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924/931/944/951/968 Forum Porsche 924, 924S, 931, 944, 944S, 944S2, 951, and 968 discussion, how-to guides, and technical help. (1976-1995)
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Intermittent Fire

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Old 11-02-2012, 01:12 AM
  #16  
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Is the tach bounce consistent? Does the motor fire at all? Have you double/triple-check spark-plug routing?
Old 11-02-2012, 01:30 AM
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ive quadruple checked it. occasionally ill get one bump my battery is dead now rotor was fine
Old 11-02-2012, 01:33 AM
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clockwise 1342
Old 11-02-2012, 01:34 AM
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The tach should bounce at regular intervals while cranking...
Old 11-02-2012, 01:36 AM
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it is
Old 11-02-2012, 01:56 AM
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Have you verified that every cylinder is getting spark?
If so, then at this point, I would pull the fuel rail with injectors attached, and crank-it over. Visually verify that every injector is working.
Old 11-02-2012, 07:44 AM
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That was the first thing I did yesterday after the fuel pump.
Old 11-02-2012, 08:08 AM
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So, just to re-cap:

You are getting consistent spark to every cylinder, and the correct firing order.
You verified that every injector is squirting fuel.
You verified cam-timing.

Running out of possibilities... How is the engine ground? I had a similar issue years ago that turned out to be the main ground-cable to the engine.
Also, how do the plugs look? Possible that they are glazed-over and not actually firing?
Old 11-02-2012, 08:15 AM
  #24  
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I put new plugs in the start of this issue. Where is the main ground located do you know off hand?
Old 11-02-2012, 08:18 AM
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Backside of the engine, on the top of the bellhousing.
Old 11-02-2012, 08:52 AM
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Idk that they are corroded but they're definitely connected I noticed last night that the insulation was crumbling off when I was timing to engine. Ill look again when I get out of work ill let you know again you've been phenomenal thanks for all the help.
Old 11-02-2012, 09:01 AM
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For a quick test, just take a jumper-cable and use it to ground the engine block directly to the battery. Then if the car fires, you know the issue.

Glad to help... not starting - it can only be so many things. Eventually we will figure it out!
Old 11-02-2012, 01:41 PM
  #28  
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I know it is a dumb question, but just to make sure... The firing order you have is correct, but is where are you starting? Looking at the distributor cap is it like this?

42
31

Like I said... I am sure it is a dumb question, but wanted to make sure.



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