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Rough idle / stalling 93 945t

posted by  JBTurbo on  Fri Jan 26 09:53 CST 2007
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last visit: Thu May 3 16:12 CST 2007
[RELATED]

I'm having a problem that seems to have happened recently, The car will start O.K. but within seconds begins to idle very rough. The tach will swing from 800-900 down to 300-400 and the vacuum guage will keep time with it(normal vacuum at the higher rpm and almost none when rpms drop) and at times will stall completly. If I give it a little gas and keep the rpms around 1000 it will hold the engine speed but still sounds and feels like its missing on one cylinder intermittantly. While driving the car seems to run fine anytime I'm on the gas or rolling at speeds >10mph. When I stop I'm back on the carnival ride.
What I've done so far:
Checked for codes - None on socket 2 or 6
Checked for vacuum leaks - Couldnt find any but according to my test gauge I've got low vacuum at idle @15-16 instead of 20 like it used to have
Recently replaced Cap & rotor(bosch), Wires (IPD), Plugs(NGK std)
TB & IAC Cleaned @ 2-300 miles ago
Swapped Iac With another used unit - no change

What I've considered:
RPM sensor?
Fuel injection resistor?
Power stage?
Knock sensor?

I'm hoping for some advice on what or how to proceed before I start guessing and spending alot to replace parts Thanks for reading my overly wordy post, and any help you can offer.




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    Rough idle / stalling 93 945t

    posted by  someone claiming to be nate on  Fri Jan 26 10:48 CST 2007 [RELATED]

    Use one of the methods in the FAQ to check for vacuum leaks (big fan of the carb cleaner method). A leaky intake manifold gasket, among other leaks, can do that to an idle. Also a dislodged "flame trap" hose (the one up from the breather box to the elbow) can play similar games.








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      Rough idle / stalling 93 945t

      posted by  JBTurbo on  Fri Jan 26 11:18 CST 2007
      Author: [PROFILE] [EVERY POST] [THREADS] [BEST POSTS] RSS Feed     [IGNORE ALL POSTS]
      last visit: Thu May 3 16:12 CST 2007
      [RELATED]

      I tried the carb cleaner method but I ran out of carb cleaner before I could rule that out So I'll be getting a new can to try again. I also replaced the flame trap elbow, the small bottom hose from the elbow to the flame trap & the vacuum line from the elbow to the manifold, but the large hose from the elbow to the intake hose was hard as a rock so I guess even if its not the cause it's time to replace anyway. Glad to have someone confirm that it coud cause my problem, Thanks!







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