Weird High Idle when Wheels are Moving.

[stuntjunkie199]

I have a quick question for you if you've got time. I've got an 89 Accord with the fuel injection that I'm using as a daily driver. It's had an idle problem that been bugging the crap outta me for a few weeks now. I can crank it up cold and it idles about like it should within spec, 1500 or so. I can rev it up and it drops right back down and idles fine but as soon as I put it in gear and pull out it starts idling at around 2700 or so, just jumps way up. So it's killing my clutch when I shift because I have to slip it out. But when I stop completely and set for a few seconds it'll drop back down and idle normal. It's weird because I can shove the clutch in and coast and it'll stay revved high until the wheels physically stop moving. But like I said and soon as the car completely stops in 3 or 4 seconds it drops back down. It's an intermittent problem, I'd say 3/5 COLD startups do this but after that its good. I'm thinking the fast idle valve but idk if it would just start all of a sudden like that or not. And the whole wheels moving vs not moving thing is throwing me off. Any ideas where to start looking? Sorry for the lengthy question. I appreciate it.

[Legend_master]

That is a strange one, I would start by checking out the brake booster. There may be a vacuum leak there that goes away when you press the brake pedal.

[2oodoor]

That is a good idea Legend_master. Very likely cause for that symptom.

I would also make sure the clutch cable housing and throtle cable housing are not tied together on the drivers side under hood. They lay in a clip attaced to the car but sometimes people slap a tie to directly together attach them which can cause the throttle pull slightly each time the clutch is pshed down.
Make sure vac advance hoses are not crossed up on the distibutor.
Fast idle device service, coolant level and bleed air from system.

[stuntjunkie199]

Thanks for the quick replies guys. I will definitely check for those vacuum leaks this weekend when I get a chance. I have a suspicion somebody took the the FITV off before and didn't reassemble it exactly correct so I am l hoping toward that one but I'll take a look at that brake booster as well, thanks again.

[stuntjunkie199]

UPDATE: So I'm pretty sure the problem is unrelated to the brakes. I found a good straight stretch of road that I could just drift to a stop. Didn't touch the brakes whatsoever, idle stayed high until, you guessed it, the car rolled to a stop. (2> mph at least). Checked the throttle cable and clutch cable and both seemed to be free of each other. So now I'm thinking the Throttle Position Sensor or another sensor. Correct me if I'm wrong, the engine doesn't know if the wheels are moving or not, and since it does it when the wheels are moving its gotta be the ECU recognizing that. So where is the TPS located to test? Any help appreciated, Thanks.

[Legend_master]

The TPS is riveted to the firewall site of the throttle body. You will need a multimeter, and gator clips. I'm not sure of the resistance that the the needs to be at. I don't think its the TPS tho, normally the car will not even run if the TPS is out. Have you checked the ecu for any codes? I really feel like this is related to a vacuum leak, or possibly the iacv or fitv.

[stuntjunkie199]

Ok so no codes are being thrown. About the FITV, I too suspected that so I'll just take it completely off and clean it thouroughly as soon as I get a chance. But something else I found odd, today I was messing around with the IACV ( which is on the front of the throttle body right?) and when I unplug it the idle doesn't change at all. However in the past when I would unplug it the idle would drop so low the car would nearly die. (<400 rpms). Any significance?

[stuntjunkie199]

Ok discovered something new today as well. While My "problem" is occurring I can shove in the clutch, turn the motor off and then right back on and it is magically gone-at least until the next time I crank it. So combine this with the lack of affect when I unplug the IACV ( last post), does that sound like the culprit??

[Dr_Snooz]

What is the condition of your throttle cable? Check the action of the butterfly plate on your throttle body. Make sure that it's not notchy.

[stuntjunkie199]

Well just playing with the motor from under the hood, it certainly springs right back, but like I said I can't duplicate the problem setting still, so I can't really keep an eye on it when it happens.

[Legend_master]

Try taking the iacv off, and cleaning. Be crefull of plastic parts if u use carb/brake cleaner

[Dr_Snooz]

You would probably notice notchiness most at very low speeds. For instance, if you get a lot of herky jerky when driving around parking lots, that would indicate a notchy butterfly or sticky throttle cable.

This is a very unusual problem and not something that happens when standard parts are failing normally. Basically, you have an outlier symptom, so be alert for outlier, oddball causes as you look around. Look for the ghetto rigs and non-standard parts that were used to fix another problem, but are now creating this one.

It could be a failing ECU. Are you getting any trouble lights on the dash? When it revs high, is it a nice clean rev that hits the same exact RPM every time or is it rough and uneven? Does the car run well overall or are there other issues going on?

I'll be interested to find out what this problem is.

[stuntjunkie199]

No, the idle is consistent and its very clean. ( i.e. it jumps right up to where it sits and stays there until the wheels stop moving.) The car itself has been well kept as far as I can tell its entire life, the interior is in excellent shape and the engine looks like a typical 24 year old engine that nobody has messed with or modded. Stock air box, nothing I have seen out of place...As far as check engine light, it doesn't come on until you've been driving for about ten minutes. Its a one blink O2 sensor, and its because the wire has been severed and I just have reconnected yet. But I don't think its a the problem, considering it hasn't been hooked up for years and gas mileage is normal and all. At this point I really get the feeling that its the IACV because I know from working on this car in the past when I would unplug the connector on it, the idle would drop way low and now when I unplug it does absolutely nothing other than turn the CEL on. Even though it has been cleaned in the past year, I suppose I'll take it off again and just see. Any light on the unplugging issue, what should really happen?

[Dr_Snooz]

You should always fix the things you know are broken before hunting for something else. Fix the O2 sensor and we can go from there.

[stuntjunkie199]

OK guys, after digging out from all the snow I finally got a decent day to get under the hood last weekend. Fixed the O2 sensor first off. I took the IACV off and used Carb Cleaner on it. Problem is still there though. However, I have noticed something and I think it could be useful. Since it has been fairly cold here lately, of the mornings I'll crank it and let it warm up for a bit before heading out. After warming up 5 or so minutes before pulling out the problem does NOT occur at all the remainder of the trip. Seems that if I fire it up and go ahead and pull out immediately is the only time I get the issue. However, then it doesn't go away when the car warms up, its there until the motor is turned off then on again. Not sure what that points to but I dont have any CEL and other than that the car runs fine. Thanks

[stuntjunkie199]

Also on a side note, if I crank it go ahead and pull out and then just take my foot off the gas the engine will continue to speed up in 1st gear until I'm at 2700 or so RPMs. Like cruise control in 1st.

[H-Wing]

First Post! Hi folks. Had to do it as I'm exited about finally finding a thread that pertains almost exactly to my issue. I have a 89 Accord 5 speed I got 2 weeks ago, it's doing the same "high idle when not in gear and car moving" thing... drops back down about 1 or 2 seconds after the wheels stop moving. Does not cause issues when shifting, and only happens when in neutral or when clutch is down. It'll shoot up to around 2500 rpms (holding steady) then when I come to a stop it drops down and almost dies, but then saves itself within a few seconds and idles fine.

Least that's how it was until today, now it's started just dying when not in gear... whether the car is moving or not. No issues with starting thankfully, as long as its not in neutral. I also just heard my first backfire today, not sure if its related.

There are some good suggestions here so far, I have no idea where to begin myself, but the thing about the "herky jerky" when driving around parking lots is dead on for me, so the "notchy butterfly or sticky throttle cable" idea sounds like a place to start. I also keep coming across posts for similar issues that point to the vacuum leaks, so I'll do some research there also for sure.

This is the first car I've owned that I feel really inspired to learn how to fix up myself (also my cheapest car ever, $500 due to being rear ended, messed up bumper and trunk only) because it's just so much fun to drive. I have a buddy with a lot of tools so that's great, but he only knows about trucks. So I'm going to learn all I can and give it a shot, and if I fail I'll take it to the shop, but that would be lame so I'll probably be spending time around here, mostly lurking and gleaning as much info as I can from folks who know what they're talking about.

[Legend_master]

I'm really leaning towards the idle air control valve as the problem. If it has failed then cleaning will not fix the problem. Try unbolting the iacv and block the air passage ways with cardboard the bolt it back down. It will make it difficult to start, but may help narrow down the issue to being the iacv. I've actually completely bypassed mine, but cold days require holding the throttle till the car warms, it's essentially just an electric choke.

[stuntjunkie199]

Thanks Legend_Master I'll try that when I get a chance. Could I just cut it out of a pizza box or something similar? Also would unplugging for a day work too?

[Legend_master]

Thanks Legend_Master I'll try that when I get a chance. Could I just cut it out of a pizza box or something similar? Also would unplugging for a day work too?

Well I used a little thinner cardboard (the back of some rtv sealant package). You just need to make sure it seals properly or you will get a vacuum leak. Disconnection will not be a good idea, as the computer will no longer recieve a signal. If anything it's simple, and can possibly point you in the right direction.

[niles]

I also did what Legend_Master is talking about. I used a piece of flexible plastic from a notebook cover. Worked great until I could afford a new valve. I have an automatic though so I blocked mine for different reasons.

[stuntjunkie199]

THANK YOU Legend_master!! I placed a strip of cardboard behind the IACV to block it and sure enough, my problem went away. Finally. So my next question is there any reason to replace the IACV? I mean the car feels like it runs generally better and other than taking a little while longer to warm up, it seems like it has no other effect.

[89trooper]

This thread pretty much nailed my issue. I'm on my 3rd LX-i and this is the first time I have encounter this problem. Just completely rebuilt the motor (broken pistons) and was getting the car ready to take to smog and out of nowhere it starts to idle at 2000 rpms when I push the clutch in and returns to normal idle after coming to a stop. Good thing I have a box of spare parts. I'm gonna change out my IACV tomorrow and see if that fixes the issue. If not I'll be back here.

[tuna55]

This thread pretty much nailed my issue. I'm on my 3rd LX-i and this is the first time I have encounter this problem. Just completely rebuilt the motor (broken pistons) and was getting the car ready to take to smog and out of nowhere it starts to idle at 2000 rpms when I push the clutch in and returns to normal idle after coming to a stop. Good thing I have a box of spare parts. I'm gonna change out my IACV tomorrow and see if that fixes the issue. If not I'll be back here.

I have this exact issue, and it's so strange. Just for clarity, it's not a sticky throttle or any sort of mechanical issue. The idle is commanded high until a few seconds after the wheels are stopped. When you stop, the idle comes back to normal. There are a few threads like this, but the only one I found with a resolution says the guy fixed it by swapping the cluster, which I don't understand.

http://www.3geez.com/forum/archive/index.php/t-61763.html

Anyone still reading this?

[JJ'sAccord]

These guys did fix their iacv which solved the problem. Interesting becausr i fix mine by turning the fiav little diaphram clockwise which solves my problem for a couple days. Maybe same symptoms but different problems

[JJ'sAccord]

You should always fix the things you know are broken before hunting for something else. Fix the O2 sensor and we can go from there.

By the way dr.snooze your very right lol wise words man.

[Dr_Snooz]

Experience is a hard teacher, LOL. You guys get the benefit of all the stuff I've screwed up.