Got a new 7 owner up here and we went to set his TPS Saturday. We did it by resistance, and before we started we found that it was at 1.3. We tuned it and he said that it was definitely idling better.

The thing is, I went to slowly turn the linkage to see if it smoothly climb to 5-6. The resistance shot up to 6 before I completed a 1/3 of the travel.

I take that to mean that the TPS is pooched, but I want a more knowledgeable comment to pass on this guy...

 

I thought the TPS read full throttle really soon. It does not extend that much. I would say it is ok.

 

Why not do it again, but this time clamp the throttle wide open and then use your finger to move the tps in and out.

A while back I noticed that on my N/T car, the tps reaches its full travel just about the same time the second set of throttle plates start to open. You can watch the linkage for the secondary set of plates and see this relationship. Anyway, when the second set of throttle plates start to open, the throttle is, in my opinion nowhere near half throttle (from memory).

And the above made me realize that when I'm doing 65/70 mph, the secondary throttle is still closed. Came up with that because I was playing around watching my meter which was tapped into the tps output. The reading on a level road at 65/70 is below the max reading from the tps. Big deal. Just found it interesting at the time.

Just put in the shifter bushings from Mazdatrix on my transmission. One happy camper. Also the turboII engine and transmission are in the N/T with seven hundred miles. Even happier camper?

 

thats me, you guys..

the idle was smoother after setting the TPS properly (the resistance trick) but again at some points it decides to jump between 600 and 800 and cant decide what to do.. "tatatatatttaaattaaattatatatatatatttttaaattaaataaa " if that makes sense to any of ya..

hasnt stalled as much, but still on the rare occasion will drop to 600 then bog itself out, and stall.. it would seem though that when it does stall, it will do it again when i let it drop to idle after starting it back up.. i know it sounds confusing, but its confusing to me too because it seems to do it at random..

 

Oops! Forgot to mention that he's got an 86 NA.

HAILERS - so you're suggesting that I 'set' the TPS with WOT? If that's so, then what would I set the TPS to? I'm accustomed to setting the baseline for the TPS and then just checking that the ohms rise smoothly when the linkage is twisted...

Or are you suggesting that I hold WOT and move the TPS 'plunger' manually and see what the readings are?

 

Black13B
Sounds real bad tps. If it jumps during its travel it be one bad tps. No known fix. Although some have written that they went to Radio Shack and bought some of that spray folk put in radio *****, and theirs worked better.

Or to confirm it being bad, borrow one off a buddys car for a trial run. Shouldn't be necessasary (sp). If it jumps around during its travel its probably bad. Junkyard time.

 

second option AMUR_

 

Black13B - I'll see if I can scare up a replacement (used) locally. Don't buy a new one - yet.

 

Amur......No, no, nope. I just meant that you could open the throttle all the way to keep it off the tps plunger. Then watch a meter while you push the tps plunger in then out. If the meter jumps or shows and open during the tps travel, then its probably bad. Digital meters are a little harder to watch than the old analog ones with the needle.

Send me your tps and I'll take a look at it. I promise to send it back!

And I see in a thread above or below this one, this day, where a fellow will sell one for twenty bucks.

 

ok ill keep that in mind - thanks Amur_! (btw, did you reply to that PM i sent? i thought you said you sent it out, but its hours later and i still havent seen it in my inbox..)

is the TPS restricted to only controlling an idle? the car runs really smooth and drives excellent otherwise - it feels like its a brand new car! but just when i pull it out of gear and let it drop to idle, thats when it cant pick between 800 and 600..

 

Black13B
I just read your last post. Only at idle??? Do this. Get a digital meter. Put the negative lead on a good ground like the battery ground. Fully heat the car up. Drive ten miles or what ever prior to doing this. Idle the car while doing this. NOW put the meter on the good ground. Put the positive lead up the backside of the green/red wire at the tps connector, WITH the connector connected up. Nothing disconnected at all. Read the meter while the car is at idle fully warmed/heated up. The meter should read one volt. If not adjust the tps screw til you get one volt. Drive the car. Check the voltage again. Should still be one volt plus or minus 0.05 volts or there abouts.

No initial set couplers in the above test nor any disconnecting of any wires/connectors. No messing with the green connector. Only a meter lead up the back of the green/red wire. Only on a 86-88 model car.

 

No, I didn't reply. I had just finished reading it when you called. I kinda didn't see the need to PM you just after speaking to you on the phone.

 

this is what Amur_ and I did.. car was fully warm, and we shut the car off, and.. uh oh.. now wait a minute.. lol.. hmm.. maybe Amur_ should explain what we did.. i thought we had measured resistance with the harness disconnected, but i may be wrong.. we adjusted it 2x, friday night and then saturday afternoon, and the problem is still there..

btw Amur_ is fine dude, when you picked up i thought you said "i just saw it and responded!"

 

i just reread the thread, and my initial thoughts were right.. (it DID idle better after adjustment, but after driving for a while the old 800x600 comes back..)

ok well ill try what you explained HAILERS tomorrow or tuesday.. (have to get another 10 day permit.. mine expired last night - i have to keep buying permits until i pass an emissions test and then i can get it plated Amur_ wasn't kidding when he said 'new owner' - ive only had it for 11 days!)

 

You don't need a permit to do the test. Just a multimeter. Then fire up the car and let it warm up to temps and then let her run a little longer. Say 20 mins altogether. Then check the voltage as described. You just won't be able to go for the drive afterwards to let the TPS 'settle.'

 

Black13B.....don't read me wrong. There are three basic ways of checking/setting a tps. The method of using a ohm meter to set it is just fine. It has an added benefit of being able to look for *opens* in the tps as you slowly move the tps plunger thru its full range. Thats good. A small problem is that a digital meter is a bit touchier to use doing that. A old swing meter or digital if you will, is more accurate when looking for opens in the tps.

 

i DO have an old crappy *analog* i guess youd call it MM.. it works but.. its pretty rugged.. i can check the resistance while opening the throttle with that.. other wise it wont measure voltage properly so id rather use a quality DMM for that part..

i tried the crappy one last night when i just let it warm up to a good temp (as amur suggested).. and testing it with the crappy MM i couldnt even get the correct voltage off the battery.. it would either read 9v or 18v... but the resistance it measures IS accuarate..

ill post results tommorrow (with analog MM).. if i can get my hands on a DMM from work again, ill test the volts from the TPS as well..

 

the TPS is fine
S4s use a narrow range TPS, mine does exactly this too
to go from 1kohm to 5k ohm takes about 1/2 of a MM. Not far at all.

 

But we didn't get anywhere *near* 1/2 before it hit 5+ ohms...

 

Black13B, If you choose to elect to buy a new TPS, let me know. I can get a sweet discount from the Dealership. My TPS went bad too. Been there, done that. As HAILERS suggested, perform the Fuel Cut Operation and If that fails PM me If you want a new one.

 

Has anyone ever seen a TPS go from about 1k smoothly up to about 1.3k, and then suddenly frop to .5k? And is the TPS basically just a potentiometer?

 

Amur: I meant half of a MILIMETER. as in a TINY amount of travel.

Crionics: Your tps IS pooched. If it drops anywhere, or goes off the scale (unlimited resistance) anywhere along the travel, its pooched.
I'm not sure how it would affect things though, as long as it reads correctly at WOT and at idle, you might be able to get away with using it for a while.