JRamos13

Hi!

im new to the the 4runner but not new to offroading or working my way around engines.

Yesterday i bought a 99 4cyl 4runner 2wd with 108k miles on it, the engine is strong and it has no problem keeping at 75mph on the highway, however it will idle at 1100rpm, when the car is in P, N or stopped. I connected my ob2 tool and noticed that the ecu is in open loop mode and the collant engine temp is at 154 +-5, after 15-20 min of idling however is not throwing a CEL, i already cheked for vacumm leaks and found none

millball

Make sure it's got a functioning thermostat of correct heat range in it.

Co_94_PU

iTrader: (-1)

School me?

Isn't it supposed to be open loop at idle and wide open throttle positions?

JRamos13

So today i change the thermostat put the oem one and now its going into close loop, on the first start up it idle perfect at about 700rpm but it started to get hot, i rode it around the temp got back down to 160 and when im stopped in D it idles around 900rpm now but as soon as i go to P or N it goes up to 1400 steady, no hesitating or anything , what should i look for next?

millball

Try to adjust the idle speed with the idle air adjustment screw on the throttle body.

Also make sure that the cooling system is 'burped' so that there is no air in it and it is absolutely full of coolant. Turn the heater temp control to hot so that coolant is circulating thru the heater core, so as to purge any air that might be in there.

JRamos13

For the 2.7 Where in the throttle body is the screw located? What gets me thinking its the temp stays at 160-165ish but at closed loop now

Charchee

Not familiar with that engine, but I doubt it has a screw being a 99 model. Most of those went away with the 22RE and 3VZE engines. Most Toyota engines use around a 190 degree thermostat. You said OEM. Did you actually get it from Toyota? OEM means a Toyota part selected for the vehicle's specific vin. Ask a parts store for a thermostat and they will most likely hand you a 160 even though that's too low. Do you still have the package or receipt with the part number? Your engine will keep trying to warm up by idling high if your thermostat is wrong. Verify that you didn't buy a 160 degree thermostat first.

JRamos13

Its from autozone, but it was a 180 one with a fail safe features, that upens up the stat in case of over heating

Charchee

Well I would sure hope it opens up in case of overheating.

180 is probably enough but you might do a search on what the spec is. I bet it's more like 190 or 195 but not sure.

Another thing you might want to look at is the coolant temperature sensor. Again, I'm not real familiar with this engine but I know on my 3.0L there are two of them. One is for the gauge and the other sends it's input to the ECM so it can make adjustments to idle speed among other things. A failed or faulty CTS will cause my engine to idle in open loop. The fact that your gauge is reading accurately may be no indication that your CTS is working properly. Again, that's how mine works. Yours may be set up differently. Figure out what sensor sends temperature information to your ECM and inspect it for loose or broken wires. Look up how to test it if you don't find anything obvious.

Co_94_PU

iTrader: (-1)

Exactly which engine is it? 3rzfe?

JRamos13

I dont know exactly, im new to toyotas in general, but its a 99 4cyl 4runner

Co_94_PU

iTrader: (-1)

Now since I had to dig that out I'll need more time to locate your idle adjustment.. I the mean time please elaborate on "hot", you have odb2 so no reason not to give exact numbers

Co_94_PU

iTrader: (-1)

Well that was about clear as mud!

First and second generation have the idle adjustment screw on the throttle body, later generations do not have the idle screw. Second gen has the idle screw bottomed out and it's not used, first generation ones have and use the idle screw.

Co_94_PU

iTrader: (-1)

Assumption #1, this is a second generation or third.
#2
​​​​You've not owned this vehicle for more than a year?
#3
it is operating as intended.

Start the engine observe a low idle speed,, place the shifter into a movement gear (not neutral or park) idle speed observed high, after several seconds the idle will drop but not return to the start up idle, return the shifter to neutral or park idle speed drops again but not to the low start up idle, repeat the shift to a drive gear idle speed increases and again drops as above, shift back to park/neutral idle drops to either the medium or low idle speeds..

This is due to the mechanics of the rotory ISC of the era which uses a simple brushed type actuator, which "freaks" people out and is why the later generations have a stepper not a can style motor, that will vary the orifice size based on where the magnetic coils line up..
​​​​​​

Co_94_PU

iTrader: (-1)

Toyota (usually) specs a dual temp thermostat, it should have a "jiggle" valve that opens at one temperature, 160 sounds about right, and a primary valve which opens (from memory) 20-30 degrees higher.

That should give you a normal range of 160-180 or maybe 190. And why I asked just what temperature your were seeing.

Charchee

No CEL after 20 minutes of open loop?

JRamos13

Thanks everybody for your help! No so far no cel, and the idle smooths out ones the truck is warmed up, the issue im having now is that when cold is not going in reverse, it o ly goes when warmed up, heres the thread:

https://www.yotatech.com/forums/f2/not-going-reverse-299122/

i dunno if it might be related, but i have been reding a lot and ive seen ppl talking about the TPS, maybe it would solve the idle issue too?