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deforiginal
Joined: 10 Sep 2015
Posts: 23
Location: San antonio, Tx
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 Posted: Fri Sep 11, 2015 11:47 am Post subject: 82 924 na starting issue and carbs |
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Just picked up a 924 that was a diy attempt repair and some things aren't right, the throttle screw has been turned as well as the CIS adjuster. At first it wouldn't start cold so I bypassed the cold start injector with a ground wire at it fires right up but won't stay running. I've tried freezing the aux air valve and it opens maybe 1/8th of the way which may be an issue but they aren't readily available to replace it. Any bypass method on that? I cleaned up the WUR as it was filled with gunk at 1 of the fuel line entries. The one time it ran the flywheel is in a different timing spot than the tdc marks on the crank and cam. Is it possible for the flywheel to have been put on wrong?
I know I want to go with carbs and get rid of the CIS but searching didn't really give as much info as I'd like. 1. Where can I find a used mani to fit the webers? 2. What is done to the injector holes? 3. Is the WUR and cold start injector and all that still needed?
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DEF Original Automotive |
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fiat22turbo
Joined: 18 Jan 2006
Posts: 4040
Location: Portland, OR
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| Posted: Fri Sep 11, 2015 12:24 pm Post subject: |
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Welcome.
Check out the How-to area:
http://www.924board.org/viewforum.php?f=16
I don't recommend the carbs, but to each their own.
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Stefan
1979 924 Carrera GTS (clone-ish)
1988 944 Turbo S (Silver Rose) |
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deforiginal
Joined: 10 Sep 2015
Posts: 23
Location: San antonio, Tx
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| Posted: Fri Sep 11, 2015 1:23 pm Post subject: |
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Thanks for the welcome! I was just in Portland two weeks ago. I like the carbs just because it cuts out all the variables that cause issues. I read the link but didn't really find much. I did a lot of the things posted there already. I'm stuck at the moment until the starter gets in tomorrow then I can attempt to diagnose more. I'm wondering what the most common part that can be bad that causes a start but not stay start condition considering I already checked the WUR.
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Fasteddie313
Joined: 29 Sep 2013
Posts: 2596
Location: MI
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| Posted: Fri Sep 11, 2015 1:35 pm Post subject: |
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Injectors... Or bad mixture screw adjustment even..
| Fasteddie313 wrote: | I'd...
Pull the injectors, Put them in 4 identical pop bottles, jump 30-87 on fuel pump relay to run the pump, Techron in the gas tank, push the metering plate on the fuel distributor to make the injectors spray into your pop bottles..
Go ahead and fill up the pop bottles a couple times to get that Techron through the system, running it is good for it, give it a chance to clean its self up..
Then empty your bottles and fill them about half way with the injectors, compare there levels, the bottles should have equal amounts of gas in them and you should observe a nice cone pattern spray from the injectors.. And it makes very cool sounds.. EEEEEEeeekkkk...
The injectors should stop when your not pushing on the metering plate, a good base setting for the mixture screw is to go rich just until the injectors spray by themselves and then back until they stop while you have the fuel pump running with the metering plate at rest...
If all the injectors don't stop spraying at the same time the ones that continue to spray or dribble while the others are off need to be replaced as they are leaking, give them a chance by running with the techron first..
If your fuel in the tank is questionable maybe you should drain the tank and add fresh fuel first..
If you have access to a CIS fuel pressure testing kit by all means use it, as before run the system with techron for a while first to give it a chance to clean itself up..
If your car has lambda or an O2 sensor system you can then tune the mixture screw by monitoring the lambda frequency valve duty cycle with a dwell meter...
My car is a turbo so small things may differ, dont take my word for gold.. |
You can likely strip clean that AAV and get it back into shape too..
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80 Turbo - Slightly Modified |
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Ozzie
Joined: 12 Mar 2005
Posts: 4448
Location: Townsville, Qld. Australia
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| Posted: Fri Sep 11, 2015 1:53 pm Post subject: |
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You will need to do fuel flow and pressure tests as it sounds fuel related.
if they come up to spec then setting up the cis properly requires adjusting the CIS screw until flow from the injectors stop when the air flap is down.
A gas tester is needed after that to tune the a/f mix properly.
Flywheels can be refitted out of alignment with TDC.
The crank pulley cannot.
The cam can be refitted back to front. Writing should be on the front.
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Porsche 924 1984 (UK import) NA
Its AUTO and its BLACK
Montego Black on black/red
Engineer of Electro/Mechanical Systems Maintenance |
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Rasta Monsta
Joined: 12 Jul 2006
Posts: 11732
Location: PacNW
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| Posted: Fri Sep 11, 2015 2:13 pm Post subject: |
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CIS will get better mileage & have more low end torque, but I understand getting a neglected system running at 100% can be cost prohibitive.
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Toofah King Bad
- WeiBe (1987 924S 2.5t) - 931 S3
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fiat22turbo
Joined: 18 Jan 2006
Posts: 4040
Location: Portland, OR
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| Posted: Sat Sep 12, 2015 12:23 am Post subject: |
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Ensure that there are no vacuum leaks in the system: replace/repair vacuum lines, replace the injector O-rings, verify the intake boot is connected and doesn't have any tears or leaks, etc.
How to rebuild the fuel distributor: (Yours is likely plugged up internally) http://www.924board.org/viewtopic.php?t=4711
Warm-Up Regulator rebuild: (Your is likely dirty and gummed up)
http://www.924board.org/viewtopic.php?t=20665
AAV Rebuild: (They can be disassembled a, cleaned and even have the internals repaired) http://www.924board.org/viewtopic.php?t=35833
How-to use a CIS pressure tester: (Use it after the above are resolved and the car is idling and warmed up)
http://www.924board.org/viewtopic.php?t=35734
I'm not sure how adding carbs, futzing with fuel system changes, plugging injector holes and vacuum ports will be better in the long run, other than perhaps the car will run poorly longer on carbs than it would on CIS? They certainly don't make any more power as proven by several Dyno tests over the years, at least not without a lot of internal modifications to the engine.
Like I said, to each their own. I replaced my CIS with EFI using Weber EFI Throttle Bodies, didn't really get it working well until I switched to a single TB on the stock intake. Others have had issues with adapting used Webers, etc. Pierce Manifolds had the intake, carbs and the base carb settings listed on their site the last time I looked. Not cheap.
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Stefan
1979 924 Carrera GTS (clone-ish)
1988 944 Turbo S (Silver Rose) |
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