Still Don't Know What to Do About My TPS!

[Justen]

So i'm not really sure what i should do about my idle problem. 90' TII, rebuilt the motor myself, streetport. I'm trying to get the idle steady, but i haven't had much luck. Floods and backfires on start-up. So naturally a bad TPS could very well be the culprit.

I checked the TPS with both a multimeter for resistance, and also with the 2-tester-light adjustment method... Failed the multimeter test, and i cant get the one tester light to come back on when i open and close the throttle plates after i adjust it.

I explained this to people on a number of forums and everyone seems to say that I definately need a new TPS, But then I hear from one of the guys at ROTARY-RESURRECTION that the multimeter test is not an accurate way of testing it. He said that he has seen TPS sensors that have passed the Multimeter test but performed like crap on a running car, and some that didnt pass and worked fine on runnning cars.

So what the hell should i do? :banghead: New TPS's are pricey, i just want to know for sure that its the problem.

[Max777]

did you delete the thermowax pellet on the throttle body or any emissions?

[RotaryDiagnostics]

Get a copy of the factory service manual (free for the download at http://foxed.ca/foxed/index.php?page=rx7manual) and work through the troubleshooting matrix in section F2. Your problem could be related to something other than the TPS. For instance, if the problem lays with the air flow meter signal to the ECU, the system will go into a fail safe mode where gobs of fuel will be dumped into the system and the timing will be modified. Don't ask me how I know.:(

[Justen]

did you delete the thermowax pellet on the throttle body or any emissions?

yes... thermowax removed, rats nest gone, air pump, emissions, etc.. gone

[Max777]

/\ Well, if that is the case, then your idle issues are from the thermowax and BAC being removed. Usually, you keep these things on the engine to improve it's idle quality.

Your TPS might be shot, so first go get another TPS, and thow it on and see what happens, this usually isnt the best way to fix problems, but for around $20 on the forums, it's nice to have a spare anyway...

You should build a twin-led tps adjuster( search) and adjust the tps to where only one led lights up... two leds mean it's too far and none means it's too close. Also check your throttle cable for smooth operation and binding. The cable on my TII sucks, atkins rotary and mazdatrix can get you replacement cables.

Depending on how cold it is in your area, when you remove the thermowax, you have to hold the gas pedal down a bit on a cold start.

The BAC valve then helps with idle quality.

[Justen]

I checked the TPS with both a multimeter for resistance, and also with the 2-tester-light adjustment method... Failed the multimeter test, and i cant get the one tester light to come back on when i open and close the throttle plates after i adjust it.

Yeah i've already tried this test, but i think you may be right, I haven't really checked my throttle cable...

But considering the Flooding problems, i'm thinking it could be a combo of that and a bad sensor (maybe even something other than tps) since it seems to be running in fail-safe mode

[My5ABaby]

What are you trying to get it to idle at? I removed all that stuff on my car and finally gave up on getting a steady 750 idle. I just upped it to 1100 and it's solid. How often do you really idle your car? Just a thought...

[Justen]

What are you trying to get it to idle at? I removed all that stuff on my car and finally gave up on getting a steady 750 idle. I just upped it to 1100 and it's solid. How often do you really idle your car? Just a thought...

that is true... but i'm not worried about the idle being perfect when i'm actually driving it, i'm really just trying to get it at a steady 750 for at least a few minutes so that i can set/check the ignition timing, because as far as i understand the timing is automatically advanced a smidge as your revs go higher than idle. Can someone verify this?

....If so, how did you get your timing right without idle at 750?

[My5ABaby]

I've never set the timing. Kevin did it when he rebuilt my engine and I've had no reason to think it would be off.

[FlybyRE]

Yeah if you remove all the emissions stuff, thermowax, BAC secondary plates etc yoru idle will be jacked.. Its not a TPS thing...

I did this and upped my idle to about 1000 RPM and I was happy.. however when the car was cold it never wanted to idle..

[Justen]

Get a copy of the factory service manual (free for the download at http://foxed.ca/foxed/index.php?page=rx7manual) and work through the troubleshooting matrix in section F2. Your problem could be related to something other than the TPS. For instance, if the problem lays with the air flow meter signal to the ECU, the system will go into a fail safe mode where gobs of fuel will be dumped into the system and the timing will be modified. Don't ask me how I know.:(

...lol Well i'm sorry if its a sore subject, but i have to ask.. did it throw any particular codes when this happened? and what turned out to be the problem?

[Justen]

Yeah if you remove all the emissions stuff, thermowax, BAC secondary plates etc yoru idle will be jacked.. Its not a TPS thing...

I did this and upped my idle to about 1000 RPM and I was happy.. however when the car was cold it never wanted to idle..

I would be completely content with an idle at 1000 rpm as well,
and i really won't mind any inconsistency of the idle once everything is set (tps, timing, ect..).
I just don't want the motor to blow at anything over 5k rpm while i'm driving it, after all the work and money spent on the rebuild.


Has anyone had similar symtoms after a rebuild?
Or does anyone have any experience setting their own idle?

I don't know what to tackle first, Timing or Potential Sensor Issues?
:banghead:

[FlybyRE]

IME This is 100% normal with the throttle body modification that you have done.. My question is what kind of vacuum do u see at idle...

After the car warm up does it idle fine on its own?

I manual set my idle to about 1000RPM (by adjusting the idle set screw on the throttle body).

As long as this is all related to the thermowax you wont have any problems with your engine blowing up.

This was exactly how my engine ran after I did my last build.

[Justen]

This was exactly how my engine ran after I did my last build.

Okay, thats very good to hear. So hopefully once i put a fpr in there it shouldn't run quite as rich as it is now.

it is still throwing codes however...

[Justen]

Alright, these are the codes its throwing:

9.....water temp sensor
25....solenoid valve (pressure regulator control (PRC))
31....solenoid valve (relief)
32....solenoid valve (switch)
34....solenoid valve (bypass air control (BAC))
42....duty solenoid (turbo boost pressure control)

now, given that i have all emissions/rats nest/idle control removed, is there anything else besides the water temp sensor that i should be worrying about? I also have elect. boost controller installed.

[Max777]

well, the water temp sensor is a biggie... you need to look into why it's throwing that code, if it's wiring, or if the sensor went bad. The rest of the codes are emissions components related. The boost pressure solenoid would normally be a problem, but since you have an aftermarket boost controller installed (correctly, I hope) it should not be an issue.

[Justen]

well, the water temp sensor is a biggie... you need to look into why it's throwing that code, if it's wiring, or if the sensor went bad. The rest of the codes are emissions components related. The boost pressure solenoid would normally be a problem, but since you have an aftermarket boost controller installed (correctly, I hope) it should not be an issue.

So with the temp sensor fixed I'll be back in business. Great, so now I know i'm on the right track and didnt screww everything up lol. It was my first rebuild so i guess i was just a little paranoid. With an FPR i'll be ready to break the motor in in no time. Thanks for everything guys. As always, you really helped me out. :icon_tup: