Hello again guys! Has anyone ever had issues with there throttle position sensor going out or acting up?
I have a 1994 toyota truck 4x4, 22RE engine and 5 speed. She has about 85k original miles and is in really good shape. Latley the engine has been idleing higher than normal. Sometimes it idles normal and some times it acts up. It started doing it on and off and latley a little more offten.

I pulled out my sevice manual and volt meter to check the sensor by putting the specifed feeler guage between the throttle stop screw and checking for continuity at the plug posts. Acording to the manual, I have continuity when there is supposed to be no continuity. I just thought I would ask you guys before going out a buying this sensor. The thing looks brand new and I dont have any check engine lights. All rubber vacum hoses are good. Any advice would be much appreciated.

 

I found it was necessary to lube the throttle linkage at least every oil change.

Have you ever cleaned the inside of the throttle body??

Perhaps I have just been lucky I never had a TPS fail

If you decide to get a new one go with Toyota Parts these engines don`t like off brand electronic parts

 

Thanks for the info! I did check my thottle cable and it is in great shape and slides great. I will lube it though with some cable lube I have for motorcycles!

On my drive home last night it was really idleing high and today on my drive in It was idleing almost normal.

I did pull the throttle body off just to look at it. It was actually kind of dirty on the inside. It was very clean in the front before the flap and behind the flap was dirty. And by dirty I mean the black, carbon blow by kinda of dirty. Not actual dirt or mud. Didnt look unusual. Have you knowen these things to need cleaning?

Should I pull that guy off and soak it in some carb cleaner dip? I have never done it to a my truck throttle body but I have rebuilt many motorcycle carbs before with good results.
Thank you!

 

Maybe try removing the EFI fuse for 5 minutes to reset the system first. I have had a TPS sensor go bad and even(or should I say especially) Toyota could not easily trouble shoot it and they were racking up the $$$$$ with just swapping/cleaning parts,sensors, etc. My symptoms were unusual, a brief hesitation(started this way at top of hill, after a few years it finally became an jerk/stutter)when maintaining speed and the check engine light would be on when this is occurring then, poof, the light would go off for months at a time and the issue would go away. If you are going to change the TPS use a genuine Toyota one, best $45 I have ever spent.

p.s. I run a wet TRD air filter and it is possible that this caused the TPS sensor issues.....

 

Thank you for the reply. Sounds like I might have another small sensor issue somewhere else. I have herd that the TPS sensor will cause an issue like you are describing, with the shutter or jerk in acceleratin. Some one was just telling me the TPS sensor would NOT affect engine idle how I described it.

 

The upper part of the manifold does need cleaning from time to time.

I did not mean the throttle cable but it does not hurt to lube that as well

I meant the throttle linkage that goes through the throttle body that has a habit of hanging up causing the high idle.

Then in extreme cases a few had that rod wear so hard the air was sucked in around the rod.

Your sure none of the vacuum hoses are cracked and brittle ??

Nothing came loose on the air intake tube ??

If the TPS has failed the CEL should be on is it??

 

Hello again, So I checked the throttle linkage and it is all perfect. opperates smoothly without any play.

I checked most of the vacum lines and they are all perfect and soft. The truck has 84k original miles and spent most of its life under a cover so most of the rubber is in good shape. Before owning my 1994 toyota pickup I daily drove a 1979 280zx and learned all about hard cracked leaking vacum lines

Intake tube looks good, I will be removing the air box and tubing just to get a better look and make SURE it is air tight.

No check engine light. It has never come on, not even for a secound. So I am thinking my TPS is not the issue. It is an intermitent problem. Sometimes it idles normal (hot or cold) sometimes it will idle just a little above normal, and sometimes it feels like it idles at 1500 rpm. when it idles real high, if I turn on my AC the idle goes up and down constantly. A few more miles down the road it goes back to normal. It is really odd. no check lights of any kind. had an issue with carbon build up in my PCV valve in my datsun, with it idleing high, cleaned it out and it fixed the problem. But my truck has 1/3 of the miles on it the Z did and dont feel like it could have that much carbon built up but I dont really know.

Thank you for the help too!

 

False, I had a TPS go out and never threw a code.
I only figured it out as on my way up to Miller Jeep trail, The high altitude is what got me wondering as it was a dog all the way up and over, Luckly it was a manual and could rev first, But there were a few spots I was smoking the clutch.


One leg of the TPS was bad, Which one I don't remember.


Back to OT
The dashpot, The little rubber boot on the shaft gets hard and does not collapse normal until warm sometimes as well as its diaphram.
Sometimes the cold idle up channel fills with crud from the coolant system, But just may be aged.

 

Hello again guys.... Still no luck in solving this high idle issue.

Today I pulled everything apart to check the possible issues guys on here have mentioned.

I pulled all air intake items apart to check for dry or cracked areas and all was good.
Drained and flushed coolant, probably not the issue here but did it anyways.
I removed the trotle body and cleaned it all! had a good amount of sticky black soot on the inside around the trottle flap and cleaned it until spotless, installed new throtle body gasket as well. Started right up but still idled high.

Nothing I have done thus far has fixed the the high idle. I am confused and have my tail between my legs at this point.

Any tips or leads would be much appreciated. thanks!

 

Just for S&G's, Check the AC idle up VSV (If you have AC, Disconnect it), I have only heard of this happening once and a long time ago, The owners AC control module was acting up and turning his AC idle up VSV randomly.


Also the PS idle up valve could be going bad.


Just thoughts

 

Another couple things to consider. You could have a sticky AFM. Having a vehicle sit for a long time can be worse than driving it sometimes. Seals dry up and mineral deposits build up. If the AFM flap isn't moving smoothly that can effect the idle.

Also the idle air bypass screw has an O-ring around it that can dry up and become problematic. This happened to me early this year. The adjust ment screw O-ring had dried and hardened. Air was bypassing the screw and causing me to have idle issues. I noticed the culprit when I had to adjust it a few times. Bought a replacement from LC engineering and problem solved.

As for the TPS I've also had one not working proper without throwing a code. It was just out of spec enough to effect my idle but apparently not enough to throw a code.

 

Thanks for the help guys!

I will look into those suggestions just mentioned!

I was just reading in a service manual that the Idle Air Control valve located on the bottom of the throttle body could be sticking open or not shutting all the way causeing a higher than normal idle. I am going to check it out today.

As for this "Also the idle air bypass screw has an O-ring around it that can dry up and become problematic. This happened to me early this year. The adjust ment screw O-ring had dried and hardened. Air was bypassing the screw and causing me to have idle issues."
Is that the little guy up towards the top of the intake manifold with a thumb screw/flat head screw in it.? Did it cause a high idle?

 

It's the big standard screw head on the throttle body, just to the left of the air intake hose. Mine caused more of an erratic idle. As things would heat up and cool down, swell and shrink, the idle would fluctuate. Probably not the issue but for the 30 seconds it takes to pull it out and check it wouldn't hurt. I've also heard of people using teflon tape to help it seal better.

If you think the IACV is the culprit, a lot of us have had that issue. The easy test is to let your truck reach a normal operating temp and clamp off the big vacuum line on either side of it. If your idle drops I would certanly pull it off and clean it and check resistance. There are many post on this procedure.

Good luck and let us know if you find the answer to your problem. It always helps the next person if the solution is posted.

 

Ok so I want to test the Idle Air Control valve.

On my 22RE it only has two connections for coolant. I removed it from the throttle body and knocked a little crud from one of the coolant line IN conections. Other than that it looked real clean. I really dont know how to test this thing so I Just pluged the hole with some strong Aluminum tape inside the trottle body and turned the idle screw a 1/4 turn and she is idle perfect. I could have a failing IACV . I used really strong aluminum backed tape and think i will drive it around for a day and see if the problem ever comes back since it has been intermitant. I dont think and hope it wont suck in my tape. Ill keep you posted! thank you all, we will get to the bottom of this.

 

If the IACV had crud in the coolant line that could be your problem. The IACV is what creates the high idle at warm up. As the motor heats up the valve closes off the extra air flow to lower the idle. If the coolant is blocked than it doesn't know the motor has warmed. Covering that vacuum line with tape won't hurt anything but you will notice a lack of high idle at warm up. I have an '86 which had a different IACV than what you are running. On mine I can remove the cover to the valve itself to clean. While in there I spray a dry lube just 'cause. There is also a way to adjust the opening that the valve closes off to allow for a higher or lower warm up idle. If the valve is not closing all the way you can adjust that opening to make up for it. Keeping in mind this will also effect the warm up idle

 

Ok We have this solved!! The Idle Air Control valve has gone out on me. I proved this by sticking strong tape over the air inlet of this IACV in the trottle body while the ingine was warm and while I was experencing this high idle. It instantly went to normal! So YES! finally got this figured out.

I cleaned it real well and checked the inlet lines at the thermostat housing and it still malfunctions. Upon investigation, these are knowen to fail on 1994 Yotas. The thermo wax pellet inside them becomes hard over time and begins to fail. Symptoms are high idle or surging idle and cold conditions can bring it on as I found out.

Thank you so much guys for the help!! It is appreciated!