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Dutch924-racer
Joined: 23 Jul 2007 Posts: 1077 Location: The Netherlands
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Posted: Mon Jul 03, 2017 1:16 am Post subject: 931 S2 cuts off @ 5800 rpm |
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My 931 S2 cuts off @ 5800 rpm, at that moment the tacho goes to 0.
Strange thing is that I don't have a rev limiter
I also got a normal rotor
The pressure sensor is bypassed to earth
The fuel relay is a KAE one
The DITC is one of a 937 but I sure it has no rev limiter because I have driven it at highers revs with my previus engine.
The car runs and start great, only the idle is to high (see other topic)
What coul it be ? _________________ 937 trackday car
Series 2 engine
951S turbo and intercooler
Fast road camshaft
Forge recirculation valve + boost controller
Last edited by Dutch924-racer on Mon Jul 03, 2017 4:25 am; edited 1 time in total |
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Paul
Joined: 02 Nov 2002 Posts: 9491 Location: Southeast Wisconsin
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Posted: Mon Jul 03, 2017 3:28 am Post subject: |
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Are you sure your fuel pump relay doesn't have a built in limiter? _________________ 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. |
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Dutch924-racer
Joined: 23 Jul 2007 Posts: 1077 Location: The Netherlands
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Posted: Mon Jul 03, 2017 4:32 am Post subject: |
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the KAE 3.300.300 doesn't have a rev limiter _________________ 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: 8886 Location: Romania
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Posted: Mon Jul 03, 2017 4:31 pm Post subject: |
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Crank sensor fault?
I drove mine at 6500 RPM _________________ https://www.the924.com |
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Dutch924-racer
Joined: 23 Jul 2007 Posts: 1077 Location: The Netherlands
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Posted: Wed Jul 05, 2017 6:28 am Post subject: |
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just did some swapping with working parts:
- temperature sensor
- DITC
- timing control unit
I also
- tested the TPS
- bridged the fuel relay
all no effect
Anybody got a clue ? _________________ 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: Wed Jul 05, 2017 7:01 am Post subject: |
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should the 'retard connector' on the right side above the headlight be connected on ROW cars ?
I am running octane 102 fuel _________________ 937 trackday car
Series 2 engine
951S turbo and intercooler
Fast road camshaft
Forge recirculation valve + boost controller |
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Paul
Joined: 02 Nov 2002 Posts: 9491 Location: Southeast Wisconsin
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Posted: Wed Jul 05, 2017 7:23 am Post subject: |
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Does your car have a knock sensor? _________________ 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. |
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Carrera RSR
Joined: 08 Jan 2010 Posts: 2309 Location: Somerset, UK
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Posted: Wed Jul 05, 2017 7:50 am Post subject: |
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Dutch924-racer wrote: | should the 'retard connector' on the right side above the headlight be connected on ROW cars ?
I am running octane 102 fuel |
Can’t remember which way round, but iirc you connect/disconnect it for a 7-8deg retard when using low octane fuel. Need to confirm in the FSM which way round it is.
Temp sensor also triggers a retard if intake air too warm/hot _________________ 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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Dutch924-racer
Joined: 23 Jul 2007 Posts: 1077 Location: The Netherlands
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Posted: Wed Jul 05, 2017 3:13 pm Post subject: |
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• A wire plug connection can be seen in the engine compartment on the left wheel housing. If it is disconnected, the entire ignition timing will be retarded by about 7°.
So it should be connected _________________ 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: 8886 Location: Romania
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Posted: Wed Jul 05, 2017 5:17 pm Post subject: |
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That's right, wire needs to be connected so you don't get 7deg retard but I don't think that also lowers the RPM limiter.
You haven't replaced the crank sensor...and please post a picture of the rotor inside the spark distributor...
This is a non limiting rotor:
This is an RPM limiting rotor:
_________________ https://www.the924.com |
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Dutch924-racer
Joined: 23 Jul 2007 Posts: 1077 Location: The Netherlands
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Posted: Wed Jul 05, 2017 6:06 pm Post subject: |
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I have the non limiter for sure
The cranksensor I didn't check yet, will swap it for another one and let you know. That is the last component of the ignition system except form the coil/ leads and wiring.
Other thing I going to check:
Forge boost controller
Forge Dumpvalve _________________ 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: 8886 Location: Romania
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Posted: Wed Jul 05, 2017 11:09 pm Post subject: |
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wait, you haven't replaced the coil yet? do that before the sensor...much easier and faster. _________________ https://www.the924.com |
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ideola
Joined: 01 Oct 2004 Posts: 15548 Location: Spring Lake MI
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Posted: Wed Jul 05, 2017 11:22 pm Post subject: |
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I think you guys are chasing down the wrong things. I don't see how coil, crank sensor, temp sensor, or retard connection would have anything to do with rev limiting. The air temp sensor retards timing, it does nothing to revs. I would also be very hesitant to tamper with a known good working crank sensor. They are really easy to damage taking in and out. In every case I am aware of, the crank sensor either works or it doesn't. If the car starts, the crank sensor is probably just fine.
After thinking about this, I did some digging through some older posts, and I've read several threads that indicate the rev limiting is in the DITC, although I have yet to see definitive proof documented in the FSM or otherwise. I would focus on the fuel pump relay, the rotor, and the DITC. Which DITC units do you have? (Post numbers). There is a difference between Euro spec, US spec, and GT spec. Maybe the US spec has a rev limiter in it and that's what you're using? I don't have a running US-spec S2, only my Club Sport (Euro spec S2) and GT. Both of these will pull past 6000 RPM with no problem. _________________ erstwhile owner of just about every 924 variant ever made |
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Dutch924-racer
Joined: 23 Jul 2007 Posts: 1077 Location: The Netherlands
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Posted: Wed Jul 05, 2017 11:57 pm Post subject: |
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the strange thing is that as soon as the tacho hits 5800 it bounces back a lot, feels like a cut off.
I tested two DITC, both good working:
5 WK 1664 (standard one) and the 5 WK 1666 (Carrera GT). Both used to rev 6500 easy.
I hope to swap the flywheel sensor tonight.
My previous engine was running fine, I rebuild it because of oil use.
Modifications made:
- stage 1 cam
- Forge recirculation valve
- Forge manual boost controller
- 951 k26/8 turbo
- other flywheel form a S2/GT(i used to have one with the rubber clutch type)
- fuel distirbutor S2 (had one form a S1 before)
The rest of the components are form the 'old' engine.
The engine also gets a bit hot, strange because I use a 944 turbo radiator with twin fans.
May be the ignition timing is incorrect. I noticed it before when I tried to adjust idle, I can't see the dot on the flywheel.
I checked the tdc, Z1 on the flywheel is correct with the markings on the camshaft and crankshaft pulley _________________ 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: Thu Jul 06, 2017 12:25 am Post subject: |
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Cam timing too retarded?
Fuel leaning out at top end? Do you have AFR?
Boost ok at the top end? Not leaking due to Forge? _________________ 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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