Help with really High Idle issue...

[Sonicblue]

Hello everyone!

Ok I am newer to Cruisers and have only owned my 1991 Fj80 for a couple of months. I have owned a couple MK1 MR2's and did tons of work on them so I am not new to Toyotas. I am starting to have a couple issues that I have not been able to solve. I am new to this forum so feel free to rub it in... its all good

First off... I searched this forum for similar issues and I did find one thread almost identical but I did not find a clear answer to the problem which is why I am asking for some help from the experts.

1991 FJ80 3fe motor, 271,000 miles. The problem is I have a very high idle all of the sudden. It wants to idle at 2100 to 2600 rpms in P and N. When driving it automatically accellerates and I have to push harder on the brake at a stop to keep the Cruiser from moving forward. When hitting the gas pedal It acts like it is gonna die and stumbles as if it is running out of fuel and then slowly will drive sorta normal until I push the gas down any further and then it will bog down and hesitate all over again.

I pulled the trouble codes tonight and got codes 21 and 22. According to the info I found on the net it looks like 21 is for a faulty coolant temp sensor and 22 is for faulty o2 sensors. I am ordering the coolant temp sensor tomorrow. Looks like it is about $30 and I will still have to track down a pair of 4 wire o2 sensors. I really need to track down a FSM for this truck.

Anyone care to share their thoughts, opinions, and or expertise on this? Would a bad coolant temp sensor cause such horrible hesitation? I am sure if the engine thinks it is cold all the time it will run rich and might have a higher idle, but could it cause all my issues?? Thanks in advance from Mud's newest member

 

[jonheld]

The problem is I have a very high idle all of the sudden.

When you say, "all of the sudden", do you mean that NOTHING has been done to the motor and one day it just started? Or do you mean that you had given it a tune up, changed the oil, washed down the motor, and then you had high idle?

Not to break chops here, but please be specific.

 

[Sonicblue]

Good call, I was not at all specific about that... sorry.

What I mean is nothing at all had been done to the truck except driving it for the past 2500 miles or so. The problem popped up under normal dry driving conditions. I had not messed around with anything in the truck at all. I did not try and power wash the engine compartment, give a tuneup or anything of the sort. The only thing I did was after the idle and terrible driveability problem showed up I did jumper the diagnostic port to pull any stored error codes from the ecm which shows codes 21 and 22. I also went over all the vacuum hoses hoping to find either a cracked or broke one or one that had came off... found a cracked one and replaced that but it made no difference.

Matter of fact, I had not even given the truck a tuneup yet because it ran and drove so great.

 

[jonheld]

OK, Good. Lets start with the very simple stuff first. With the motor off, reach over the top of the intake to the throttle body and work the throttle back and forth a few times by hand. Take not of any "sticking" in the feel of it and where it comes to rest when released. Check for a sticking cable. Throw some WD40 down the cables to keep them moving freely.

If you have a hand throttle, make sure it is fully released.
Make sure your accelerator pedal is free.

WIth the intake tube off, note the position of the throttle plate as you work the throttle by hand. Make sure there is no chunk of carbon poop that has worked its way in ther preventing the throttle from closing all the way.

Start with that and make sure there are no mechanical issues first, then we'll move to the harder stuff.

 

[ToyotaDon]

The code 22 (Water temp sensor) could be affecting this also. I first want to stress that just because a code sets, does not mean the part is bad. The ECM looks at the whole circuit and detects any malfunction anywhere in that circuit.

Now, if the Coolant Temp Sensor circuit is open, the ECM will see this as -40 degrees. It will richen the mixture to its max, which will cause poor running, acceleration, etc.

With a rich mixture, the reading from the O2 sensors will be skewed, this could cause the code 21. Again, check circuits before replacing parts.

 

[Sonicblue]

Ok.. heres the update...

The Coolant Temp Sensor came in today but the thermostat did not. I went ahead and installed the new coolant temp sensor and cleared out the stored codes. Started up the truck and ran until it reached operating temp... smooth normal idle, good throttle response, and did not smell rich at all.

I then took the truck for a drive. It ran perfectly! No hesitation, no super high idle, just ran perfect and idled super smooth around 750 rpms. I checked for codes again and none came up, not even the codes for the O2 sensors which showed up the same time the truck started having bad hesitation and really high idle.

Is it possible I killed two birds with one stone?? I think I might have lol.

Thanks again to Jonheld and ToyotaDon. I really appreciate the quick and helpful feedback you both have given!

 

[geoff70]

i have a simular problem with my sahara how do i clear any stored codes,please thanks geoff