Junkers88

1989, 22re, 5 speed, 4x4 4runner.

Yesterday I replaced the plugs/wires/cap/rotor and drove it around with no issues, came home and put the AC belt on to check the system and again drove it around with no issues and the AC on.

This morning on the way to the office and again a few minutes ago the idle got funky.

At start up, dead cold it will now idle at 2500rpms+, once it gets about halfway warmed up the motor will surge from 1000rpms to 1500rpms and it doesn't matter if the brakes are applied or not. Once it warms up completely it idles at either 750rpms or 1000rpms and can't seem to make up it's mind.

So far I've read that it might be air in the cooling system but I don't have any leaks so I don't know how air could have just appeared in there. I also read that it might be that the idle is set too high and the ECU gets confused (I'll idle it down here in a few minutes and see if it helps), it also might be the IACV or the AFM so I can swap out the Supra MAF for the original and try that tonight but the IACV is almost 300$ from Napa and I really don't have that kind of money right now.

So if any of you had these symptoms and got it fixed let me know what you did to correct the problem.

Thank you.

874runnersr5

could also be the tps out of adjustment..
i adjusted my tps and my idle is a steady 900..

Junkers88

I ohmed mine about 6 months ago and it was all well within specs. I can't see it suddenly going south on me but I'll check that as well.

Thanks

DupermanDave

I'd also lean towards a TPS adjustment. If nothing in your engine has changed, most likely it's a sensor gone bad.

MrPeepers

Maybe you knocked something loose? Vacuum leak, EGR valve?

toyota4x4907

Do you have enough coolant in the system, Junkers?

abecedarian

The ECU's on these trucks are fairly dumb, only responding to sensor inputs to control injector pulse width, timing and the various VSV's (EGR, fuel pressure up and AS-Valve/PAIR-- A/C idle up is controlled by the a/c amplifier). The only control the ECU has over idle speed is via adjusting the timing, and I can't imagine any reason for the ECU to advance enough when cold to get 2500 rpm's, not that it's even programmed to do so.

Anyways. Any chance you knocked something loose putting the a/c belt on? It sounds like a vacuum leak to me, if it was working the day before.

Junkers88

Well I ran over all the vac lines and none were loose. I checked all the wires I could get my hands on, checked the coolant etc and found nothing odd. So I let it get to operating temp and it was sitting dead on 1000rpms at idle, I backed it down to 750rpms, shut it off, let it get back to a cold idle temp and when I fired it up it idles cold at 1800rpms and hot at 750rpms. I have no idea how it idled itself up like that or what was causing all the strange behavior. Now that I have it warmed up I'm going to put the test light on it and check the timing just to be sure it's still sitting at 5*BTDC.

Thanks for the ideas folks, hell I'm stumped but happy that it stopped.

93YotaMonster

hey it could be the IAC (IDLE AIR CONTROL VALVE). i had the same problem i replaced it and it fixed it.

Junkers88

Yeah but I don't have 300$ for a new one.

abecedarian

You've got the one integrated with the throttle body, right?
If so, maybe you've got some stuff built up in the coolant passage causing issues with water flow.

93YotaMonster

i only paid 109.99 for mine at auto zone.

Junkers88

Update here.


I got the idle set back to 750ish and checked the timing, it was probably 10* after TDC..... God only knows why, the damn mark on the pully was about 1/4" past the indicator. I'm thinking that it was set like that due to the poor perfomrance of the motor when I got it. I set the timing back to 5*BTDC and the idle dropped to less than 500 so I adjusted it back to 750 (dead on this time) and after letting it sit to get cold (over night) it now idles up to 1800 cold, 750 warm and I've lost that strange dead spot at 2200 when I'm accelerating.

I may still pull the IACV and clean it but for right now I'm freaking happy.

Just a note here. If I had listened to you guys when I first got this thing I would have found that damn loose - connection, checked the timing and a handfull of other stuff and I never would have had any of these issues.


For the New Folks. LISTEN TO YOTATECH AND DO SOME SEARCHING!!!!!



/me feeling like an ass.

BigBluePile

iTrader: (3)

Awesome man, glad to hear you fixed it!!!

Junkers88

Thanks! Every little thing that I do to this rig gets me closer to driving up there and teaching you how to wheel...... be afraid......be very afraid.

BigBluePile

iTrader: (3)

Oh snap! I better get my stuff together then!! lol!!!

Skilo47

mine is surging to .

it did this one time before but i just replaced the thermostat and changed the plugs and that made it stop for about a month then it just now started doing it again.

i flushed the radiator and replaced the thermostat (again) but this time that didn't fix it.

any sugestions.?

Junkers88

My problem was the idle being set too high and it being out of time.

Time you rig then make sure the idle speed is set correctly.

Skilo47

how would i go about setting the timming? do i need a computer to do that?

Junkers88

All you need is a timing light which you can either rent or buy. I bought one a few years ago for 20$ and have used it several times. The timing light even has directions in the package. If it's still a little confusing post back up and I'll try to take some pictures of the process.