ieandro

Hey all,

So my '94 22RE 5-spd has progressively gotten worse in idling this winter.

It now idles at 1100-1200 consistently and the idle "sticks" at 1600 or so between gear changes and does not drop until the brakes are applied and then drop in almost a step like fashion. Sometimes it the rpm drop is sudden and drops all the way to its normal 850 rpm and then realizes its fu˘ked up and climbs its way back to 1100-1200.

I think it's a vacuum leak.

Maybe even a coolant issue? (It hunted one time when i was low on coolant and it needed a bleed)

I honestly don't know where to start with this one. Im hoping someone more knowledgeable can point me in the right direction. It's cold out here in Jersey and would like to reduce my investigation time outside.

Thanks!

dodge79

have you played with the idle screw

ieandro

I haven't touched the idle screw or know if the previous owner did, but would that explain why the idle likes to stick between 1500 - 2250 rpms?

I'd like to add some more info to the issue:

-it sticks between the above rpm range when shifting in that range (mostly 1st to 2nd).

-If I blip the throttle at neutral to 2500 it will drop back to its 1100 rpm.

-In frustration after driving for a while, I drove aggressively mashing the throttle and shifting at 3000+ rpms and found the idle settled back down to 900-950 rpms.


I've searched google and found some articles on a possible brake booster issue causing the idle to drop when depressing the brakes. Thing is my "normal" idle doesn't drop when I press the brake (1100 or so now - used to be 850 a few weeks ago), but it drops the idle when it sticks in the 1500-2250 rpm range. If I didn't step on the brake, it would just stick there until I blip the throttle past 2250rpm.

Anyway, how can I test the function of the brake booster / vacuum? I hope that it's that because a new booster is $100+

Thanks to anyone who can help out.

Gamefreakgc

Don't buy any parts yet. Your issue sounds most likely the effects of either a dirty accelerator cable (or cruise control, if you have it) or a dirty throttle body, causing the throttle to stay open. You can usually blip the gas pedal and it'll return to normal, right?

Remove the air cleaner hose (the big black accordion looking one) and peer down into the throttle body. Open the valve manually and close it fast, and then slow and see if it ever sticks and does not close entirely. Even if it doesn't, a good cleaning here is always a good idea.

Next, press on the gas pedal (when off, obviously) while the hood is up. Look for the movement of the valve. If it ever appears to stick and not close or if your gas pedal is very resistant, you'll need to clean it. Remove the cable from the back of the pedal (it snaps in, you'll figure it out) then remove the two bolts in the engine bay along the fire wall. Disconnect from the throttle body valve and remove the cable. Look for fraying or any un-even surface. Usually you can trim it up ok but if there's anything terrible you'll need a new cable. Then shoot a ton of carb cleaner through the cable housing. Then get some chain lube or white lithium lube and work that from both ends of the cable housing using the cable. Hook it all back up and then adjust the cable so you have a little slack (if it's too tight it'll keep the throttle open).

That should do it. If that's not the issue and everything checks out ok with no sticking, let us know.

ToddShaw

Take a look at this you tube video. It is excellant and may help you.


I sent this to another person who had a similiar issue as you.

Hope this helps,
Todd

ieandro

Gamefreakqc,

Thanks for the tip. I will clean out the TB once the weather gets a bit warmer than 9 degrees. What I did do yesterday was spray the throttle spring with some Aerokroil and this morning it didn't stick on my commute into work. Even the idle went to 900 after about 10 minutes of driving although it went back 1000-1100 when i finished my commute. I'm starting to hope that the TB just needs a cleaning

Toddshaw,

If cleaning doesnt solve the issue I will follow your advice.


Also, can anyone explain why when the idle sticks, depressing the brakes makes it drop to its normal idle?
From my readings, some had issues when depressing the brakes and making their idle drop to sputtering condition like in the 250rpm range. Although in my case it just drops it to normal idle when it sticks.
I've also read about the dashpot, which I will look at too when i remove the TB.

ToddShaw

Ieandro, Sounds like a vacuum leak. Possibly internal to the brake booster. These are expensive, about $200.00. Might be able to find one in a wrecking yard to save some money.

You would need a vacuum pump to test it. They are about $40.00. http://www.autozone.com/autozone/acc...fier=70116_0_0_

Also check this video out. It will show a way to check for vacuum leaks on your truck. VERY VERY Helpful. THANK YOU ERIC THE CAR GUY!!!! His videos are always very helpful to us backyard mechs.


Hope this helps,
Todd

Gamefreakgc

The brake booster applies vacuum to give extra power to the brakes so you don't have to mash the pedal to stop. If it's just a dirty throttle body, then the extra vacuum pull could suck the valve shut a little more. Or, it could be a vacuum leak on the hose or the booster itself. What you are describing does not sound like a busted booster though, so don't worry about that yet until you have the idle surged fixed.

The dashpot is just a spring loaded air piston. It does not affect the throttle closure unless you messed with the screw adjustment. It's only purpose is to slowly close the throttle for a smoother deceleration and better emissions.

ieandro

*UPDATE*

Okay. The official problem was .. the dashpot. I braved the elements today to follow Toddshaws posted video on whatever you call that port that may have been plugged - turned out it was super clean so no issue there. I started the engine and manually played with the throttle linkages to try to replicate the issue and was wondering why it idled normally at 1100. You can blip the linkage and it would shut, but you could still manually move it about 1-2mm and then idle to around 1000. A neighbor walked by to see what I was up to and explained that the boot around the dashpot was blown and the spring was exposed and told me it was no good. Thing was I inspected it and thought the spring tension was so light that there was no way it could be hindering the throttle return since the throttle spring was quite snappy. So i removed the screw adjustment that contacted the dashpot pin and throttle linkage and voila! no more sticky idle. I even twisted the idle set screw 3/4 of a turn clockwise to get it humming at a perfect 750 rpms. I guess the way the dashpot was broken made it surge sometimes, but could not figure out why the idle was also hunting. I thought with it being broken it would just physically keep the throttle partially open and keep the idle high.

Anyay, went back in to research about the dashpot removal and subsequent ill effects, but the consensus around yotatech leans towards the "no big deal" side. Many have said that it's there as an emissions part and for (a lack of better wording i presume) smoothness in driveability.
The rpms do drop dramatically between shifts and the exhaust has an almost sweet backfire since I don't have an actual muffler. I will still do the TB cleaning this weekend.

So the question remains - should I replace the dashpot? I'm thinking I should. Also, a google search for a 22re dashpot doesn't seem to net any results. Is this a Toyota specific part? Rockauto doesn't list it under emissions or fuel/air tabs.

Also .. Thanks for everyone that's contributed.

Mudcat

Mine is acting the same as you describe, I am going to check my 94 for the same issue. . Thanks.

Romans117

Sounds like two issues. Dashpot and manual transmissions have a vacuum valve to moderate the rpms when shifting. The vsv is suppose to prevent the dramatic increase in rpms when shifting. Get a manual and check it out.

combatcarl

I don't know about a vsv for idle control during shifts. I know on my 89 22RE, fixing a vacuum leak, cleaning TB, and dash pot removal fixed my issues. Many times, cleaning the IAV under the TB fixes hot start/hunting idle issues also.

Gevo

Dashpot itself wouldn't cause surging idle. Unless this dashpot was form a fairytale land where car parts can talk and do mischievous things!! I think it was your throttle linkage, once you played around with it something clicked back to normal.. However, as you described your high idle can be caused by the dashpot. The FSm seems to think that the dashpot needs maintenance and that if the breather in the back of it is clogged it won't compress, thus causing your high idle symptom (and perhaps even would explain why when you blipped the throttle it would settle down lower sometimes)... so read the section in the FSM, it's very easy to clean. Your spring would get weaker in time, not stiffer, unless rust has choked the life out of it.

Again, surging idle.... only the Toyota gods can cause a dashpot to do it (unless on your car the dashpot is significantly different than mine and has air hose and such as you described)

cheers!

ieandro

Except my faulty dashpot did cause my idle to surge so mine must have came from that fairytale land that you speak of.

Removal fixed both surge and high idle.

Gevo

Fair enough.. first of all I'm gla dyour problems are solved. For my education, can you tell me if this is the dashpot that you have? Scroll down to page EG1-198.
http://personal.utulsa.edu/~nathan-b...34throttle.pdf

Thanks

ieandro

yes. the dashpot shown was the one on my truck.

Gevo

Ok, so not to be arguing for the heck of arguing, but I do want to point out the mechanics of a dashpot, by definition, is passive. It decelerates at a controlled rate, surging idle would mean that your dashpot was somehow providing an acceleration in the opposite direction that it is intended to work. It has a spring, sure, but the spring energy will die out very rapidly and unless a force acts on the spring, it will no longer provide a response.

My point is, the removal of the dashpot may be a band aid to a larger problem that is still there...

good luck.

ieandro

As I understand it, a dashpot is nothing more than an emissions control device by allowing the throttle body to stay open longer to allow lingering gasses to escape thereby reducing high levels of unburnt fuel to stay in the pipes when the throttle is abruptly shut without it.

Generally, most of the posts here about the removal of the dashpot causes no adverse reactions because of the dashpots intended use - an emissions control device. it does not actually play a role in the driveability of the motor such as an oil pump or a spark plug.

Honestly, without it my engine still runs smooth, dependable and still gets the same, somewhat ˟˟˟˟ty mileage i'm sure it got back in '94.

kcaudill

Pic please

Gamefreakgc

Yup, no ill effects. It's just a spring loaded air cylinder, nothing more. With manuals though, it does jerk a bit when decelerating so a bit of an annoyance.