1996 pajero with high idle-sometimes

Submitted: Sunday, Jun 19, 2011 at 08:16

ThreadID: 87074 Views:7367 Replies:6 FollowUps:0

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silverpaj

Hi guys,
thought that I would see if any of you lads can help me diagnose an idle problem before I throw money at it.
I have a 1996 NJ Pajero with a 3.5L V6. The engine runs fine, no misfire or low idle and runs smooth. the problem is that the engine seems to sometimes idle at around 2000rpm when I pull up at traffic lights, and will sometimes drop to around 1000rpm. It has been idling high off and on for a while with no engine light coming on, last Sunday the engine light did on for the first time and stayed on most of the way home but went off once the car decided to idle better. It does not do it all the time but is annoying because it is obviously harder on the brakes trying to pull her up. I read a thread on another site of a guy having the same trouble and the reply was that it is most likely the idle air control unit or stepper motor as some prefer to call it. I have checked all connections and carried out a resistance check on the stepper motor and all circuits read around 28-32 ohms as they should. I have pulled the stepper apart and given it a good clean but still have the high idle problem. I have another black electrical part that mounts on the above left of the intake (it seems to connect to the internal butterfly) and was thinking that this part may be faulty.
Can anyone help shed some light on my problem, I am not sure that a mechanic could help me diagnose the problem because the car runs fine most of the time and it would appear that everything is all ok if hooked up to a diagnostic machine. I can send pics of the parts in question should that help
Thanks for any help!

Cheers
Mark

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Reply By: Member - Doug T (NT) - Sunday, Jun 19, 2011 at 08:34

Sunday, Jun 19, 2011 at 08:34

Spray some WD40 on all the linkages , it's probably just sticking a bit.

.

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AnswerID: 457865

Reply By: Member - Mark G Gulmarrad - Sunday, Jun 19, 2011 at 09:17

Sunday, Jun 19, 2011 at 09:17

Mark

had a friend who had a problem with the idling on her Pajero. it was missing under acceleration and idling inconstantly at times. she bought some Circuit Board Cleaner from Jaycar and sprayed the MAF sensor with it and now it runs like a dream. Circuit Board Cleaner

she previously used a MAF sensor cleaner and it only worsened the problem ( sounds like it left a residue on the MAF sensor)

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give all inside this area a good spray with the cleaner.(the arrow points to the actual sensor & and be very careful NOT to touch it with your fingers just the spray)

AnswerID: 457872

Reply By: Member - Toyocrusa (NSW) - Sunday, Jun 19, 2011 at 10:26

Sunday, Jun 19, 2011 at 10:26

Hi Mark. The second black electrical part you mention is called the "throttle position sensor" If you had the engine check light come on it would have to leave a code in the computer unless it has been erased. A scan tool with the Mitsu program would tell you what the code means and it could possibly be that sensor. Most mechanics or Auto Electricians would have the scan tool. Cheers,Bob

AnswerID: 457884

Reply By: howesy - Sunday, Jun 19, 2011 at 20:46

Sunday, Jun 19, 2011 at 20:46

things to check (some of which u prob already done)
Clean throttle body
Clean Maf sensor
Stepper motor check and clean
linkages and also check O2 sensor and water temp sensor as readings from both these can affect it. check connections 2 them as well

AnswerID: 457936

Reply By: peteC - Monday, Jun 20, 2011 at 17:11

Monday, Jun 20, 2011 at 17:11

not sure about the Mtso but some cars that age use the alternator to operate part of the auto choke, hence increased revs. There was a wire comming off the alternator to the choke mechanism (used to tell the choke if the car is running), you might check these connections because a bad contact will cause the issue. Doesn't cost anything to try.

AnswerID: 457997