I would check all the plugs just to make sure you don't have a stuck injector.
That may also cause that type of condition.

 

Wednesday, I'm going to take the day off to work on the truck, so hopefully I'll have it all figured out then.

Chris

 

Jamie's asked for MAF voltages, but I didn't see anyone mention cleaning the MAF.

Also, there's a vacuum line underneath the TB that has caught a number of people after cleaning. As you face the inlet side of the TB, there's a fitting underneath the TB opening that faces towards the back of the engine. Check to be sure that line is on all the way and not leaking.

It's one that has to be removed to get the TB off, and is often forgotten to put back on afterwards. The symptoms end up being much like what you guys are describing.

Mine was off for 13 months before Dr. Z noticed it in a random picture I had posted.

 

Well, I went out and checked the MAF. It read about .5V at rest w/ no air. About 1-1.3V with me blowing into it, and about 2-2.4V blowing into it hard. Seems like that is working. I went to test the TPS... Well, you are supposed to get continuity w/ a .013 feeler gauge, and at .021 you aren't supposed to get any. Well, when I tested it, I got none throughout the whole way of the throttle. So it looks like we have a winner! Hopefully. I am going to run down to my trusty auto store and grab one and see if that fixes it. I'll post as soon as I have the results! Thanks for all your insights!!

Ryan

 

It is not all that much of a mystery, just systematic trobleshooting that saves the day! The MAF voltage sounds fine to me too. You should also get a smooth voltage variation through the throttle's full range of motion. I hope that gets it, but if not post again and we'll keep at it til we get you back up and running %100. Does sound promising to me as well.

 

Where is the TPS and how did you test it, because when I hooked my BR-3 up to my truck, it reads fine on the TPS, but could it be bad and still read okay on the BR-3? I'm taking the whole day off tomorrow to fix this damn thing, and I would love to hear how it went for you today by replacing the TPS. Please tell all!

Chris

 

Chris,

The TPS is on the left side of the throttle body if you are facing the intake and the throttle/accelerator cable is on the right. It has three conductors and are situated in a vertical order. You want to put your probes of your multimeter on the two bottom ones. If you have the Haynes or Chilton's manuals, they have a test you can do. If you insert a feeler gauge of .013in between the throttle stop screw and lever you should get continuity. If you put on that is .021 you should have no continuity. Atleast that is what the Chilton's manual says. Hope this helps!!

Ryan

P.S.- Also, bought a new TPS and going to install it tomorrow. I'll let you guys know what's up.

 

I'm not totally clear on what you just said, but I'll see what I can find out today. Good luck on your install, and I can't wait to hear what you find out.

Chris

 

Sorry about that, it was late... Here's the picture. The TPS is on the left side of the picture. It's a black connector that has three conductors. Then use the test I typed above. Hope that helps!!

 

Man am I happy! Today I attacked the problem using Carb Cleaner as one mentioned on here checking to see if any of the hoses were leaking, including the manifold, etc.

Guess what? I found the problem! My gasket between the throttle body and the intake manifold was leaking bad. When I sprayed the carb cleaner on the sides of the gasket, it would choke out the motor. So, immediately, I replaced the gasket, which resulted in another problem.

I didn't have my laptop at the store with me, so when the leak was gone, there was too much fuel, since I had to have more fuel added using my SMT-6. But, after pressing the brake and giving it a tad bit of gas while stopped, I was able to make it home to get the laptop to reduce the fuel.

So, I'm resetting the ECU, I dropped the fuel back down to zero in the SMT-6, which is where it should be, and then I'll try it out. But without resetting the ECU, te idle went right to the normal level, which I was very happy about. The only problem was without resetting the ECU, it wouldn't rev very quickly, which I think will change here in a few minutes when I try it again.

I'm so freaking happy to have found the problem, and I couldn't have done without you guys on here. At least I didn't have to buy any expensive parts, just some carb cleaner! I love it!

Chris

 

Told you.....

Congrats on solving the problem!

Gadget

www.GadgetOnline.com

 

You da' man! I couldn't have done it without you!

Chris

 

Oh, Gadget.....

 

I'm glad you got yours fixed Chris. I still, unfortunately, have the problem. I replaced the TPS and reset the ECU to make sure everything was cleared out. Still no luck, it revs like a mo-fo. However, when I am driving down the road like on normal highway trips, the gas mileage is fine. So I don't think I have a faulty injector or anything. I have a feeling some of this is in the throttle body coil springs that snap the throttle back in place when I let off the gas. Many times it will bob back down to about 1000 and then jump right back to like 1500 or more. But then I quickly hit the throttle and let the pedal snap back, and it will go back down to 1000 or so. Anybody have any ideas? Any ideas are appreciated! I can't stand a car of mine not running right. It's a pet peeve of mine! Thanks!!

 

Hey man, I'm sorry it didn't fix your problem. I would highly recommend buying a can of carb cleaner and spraying all your gaskets on the manifold, throttle body, and all the vaccuum hoses as I did, and my guess is that you've got a leaky throttle body just like mine. I would at least try it, because it's cheap to try and easy to fix in most cases.

Do you have any check engine lights on? I would think that if you have a stock 4runner, that a 171 code would be trigggering if you have a substantial leak like I did. As soon as I fixed the leak, I was running too rich, because I was having to add fuel to compensate for the leak. Let us know how it turns out!

Chris

 

With the engine running, run your fingers around the edge of the throttle body at the point that it attaches to the manifold. Apply some decent pressure to the seam as yoou go, and see if the engine speed changes at all while you do so.

If you can affect engine speed by finger pressure around the seam, then the TB gasket is leaking.

I once replaced the TB gasket on a friend's rig and put the new one in 90 degrees out of alignment. At first glance, it "looked" okay, but it was leaking just enough to cause a problem.

 

I don't think it is the TB torsion springs but you can test it it with the car off. Disconnect the inake tube at the throttle body (like you are going to clean it) and try to open the throttle manually. You should feel some decent resistance by hand (ie it should not just flop right upen easily). If not you may be right, but otherwise I am sure it is something else. You should also see the throttle plate seat nicely on the inside bore of the TB, if not there may be something hanging t up somewhere.

This is also almost a sure sign of an engine vacuum leak as well because when you accelerate you lose vacuum but when you deccelerate, vacuum goes up. So when you are getting the idle to dip it is becasue the engine is pulling more vacuum until it goes back to idle and the vacuum drops again and the RPMs creep back up.

I would urge you to get a can of carb cleaner and spray the seams of the intake, throttle body, basically everything from the MAF on up to the engine itself.

Have you taken anything apart or done any disassembly of any portion of the intake at all? With Chris I knew he had a S/C on there before so my guess was that something was leaking when he put it back together. In your case I have no idea what you have done work on so I need to guess at possible areas for a solution.

Keep workin with us and I am sure we'll get it fixed.

Just try the carb on everything for now and post back.

.....and I hear ya on the pet peeve part too!
Nothing get me more fired up than a machine that won't do what it is told.

 

I tried spraying the carb and everywhere I could with carb cleaner and noticed no leaks anywhere. All over the throttle body and everything! It's sooo agravating. I am going to go over the whole thing with a fine tooth comb in relation to the vacuum hoses. I don't understand it, I probably will replace all the vacuum lines to make sure none are punctured. Everything seems to be connected. I have done nothing to the truck in the way of modifications. I mean, I tune it up reg. and change the oil reg. nothing that would affect the truck this way. I'm going to keep at this 'til I get it fixed. I don't want to pay the dealership( ) hundreds of $$$$'s b/c of this stupid thing!!:cry:

 

If you have the $$$$ you might consider an OBD II tool like the one in my sig.
It does help alot on the diagnosis and we can get readouts on all the sensors at once.
It will also give you any intermittent codes (that do not trip the CEL)

I the carb stuff did nothing for ya then definately go after all the vacuum lines.
Do you have any way to take a digital pic?

Check all the hose ends (they tend to crack at the point of attachment.
Also check the intake tube and all the silencers (make sure all is tight).

Just be patient and I am sure the mystery will be solved soon.

 

Alrighty, I have checked absolutly everything on this freakin' machine. I have now deduced that it is the throttle body butterfly and shaft. During normal operation the butterfly is still slightly open. I have checked all vacuum operation and everything checks out. The butterfly moves left and right inside the throttle body throat, and hangs on the sides and doesn't close all the way. I think I could put a teflon or plastic washer in between the shaft and the throttle body to keep the butterfly from moving back and forth. Question is, how in the world do you take the shaft off the throttle body!! I tried to remove the screws on the ends, but it looks like there are snap rings holding everything else in place. Does anybody know if there are rebuild kits for these? Please?