Topic: idling high, and reving up and down. UPDATE!!! Horrible Grinding Noise

[Mega Baby Huey]

  hey there...i have a 1993 toyota pick-up, with a newly rebuilt 22re, with a upgraded cam. before it was rebuilt it would idle high, and bounce between 1700 and 2000 RPM, we blamed it on the knock sensor since it was knocking so bad (it had a bent rod). so it sat for four months till i could get it rebuilt. after it was rebuilt the problem seemed fixed, until about a month latter. it started small, every once and a while it would rev while idling. but as time went by it got worse... now it's exactly like it was before, if not worse. i thought it was the o2 sensor so i replaced that, and while it turned off my check engine light, it didn't fix the reving . but now every once and a while the check engine light comes back on, but not for very long. i've about had it with the truck, as it broke the joint between the rear axle and the drive shaft not long ago and i had to put it in four wheel drive to get home!

[Marlin]

The most common cause for "hunting" is the throttle position switch being out of adjustment.
When the engine is idling [air box door closed and low idle], the computer must see base idle.
After loosening the philips screws, I recall rotating the switch CCWise and it solved the hunting.

[kneedownnate]

Don't forget to drop your idle before messing with anything else too. 

[Kaptain]

hey there...i have a 1993 toyota pick-up, with a newly rebuilt 22re, with a upgraded cam. before it was rebuilt it would idle high, and bounce between 1700 and 2000 RPM, we blamed it on the knock sensor since it was knocking so bad (it had a bent rod). so it sat for four months till i could get it rebuilt. after it was rebuilt the problem seemed fixed, until about a month latter. it started small, every once and a while it would rev while idling. but as time went by it got worse... now it's exactly like it was before, if not worse. i thought it was the o2 sensor so i replaced that, and while it turned off my check engine light, it didn't fix the reving . but now every once and a while the check engine light comes back on, but not for very long. i've about had it with the truck, as it broke the joint between the rear axle and the drive shaft not long ago and i had to put it in four wheel drive to get home!

Pull the codes and see why the Check Engine light is coming on... in most cases that will point you in the right direction

[Mega Baby Huey [OP]]

Pull the codes and see why the Check Engine light is coming on... in most cases that will point you in the right direction

it's in the shop at the moment getting the driveshaft fixed, but i will as soon as i can. the problem is that it only comes on once and a while and it seems that when it does i'm running late and don't have time to check it...

[attitude of gratitude]

Check the coolant. Sounds crazy I know! Gets air pockets around the ECT and gets the computer all confused. Worth a shot

[Mega Baby Huey [OP]]

i know... already did. my tercel used to do that when it was running low on coolant.

[Yota87Truck]

He figured out how to get it to stop reving up, But we cant find how to lower the idle.  The manual says that the computer controls the idle.... it is idling at about 1700 RPM

[DeMented Toys]

On the intake side, under the intake there is a cold idle valve that coolant flows through.  It causes the engine to idle higher when you start it.  If this valve gets a bit of trash in it or gets old it can cause the engine to idle high.  Then when you put on the brakes, the computer cuts the fuel and the idle drops, then goes back up, so the computed cuts the fuel, ect. ect.  So the rpms bounce up and down.  It's because that valve is sticking.  So it may stick sometimes, and may work right other times.  Mine does the same thing off and on.  I flushed out my coolant system to clean it out and it has been working fine for the last month or so. 

At first I thought it was the TPS so I replaced it, but it didn't fix it.  Then I replaced the Mass Air Flow, but that didn't help...  Finally narrowed it down to the Cold Idle Valve.  Hope this helps.

[Yota87Truck]

Thanks, we will look at it.... Oh, and it only idled fine for a little  bit.... It is back to reving up and down.   But the adjustments we made did help some.  its reving from 1K to 1.2K instead of up in the 2K range.  We will try flushing the coolant system tonight if we have time.

[Yota87Truck]

We flushed it out.... It seems to work great now.... I also didn't notice the comment about what happens when the brakes are applied but tonight we noticed what happens when the brakes are applied.... so yea... it was exactly what was wrong... thanks

[DeMented Toys]

We flushed it out.... It seems to work great now.... I also didn't notice the comment about what happens when the brakes are applied but tonight we noticed what happens when the brakes are applied.... so yea... it was exactly what was wrong... thanks

Glad it worked out for you.   

[Yota87Truck]

Where is this cold idle valve located?  It worked for a while.... ran great, but now it is back to it's old habits

[DeMented Toys]

It is under the intake.  There is a rubber line attached to it for the coolant to run through. 

[Mega Baby Huey [OP]]

well, it kind of fixed the problem... it still revs, just not as badly and not as often. i'm gonna have to clean it out manually. plus something else broke and now when i rev up over 3500 rpm's (or occasionally when it's idling up and down), there's this horrible grinding sound! it happened when i was trying to make it up this steep icy driveway. i thought if i could get a bit of a run at it i could make it, cause the ice patch was patchy, and barely longer than my wheel base. i couldn't make it, and as i was trying to back up my front tires were on the ice so i had now way to steer. and i may have slid into the house (didn't do any damage). to get out i had to put it in four low (without locking the hubs) and get the back tires onto the ice to get them to spin, and do a kind of uphill-powerslide-away-from-the-house manuver. the rpm's got up to about 5k. and it just started grinding. the power's not affected and there's no check engine light. heck it doesn't even vibrate while i'm going down the road. and it only does it sometimes... i'm lost... and pissed  ...