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Skida

TPS/ Throttle questions

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Hi i hope someone can help.

 

I have recently put a new 80mm Accufab throttle body and after market plenum on my RB in my s13 Silvia,

 

The problem im having is the car starts and idles fine and drives ok but when you try and give it some boot it seems too hit a flat spot...

 

I have tried to set the TPS to the right settings but cant seem to get the .5v closed and the 5 v open that i have read on the net that is needed so i guess i will have to see a auto sparkie for that but what im wondering is if anyone knows if it may be something else not the TPS

 

Any help would be greatly appreciated

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I changed mine last week.

The whole throttle body with the TPS.

 

You should have ordered one with the TPS set. So much easier.

 

Don't let the dudes rip you off, if you think it's the TPS tell them to do that and nothing else.

 

Some wank tried to rip me off 2 weeks ago, told me my auto is f**ked and it'll cost me a grand to fix (If he does it)

Came on here and I got told it's the TPS, so I changed the throttle body and it changes gears smoothly now. Nothing wrong with the auto.

 

But yeah, if your certain, then do what you think, if not then try something else.

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^^^ totally unrelated reply???

 

he already has a tps, has a throttle body, and it is not a stock item its 80mm.

 

go down to Kmart, buy an electrical set with a cheap multimeter in it, if you dont already have one. i have one and it works well.

 

see what you get throttle wide open and closed.

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Thanks for the quick reply's, Now this is were I openly admit I know bugger all about automotive electrics, I have a multi meter now I have tried all the settings on it the best I can find is on one of the settings it says -.094 closed and -.051 open but I really unsure if i have it on the right setting or not.

 

Sorry for my stupidity but of some one could help it would be great?

 

Could it also be a problem with my ECU? my current ecu is Gizzmo chipped and ran fine with the old motor, but after the change the motor runs fine doesn't seem to be over fuelling or have any signs of it leaning out it just has the flat spot when you try and accelerate

 

Thanks again

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Sounds like your on AC voltage reading. On the meter turn it too the setting with a V and A STRAIGHT line NOT the V with a squiggly line. The straight line v is volts dc which is what you want. It should also say DC on the screen when using dc voltage. Then have your black lead on a good earth point and the red lead onto the signal wire. To double check you are doing this correctly you can try it out on the battery and see your battery voltage on the screen (around 12v depending on charge).

 

0-5vlts is the values it will feed the ecu which then takes this and uses it in it's processing.

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Thanks for that mate will try that tomorrow, Dose anyone have any other suggestions as to what may be causing the dead spot?

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Yea it seems to rev through it from memory trying not to drive it too hard just worried it may be detonating.

Cheers for the idea I will go over the coils and assorted wiring with a fine tooth comb

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the 0.5v is important the 5v is not so important.. the TPS isnt setting the load scales anyway.. its a combo of RPM and airflow.. tps is just for a little enrichment and for idle..

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Well have gone though everyone's idea's coils are all good, got my multi meter on the V with a straight line but cant get it to show a reading on the 20 setting or the 200 setting so i took the tps off and started the car it idles fine and revs up like it did before but even when i turned the tps with car at idle nothing changed,

 

So im guessing with the combo of the no reading on the multimeter and the no change when removed from the car that the TPS is shagged and ill need to get a new one?

 

If I am wrong in thinking this please some one tell me because i would love to save the 75bucks its gona cost me for a new one

 

Thanks

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if there is no voltage on any of the pins then you have an ecu problem.. or wiring fault.. the tps should have 5v.. signal (0.5-5.0~v).. and ground..

 

get the factory manual for your car.. read the section on TPS.. then go grab the multi meter and do the tests they are very straight forward.. continuity check for broken wires.. resistance check for TPS.. and voltage check for ECU issue..

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Sorry i should have said the 5v running to the tps for power is there and the ground is good i just cant get any reading from the Signal wire,

 

I will try and find the Manual for the rb on line im not to sure what model its out of though might be a cefiro or a skyline not to sure how much difference it would make

Edited by Skida

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Just so I am sure I'm doing this right using the earth for the tps and for the power wire i get 5v but when trying to read the signal wire closed it shows 0.01 and open 0.00 and this doesn't change no matter how i position the tps on the throttle body

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normally the top pin = power lower pin = ground and middle signal....

 

disconect the TPS.. set the multi meter to ohms and measure the resistance.. you will get a fixed resistance between ground and power.. and you should get a resistance between signal and ground and signal and power.. by the sounds of it your tps is shot... the resistance will confirm it.. then with the meter on the signal wire turn the tps it should gradually increase and decrease depending on which way you move it.. and the resistance between signal and ground and signal and positive should add up to the resistance between +ve and ground..

 

make sure when you measure continuity you unplug it..

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Cheers chris2712au for all your help

 

This is what I found I set the multi meter to ohms and the 20k setting

 

Power + Ground = 3.91

Signal + Ground = .83

Signal + Power = 3.34

 

with signal and power connected and turning the tps it decreased from 3.4 closed to .25 wide open

 

with signal and ground connected and turning the tps it increased from .83 closed to 3.72 wide open

 

Hope some one can clear this up for me because its as good as a foreign language to me

 

Thanks again for the help

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I dont know if it is your problem but at work when we are changing a throttle position theres a method involved off setting it. We measure the voltage of the signal wire and there should be factory sepcifications to how much it should read closed between like 0.55 to 0.75 volts then you tighten the sensor.

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sounds like it is ok to me.. it can be that when you are attaching it to the throttle body it is not turning the sensor.. on some throttle bodies i put it in then turn it clockwise so the sensor is infront of the pin that goes through the throttle shaft.. but thats on the s15.. install the tps again then using the throttle with the tps unplugged make sure you get those resistance readings again.. If so there is something dodgy potentially with your ground that your using to measure the voltage.. if not then the throttle shaft is not connected to the sensor properly.. as if the resistance changes the voltage has to as well.. when you plug it in..

 

but on the topic of grounding.. it can be that the TPS may not be grounded but if you measure the 5v.. you should have a good ground.. where are you measuring the voltages from when it is plugged in.. at the plug or at the ECU.. and is it a PFC ? are you able to read it via display ?

Edited by chris2712au

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I'm measuring it from plug about 2 inches from the TPS, nope not PFC just a chipped standard cpu.

 

Just checked that the throttle is actually moving the TPS and as far as I can see its moving fine. and even with the tps removed and turning it still no result

Edited by Skida

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did you repeat the resistance check at the second plug or directly off the TPS ? to me it sounds like wiring.. measure directly at the tps.. if there is 5v and gnd there then the wire from the second plug to the tps plug is open circuit / broken..

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The TPS is a sealed unit( if you Google search 80mm accufab throttle body it should show a pic, would put one up but not sure how to)

 

I have probed the wires right next to where it goes into the tps and still get the same reading 5.1 votls for power and 0.01 for sensor with ignition on and 0.04 with car running. this doesn't change when using the earth for the tps or going of the body,

 

i also did the resistance check from as close as possible to the tps

 

Sorry i know my lack of understanding is making this harder than it seems it should be, I really do appreciate all the help and feed back

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can you get some pics of the tps mounting position and tps that you have.. you will have to upload to photobucket and link in your post..

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Hi sorry i have been away I will get photos of TPS and post them up soon

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is that a standard TPS ? or a tps that come with the throttle body.. as it could be the ecu does not like the resistance / load that that sensor is providing.. I would of expected that the 5V would of got pulled down.. but you are measuring at the spade connectors ? and with the wires disconnected and using the throttle cable the resistances change on the signal / ground / +ve ? then the signal voltage should change.. I am thinking now there is a wiring issue.. can you do the resistance check and give the wire colours.. then do the power check on the harness side and give the wire colours.. as I think you have a wire mis match ?

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That is the TPS that came with the throttle body the ecu shouldn't have a problem as it was working with my mates rb20 on a standard ecu a couple years back, (and on his 700+hp RB30 but he had a link in it by then that was before a snapped cam and a leg out of bed)

 

I have measured from the spade connectors and from probing the wires as close as i could get to the tps

 

will do the resistance and power checks tomorrow and put them up as soon as i have done them.

 

One explanation I was told is that some one have over turned the tps and damaged the connections inside so but not to sure if that sounds right

 

Thanks again for the help

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Power test on harness side is 5v going to the red wire that's using the black wire and the chassis. and no power reading for the black and greed

 

The resistance test

 

Orange and black = 3.91

Green and black =.83

Green and orange =3.34

 

Green and orange connected and turning the tps using the throttle it decreased from 3.4 closed to .25 wide open

 

Green and Black connected and turning the tps using the throttle it increased from .83 closed to 3.72 wide open

 

 

Cheers

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Is it the throttle position sensor or another problem, the engine should still run off maf and load points even if you unplug the TPS.

 

I would personally check the tune, when upgrading throttle body to a larger item you will loose inlet airflow velocity giving you a flat spot down low and more horsepower in the higher rpm.

If you want to eliminate the flat spot, get it tuned to suit that throttle body. If you miss the down low poke your car used to have, put a 60 or 70mm throttle body on and you shouldn't have to tune around it. 80mm seems to throw the airflow out too much for the computer to compensate especially with an aftermarket plenum.

 

 

 

 

 

www.fat333performance.com.au

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I see what you are saying RIP 5 litre but flat spot is only up top when I start trying to 'enjoy" the car. down low it is almost as responsive as it was with the stock plenum and throttle body.

 

I cant get the right signal from the tps so i am starting with that as my first problem, tune etc are next on the agenda I am currently pricing for a link and full dyno tune but funds are holding me back right now

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ok well i see it like this

 

http://i257.photobuc...s2712au/TPS.jpg

 

what you need to do is just connect the red wire to orange.. and connect the black to ground from the tps..

 

From what you are telling the green wire seems to be the wiper.. (signal wire)

 

if you put 5 volts red on the orange and connect the ECU / engine ground to the black then when you move the tps you should get a signal of 0~5V and it should vary when you move the TPS.. when you measure green to black.. or green to orange

 

what you then need to do is to look at why when you connect the green wire up to the ECU the voltage is not still there.. it could be that the TPS input on the ECU is damaged.. this could be from an incorrect connection..

 

we will check after the first test.. it would be handy to see where the red black and green are connected.. is it a stock harness and ECU ?

 

if you set it to 2k black green and 2k green orange you should be at half throttle.. and the voltage should be around 2.5v..

Edited by chris2712au

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Hey mate yea its a stock ecu and harness all be it swapped from a r32 into my s13,

 

Your right with out the signal wire attached it dose read the right vaults found the pin out on the ecu it looks ok no damage around it and seems to be held in tight so will trace the wires and see what i can find

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