Question about 1994 Volkswagen Jetta

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1994 vw jetta. When cold idle is perfect. After warmed up, it idles rough in drive while stopped, but placed in neutral or park and it is smooth. Plugs, wires, distributor cap, rotor all replaced. Driving the car is smooth at all speeds, it is only when it is warm and idling in park that it is rough.

Posted by desertmac150 on

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1 Answer

Rick M

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  • Volkswagen Master
  • 4,047 Answers

Check out the idle air control valve and the passages

Posted on Jan 16, 2018

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5 Related Answers

Anonymous

  • 160 Answers

SOURCE: rough idle

if you have a vacuum gauge you can check egr to see if it holds vacuum if it don't replace

Posted on Nov 12, 2008

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Dana H

  • 129 Answers

SOURCE: distributor cap and rotor location on chevy silverado

Most chevy 5.3 do not use a cap and rotor. Most have single coil per spark plug and wire. Trace spark plug wires to coil usually above the valve cover.

Posted on Dec 28, 2008

BRADLEYFRANC

Bradley

  • 104 Answers

SOURCE: high rev, rough idle in golf

If your car is fuel injection,try changing the cold start temp sender.

Posted on Aug 14, 2009

Richard Scordino

  • 6982 Answers

SOURCE: running rough, spark plugs, distributor cap, rotor

First thing you need to know is which cylinders are missing. Then, don't forget there is an engine beneath the electronics. Do a quick test with a vacuum gauge and do a compression test. Check the distributor shaft for side play. If everything checks out good, then do electronic component testing. have a code check run (many parts stores do this free) and get a chiltons or haynes manual and follow test procedures in there.
I refrain from giving repair suggestions with problems like yours because people keep changing instead of testing parts. When I work on my vehicles or other peoples cars, I do testing to avoid buying expensive parts that most times won't correct the problem. At this point the most I'd suggest is to clean the mass air flow sensor wires with a Q-tip and carb cleaner...that often helps and is free. If you run into a problem with whatever you find, ask and I'll try to help.
good luck

Posted on Oct 05, 2009

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Anonymous

  • 1 Answer

SOURCE: VW Golf Mk3 2.0L 16v low idle rev/cold cut out

hi i have the same problem.but i cat find what to do.iff u eill find out please le me know.07853592087

Posted on Jan 18, 2010

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1 Answer

I have a 1994 Honda Accord 4 door v6. I have rough idle when in drive and smooth idle when in neutral. Also rough take offs from a stop or slow speeds. If I pump the gas pedal a few time the rough take...


  • does the engine miss? bumps is a rythmic pattern?
  • an engine miss will appear to diminish at higher rpm due to centrifical force.
  • other possible problem broken or flat motor mount.
  • is the idle rough in reverse?
  • if not
  • open hood
  • start engine
  • Left foot on brake (hard)
  • start engine
  • watch engine as you select drive
  • still holding brake with left foot / throttle gas with right foot
  • does engine dramatically move?
  • if so replace motor mount on offending side
  • if not possible engine miss or transmission problems

Jul 10, 2010 | 1994 Honda Accord

1 Answer

Same issue with the rough idle with a warm engine 4.0 Ranger


i would think a plugged fuel injector on # 6 cylinder could be the problem,or a big vacuum leak at that cylinder
a valve burnt/stuck could be but you dont see much of that anymore
could be coolant leaking into cylinder from leaky haed gasket but you would have to add coolant every so often
i would check #6 cyl. spark plug after driveing around a while if it looks new, ie no deposits on it then an injector would be what i would change next

Mar 20, 2010 | 2004 Ford Ranger

1 Answer

In cold weather, car seems to idle too low, stalls, lags on accel


replace the thermostat it is probably stuck open flush the cooling system and replace with new antifreeze

Aug 03, 2009 | 1994 Plymouth Sundance

1 Answer

2001Pontiac Grand Am Rough Idle In Drive Only


I had the same problem with '99 GA I changed the idle control valve , solve the problem

Mar 23, 2009 | 1999 Pontiac Grand Am GT

1 Answer

ROugh idle


there are 2 things that usually cause this, one is a dirty intake idle control valve and the other is hard engine mounts, I would say that both most likely apply to your car. try cleaning the intake with the following procedure from Ford.
Here is the most common cause of surges and stalls and low idle rough idle, it is the idle speed control air-bypass valve and throttle valve (IAC for short), they get full of gunk over the miles and cause idle issues (stalls, low idle) like yours, Get a can of intake cleaner from any local parts store, not carb spray, intake cleaner, it is made by a company called CRC, remove the air intake hose to the engine, hold the idle high so the engine won't stall, then spray the can of cleaner into the intake while keeping the engine running, use at least 1/2 the can, shut down the engine and disconnect the battery for 5 minutes, then restart and complete a number of mixed driving cycles, town, freeway, stop and go etc., after a few days the problem will go away as the system will relearn to the clean intake.

Feb 18, 2009 | 1994 Ford Probe

1 Answer

01 VW Jetta Vibration Problem


Check the motor mounts. They might be worn or loose which can cause vibration felt when the engine is reved up or running at higher rpms than at idle.

Jan 13, 2009 | 2004 Volkswagen Jetta

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