Throttle Position Sensor. My Fix. Problems Gone.

[Cubes]

Now that I am at uni, I do a lot of short trips with the car stone cold. I live 5km's away from campus. Hell I’m only using $30 of petrol every week including weekends. I used to spend close to $90. Mind you I’m not on $1160p/f clear any more, instead a measly $310p/f.

Now for the Diagnosis.

When the car is cold:

- On the initial start the idle would splutter and struggle for 1/2 a sec then the revs would rise to 1100rpm;

- and when idling, if you attempt to press the accelerator ever so slightly the rev's will slightly raise like I was twisting its arm but the motor will sound strange and splutter;

- cruising down the road attempting to sit on a certain speed the car HAD a slight flat spot. The sound difference can be heard through the CAI. Accelerate a little more and it takes off.

These problems were still evident once the car was warm however they were hardly noticeable. The start still spluttered a little but nothing like when cold.

In first gear attempting to idle around a car park you could notice a notchy on off feeling with the accelerator. It made life a real pain in the arse.

ANYWAY... I've always suspected the TPS.

I've finally got so sick of hearing driveline slack when looking for a car park due to the notchy on off accelerator and all of the above hassles.

So out comes the screw driver . I loosened off the two screws and got the feel of how the TPS operated.

The TPS was set roughly to around 9/10th's clockwise to its total range of movement. When setting it fully clockwise, it caused the car to have an extreme flat spot on light throttle, it basically amplified the problem. I started to GRIN. Get the butterfly’s etc etc...

I then turned it anti-clockwise until I heard the rev's raise then backed it off with a slight touch of the screw driver. Tightened her up and took her for a test drive.

First thing I noticed is that on off throttle transition was extremely smooth BUT... when gearing down it felt like an AUTO and the exhaust would ever so slightly pop or gurgle if you like.

I pulled over and noticed that the revs were idling a little high so I must have accidentally knocked the TPS ever so slightly when tightening up the screws.

I dropped it back again until the idle dropped.

The TPS is now set to roughly 7/10ths.

NOW... No more horrid on off throttle transition in gears and it also starts perfectly (no splutter), and the best part the cold driving or cruising flat spot is now totally gone.

The TPS is extremely sensitive to the slightest movement.

It may be a co-incidence or possible it may have just patched up an underlying problem.

Any one got any comments or experience with the TPS?

:alien:

[hippy]

whats a TPS?? and where is it located??

i mean how exactly does it work??

[Cubes]

Basically it tells the comp. if you have your foot on the accelerator I guess.

Hence the flat spot. Maybe on light throttle the ECU was being told that the Throttle is still closed when really it wasn't.

[kabab]

Yeah my car does the same thing i usually just turn it on give the accerator a stab to get the rev's stable then let it idle for 5- 10min.

[Cubes]

Do you get a slight kind of flat spot for the first km or so?!?!?

I don't really warm up I just drive it really easy.. 3000rpm max rev's with light throttle. Well It gets maybe 30seconds or so while saying cya to the fiancee and putting on the seat belt.

lol... Just looked at the Avtar.. Took me a while..

I've just been out enjoying the last of my tyres.. They are getting low and very very slippery.. Powering on in second causes instant wheel spin snakeys over the road.... :burnout: :burnout:

[kabab]

Yeah its like there is a HUGE HUGE flat spot at 2Kish you can feel the car get stuck there then urge forward.

[MicK51]

i had a problem with my car idleing to high so i pulled the TPS off... looked at it... put it back on and it started idleing perfectly!

i do have a big flat spot just before it comes on boost when its cold though, and the 1st set of lights i come to i usally have to give it a little poke to stop it from stalling but once its warmed up its fine.

[whistla]

im having problems with my TPS too, although different to your cases

i dont get any flat spots not idle problems but on my handcontroller for the Wolf the TPS sensor reads all sorts of numbers when i have my foot off the throttle

sometimes at WOT, sometimes halfway, but this doesnt effect the engine at all which baffles me because the wolf uses TPS/Load/etc to determin ignition/fuel/etc

seems to reset to 0 TPS when u rest your foot on the accelerator, but once u let all of it go, it goes erratic

im thinking dodgy earth? connections seem fine though

i dont know

[Cubes]

Yep thats the adjustment of the tps...

Mine is now gone... mwaahahahahahhahah..

Kabab described it perfectly..

[Cubes]

Whistla.. Maybe the Wolf3d is correcting any idle or flat spot problems.?!?!?!?

Have a fiddle with the adjusment of the TPS... It is pretty easy to reset back to standard. Just take note of where it is.

[whistla]

damn screws wont come off!

[2rismo]

umm... my tps looks like its not even connected!??!

does power fc not use it?!?!? baffled.

[Brody]

WTF is the tps located?

[Doctor]

a black thing with a plug hanging out of it on the throttle body.

[Cubes]

Well its been two mornings with no flat spots.

[dojobi]

OMG you guys just described my problem exactly. I have this HUGE flat spot around 2K rpm and then it's as quick as normal. I'm going to go and check mine.

[Cubes]

To test that it isn't adjusted to much to the left (Anti-Clockwise) sit in 3rd down a hill and the motor should sound like its getting no petrol.. Hence no gurgling.. just an anoying bwaaaaaaaaaa.

If you get what I mean.

I used to also got a lot of poping and some times backfiring between gear changes on light acceleration.

This has also now dissapeared..

[Dragon18]

woutl this problem also apply to other nissans etc?

guy i seriously think that we shoudl creat a site or page with all the problems that you guys solve instead of pointless hours searching and asking questions when it has been solved before what ya think +)

iam willing to set up a site =) and do i t=)

[Cubes]

I had the same problem with my VL Commodore.

Not sure if it was the TPS or if they have one however.

That used to start perfectly though. But it did have the flat spot on the tip of the accelerator. It was slightly different. But basically felt the same.

[Gumby]

Don't know if this helps, but I used to have a Nissan Bluebird with a Z18 Turbo and Autronic Management. Tuning was performed with a laptop and on this you could see what all the sensors were reading as well as seeing what the computer was reading for throttle position from the TPS. It would use throttle position to assess load and then the fuel and timing map was made up by plotting load against rpm.

In other words, if your Throttle Position Switch is not reading 0 where your butterfly is closed or at idle pos, your mixtures and timing are quite likely wrong for that condition, then when you open halp throttle, your TPS tells the comp you're 3/4 throttle and again your mixtures are sell out. This is what causes your missing and erratic leading and trailing throttle. I used to stick the PC onto the Auronic once a month to recalibrate the TPS, never knew why it kept going out but it did.

Hope that helps.