>>but if the sensor is just plain shot, does it give 0 V or erratic readings?

dunno, both maybe possible however i think if it reads 0 you will get limp mode or somthing like that.

If it reads zero you are probably not testing it correctly :-)

thanks

anyone have experience testing a shot TPS?

The TPS is just a variable resister. Based on the electrical diagram and not having torn one apart (yet). It simpley allows different voltage drops depending on the throttle position. Very less to no drop in resistance at wide open / to alot of resistance at idel. IF a winding is worn or open the resistance will have a dead spot ( no resistance) then come back when the dead spot is passed in either direction. Also if resistance is increased by bad contac to the windings, the position (resistance) will read to the ECU a false position. The ECU relies on the TPS to tell it where the throttle is. How this is interpited by the ECU is the unknown. The ECU is designed to cause certain things to change as we all know due to alot of inputs (sensors) at alot of different RPMs. What it does at idle mostly concerns emissions. At wide open its trying to prevent the engine from exploding. So depending on what is wrong with the TPS determines the way the car runs or doesn't run or runs then cuts out and dies.

yeah that's why I think it's shot, the resistance is out of spec and adjusting it doesn't help...getting a new one tomorrow (thank you, Fritz, saved me $$)

K, guys, I have a PowerFC w/ Commander and have this problem on my FD. Can I adjust the TPS with just the readings on the Commander or do I still need a volt meter?
I did some research and somewhere it said that the VTA1 and VTA2 in the ETC menu mean something, so today after I drove the car to work, I shut it off and got these readings.
Close Throttle: VTA1=.49 VTA2=1.07
WOT: VTA1=4.37 VTA2=4.97

Can you guys tell me anything about my car with these numbers to do I need the volt meter? Also, what are the correct numbers supposed to be? Thanks for everyones help on this!

no, the Power FC makes the job much easier, just read straight from the Commander

VTA1 = full range sensor
closed throttle = 0.1 - 0.7 V
WOT = 4.2 - 4.6 V

VTA2 = narrow range sensor
closed throttle = 0.75 - 1.25 V
WOT = 4.8 - 5.0 V

you're good...mine is almost identical (now that I have the new sensor installed and adjusted)

Intermittant Fuel Pump?
 

The mechanic thinks he has finally traced the intermittant bucking and surging and engine dying going downhill to an intermittant bad fuel pump. Has anyone else had such problems traced traced to the fuel pump?

get a fuel presure gauge on it, run some tests, and you will know if its the fuel pump

keep in mind it may be the connections to the fuelpump and not the fuel pump itself, that is why its good to check the coltage its getting at both high and low voltage conditions

Still boggin
 

New plugs, Fuel pump and regulator replaced, voltage regulator replaced, ?dash pots? freeded up, TPS adjusted again, ... and it is STILL bogging down under light acceleration, still some oscillation; and also occasionally dies going downhill (automatic trans), which can be exciting if you don't notice it.

This bird has been a lot of trouble this summer!

Shop givin up, unless it is dirty injectors
 

The bogging, hunting oscillation, hesitation and surging at light to moderate loads is still going on. The mechanic seems to have given up on finding a cause, unless it is sticking injectors. Extra fuel smoke on startup makes him suspect the injectors are leaking into the chamber on shutoff, and maybe when it is running. It might be only noticable under light loading. He poured in some Techron and suggested I do the same for a few tanks.
I don't have great confidence that engine cleaner will fix the problem.
Any other good ideas? Would it be worth it to pull and clean or replace the injectors?

ciao

I am assuming that when you test the voltages between the two wires that closed is obviously with the throttle completely closed and that open is where you manually open the butterflies by hand at the throttle linkage as far as you possibly can go and then record that reading. Is that correct?

I'd like to know what would be the effects of doing this adjustment without the car being started and warmed up to normal operating temps.., incorrect readings?

Also my last question is in my case I am only getting the same reading whether I rotate the tps, or open the butterflies simulating WOT. The voltage does not change for either probe no matter what I do to the tps. I get a constant .05v for the second to the top wire, and 2.5v for the bottom wire.

>>I am assuming that when you test the voltages between the two wires that closed is obviously with the throttle completely closed and that open is where you manually open the butterflies by hand at the throttle linkage as far as you possibly can go and then record that reading. Is that correct?


yes, or just have a buddy push the gas pedal to get the wot reading :-)

>>I'd like to know what would be the effects of doing this adjustment without the car being started and warmed up to normal operating temps.., incorrect readings?

none...the cars temp or ambient temp have no affect on the voltage reading


>>Also my last question is in my case I am only getting the same reading whether I rotate the tps, or open the butterflies simulating WOT. The voltage does not change for either probe no matter what I do to the tps. I get a constant .05v for the second to the top wire, and 2.5v for the bottom wire.

you are either doing the test wrong or your tps is totally broken :-)

The only reason the manual says to heat the car up beforehand is to make sure the thermowax/AWS is not getting in your way and holding the throttle partly open (which would give you a high reading on your fully closed measurement).

ohh good point... sorry i took that crap off both my FDs... :-) forgot about that stuff.

okay thank you for clearing that up for me guys.

Just thought some of you might want to see what actually goes wrong with these things:
http://i9.tinypic.com/33vlulf.jpg

The construction is actually pretty good, but instead of sealing it Mazda made it "breatheable". This, combined with the lack of any drain hole at the bottom made for a very bad idea in humid climates (like Houston). And yes, those are beads of condensation on top of the circuit board in the above pic.

http://i7.tinypic.com/2vxgkkl.jpg

Here's a better shot of the condensation:
http://i10.tinypic.com/2iiwjrn.jpg

So anyways, I figured I'd take mine apart just to see what was inside, but after cleaning all the buildup off the circuit boards and re-soldering(sp?) the connections, mine has gone from completely out of spec to working perfectly. So now I'm thinking of reusing it. Of course, I've dremelled the casing up quite a bit, but it's probably re-assemble-able. I'll post pics of the re-assembly in case someone actually wants to rebuild their sensor. FWIW, I could have done it with two cuts if I had known what was inside.

Oh, and as to why someone would want to go through the trouble? Dissection to re-assembly took me about half-an-hour, not having any idea what I was doing. Purchasing a new TPS? $198.

Re-assembled with hot glue. Probably not a good idea. I will most likely remove the hot glue on the outside and re-incase the whole thing in high temperature epoxy. On the other hand, it's in and my car is running.
Readings before:
VTA1: 0.83V-2.37V
VTA2: 1.29V-3.92V

Readings now:
VTA1: 0.50V - 4.37V
VTA2: 1.00V - 4.97V

good data :-)

Does anyone know whether "gcthree" found his gremlin? I'm in exactly the same position with car down, have done the same diagnostics...

well i get the perfect volt readings almost at extreme clock wise position. but there the car does nt run good i test drove and adjusted it where i liked it some in the midle position car runs great but voltage there is 1.76 closed and 0.86 closed for the black wire. strange isnt it but car runs here good and on the corect setings with the metter it runs pretty bad with lots of hunting dor idle

If you have a powerfc, you need to have it re-learn the correct settings for the idle air control valve after you fix your tps setting.

BTW, I also had to tighten my throttle cable before I could get my PFC to read 5V at WOT, i.e. even with the pedal all the way down I wasn't getting WOT before.

Now I am.

The car is scary fast.

there is an adjustment screw below the throtle body where to adjust that ?? and what if i close it full tight closed and adjust race from the cable ??

Sorry, I don't have a picture, but if you look where the elbox connects to the throttle body, it's inset a bit near the bottom right screw. It's not like the other adjustment screws, just a flathead that screws in and out towards the driver side of the car (U.S.). You want to adjust your idle there because if you adjust it with the butterfly screws, the reading on your TPS will show it to be slightly open causing your computer to think your car is not at idle.

where to adjust the screw when adjusting the tps originaly ??. Can i have a simpler guide to adjust the tps ?? i tried once but didnt work

this is what i did. i attaced the negative of the volt meter to the engine throtle body and positive to the wide and narow band turn by turn and go the correct readings on the extreme clockwise position. but there the car didnt run fine. ok i just passed throguh a very hot summer and i realized i have removed the water vavle and water is circulating the engine from start so it doest warm up quick. can that be problem ?? I would appreciate if someone gives me a step by step guide again. if possible email me at mrhot2000@hotmail.com

keep in mind i am running a stock ecu on a type rb auto touring. only mod is the kaki moto racing exaust system

bump

Now this Symptom is fixed on this RX
 

Another pass at solving the problem was made. A close look at wires versus diagrams revealed that somewhere in the car history, a (grounding?) wire between the automatic transmission and the engine computer had gone missing. Whatever ground path had been serving adequately for this connection had apparently gone intermittant. Putting a wire back between the two has stopped the bogging / hesitation/ surging/ hunting.
Voila!

well i just fond out my engine was grounded well enough but the body was only grounded using the tiny ground kit wires even the battery negative terminal wire is connected to the engine. I hope i will get a better result now

hey guys i cannot get the tps to be at your specs. if i get the black wire at .4v the green/red wire will be at like .856. and if i get the green/red wire at 1.v the black is at .330v. is there something thats wrong here i've tried everything yet i cannot get it to go to the specs. its pretty weird cause its not a specified difference between the two like .500v. before someone says it too its not the harness because its all new. does anyone have the ohm specs to check the tps or a way to check it out? if you guys can get back to me with some advice that would be great!

-Lance

i can't believe such easy fixes take care of such big problems, i also can't believe how old this thread is.

I don't remember exactly what they were, but at one extreme there was about 2 ohms resistance, and the other pretty much infinity (on both sets).

It doesn't sound like yours is out of spec, but it is weird that one voltage goes up and the other goes down.

Well I am getting 0.66 on 1.27 lower then this car starts to hunt for idle after warmup

i did this adjustment and now sometimes it idles at 750 but then i can drive around and stop at a light and it will be at 1400-1500. when the cars cold for the most part first 10 mins of driving after warm up obviously it has a dead spot in the first part of the throttle then comes alive and sometimes backfires. im almost thinking it could be the wax rod assembly on this thing... anyone know any pfc settings to try before i rip out the wax rod setup? i wish we could get some specs on the tps ohm resistance.

also check your wire harness connection to the TPS sensor some times they break up and get bad connection...

is anyone using this adjustment on a ported motor, my car is surging and my motor is freshly built and ported... on 25 miles on it... someone told me it was cause the PFC is searching thru cells to work for the port, and that i would need a datalogit to fix the problem?

check out my problem. i was checking via PFC that my TPS full range sensor (VTA1)voltage is always higher then the narrow range (VTA2) voltage. example: when i adjust my TPS narrow range sensor (VTA2) to 0.75volt at closed throttle, i get 1.45volts at full range sensor (VTA1).

The full range (VTA1) voltage is supposed to be lower then the narrow Range (VTA2) voltage right?

P.S. my WOT voltage reads perfect VTA1 full range shows 4.48 volts, and VTA2 narrow range shows 4.98 volts at WOT.. any idea guys?

P.S.S. I did this with the car completely cold would it make a diffrence since i eliminated the wax rod fast idle cold start crap

Hunting for idle is not a bad thing. That's your computer trying to re-learn the proper idle settings, since before when your car was "idling" your computer was reading it as "under acceleration".

Set it properly, let it do the re-learn.

No. Once the thermal wax is gone it makes no difference.

This sounds more like an air leak than a TPS problem.

so why cant i get the voltage in spec, if i get either or volatge in spec the other one would be way off. like when i put the narrow range voltage in spec the full range is out of wack. example narrow range is set at .75 volts closed then full range would be at 1.45v, and isnt the full range voltage be at less volts then the narrow range voltage. but when i give WOT both voltage are in spec no matter where i set the tps

ok i found the situation with the TPS, i cut it open and i was rusted like crazy inside, so i took it aparts cleaned its and solder it. put the TPS back in and bam... its right on the money... happy ass hell i am.

now i reset the pfc and let it go threw its learning process and it is surging still. Someone told me it was because the motor is ported? i thought i seen a few guys with stock injector ported motor and pfc running fine with stock PFC maps?

^ thats the exact situation i had when setting the voltages!!!! maybe i should crack mine open to see if its defective? does anyone know the going Ray Crowe prices on a new TPS sensor. i have a spare tb with one on it but i suspect that if this one on my manifold thats always under the hood that is away from weather elements is bad that my spare in storage has accumulated some moisture aswell. this is kinda exciting if its the tps this problem quite annoying when you have a new motor in the car and it runs shitty. :(

I believe they're fairly pricey, check back a few pages. I've also got pics earlier of what the inside of the TPS looks like.

is your motor ported?

yeah looks like its $198. i guess i'll call Mr Crowe tomorrow and see the exact price!

Kashent, what eactly did you use to clean up the connectors? alcohol and a wire brush? im might as well tear mine apart and if its not possible to salvage try my spare or pay that nasty bill! let me know... :)

Yes.

Stax electronics cleaner + really fine sandpaper, but alcohol and wire brush should work fine.

I believe Ray had it for $170ish.