Idle Problems (1 Viewer)

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KliersLC

KliersLC

Joined
Oct 14, 2004
Threads
231
Messages
3,966
Location
Virginia Beach, VA
Howdy,

My 3.4L in the T100 is having some problems idling. It was working fine until I cleaned the throttle body, and now it idles way too high, and varies between 1800 and 2500, with no throttle.

I triple checked the throttle body to ensure that the throttle plate is closing completely, and that there was nothing stuck in there holding it open. I also triple checked my vacuum hoses to make sure that they are all hooked up, and even ran a vac test and the vac system checks out fine.

Pertinent info: 95 T100, 158k, I also changed the oil and did a coolant flush at the same time as cleaning the throttle body.

So, What did I screw up?

Thanks,
Dan
 
Not that I know of, I just pulled the intake hose and cleaned the plate with carb cleaner and a toothbrush and then reinstalled.
 
hmmmmm.

thats odd.
i am unfamiliar with this engine. are there vacuum hoses on the throlle body like the 22RE that you could have crossed?

the only info i can give you is this:
i once worked with a guy that did a T-body service on a regular injected honda four banger.
after the service it ran like s***. and later he faulted the intake air contoller coolant tempature sensor. its not bolted anywhere near the t-body, and i didnt understand his reason for diagnosis. but he swapped it out and it ran better.

i think it would be a good idea to check out you O2 reading and determine if the truck is lean rich or stociometric.
maybe this method will assit you in narrowing this down.
 
Forgot to mention, no CELs but I'll check out the o2 readings and the TPS tomorrow. Is the TPS cleanable? I know it is on the 80, but truthfully, maintenance on the T100 has been little to none so far, aside from oil changes.....
 
i wish i knew more about this engine to help you. you should post a link to this thread in the later model truck section. heck, i dont even check there, as i dont want to give all kinds of advice on technical problems for engines i am not familiar with.
 
WristPin said:
i wish i knew more about this engine to help you. you should post a link to this thread in the later model truck section. heck, i dont even check there, as i dont want to give all kinds of advice on technical problems for engines i am not familiar with.
Click to expand...

just checked that section. :doh:
 
KliersLC said:
Forgot to mention, no CELs but I'll check out the o2 readings and the TPS tomorrow. Is the TPS cleanable? I know it is on the 80, but truthfully, maintenance on the T100 has been little to none so far, aside from oil changes.....
Click to expand...
yes you can clean it.but beforeyou do check the install instuctions:beer:
 
2ndGenToyotaFan said:
I'm going to move this over there. You can delete the other thread you started. :cheers:
Click to expand...

Well, see the problem is that my T100 is a 95, so it is covered by both sections, 79-95, and also 95 and up. I posted it in both because there might be somebody in the newer section who is familiar with the particulars of the 3.4, but there are far more experienced mechanics in the 79-95 section. The T100 line started in 93, so it kinda crosses the boundaries.......

Dan
 
Did you use carb cleaner or intake cleaner? I've been steered off of carb cleaner for anything that involves sensors with the warning it's liable to roast 'em.

After cleaning my TB the last time, I found I did bork something about it (either the plate pin, butterfly spring or bushing) just enough to keep it from closing completely. Your toothbrush method makes me wonder a bit, but I wasn't there to see if that cleaning method might have something to do with it.

Visually mine was fine; two different mechanics initially though it was fine, too, but it was done for. With the engine running I was finally able to detect the slightest -the slightest- little bit of slop which never closed on its own again. To make matters even more fun, the AC idle up valve (the little box sorta hanging out in space over the PCV) decided to go out right after I replaced it. With the new (used) TB the idle came down but not quite enough, so it took that AC valve (revealed itself with a code never evidenced by a CEL) after I plugged in a replacement TB to solve the problem.

A way to clean the sensors fairly sufficiently (the IAC could be another culprit) without breaking into them is to use a good sensor safe intake cleaner, hose the bejeezum out of the TB after you get the bulk of the gunk out and ever so lightly tap the TPS and IAC with a screwdriver handle as the stuff runs down into them. I think the best sensor-safe solvent I've used is the Toyoguard I got once from Gettel in Florida. Kind of a pain to have it shipped, so I usually go for CRC Intake Cleaner or Deep Creep off the shelf.

I'd give a whirl at gently cleaning those sensors again, test the resistance on them if nothing improves, check for any codes and if nothing shows up be prepared to hit car-part.com for a throttle body.

Just my experience with the same problem. Good luck.
 
Update,

TPS seems to check out fine, but I am waiting on the FSM to arrive to make sure the values check out. It was very clean though. It seems to function the same as the old ones, but it is a non cleanable sealed unit, so you can't take it apart.

I removed the idle air control solenoid, and the little flapper inside seemed to be a bit stuck, so I cleaned that out with Q tips. it now functions, and with the solenoid removed, it idles fine, but when I install the solenoid, the darn thing opens up the IAC flapper and it idles up again.

So, this tells me that the IAC solenoid is being told that I need a high idle for some reason. Still no CEL, so the high idle works off of tow systems--the AC and the temp system. I did a coolant flush, so is there any chance that the flush would cause the coolant temp sensor to read low temps and bring the idle up? Could this be a faulty temp sensor, and if so, how to test it?


North40, I just propped the throttle open with a screwdriver and scrubbed away, there is no play, and the high idle seems to be coming from something that controls the IAC.
 
landtank said:
you might check the throttle cables. I'm assuming you removed the throttle body and turned it over and around to clean it. At that mileage the cables are likely suspects without being disturbed.
Click to expand...

No, I didn't remove it, although I probably should have. I had just cleaned the TB on the 80 the day before without removing it, and suffered no ill effects, so I thought I could get away with it on the T as well. All of the cables are in good shape, there is a bit of slack between the TB and the cable sleeve when the pedal is released.
 
Update:

Well, after fiddling and fiddling, I figured out that I goofed up the throttle body. The FSM says use carb cleaner, but the local toy dealer said that the 3.4 TB has a special film on it that gets eaten by the carb cleaner. I compared my junkyard TB with my old one, and could detect no film, but that doesn't mean it isn't there. I suspect that the film may have been on the Idle Air control valve and that is what was eaten, but I am not motivated enough to take the new IAC and put it on the old TB to see if it works.

Anyhow, an 85 dollar junkyard TB was the fix....

Cheers,
Dan
 
I was under the impression that an entire throttle body was a bit more spendy than that. They list at online places at 150-300 used....
 
KliersLC said:
Update:

Well, after fiddling and fiddling, I figured out that I goofed up the throttle body. The FSM says use carb cleaner, but the local toy dealer said that the 3.4 TB has a special film on it that gets eaten by the carb cleaner. I compared my junkyard TB with my old one, and could detect no film, but that doesn't mean it isn't there. I suspect that the film may have been on the Idle Air control valve and that is what was eaten, but I am not motivated enough to take the new IAC and put it on the old TB to see if it works.

Anyhow, an 85 dollar junkyard TB was the fix....

Cheers,
Dan
Click to expand...
:beer:
 
KliersLC said:
I was under the impression that an entire throttle body was a bit more spendy than that. They list at online places at 150-300 used....
Click to expand...

They were the last time I looked. I scored a used one for just under $150. Most were in the $300 range and a new one priced out around $700 iirc (with the unspoken discount figured in iirc).
 
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