Piranha

Hey,

I just did the TB mod, and after recalibrating the TPS my problem has gotten a little worse.

I think there are actually 2 problems...

1. When I slowly press the accelerator down when engine braking (lots of vacuum), the needle on my boost/vacuum gauge hops toward 0, then as I keep pressing it down, it jumps back to where it SHOULD be, and moves to positive pressure slowly as I press the gas down. Sometimes when the car would be *really* hot it would not do this (and when it was hot out.) Adjusting the TPS using the resistance method and putting it to 1K ohms didn't do anything except...

2. After doing the TB mod and adjusting the TPS, whenever I push the gas over 1/2 the throttle I get pretty bad bogging/backfiring/bucking. I can get it up into the high rpms if I let the thottle off a bit when I floor it, but it isn't pretty.


Any help is appreciated!

thx!

RETed

Where's the upgrade fuel pump?


-Ted

Sniper_X

I always set the TPS using the leds on the harness that I made. (the test lamp)

This way i know that the ECU is seeing what it needs to see.

Otherwise, I would be GUESSING that 1Kohm exactly is it.

I have never had issue wuing the lamp, but the 1kohm thing never worked consistently.

Why ignore the ECU? Its opinion is all that matters.

fLyiNgOuFeR

try setting it to 1.0v instead of ohms. i've never tried the ohm method but the volt method worked for me

Bambam7

NONE of the other methods for adjusting the TPS besides the factory lamp method has worked for me.
Whenever I try to set it using the Ohm or Volt method, the drivability suffers (jerky on/off throttle) and I would get a bad hunting idle when the car starts warming up- also the same idle when I just barely touch the gas... you know... the whump, whump, whump....
The lites method is the only way to do it IMO.

Check the voltage from your O2 sensor it the high RPM's-see if it's running way too rich or too lean (hope not, your engine would be fried by now)

The vacuum prob doesn't sound like a problem too me... isn't that the way it's supposed to read?? Anyways, I would check for vacuum leaks... and I know I keep preaching this, but re-grounding a few key points has worked wonders for people. The engine-firewall, the boost sensor, and the AFM- basically anything grounded by the brown wire w/black stripe.

Also- make sure your injectors are OK.

Sniper_X

The reson that nothing other than the lamp method has worked for you is that all the other methods are "shots in the dark" as to whether or not the TPS is sitting in a position that makes the voltage and resistance is EXACTLY in line with the ECUs perception of the TPS position.

The ONLY METHOD that is going to work 100% of the time is the lamp method. (you can use a voltmeter to see if you get +12v on the same connector) but this is the ONLY way that you are setting the TPS corecctly.

Why IGNORE the ECU check lamp?!

Its NEVER WRONG, and the ONLY thing that matters!

This isnt an opinion, its the way its designed, and therefore fact.

Anything else that works is pure coincidence.

akageals

Guys,

Is there a write up on the light method. I've always done it using 1K ohms as the guide. How do I use the lights?

Bambam7

You don't need lights, or even 2 voltmeters... 1 is all you need.

The green, 3 prong connector that's in front of the pass. side shock tower, by the presure sensor, is what you use.

Make sure the car is FULLY warmed up, shut the car off, and turn the key back to ON. (but don't start it)

The connector has one prong on the top, and two on the bottom- like triangle shaped....
Grab the voltmeter, stick one probe into the single, top prong, and leave it there. Check to see if you get 12 volts between that top prong and EITHER of the bottom ones. I can't remember which way you turn the screw on the TPS, but when screwed at one exreme end, you will get voltage from BOTH bottom prongs, and at the other end, you won't get voltage from either of them. Right in the middle there is a tiny point where you get voltage from ONLY ONE. This is what you want.. just turn the screw untill only one prong has voltage. Then it's set exactly. Make sure you snap the throttle a few times just to make sure it's close properly...

rico05

I love you Bambam. After work....resetting the TPS.

Sniper_X

While BamBam is right, its more difficult and time consuming to do it this way.

You should also flip your screw driver over and tap on the throttle body a few times to make sure that the setting holds.

It WILL change until you get it juuuuuust right.

Also flip the throttle (via the cable) a few times to verify that your TPS setting doesnt change from that either.

Eventually, after tapping and flipping, the TPS will always return to the right place.

But trust me, getting two VERY LOW WATTAGE bulbs and making a test lead with spade connectors is the way to go.

I can set a tps in about 5 minutes (and thats if its a VERY hard one to set).

rico05

Hey Sinper, got a link for a how to? I am gonna try the Bambam method after work, and if that dosen't work I will go test lamp city.

Sniper_X

Simply get some:

shrink tubing (assorted sizes)
Wire
Crimp on spade connectors
two low wattage 12v bulbs from RS
Solder stuff

Take the bulbs and connect two of thier leads together.
This is the common (ground) lead

Then solder wire to all three leads
Slide the shrink tubing over each solder joint and shrink it.

Then slide a LARGER peice over all 3 wires and up to the base of both lamps to cover all three shrunk leads.

This will solidify the mess into a rod with two lights sticking out.

Then, you can take shrink tubing and gather all 3 wires every few inches for appearances sake a this time if you wish using small collars of shrink tubing.

Otherwise, crimp on 3 spade connectors.

Make sure that you can determine which of the 3 wires is the common ro GROUND wire and either mark that one or put a different color spade connector on it.

now, simply plug the ground wire in the top single connector and the other two in the other two connectors, doesnt matter direction as long as the ground is in right.

You will now be able to set the TPS the way the ECU needs you to.

2 lights, turn counter clockwise
no lights, turn clockwise
1 light, you got it. (just tap and flip a few times to be sure)


Also tap and flip after you lock down the TPS (lightly is all it takes)

RETed

Too bad, even the voltage specs would show that your TPS fails the WOT test.&nbsp The lights test will not show you this is the case.&nbsp Excessive resistance at WOT will cause high RPM hesitation, which the lights method will have no clue on.

This is why I recommend a resistance test.&nbsp If this fails and you still got hesitations, something else is wrong.&nbsp Please don't blame the test for being inferior, as I have gotten 100% success of setting the TPS or detecting a no-good TPS using a DMM and measuring resistance.&nbsp Others have tried it, and the majority have had success with it - this is why I have posted a write-up on my site.&nbsp The lights test cannot detect a bad TPS in any way, especially a WOT "blow-out" which is the most common failure of the TPS in the first place.

The original poster explicitly states he's done the throttle body mod.&nbsp How come no one blames the hesitations on that?&nbsp My throttle body mod page explicitly states this mod will cause low RPM hesitations.

The original poster is also using the stock boost gauge to give you an idea of the transition from vacuum to "0" manifold to boost.&nbsp The stock boost gauge, IMO, is a bad indication for what it truly happening to pressure in the engine.&nbsp Please, get a good aftermarket boost gauge and check the numbers.&nbsp The stock boost gauge is nothing more than an indicator that your boost sensor is working.



-Ted

Aaron Cake

iTrader: (1)

I agree with Ted. I've always set TPSs with an ohmmeter, and it has always worked for me...

Piranha

Ted, I was using the writeups from your page btw. I was NOT using the stock boost gauge, I never said I was... I thought that thing was useless

I have an Apexi whatever it is I bought last year; the vacuum one. I'll try the voltage TPS thing; I was using the resistance, and I know I just played with it (before I messed with the TB) and i had it pretty close (no jumpities).

As for not having an upgraded fuel pump, I don't hit fuel cut with my mods. It's a jspec engine in there, and I do have an intake restriction (idiot that installed the engine, and I bought the car like that) that I am going to take care of, or it is something else. I was planning on buying one quite soon though, anyway.

Thanks for all the replys!

HAILERS

The end result when the tps is set correct is a one volt input to the ECU whether you use one meter, two meters, and ohm meter, two lights or whatever combination I left out. Setting the tps by adjusting to one volt with a fully warmed up engine does have a drawback compared to the ohms method. That drawback is you can't tell if the tps has a flaw thru its full travel. But you can do the same by watching the voltage move smoothly thru the travel of the tps from one volt to approx 4.5 volts.

I've got the bug lites and done it that way. The end result is approx one volt at the input to the ECU from the tps.

If the only way you know how to set a tps is by the two bug lite method, your gonna be a lost puppy the day the transistor for the switching or relief solenoid go south and you have but one light to look at because there is no ground signal from the ECU to the check connector

Setting the tps isn't brain surgery and to limit yourself to only one method is to screw yourself. And no, I'm not arguing with a word Ted said. In fact if you continuously have tps problems, that would be the way to go. I don't even have marginal tps problems, and have been tempted to try to buy some of the tps that people have said were bad. Ain't gonna make that offer after posting this. Too many mean spirited people out there.

If you question the one volt output, see the fsm under Control Unit for the input from the TPS to the ECU. 86-88 models, one volt approx. 89 and up(page F2-78) one volt for the narrow range and 0.8v for the full range with the engine at idle. At full throttle the narrow range approx 4.3v and the full range at approx 5v.

I can set the tps using any of the above methods and the end result is one volt at idle and a smooth transition of the voltage thru the full range.

Time to cut and run from the brick bats.

I think I'll ignore this thread for sometime. I can hear the keyboards a clickin away already and the ceiling falling in.

Oh! I can find a good use for the two bug lights if you have a 86-88. Use it to drawdown the engine fault codes.

Piranha

Heh, I did a search for the voltage method and found a post from Hailers. I did it, and my boost meter needle jumping has stopped, but I do get a little bit of boginess when I stomp it. I'm going to buy an A/F meter so I can have some idea what is happening.

Sniper_X

I know about the resistance test.
And yes, thats how you determine if the TPS is bad.

My statments are based ENTIRELY on the assumption that the TPS is good.

The Factory service manual shows how to test resistance to see if the TPS is good/bad.

I didnt blame the throttle body mod on the hesitation because I did this once before and got flamed on how people should be able to mod thier cars and have them work too!

(That logic is pure insanity, but whatever.... I only can beat my head on a brick wall so often before giving up)

One more time....
The throttle body mod is VOODOO MAGIC and BOGUS!

Its like walking though a dark room full of sharp sticks if you ask me!

Your lucky if it doesnt come back to poke you in the ***!


ANY WAY....

Yes, I think the TB mod might CERTAINLY be an issue.

Otherwise, the REAL factory way to adjust the TPS is...
(this if from memory so you'll have to look up the values)

At the ECU, check for the proper voltage at the proper wires with the throttle closed (or WOT, i cant remember)

Adjust the TPS mount to get the right voltages.

THEN use the lights to adjust the TPS.

If this doesnt work, then see if the TPS is bad using the resistance test.

Using any of the above mentioned methods for anything other than the reasons above is a waste of time.

The votage check is to see if its mounted in space right.
the Resistance check is for seeing if the TPS is toast or not.

the lights are to adjust the TPS to the actual position of the throttle.
(This part is what most of us need to do. (that and the resistance check to see if its a good TPS first).

RETed

It also sets idle adjustment pretty good in my experience.&nbsp So you're killing two birds with one stone.


We're talking about a Mazda here that is 10+ years old.&nbsp Wouldn't you think this is a pretty bad assumption given the situation?


Guess your comments and experience breaks all the laws of logical reasoning, fluid dynamics, and mechanical engineering...


-Ted

Sniper_X

I am NOT saying that porting is voodo and bogus, just porting the throttle body on a mazda rx7.

Someone show me efore and after TB mod on a dyno and i'll beleve it.

Sniper_X

He was saying that he was "Adjusting the TPS using the resistance method and putting it to 1K ohms "

Thats hard to do if its open or shorted, intermittant failure is still possible, but I was merely responding to his method of adjustment.

It was just not exactly the right way to do it assuming all else was okay.

The resistance method is to check for a GOOD tps.
1kohm, its most likely good, just adjust it and test drive to be sure there isnt a intermittant problem is all that was left.

But if your putting the time in to set the thing, I would assume that you would check it to see if its good.

He didnt give any indication that is was BAD yet, just that it didnt work after he "adjusted" it.

What he did was the wrong method for the desired operation.

He used the TPS resistance test to set the throttle position.

that you do with a meter or the checker lights on the lamp connector.

Piranha

Well, if you are going to use the resistance method... and as per any writups using the resistance method, aren't you supposed to check to see if it is good/bad? Mine is good, I've checked it probably 5 times the last couple months trying to set this thing. :-/

RETed

This is why there's a short description to test the entire range of the TPS.&nbsp If there are any inconsistencies, it would be obvious looking at the resistance.


When I diagnose a car, I assume the worst.&nbsp This means, using your experience, you look for all the possible problems associated with a given symptom.&nbsp For example, when I do a TPS adjustment via resistance, I check the entire range first before I set it to 1k-ohm.&nbsp It's the logical thing to do.&nbsp I'm only going to say this once; it sounds like your methodology is different.


I sounds like a broken record, or else you mixed up the terms and actually meant: "The LIGHTS method is to check for a GOOD tps."&nbsp The resistance method will confirm if the TPS is bad or good.&nbsp If the TPS is bad, what exactly is the failure - some of us are curious to find out.&nbsp It looks good to my customers that I can visible show them what is happening with the TPS and explain to them why this is "bad", versus "oh, your TPS was bad, and I swapped it out for a new one - that'll be $200 please".


If you are experiences enough on adjusting TPS's, you should know to pop the throttle open several times to see if it changes.&nbsp Reading resistance, I've seen the idle setting change as much as 200&#937, which is off by 20%!&nbsp I always snap the throttle open and close several times to get a "stablized" setting.&nbsp It only takes another 30 seconds to check full travel and WOT resistance readings.


See above for my troubleshooting methodology - I don't want to repeat myself again.


What do you mean by this?&nbsp The throttle plates cannot be adjusted via the TPS adjustment screw short of binding the adjustment - hell, I don't even think that is possible either.&nbsp Isn't the TPS used for "throttle position"?&nbsp Isn't it a "throttle position" sensor, right?&nbsp So what's wrong with this?



-Ted

HAILERS

The voltages seen at the ECU are a result of what you do to the tps. Just a foot note.

Sniper_X

This sounds like a methodology war, but its not that important to me.

I meant what I said about the resistance test.
Its to check for a GOOD TPS.

The lights are to set the throttle position screw.

The voltage method is to set the TPS's position on its mount in space..

Yes you can tell MORE them just these things from each of these tests, but thats neither here nor there....

I was just trying to end his confusion as to why it wasnt setting right.

He needs to test the resistance and voltage, then actaully SET it with the test connector on the harness with lights or a meter.

Any other method will send him off in tangents that waste time and dont adjust it to the ECUs satisfaction.