

dpw928 · Joined: 02 Nov 2002 Posts: 1860 Location: owasso, ok 74055

This time of year, with the lower air temps, you will get more condensation in the exhaust after shut down. When you restart the car, a lot of the condensation is blown out and the rest evaporates as the exhaust heats up. This is normal unless it is still blowing black exhaust after the engine is warm.

Dennis
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81 931 5 sp
78 928 5 sp Silver
78 928 AT Euro Black

mgatlag · Joined: 02 Aug 2007 Posts: 647 Location: Avon, IN

That makes sense about the temps, I'll check it again after it's good and warm. I would like to do a test on the CIS system still but don't I need a special tool to do it?
_________________
Michael
'77 1/2 924 N/A- 5 speed Audi box
'04 Ford Taurus - gone!!
'92 Jeep Cherokee Laredo - gone!!

Porsche... better than tea with Miss McGill
(Slap Shot)

dpw928 · Joined: 02 Nov 2002 Posts: 1860 Location: owasso, ok 74055

The CIS system is quite stable so unless it has been adjusted previously and still runs good, it is probably OK. To test it you will need a CIS test gauge set (JCW for $60) and to adjust the A/F mixture you need a long 3mm hex wrench.

Dennis
_________________
81 931 5 sp
78 928 5 sp Silver
78 928 AT Euro Black

Paul · Posted: Mon Nov 19, 2007 10:59 am Post subject:

If it starts every time, if it's running fine and if your mileage is above 20 mpg on the highway, LEAVE THE CIS ALONE.

Do the normal tune up stuff...
_________________
White 87 924S "Ghost"
Silver 98 986 3.6l 320 HP "Frank N Stein"
White 01 986 "Christine"
Polar Silver 02 996TT. "Turbo"
Owned and repaired 924s since 1977
Porsche: It's not driving, it's therapy.

Mike924 · Joined: 12 Aug 2004 Posts: 2601 Location: IoW UK

If you mainly do short journeys, soot can build up in the exhaust and get washed out by the condensation in colder weather. If this is the case, take your car ona a good 1/2-hour+ highway journey. This will clear things up (for a while).
_________________
1985 Porsche 924 'Lux', Kalahari Beige (my ex)
1993 Porsche 968 Coupe, Midnight Blue, 6 spd

'There is no substitute for a little grease under your fingernails.' - Chrenan, 924board.org