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Dutch924-racer
Joined: 23 Jul 2007 Posts: 1077 Location: The Netherlands
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Posted: Fri Jun 30, 2017 4:45 pm Post subject: Idle setting problem on 931 S2 ROW UPDATE + VIDEO |
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I tried to adjust the idle on my 931 S2 ROW.
The manual says you put the inletmanifold sensor behind the fire wall en use a stroboscope and adjust untill you see the dot on the flywheel in the reference adge.
But I got the screw all turned to the right, and can't get in further. But I don't see the dot.
If I put the sensor back in the manifold I do see the dot appear.
Am I doing something wrong ? _________________ 937 trackday car
Series 2 engine
951S turbo and intercooler
Fast road camshaft
Forge recirculation valve + boost controller
Last edited by Dutch924-racer on Sat Jul 22, 2017 3:29 pm; edited 2 times in total |
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morghen
Joined: 21 Jan 2005 Posts: 8884 Location: Romania
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Posted: Fri Jun 30, 2017 5:27 pm Post subject: |
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There is a clear procedure, yes...but I'm lazy and just turn that air screw until the RPM suits me and don't disconnect anything....has worked like this for many years. _________________ https://www.the924.com |
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Carrera RSR
Joined: 08 Jan 2010 Posts: 2309 Location: Somerset, UK
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Posted: Fri Jun 30, 2017 10:39 pm Post subject: Re: Idle setting on 931 S2 ROW |
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Dutch924-racer wrote: | I tried to adjust the idle on my 931 S2 ROW.
The manual says you put the inletmanifold sensor behind the fire wall en use a stroboscope and adjust untill you see the dot on the flywheel in the reference adge.
But I got the screw all turned to the right, and can't get in further. But I don't see the dot.
If I put the sensor back in the manifold I do see the dot appear.
Am I doing something wrong ? |
Did you block the hole when you removed the sensor?
Agree with Morghen. Adjust the air bleed screw on the throttle body to get the best idle speed _________________ 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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Dutch924-racer
Joined: 23 Jul 2007 Posts: 1077 Location: The Netherlands
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Posted: Mon Jul 03, 2017 1:06 am Post subject: |
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yes I blocked the sensor.
The problem is the engine runs 1500 rpm at idle and the scre is al turned in.
If I pull the conector of the temperature senor on the inlet manifold it runs nicely 900 rpm
Could the sensor be broke, is there a way to test it ? _________________ 937 trackday car
Series 2 engine
951S turbo and intercooler
Fast road camshaft
Forge recirculation valve + boost controller |
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morghen
Joined: 21 Jan 2005 Posts: 8884 Location: Romania
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Posted: Mon Jul 03, 2017 4:31 pm Post subject: |
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yes, it has to have a certain impedance...do you have a Haynes manual? _________________ https://www.the924.com |
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Dutch924-racer
Joined: 23 Jul 2007 Posts: 1077 Location: The Netherlands
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Posted: Tue Jul 04, 2017 4:16 am Post subject: |
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I found this in the manual, so it coul aslo be the TPS
• If the temperature sensor fails or the wire is pulled off, the ignition timing will be retarded. Also when making idle adjustments, make sure sensor temperature is below 60 °C (120 °F) (see idle adjustments).
• If the throttle switch fails or a wire is pulled off, there will be no ignition retard during starting or coasting, and the idle speed will be too high.
test the intake air temperature sensor with an ohm-meter. Remove it and heat it to 50°C (122°F) - it should read between 1500Ω-1830Ω. (It can be heated in water or by a hair dryer.) -And if you're willing and able to test again at a higher temp, right at 100°C (212°F) it should read between 280Ω-350Ω.
at 20°C(68°F), it should read between 4.5kΩ and 5.5kΩ
at 25°C(77°F), it should read between 4.2kΩ and 5.2kΩ _________________ 937 trackday car
Series 2 engine
951S turbo and intercooler
Fast road camshaft
Forge recirculation valve + boost controller |
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Dutch924-racer
Joined: 23 Jul 2007 Posts: 1077 Location: The Netherlands
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Posted: Sun Jul 09, 2017 4:37 am Post subject: |
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I still have a high idle, about 1250 on a warm engine. Th idle screw is all turned in so no lower adjustment possible.
I checked the timing, the dot on the cam and Z1 on the flywheel are nicely aligned
I found this picture on the board, If I check at idle with a warm engine is is abouw 8 degree beford tdc, is that ok ? The flywheel markings are not visable at idle.
If I folow the idle adjusment procedure: https://www.porscherepair.us/porsche-924-turbo/info-yij.html I can't see the dot on the flywheel at any time.
I did notice when I push the throttle by hand with force backwards, idle will drop. Could the throtthe body be worn or is that normal ? _________________ 937 trackday car
Series 2 engine
951S turbo and intercooler
Fast road camshaft
Forge recirculation valve + boost controller |
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Carrera RSR
Joined: 08 Jan 2010 Posts: 2309 Location: Somerset, UK
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Posted: Sun Jul 09, 2017 6:49 am Post subject: |
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Is the throttle butterfly closing completely? Could be letting air through.
Also the seals on the shaft can crumble and let air in. Dan sells a rebuild kit. _________________ 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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Dutch924-racer
Joined: 23 Jul 2007 Posts: 1077 Location: The Netherlands
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Posted: Sun Jul 09, 2017 3:27 pm Post subject: |
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I turned the thorttle stop screw all the way back, so that could not be the problem, just curious if it alway be open a bit for idle ?
Can anybody test it on his car if you put your throtthle backwards by hand idle wil drop a bit _________________ 937 trackday car
Series 2 engine
951S turbo and intercooler
Fast road camshaft
Forge recirculation valve + boost controller |
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Carrera RSR
Joined: 08 Jan 2010 Posts: 2309 Location: Somerset, UK
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Posted: Mon Jul 10, 2017 3:57 am Post subject: |
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Throttle stop screw shouldn’t be touched. If you back it off it allows the butterfly to over rotate, it becomes open and allow air past. Pull the boost tube and check if it remaining open by not closing fully or over rotating and reopening. _________________ 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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Dutch924-racer
Joined: 23 Jul 2007 Posts: 1077 Location: The Netherlands
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Posted: Sat Jul 22, 2017 5:56 am Post subject: |
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Update:
I adjusted the mixture leaner and the idle dropped. I was now also able to see the 'dot' on the flywheel when following the idle setting procedure
At idle the mixture is now is lean about 16-18. But when driving is is all fine. Sprak plugs look good also.
The 924 now idles about 800 rpm.
The only doubt I now have is my vacuum, see vidoe below.
Could this be my stage one cam (Intergal profile) or another problem ?
https://youtu.be/zg0LAZE1M-0
https://youtu.be/zg0LAZE1M-0 _________________ 937 trackday car
Series 2 engine
951S turbo and intercooler
Fast road camshaft
Forge recirculation valve + boost controller
Last edited by Dutch924-racer on Sat Jul 22, 2017 3:29 pm; edited 1 time in total |
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ideola
Joined: 01 Oct 2004 Posts: 15548 Location: Spring Lake MI
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Posted: Sat Jul 22, 2017 6:41 am Post subject: |
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Yes, could be cam, the more aggressive profile can definitely affect idle. _________________ erstwhile owner of just about every 924 variant ever made |
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Carrera RSR
Joined: 08 Jan 2010 Posts: 2309 Location: Somerset, UK
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Posted: Sat Jul 22, 2017 6:11 pm Post subject: |
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I run 1000rpm with lightened motor and fast road cam. It will idle at 800 no problem but feels too low. At 1000 it idles far smoother and seems kinder to the motor _________________ 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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Dutch924-racer
Joined: 23 Jul 2007 Posts: 1077 Location: The Netherlands
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Posted: Sat Jul 22, 2017 11:18 pm Post subject: |
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Steve, did you ever test with a vacuum gauge ?
With the 800rpm idle the stroboscoop gives TDC on the back of the camshaft gear. _________________ 937 trackday car
Series 2 engine
951S turbo and intercooler
Fast road camshaft
Forge recirculation valve + boost controller |
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Carrera RSR
Joined: 08 Jan 2010 Posts: 2309 Location: Somerset, UK
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Posted: Sun Jul 23, 2017 5:44 am Post subject: |
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Never run a vacuum test.
I also wouldn’t idle at 16-18 afr. Mine fluctuates between low 14’s and 15. Usually bang on 14.6-7. _________________ 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
Now www.924board.org/viewtopic.php?t=34690
Then www.924board.org/viewtopic.php?t=31252 |
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