arielb1

I’m troubleshooting my TPS. I have so many questions I need answered. I spent the five hours yesterday reading and learning from many postings.

I used this link below. Im not at all proficient with a multimeter, but below are my results.

http://www.4crawler.com/4x4/CheapTricks/TPS/index.shtml

I have a 94 4Runner with 3ZVE engine. With multimeter set to 20K ohms, below are my readings.

1. VTA – E2 results = .81

2. IDL – E2 results = 1 . ( I guess this means open. No matter if throttle is open or closed, this does not change)

3. IDL – E2 results = 1 (no change in number regardless if I move the throttle.)

4. VTA - E2 wide open throttle = 5.25 at the highest (I see the numbers change as I adjust throttle. The numbers does not move gradually or smoothly, but it does have the highest reading 0f 5.25.)

From what I gather, my TPS is bad because of results from 2 and 3.

What are your thoughts on my results? Does it appear to you the TPS is broken? I can just buy one, but I want to really learn.

I get 14mpg, the idle is 1000 that can jump to 1200 rpm that is erratic, slower acceleration. I am a conservative (easy) driver. This is city driving. Otherwise, the truck runs fine.

Many many thanks for the education. I am truly thankful.

OutlawMike

Just to confirm,

You are using the correct thickness feeler gages in between the throttle stop when doing the second and third measurements? You should be using a .020" feeler and a .030" feeler.

And, for your multimeter, does it read "1" when it is reading infinity? Is that what your instructions say?

So, with your meter set to 20k ohms range:

You measure 810 ohms on the VTA-E2 with no spacer in the throttle stop, at idle. This is slightly high, 10 Ohms over spec.

For IDL-E2 with both the .020" feeler and the .030" feeler you measure infinity, correct? You should measure infinity only with the .030" feeler, so #2 is out and #3 is correct.

And for the VTA-E2 measurement at WOT you measure 5250 Ohms, which is within the specified range.

I see that you have issues with measurements 1 and 2. You are little high on measurement 1 (10 ohms) and you should be reading less than 2300 Ohms on measurement 2. This may explain your idle issues, as the computer is looking for a low resistance on IDL-E2 when the throttle is closed. It does not see this and thinks that the throttle is partially open.

You may not need a new TPS sensor, you may need to turn it just slightly. On my '89 I rotate it counterclockwise (when looking at the sensor from it's top) to decrease resistance on measurement 2 (IDL to E2 w/ .020" feeler on the throttle stop). It is very sensitive to adjustment, so I just barely loosen the screws and carefully rotate it until it just barely registers resistance on that measurement. I have never gotten it set any higher than 150 ohms, not even close to 2300. Then, recheck the rest of them. #1 should drop well below 800 when you do the adjustment fo r#2.

The trick is to not rotate it too far and have #3 (IDL - E2 with .030" feeler) go from and open / infinite to measuring some resisance. There is a small range in there that all will work.

You should not be moving the throttle on #2 and #3 as you state in your message, they just get the feeler gage to space the throttle open .020" and .030", respectively. Off idle they are supposed to read infinity, so moving them tells you nothing other than yes, they read infinity off idle. That is how the computer knows you are at idle, or, off idle.

Good luck.

Mike

arielb1

WOW... thank you so much OutlawMike.

Again, I am still learning. I didn't realize I had to have the feeler gauge in the throttle stop. In fact, I couldn't figure out where to put the feeler gauge into. The picture in the website is so blurred. If I look at my throttle body, there are two places I think to put the feeler gauge. Hopefull I will be able to tell in the FSM where to put the feeler gauge.

I am at work now. When I get home, I will follow your FANTASTIC directions. You did a GREAT job explain it for me. I can't thank you enough. The time you took to explain it to me is so appreciated. Not to sound completely stupid, I have read it three times. It is getting clearer the more I read it. This is is the process of learning - I guess.

Followed your other post regarding runing hot water through the throttle body ports. The coolant ports on my TB is completely clear.

I will redo the measurements later this evening.

Why do I need to turn the TPS? This is factory setting. Is it that my truck has 119K miles and I have to adjust items time to time? I had a mind set that once factory sets it, I forget it. In other words, dont mess with it. I have the same mind set with the idle screw..dont mess it with. Not sure if this is the right mind set. For now, it is all I know.

When I turn the TPS, I assume the throttle body is still on my table and not hooked up to my truck.

I get a number one on my multimeter when I have 20K ohms set and the two red and black leads from the multimeter held up in the air not touching anything. I suppose when it is touching the two points IDL and E2 and I get no numerical reading but a number one, this means open/infinity. Please forgive me..I am doing my best here.

thank you so much.

arielb1

I ran the test again this time with the feeler gauge. The FSM shows exactly where to put it, right underneath the throttle coils.

VTA-E2 measures .81 still. The 4Crawler link shows 200-800 for my 94 3ZVE engine, but the FSM shows .47 – 6.1k ohms is the proper range. I understand I am over 200 ohms over range, is this correct?

IDL-E2 using a .50mm feeler gauge, I measure a 1 (open circuit or infinity I think what this means).

IDL-E2 using a .80mm or .030, I still get a 1. If I move the throttle, it stays as a 1.

With Wide Open Throttle, VTA-E2, I get 5.25

So from the looks of it, IDL-E2 showing a one with .50mm, I should pickup a new TPS?

Many thanks – I learned so much.

OutlawMike

I'm still not sure if you are putting the feeler gauges in the correct location. What do you mean by throttle coils? The return springs?

On the throttle body, the side towards the front of the motor when it in installed, there is a threaded stop that is the hard stop for the idle position. It has nuts on it that lock it in position after adjustment. The feeler gauges should go in between the stop and the tip of the threaded shaft.

Is that where you were putting them? If so, that is correct.

The TPS is designed to be rotated to set these numbers. After 100k miles the sensor may have drifted over time and no longer measures to the factory spec. The sensor is not bad, just out of adjustment. You could buy a new one if you want, but I would try to adjust the one you have first. You will have to do the adjustment on the new one, as it also has slotted holes to allow rotation.

arielb1

Okay, Im totally wiped out. Embarrasingly enough, I have spent 7 hours messing with this.

I was having a hard time getting a reading with the TPS as I tried to adjust it. At times I would get an Open/Infinity, then all of the sudden, I would get resistance. I tried it with another multimeter and it did the same behaviour. It was three hours until said screw it.

This afternoon I purchased a new TPS. Luckily I have money. Anyway, I couldn't get the numbers to line up. Test 2 and 3 are the hardest. I'm very patient and meticulous person. Even with slowly turning the screws gently as I kept the TPS in check, I could not get #2 and #3 to work out together. It is less than a hairline adjustment.

I can see the throttle opener is keeping the throttle stop from holding the feeler gauge in place. It appears the throttle opener is holding the gap open too much. So the .50mm feeler gauge is sitting loose inside.

As such, here are my results.

Setting multimeter at 2K,
#1. 700 (200-800 is range) good here
#2. 017 (<2.3K is range) good here I suppose
#3. 018 ( open/infinite) nope...
#4. 4.51 (3.3K - 10K) I had to change multimeter to 20K to get this reading.

Again, it was literally a 1/2 a hairline differences. Either I got #2 and #3 was off, or viseversa. It was increadibly tough to line this up. I had an easier time working on my bimmer's oil seperator which is rated an 8 than getting this to line up. I learned so much and finally got the feeler gauge placement dead on.

I installed it on my truck. It appears problem solved. No more surging idle problem. Yipee. However, my idle is still high 1,000 rpm. Im contemplating messing with the idle screw to lower it. Otherwise, the idle is level - it doesnt bounce up or down.

Good to go? thoughts? Many thanks Mike.

OutlawMike

You may want to adjust it on the bench, as that gives you better access with the feeler gauges. If it is not tight with the feeler gauge, you are adjusting with the wrong throttle setting.

I have a set of feelers that are only 1 inch long and 1/4" wide. They are in a Craftsman spark plug gap tool set. Those work great, as they can get in there without hitting anything else.

But, I know you have been at it for a long time and it can be frustrating.

No worries messing with the idle adjustment screw. If you screw it in, the idle will drop. Make sure that you jump the test terminals in the block over on the passenger side fender. That will kill the vacuum advance circuit. Then, adjust the idle to spec, check the timing, adjust the timing if necessary, then check the idle again (timing affects idle RPM), check the timing again. You should not have to do that circle more than once or twice.

Oh, and the O-ring on the idle adjustment screw gets brittle over time and can be the source of a vacuum leak. If the screw goes in and out really easy, no drag, you might want to get a new O-ring. You can get them at the hardware store, just find one that fits. To take it out, screw the idle screw all the way in, counting the number of turns it takes to bottom out. Write that down. Take it out, replace the O-ring, screw it all the way in, then back it off the same amount that you counted. That will get you close enough to then adjust the idle as above.

Good luck,

Mike

arielb1

I did work on the TPS on my work table. I had the entire throttle body off the truck.

The feeler gauge is not tight because the throttle opener is keeping the lever from hitting the throttle stop. As such, the feeler gauge is not held in place tightly. Can the throttle opener be bad? If I push on the throttle opener, then the lever holds the feeler gauge against the throttle stop. Yes, I realize I adjusted with wrong throttle setting I didnt know how else to do it. The throttle opener kept a pretty large gap so my feeler gauge would not fit. Only the .030 feeler would hold tight. I needed my truck working this weekend.

I will pick up a feeler gauge up at Sears this weekend. So far, I have driven the truck 85 miles. It is running like it was and the idle is not bouncing. It is stable at 1000 rpm even after it is normal operating temp.

I dont understand "jump the test terminals in the block over on the passenger side fender." Last I worked a timing gun was in high shool 26 years ago..will I need to buy a timing gun? I will read up on it in the FSM.

I will do what you stated on the idle screw. I will check on this thread when I can

Thank you so much OutlawMike. You have taught me so much and keep me motivated. You are my inspiration. I will read up on the timing thing tomorrow. many thanks