UpInSm0kE

This may seem like a dumb ? but I am looking at the FSM for how to test the TPS sensor how do you apply vacum to the throttle opener? Is this nessesary?

hross14

Huh??--unless there is something different on the Tacomas--I am not sure what they are talking about unless it is the Dashpot. I hook up my scan tool from URD and graph the TPS---but i doubt you have one so you need to follow the direction on which pins to connect to on the sensor itself. after you get that figured out, very slowly open the throttle and keep a sharp eye on the readings. Any unusual jumps means the TPS is bad.

How does the coolant look and the other items?

UpInSm0kE

hross I was stumped to. The Toyota Tacoma FSM said to "apply vacuum to the throttle opener" then test at fully closed, fully open, Im not quite sure what the - means here is the link to what I was looking at. I had to use the 2000 tacoma to get the TPS specs the only one close to my year was a 96 but that had the 4 wire TPS and mine is the 3.

http://www.ncttora.com/fsm/2000/Repa...0Body/insp.pdf

The results of the TPS testing was as follows (without applying vacuum):

Fully closed - 0.5 ohms
Fully open - 2.4 ohms
- (VC-E2) - This one out of wack the first time I measured it at 7.2 ohms and then re-tested about 5 mintutes later and showed within spec. does the "-" mean to leave it fully closed and test from pins VC-E2?

I will have to double check at lunch today what the results are by slowly moving the throttle on each setting as well.

Coolant was a little low so I added some to the system and checked for air and could not find any.

Cuthroat72

One more thing to check, and this happened to me. I have a 5spd 4Runner, and it has 217,000 on it. I recently ran into a similar problem. I cleaned the IAC 4 or 5 times, and still ended up at idle of 2,000-ish. I found that if I revved the truck to 5K rpm, and immediately let off, and it would idle normally, but as soon as I got back in the gas it idled back up.

Long story short: the butterfly of my throttle body was rubbing on the wall of the throttle body, and not allowing it to close all the way. It's an easy thing to check... With the truck idling high, I pulled the "wheel" where the throttle cable attaches toward the radiator gently, and it would idle down. With the throttle body removed from the truck, and a light, I could see scoring where the brass of the butterfly was rubbing. I ended up having to buy a throttle body. Good luck man.

hross14

Smoke--ok, now i know what they are talking about--there should be a vacuum line going to the dashpot/throttle opener. It is right there on the TB.

I dont know the values off the top of my head but you could also try heating the sensor up a bit--this increases the resistance in electronic items and this is when it acts up.

Also check out your dashpot to see if it is sticking also....its hard considering i am not there to look at the truck--alot of little things that might grab my attention you might not be seeing. This is what its about though when it comes to trouble shooting problems.....

UpInSm0kE

Hross I checked the TPS again moving the throttle up slowly and there is nothing indicating a bad TPS from what I can see on the ohm meter. I am going to test the dashpot tonight and see what happens. If not I think I am just going to bite the bullet and buy a new IAC valve. Right now the truck idles around 1000-1200 and dosent appear to be having a problem starting like before but when I unplug the IAC it idles normally so is the problem most likely in the IAC?

hross14

I think there is a procedure to sweep the IAC also. Not sure--but it seems like you have covered your bases. To bad you didnt have a graphing meter to test the TPS.....

Anyways what made it drop from 2000 to 1200?

UpInSm0kE

hross This is the breakdown on the idle issues.

1. Truck started to idle at 2K constantly
2. Disassembled original IAC valve and attempted to clean IAC. This brought the idle down to 1200 rpm.
3. Ordered a Guaranteed and tested used IAC valve off of ebay and put that on and the truck went from 1200 to 2K and started engine loping as well when I hit the brakes. Would not start either when engine was hot.
4. Put back on original IAC and this brought the idle back to 1200 rpm. This is why I was thinking the IAC valve because it is the only thing changing the idle at all it seems like.

ubermoto

I am having the exact same problem with mine...

https://www.yotatech.com/forums/f2/3...h-idle-198330/

Have you tried manually playing with the throttle linkage like Cutthroat suggests? Another thing you can try is some spray-lube (no WD-40!) on the butterfly axle/linkage. I haven't gotten to the bottom of mine yet, but it appears it *may* be correcting itself over time. On the drive home, it would settle in at 1250 rpm whereas before it was up around 1750...

Also, something to think about - have you pulled your EFI fuse? This gives power to your ECM brain box. If you pull it for 15 min, the ECM resets itself. Something you may want to do when swapping IAC valves and such since they're all a little different...

Did you test your IAC valve? The procedure is listed in the FSM. Basically you hook up the middle terminal to neg post on your battery and the other two terminals to the pos post (not at the same time). One should close the valve, while the other should open it. When I did this test on mine, the valve never closed *100%* - there was always still a little gap. I'm not sure if this passes or fails the test.

Here's something wierd that mine is doing - when I clutch after runnin' bout 3000 rpm, the engine will drop to around 1000 rpm then climb quickly back up to 1250...

I feel you pain. These things drive me nuts!

hross14

at this point i dont know what to tell you. I would have to be there to check it........

UpInSm0kE

Hross Thanks for all the help man I really appreciate it. I will post back in the coming weeks with a solution I still need to test the IAC valves that I have. Moto I have tried everything that you are describing except test the IAC valve. I noticed with mine as well just looking at it that it isnt closing all the way either I would assume that it would need to close all the way. I will test that tonight or tomorrow and post back. I have pulled the EFI and disconnected the + battery cable sometimes all night and no difference I will let you know what I find out about the IAC.

UpInSm0kE

Alright guys the Idle problem is fixed. I read on another forum that if you put to much sealant on the housing to the valve it can cause some problems with the idle. I pulled it back apart yesterday and sure enough the sealant was all over the magnets. I cleaned it off and resealed with a minimal amount of RTV and the idle is fixed. Here is a link to the post that got me wondering https://www.yotatech.com/forums/f2/b...estion-129426/ Thanks everyone for your help.