Jump to content
SAU Community

Recommended Posts

Finally decided to adjust my TPS to hopefully fix the 4WD light coming on, as the error i got on th eattessa computer 7 long flash's anda 5 short ones, did some research and it comes up with the TPS.

My TPS voltage on iginition was under 0.4v on my hand controller, after some reading it should be above .4 and under .5v is the general concensus.

So i have adjusted my tps to read these values with the ignition on (motor not running), but under the sensor/check on the hand controller, there is a IDL option, and previously the dot was black on idle, but not with the adjustment sometimes its clear sometimes its black.

will this impact anything?

What does it mean?

I have a feeling it means the ecu is in "idle" mode, but maybe i have adjusted my TPS to much and it thinks there is some load on the motor?

Little confused and not 100% sure if my theories are correct.

Any advice would be great!

Link to comment
https://www.sau.com.au/forums/topic/434737-adjusting-tps-power-fc-question/
Share on other sites

The TPS is basically a 2 part sensor. One measures variable resistance to get your throttle position, so varies between 0-5V depending on the throttle position. There is also a digital (on/off) switch that will probably be what is bringing the IDL light on. It's been a while since I've played with my Power FC, but pretty sure everything you are saying sounds alright, that switch should be on (Black) when no throttle is applied, and off when throttle is applied.

0.45v I think is what generally the TPS gets set to

I had some problems with (from memory) the idle sensor light in sensor check. I thought it was under another name in my GTS-t Power FC but could be wrong

I played with the TPS after I got a new TPS sensor (chasing another issue) and never had this problem again. So not saying its the sensor but could be

I think when I originally had the problem it went away after a bit of driving.

Hmmmm...

So if my IDL switch is saying its off (as in not black) when the car is idling with obviously no throttle applied.

Will it be a issue?

I assume its just not running the idle map?

My car's idle is a bit shit, because i cleaned the butterfly's on my throttle bodies when I upgraded the turbo's >_<

So that could even have something to do with it, none the less i think it was operating properly before.

EDIT: Also i thought the max reading was 4v on wide open throttle?

Edited by Booki

I don't have direct experience with RB26 TPS, but the nearest equivalent ECU I have experience with is RB20. RB20 do not have a variable resistor for the ECU. There is only closed throttle and WOT switches. The variable resistor in the RB20 ECU is unused on manuals and reports to the TCU on autos. So, not a useful example, you might think. But I shall plow on regardless. I worked out that the best way to set the TPS on RB20 was to have it so that the closed switch would come off at the slightest, tiniest hint of opening of the throttle. This would cause the ECU to double fire the injectors (they do this little double click batch fire thing as you crack the throttle) and give the best throttle response for driving off.

Fast forward to ECUs with variable resistor TPSs like RB25s and so on. You need to set the TPS voltage at idle so that the ECU activates the idle condition (so that is the IDL light on PFC) and so that it takes only a teeny, weensy movement of the throttle to make it turn off. That is generally at or near 0.45V like the guys above have said, but it may be a little more or a little less.

So, for your car, it seems like your TPS might be set just a tiny bit too high. Back it off a tiny bit so it stays convincingly in idle mode when you're idling. Job done I expect.

It was set correctly before but the attessa system would throw up codes because the volt reading would sometimes be low, might have to fiddle with it some more. Its at .41v with ignition and goes a little higher when the car is running.

Is that normal?

0.41 is a little on the low side, but not out of range, and the fact that it increases with the engine running is normal because the voltage reading only occurs because it is a variable resistor across notional 5V supply, but the 5V supply is not regulated to perfection, so it tends to increase in voltage a little when the alternator boosts the 12V line. So really, it's not 0.41V in your case, because I'd only do the measurement/adjust with the engine running anyway.

  • 6 months later...

just digging this up

so ive been having idle hunt issues with hot start and also when i put the clutch in at about 2.5k+ revs

done heaps of reading about afm aac ect, have considered cleaning them again, but i did notice some say tps

i looked this morning and realised on ign or car running at idle its .35v which i understand as low, anything btwn 0.45 and 0.5 is good

so looks like it needs adjusting.

http://www.skylinesaustralia.com/forums/topic/404812-help-setting-tps-on-r33-s2/

found that thread but can i adjust the tps without a multimeter and use the powerfc hand controllers reading?
also does it affect anything tune wise?(will i need to check afrs or anything)

just digging this up

so ive been having idle hunt issues with hot start and also when i put the clutch in at about 2.5k+ revs

done heaps of reading about afm aac ect, have considered cleaning them again, but i did notice some say tps

i looked this morning and realised on ign or car running at idle its .35v which i understand as low, anything btwn 0.45 and 0.5 is good

so looks like it needs adjusting.

http://www.skylinesaustralia.com/forums/topic/404812-help-setting-tps-on-r33-s2/

found that thread but can i adjust the tps without a multimeter and use the powerfc hand controllers reading?

also does it affect anything tune wise?(will i need to check afrs or anything)

do you have a stock ecu or powerFC....idle control is either closed loop with the o2 feedback turned on or open loop (set by tuning it) if its hunting this can becuase it is running too lean at idle.

power fc

yeah just weird that its fine most times, but only when started hot it will hunt for a couple of seconds, if i clutch in from about 2.5k and above and keep my foot on the clutch it will drop to 500 and up and down for a couple of secs then fine, just figured the tps needs adjusting as a start as its slightly low

Edited by MatthewT85

yeah did that, turned it to roughly 750 was going between 730-880ish there abouts and then plugged it back in, started and it was hunting for ages(10secs didnt normalise till i took the key out and timer was counting)so that didnt help unfort if anything made it worse

Ummm....Badgaz......closed loop idle control has nothing to do with mixtures. It is, by definition, "closed loop idle speed control" not "closed loop mixture control".

Closed loop mixture control barely works at idle anyway because the O2 sensor usually gets too cold to work quickly anyway. Regardless, they are two totally separate things.

I remember when I turned my O2 feedback control off and idle didn't change at all. I was under the impression that at idle (when the TPS indicates closed throttle) then the idle IGN and fuel maps are active and the o2 sensor is all but ignored

I had some problems with my TPS not putting the car into idle control for some reason even though the voltages were fine. I pulled it off, messed around with it a bit checking it was operating fine then put it back and all of a sudden it worked again. Strange but something to think about. I ended up buying a new TPS and never seemed to have any issues with it, so maybe my old one, although it indicated it was alright, actually had a problem.

Its a good idea (Although probably not practical for the OP if Power FC is tuned and running) when first installing a Power FC, to check all the sensors and switches are O.K and adjust the TPS to the correct position before performing the Data INIT.

Problems like these are not a problem on newer ECU's. The Link I have now for example has TPS calibration in the PC Software, so if it ever seems like it has a problem, you can just recalibrate it so it knows were 0% and 100% are and its happy again. I'm still a supporter of the Power FC however, as for what most people need it is a pretty good simple replacement ECU. The Link is a much better ECU, but not everything on it is necessary for most

cheers guys, i think i might adjust the tps to reflect 0.45v or slightly above and go from there, maybe have to look at cleaning afm and aac again.

but yeah seeing as though everything ive read has said my voltage is low might be a good starting point

I remember when I turned my O2 feedback control off and idle didn't change at all. I was under the impression that at idle (when the TPS indicates closed throttle) then the idle IGN and fuel maps are active and the o2 sensor is all but ignored

I had some problems with my TPS not putting the car into idle control for some reason even though the voltages were fine. I pulled it off, messed around with it a bit checking it was operating fine then put it back and all of a sudden it worked again. Strange but something to think about. I ended up buying a new TPS and never seemed to have any issues with it, so maybe my old one, although it indicated it was alright, actually had a problem.

Its a good idea (Although probably not practical for the OP if Power FC is tuned and running) when first installing a Power FC, to check all the sensors and switches are O.K and adjust the TPS to the correct position before performing the Data INIT.

Problems like these are not a problem on newer ECU's. The Link I have now for example has TPS calibration in the PC Software, so if it ever seems like it has a problem, you can just recalibrate it so it knows were 0% and 100% are and its happy again. I'm still a supporter of the Power FC however, as for what most people need it is a pretty good simple replacement ECU. The Link is a much better ECU, but not everything on it is necessary for most

Initially i had thought that as my ign was showing different in my logging to what it showed on the map....but i tried adjusting the fuel map at idle and watched the afr's change. it'd be nice to have power excel to see if there is an idle control system unseen through the fcdatalogit.

the tps will not affect your tune mixtures.

so i adjusted the tps to 0.45v and it looks like ive fixed the hunting on clutch in and hot start, but ill drive it round for a couple of days before saying its 100% fixed.

also for anyone else thats gonna try i pretty much stripped the screws and had to use vice grips to loosen them first.

i think ill also do the idle reset soon too

Create an account or sign in to comment

You need to be a member in order to leave a comment

Create an account

Sign up for a new account in our community. It's easy!

Register a new account

Sign in

Already have an account? Sign in here.

Sign In Now


  • Similar Content

  • Latest Posts

    • Oh, that's grim. Something bad has been happening there.
    • Put an endoscope down the hole and saw this. Not quite all around the bore but a good 60% at least. Chin to the chest and towards further disappointments I guess.
    • 2 does "sort of" applies, maybe......but looking at what parts would be needed for the swap to get engineered, registered, and insured, and basically that's everything under the car, the modifications the make it legal would be problematic and horrendously expensive, all for a street car that just cruises around and hits a few twisty roads on the weekends Also, from looking at the NSW rules and Regs, with all modifications that is required just to make the car safe and not twist itself to pieces, and then actually get registered for street use, may still be impossible nowadays As for 1, when you add in a fresh engine, fresh transmission, rear cradle and diff, tailshaft, suspension, brakes, cooling, and all the other fabrication required, your probably looking at up to $100k to do it right, all for a 20 year old MX5 that is over engineered and you would never be able to actually use the power it has on the street, much like your beastie, which I love, but you actually track that thing and can use all of its powers in anger, in a safe environment  Hell, the old Bogan Cruise Ship had more power than I could use on the street, and in hindsight, I went a bit silly on that thing, it didn't really need the 500hp it had for what I actually used the car for, it was fun, but basically unusable on the street if you value your licence  As for cams, yeah, I'll probably book it in for them to get installed and tuned soonish, like next month after MX5 Mania are back at work....... and yes, I've already sent a email to bin the turbo quote and quote instead to install cams and a new Fluidampr balancer that will suit the 2.5 better than the OEM 2.0 balancer that is swapped over for the 2.5 install, as the balancer needs to get pulled to time the cams it's a while your in there sort of thing I did think a bit about flex fuel for a laugh, but being na, and no where really around locally anymore to get E85, I've binned that idea, so no sweet sweet corn smells are set for the car I wish E85 was more of a standard fuel, it's better for the environment, better for tuning, plus that sweet sweet smell we all love As for fitting in the family, that's not needed, as everyone in the family already owns a car that can seat 5 humans comfortably enough, the MX5 is "my toy" As for buying a car that is already built, nah, I would rather pick and choose my parts, I enjoy the process, and in the big picture, the additional cost is well worth the enjoyment, and the occasional frustration, I get out of doing it, albeit with other people spinning the spanners, and me, just paying the invoice 🤣
    • Excuse me, but 2) does apply 1) Would also apply if you consider how much is spent in the alternatives. Also there's the option of 3), buy one pre-built that you can put your family in (it's me, it's my car)   That said, I went on a ~500km drive the other day. I didn't use anything more adventurous than 3rd/4th gear at about ~3000RPM and 50% throttle and I was going as fast as anyone has any sense doing on a public road, with enough grip to the point where I didn't want to go any faster. I was obviously under the limit of the current car etc etc. MX5 with 2.5 N/A to achieve the same speed would be more fun for any road scenario. Maybe consider cams. I wouldn't boost it. The use case is just not there and it won't actually make the car more enjoyable unless you really do plan on wringing gears from 1st to 3rd (at least) at 100% WOT on a public road to 150+kmh.
    • Great if: 1. You had all of the money for everything else that is required  2. Lived in a country where you could actually do this and drive it legally on the road Sadly, neither applies to me As for the turbo, I am having second thoughts, mainly for engineering/registration legality reasons and insurance  Not saying I've finished doing stupid things that I probably should do to the MX5, but boost, and V8 engine swaps isn't on the cards Strange, but true 
×
×
  • Create New...