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ggrecian
Joined: 20 Oct 2013
Posts: 29
Location: Pa
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 Posted: Wed Dec 18, 2013 9:03 pm Post subject: Need a mechanical angel for Christmas!please help! |
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1987 924s ran fine with a vacuum leak at intake manifold gasket for 40k miles.Vacuum leak at the intake manifold cylinder #1.bought new gaskets...took off fuel rail.intake manifold.replaced gaskets.put back together.crank no start.no spark.replaced spark plugs rotor button and distributer cap and plug wires were within 6 mos old.still no spark.had speed and reference sensor plugs reversed.corrected.now spark.still crank no start.bought and replaced fuel injectors.same.bought and replaced dme relay.same.battery was going.bought new battery from napa.still crank no start.took timing belt cover off verified timing belt on and operational.bought new speed and reference sensors.replaced.still crank no start.connection at reference sensor damaged.rewired.soldered shrink tubed and taped new connection at speed and reference sensors.still crank no start.sent dme computer to ecu doctors..bench tested "good" no problems..still crank no start. replaced J boot at intake.vacuum hose to idle control valve.small vacuum hose from idle control valve to intake manifold kinked and chewed up limiting airflow there.ordered new one.would that cause crank no start?any other ideas?
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porschelover |
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fiat22turbo
Joined: 18 Jan 2006
Posts: 4040
Location: Portland, OR
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| Posted: Thu Dec 19, 2013 1:04 am Post subject: |
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Verified that you've got fuel?
Hows the AFM?
Pull the rail and verify the injectors are firing when cranking (be careful with the fuel, try to place them into clear jars before cranking).
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Stefan
1979 924 Carrera GTS (clone-ish)
1988 944 Turbo S (Silver Rose) |
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ggrecian
Joined: 20 Oct 2013
Posts: 29
Location: Pa
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| Posted: Thu Dec 19, 2013 1:17 am Post subject: |
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Thank you for post.have 36 psi at the fuel rail while cranking...noid light on injector electrical connections do not show pulse?what to check on the AFM?
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porschelover |
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fiat22turbo
Joined: 18 Jan 2006
Posts: 4040
Location: Portland, OR
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joecitizennn
Joined: 12 Sep 2005
Posts: 2096
Location: no mans land
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| Posted: Tue Dec 24, 2013 3:41 pm Post subject: |
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| ggrecian wrote: | | any other ideas? |
You say the car has spark. Try spraying carburetor cleaner into the throttle body. If it does not hit off then pull your dme plug and check the speed and reference sensors at the DME plug while cranking the motor. Checking direct at the computer plug eliminates alot of BS
| joecitizennn wrote: | [ Check you crank sensor and speed sensor output at the dme plug.
Description of plug connector can be found here.
http://www.the944.com/connector.htm
Testing
With the plug removed from the computer check between pins 8 and 27 (speed) and pins 25 and 26 (reference) while cranking the motor. You can use an oscilloscope if you have one, but you probably don't so a fresnel lense LED from radio shack can be used. It will show you if the sensors are working or not, and works quite well. |
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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 |
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924 FAQ (Technical)
