Leeroy_25

Guy's this is a problem I have had for a while and seems to be getting worse. I rewired the plug recently as I thought the earth was not great but that hasn't helped. I am running an LTX-12 ECU on a 20B in an FD3. Cosmo TPS sensor. What happens is I calibrate the TPS when I switch on. So cold. All fine.. then as the engine warms up the calibrations wonders off and I start getting a TPS CAL warning so I need to remove some of the correction to bring it back in line. Which seems to be fine for a while. It may wonder a bit more again but once fully up to temp seems to hold pretty steady. but then when I switch off and all is cool again the TPS will have a reading when I come to drive it from cold again so I need to re-calibrate and so the process starts again. I did have it to a point I could just about live with it from hot to cold but it seems to be getting worse. I am not sure if this is TPS related or ECU related. Anyone else had this issue and can help work around it if it is ECU? I plan to try and take a 5volt reading and resistance reading across the TPS when cold and again when hot next time I get to run it if I can work out how to do the resistance reading. I am hoping that might confirm if it is the sensor or the ECU? Any guidance on that would be appreciated too.

The only reason I need the TPS is so idle kicks in and decel works properly. Could I change to just a microswitch or run the TPS of the narrow band wire instead? I gather the manual asks to wire it up for wideband operation but being that I only need it for detection of idle.. i.e throttle closed would that work and solve the issue? Would really appreciate help on this one as it is one of the last and main niggles I have with my set-up/tune!

Thank you
Lee

Banzai-Racing

iTrader: (11)

If you have the throttle body thermal wax still, then you need to set the TPS when fully warm, then when the car is cold it will show a few percent open, because it is. As the water warms up, the throttle will close and bring the reading back to 0%

Leeroy_25

As far as I am aware the thermal pellet is all gone... Unless something got left behind? No water the to the throttle body and secondary butterflies removed. Can the dampner part cause the same problem? I can see your train of thought as it does kind of feel like something like that is happening. The only thing I would say is I don't think the rpm changes. So it will warm up to the point all water correction in the map is off and find a stable idle around 1160rpm. I am pretty sure idle is still the same when the TPS starts to run out once it has got really hot through the engine it changes marginally as the TPS goes out of cal due to the idle timing dropping out but it does not increase or reduce other than that which I have noticed.

insightful

the factory sensor is a pile of crap, you're better off trying to rig up an alternative sensor.

Leeroy_25

Do you know if running it off the narrow band output only will help? It might just be a case of try it I guess. Other than that any other thoughts as to what I can put there? I think I literally need a signal to show I am on idle and that's it?! I don't believe it is used for anything else?

insightful

the microtech only uses the TPS for idle maps and transient rapid throttle increases, so wide or narrow range TPS doesn't matter. it only cares about a roughly 10% throttle increase and whether the sensor is in range when the throttle is closed.

technically you can map the car to run without a TPS perfectly fine. i got tired of screwing with mine, so i disconnected it a couple years ago and adjusted my 1k maps accordingly.

Leeroy_25

Okay.. So I went ahead and tried it.. not quite what I expected.. It seems that if you have it wired to wide or narrow the TPS readout seems to react in the same way? i.e TPS goes from 0-99% as you press the throttle through the range? I expect narrow to only work up to 50% or go straight to 99% or something?
I took a load of readings off the TPS when cold. input voltage. Signal voltage and Resistance across it. I then did the same when hot and values for resistance and volts and changed very slightly as would be expected. I drove the car with it wired to narrow band instead and set the TPS up. I now need to wait and check what it shows cold as it seemed to hold steady when I was driving. Was dipping in out out of TPS Cal every now and then but not reading a % value. I may just need to give it 1% more compensation but thought I would leave it at that and see what i have form cold now to see if it is any better. I expect not as the adjustment came a heck of a long way down from when it was cold..but I did adjust it down pretty soon after I started. We will see.

insightful

the narrow reads full throttle at approximately 33% input. ie step on the pedal 1/3 of the way and it reads full
the full range reads full throttle at... full throttle.

Leeroy_25

Hmm.. I will have to double check, but I am pretty sure mine is reading full throttle at full throttle for both?! Which I was a bit surprised by. I could have been having a funny five. I plan to go and check tomorrow to see what the tps readout says now it is all cold again. Ran out of time today.

Leeroy_25

I managed to get out and check the TPS last night. I found 6-7% on the readout (cold engine) when I connected up the laptop. Bugger! So is it TPS? The voltage in and out and resistance only had very slight changes hot to cold when I checked last time so I am not sure that could amount to the readout change I am seeing? Could the Dampener or linkage physically move as the engine warms to change the TPS readout? Or is it the ECU somehow at fault and changing value with time?
I also double checked the narrow band pedal response and I would say at about 3/4 throttle it reads 99% definitely not 1/3 throttle though.
Could really do with some help here as I don't want to fork out for a new TPS if it isn't the issue!

insightful

you really should just adapt a different TPS, like a common GM type sensor.

Leeroy_25

Have you got any recommendations.. I don't think it is quite that simple. Rotation direction and orientation need to be similar and while trying to find something similar before it seeks like the Cosmo one is different to almost every other one! I know there are some Toyota ones that fit and I found a supra one a while back but when I wired it up I could only get it to read something like 0-50% or 50%-90% with massive correction values. Maybe it was a dud? Or runs off 12v. Or maybe 0-50% would have worked knowing what I know now. I don't have it now anyway to check. It looked identical to the Cosmo one too so my worry would be that if the cosmo one is unreliable then so would that be. I would really love to confirm 100% if it is the sensor before I spend time trying to adapt something else. Are we sure it cannot be an ECU glitch or the dampener or something else in the linkage changing with temp? It was not this bad before I am sure of it. Sure it has got worse as time goes on. Thanks for info and suggestions.

Aaron Cake

iTrader: (1)

Commonly uses is the Ford TPS. Very easy to adapt to the rotary throttle body.

Used on a wide variety of cars. Here's the first hit from a Google search as a reference:
Throttle Position Sensor, Ford Fuelairspark.com

Leeroy_25

Thanks for the tip there Aaron, after looking through lots of tps the other day, it looks like there are a couple Mitsubishi ones, Suzuki and Daihatsu that use the same plug. A couple see to connect to the spindle bit in the middle like this Ford one. I. E it it slips over something. Is that hole in the middle meant to pick up on the nut head or you need to slip something over the nut head to go inside that?
Is your thought it is the TPS or the Ecu it seems quite a few people have TpS issues running the Micro tech? Is it more sensitive to the input or something?

insightful

no, it's just the stock sensor sucks. which i said before. microtech should have made the input set range broader though, to compensate for the sensor sucking.

Aaron Cake

iTrader: (1)

The hole is made to accept a nut on the shaft of the stock Ford throttle body. But it is easy to grind the nut on the rotary throttle body to fit.

Don't worry about it being the same plug. Just change the plug on the harness to match.

The Microtech does seem unusually sensitive to TPS jitter in my experience.

Leeroy_25

Thanks again for input guys.
Insightful. I did take it all on board first time but I wanted to be sure no one thinks the ECU could be at fault too before I go spending time and and money to rig up a sensor from something else! I guess other ECU's have done what you said to make them less sensitive to the sucky sensor! I found a few with a bore in the middle like that ford one and a couple that appear to have the same sort of plug as the cosmo too.. So I will hunt around a breakers first and test something out. Then if it works I will go get a new one!

Cheers.. i hope this sorts out that issue once and for all!

Leeroy_25

Been dabbling with this issue on and off trying to get hold of a suitable TPS I can adapt easily. I found there are a couple of Mitsubishi ones that fit and use the same plug. I got a late model one which is way small but I might be able to come up with an adapter for it. Question is when I wire it in I have to add 50% correction to get the TPS readout to start on 0% with the module sat in free space. i.e no preload. Is that an issue? The next question is when I move it it takes maybe 1/3 of a rotate to get it to go form 0-99% which seems very sensitive? If anything I would imagine I want a less sensitive TPS? But maybe it is just where it is off and for all I know that movement equates to idle-full throttle?
Thoughts please?

Leeroy_25

Just realised my stupidity on the rotation comment. Of course 1/4 of a rotation is basically throttle closed to throttle open. so approx. 1/3 rotation on the tps would be fine spot on allowing for some pretention! For some reason I was thinking half a turn to open and close the throttle! idiot!
Interested in thoughts on the correction input needed to zero it in the first place though? Is it a problem?

armans

iTrader: (2)

Are you able to check the readout on a warmed up engine but ignition off to make sure your problems are not ground loop or electromagnetic interference related?

highnitro12187

iTrader: (21)

I had this problem for a little while on a different ecu. Turned out i didn't have my grounds as perfect as they could be, It stayed calibrated after i fixed them.

Matt

Leeroy_25

I don't know how you could check this with ignition off or what I would be checking to determine what you are asking Armans. But I can tell you that I ran a new ground directly from the TPS to the chassis a while back as I thought that was the issue. Unfortunately not.. I would say it maybe helped slightly in general.. but did not fix the issue I see between cold and a warmed up engine. So this is why I had the idea to try a new tps from something else and see if I still get the same issue. if not happy days.. but if it carries on I either need to look deeper or find a way to work around this?

armans

iTrader: (2)

What I meant was having the key on but engine not running and see if you still get funky readouts. Perhaps a better test would be disconnecting TPS ground from chassis and connecting directly to the battery negative instead and if you still get wrong readings then I think pretty much TPS is shot.

Leeroy_25

Oh.. For sure you still get freaky readings engine off.. I have been doing most of my checks engine off.. The original earth went via ECU of course. Then I took that off and made a new earth to the chassis which I am 99.9% sure is bang on.. same issue. Battery is in the boot so earthing direct to that I would have to go get some long length of cable. I don't have any other earth issues I know of so I am pretty confident the new earth is good. So that gives me an issue with either TPS or ECU. if I can swap the TPS for this Mitsi one that might tell me.. I just want to check if large calibration values on the ECU end to get it to read 0% to start with are likely to cause a problem?

armans

iTrader: (2)

What's the voltage range on this Mitsu TPS though?