High Idle...Then drops...Then High idle again?

5028 Views 5 Replies 3 Participants Last post by 01Sennaguy, Dec 18, 2020

stioffan

Discussion Starter · Sep 17, 2014

I first noticed it when I gave someone a jump last week. At startup it revs to about 2300rpm. after ten seconds it will drop to about 1500, ten more seconds and it is back up. So if I am driving under 40mph I can feel it going up and then dropping. It will keep me moving at 38mph on the high idle and fights me when I brake to stop. I don't think its doing the transmission any favors either. Has anyone had this problem before?

Save

1 - 6 of 6 Posts

pjksr02

· #2 · Sep 17, 2014

What year is your van?

How old is your battery? Sounds like your van may be trying to charge it.

Ever cleaned the IAC valve and/or throttle body? The IAC valve commonly gets gummed up, and causes idle problems, but typically the problem is stalling.

Is your a/c (or defogger) on when the idle is fluctuating?

Save

stioffan

Discussion Starter · #3 · Sep 17, 2014

2002 sienna. I thoroughly cleaned IAC valve a month ago. I do suspect the battery may be the problem. Its 4 years old. The fluctuations occer constantly regardless of whether the defogger is on.

Save

pjksr02

· #4 · Sep 17, 2014

The only time my 2002 ever idles that high on start-up is if it's very cold outside or if the battery is discharged (or has just been changed, as the computer is relearning parameters). Hopefully the battery is the problem in your case. The only caveat is that I have never experienced a variation in idle: it starts high, then kicks down eventually, but doesn't go back up to high idle, after warm-up.

Save

Reactions: 1

01Sennaguy

· #5 · Dec 18, 2020

stioffan said:
I first noticed it when I gave someone a jump last week. At startup it revs to about 2300rpm. after ten seconds it will drop to about 1500, ten more seconds and it is back up. So if I am driving under 40mph I can feel it going up and then dropping. It will keep me moving at 38mph on the high idle and fights me when I brake to stop. I don't think its doing the transmission any favors either. Has anyone had this problem before?

Hi check voltage output on your battery with disconnected if it has 12-13 volts it is good then check it with van running should be 12-13 volts if not could be altenator or a charging sensor fuse if an out zone near you they will do it free

Save

01Sennaguy

· #6 · Dec 18, 2020

01Sennaguy said:
Hi check voltage output on your battery with disconnected if it has 12-13 volts it is good then check it with van running should be 12-13 volts if not could be altenator or a charging sensor fuse if an out zone near you they will do it free

Ps also look for vac leaks and wires disconnected

Save

1 - 6 of 6 Posts

This is an older thread, you may not receive a response, and could be reviving an old thread. Please consider creating a new thread.

Top Contributors this Month