Stagea Jerky On And Off Throttle

[sturb25]

I have a stock series 2 manual and when i got it, it was the smoothest car ive ever driven. I took it to my mechanic shop who is a well known dyno shop in melbourne. After getting it back its not smooth on and off the throttle, its got a little jerk. more noticeable when going realy slow but never the less noticable all the time. Its starting to give me the shits. I took it back to my mechanic and he said that theres nothing wrong with it, but i know what it was like before. so im stuck with it. Apparently the only thing they adjusted was the tps (throttle position switch). Does anyone know much about this switch and if it can be adjusted without hooking it up to a computer and where it is located?

Help anyone

Thanks

Stu

[QWK32]

i know exactly what you mean. i accidently did it once when i was working on my old 32. it feels like the accelerator is lagging, and then all of a sudden it kicks in. and yes, it is related to the TPS. i cant remember which way it is but its if the TPS's closed voltage is a bit too high or too low it will cause this.

the tps is on your throttle body just before the inlet plenum. it needs to be set to the correct voltage when the throttle is closed, 0.3-0.5v. if your any good with a multimeter you can fix it up yourself, otherwise i'd take it back and tell them to get it sorted.

[sturb25]

i know exactly what you mean. i accidently did it once when i was working on my old 32. it feels like the accelerator is lagging, and then all of a sudden it kicks in. and yes, it is related to the TPS. i cant remember which way it is but its if the TPS's closed voltage is a bit too high or too low it will cause this.

the tps is on your throttle body just before the inlet plenum. it needs to be set to the correct voltage when the throttle is closed, 0.3-0.5v. if your any good with a multimeter you can fix it up yourself, otherwise i'd take it back and tell them to get it sorted.

Thank you very much, it sounds as though your on the money. Another question is how do u adjust it? is there some sort of screw to adjust the voltage? What does it look like? the only thing i can see on the throttle body is a little black solonoid type thingy with about 6 wires coming out of it. Would that be it?

Thanks again

stu

Edited June 18, 2009 by sturb25

[QWK32]

best i can do for you at the moment, is this pic. the black part circled in red is the TPS. the yellow circle is one of two bolts you loosen to be able to adjust the TPS, the other bolt is at the bottom of the TPS, you'll have to remove the covers to see it. once these are loosened, you don't have to remove them, just loosen. you turn it clockwise/anti-clockwise to adjust the set voltage.

you need a multimeter, one probe goes to ground/-ve, and the other goes to the TPS variable output (without rooting though wiring diagrams to find it, or probing for it, i cant tell you exactly which one it is) either on the TPS itself or the TPS signal input on the ecu plug. at the TPS itself should be the easiest to probe. then just turn the TPS until you get the correct voltage. then do the bolts back up, and recheck the voltage is right and nothing has moved while tightening it up. also take note that you have to set the voltage with the throttle closed.

another way to do it without a multimeter is to hook it up to a laptop and use a consult interface and monitor the voltage through that while you set it.

i suppose if you don't want to stuff around with all this you could just loosen the bolts, slightly move the TPS in one direction, tighten it back up and go for a drive and see how it feels, if its worse turn it the other way. its not ideal and you would still want to get it checked properly but it may help make it more drivable until then.

Edited June 18, 2009 by QWK32

[sturb25]

best i can do for you at the moment, is this pic. the black part circled in red is the TPS. the yellow circle is one of two bolts you loosen to be able to adjust the TPS, the other bolt is at the bottom of the TPS, you'll have to remove the covers to see it. once these are loosened, you don't have to remove them, just loosen. you turn it clockwise/anti-clockwise to adjust the set voltage.

you need a multimeter, one probe goes to ground/-ve, and the other goes to the TPS variable output (without rooting though wiring diagrams to find it, or probing for it, i cant tell you exactly which one it is) either on the TPS itself or the TPS signal input on the ecu plug. at the TPS itself should be the easiest to probe. then just turn the TPS until you get the correct voltage. then do the bolts back up, and recheck the voltage is right and nothing has moved while tightening it up. also take note that you have to set the voltage with the throttle closed.

another way to do it without a multimeter is to hook it up to a laptop and use a consult interface and monitor the voltage through that while you set it.

i suppose if you don't want to stuff around with all this you could just loosen the bolts, slightly move the TPS in one direction, tighten it back up and go for a drive and see how it feels, if its worse turn it the other way. its not ideal and you would still want to get it checked properly but it may help make it more drivable until then.

Thanks again. will let you know if i have any dramas

[chef_stagea]

my autech does this too...

if u put the foot in to like half way in a high gear... like 4th at 60ks... and pull it back to a 1/4 of throttle it jolts like 2 or 3 times... if u rip the foot off it stops instantly... would this be the same prob?

why would the voltage change? just ware and tare?

[sturb25]

my autech does this too...

if u put the foot in to like half way in a high gear... like 4th at 60ks... and pull it back to a 1/4 of throttle it jolts like 2 or 3 times... if u rip the foot off it stops instantly... would this be the same prob?

why would the voltage change? just ware and tare?

sounds as though youve got a different problem, mines like a tiny jerk and it only does it when your on and off throttle all the time. hardly noticable but more noticable when your driving at 2-5km/h realy slow.

Hope that helps, but probably not!

[sturb25]

best i can do for you at the moment, is this pic. the black part circled in red is the TPS. the yellow circle is one of two bolts you loosen to be able to adjust the TPS, the other bolt is at the bottom of the TPS, you'll have to remove the covers to see it. once these are loosened, you don't have to remove them, just loosen. you turn it clockwise/anti-clockwise to adjust the set voltage.

you need a multimeter, one probe goes to ground/-ve, and the other goes to the TPS variable output (without rooting though wiring diagrams to find it, or probing for it, i cant tell you exactly which one it is) either on the TPS itself or the TPS signal input on the ecu plug. at the TPS itself should be the easiest to probe. then just turn the TPS until you get the correct voltage. then do the bolts back up, and recheck the voltage is right and nothing has moved while tightening it up. also take note that you have to set the voltage with the throttle closed.

another way to do it without a multimeter is to hook it up to a laptop and use a consult interface and monitor the voltage through that while you set it.

i suppose if you don't want to stuff around with all this you could just loosen the bolts, slightly move the TPS in one direction, tighten it back up and go for a drive and see how it feels, if its worse turn it the other way. its not ideal and you would still want to get it checked properly but it may help make it more drivable until then.

This is probably going to sound realy dumb but i want to get it right. when adjustinng the TPS u said to adjust it with the throttle fully closed. does this have to be done with the car running or ignition on. sorry it sounds pretty dumb but i dont want to stuff it up.

Thanks

Stuart

[QWK32]

engine doesn't have to be running but ignition has to be on, so the put the key in the ON position.

[sturb25]

engine doesn't have to be running but ignition has to be on, so the put the key in the ON position.

My TPS was reading 5.1 volts so i changed it to 3volts. tightened it up and rechecked. it read 2.9volts, went for a drive and it felt better but still not 100% so i tried 3.5volts. it seems to of improved quite substantialy but its rasied my idle to around 1500rpm. Is this normal? I adjusted my idle screw on the throttle body which lowered it to normal rate. Should i have adjusted that?

Stuart

[_Ryan_]

do you mind PMing me where you took it? i am thinking i might take mine somewhere to get adjusted but i need to know where not too go if that makes sense, not to pay out the workshop, but just i dont have heaps of money to waste paying to get jobs redone when they should be done right the first time.

[QWK32]

My TPS was reading 5.1 volts so i changed it to 3volts. tightened it up and rechecked. it read 2.9volts, went for a drive and it felt better but still not 100% so i tried 3.5volts. it seems to of improved quite substantialy but its rasied my idle to around 1500rpm. Is this normal? I adjusted my idle screw on the throttle body which lowered it to normal rate. Should i have adjusted that?

Stuart

no, i think you misread, it should be between 0.3 to 0.5v, not 3.5v. thats why you have an increased idle, because the TPS voltage is way to high. the TPS output scale is from 0-5v, setting it to 3.5v is like telling the ecu you have your foot 3/4 the way on the throttle, hense high idle.

Edited June 19, 2009 by QWK32

[RS4StagMan]

From the R34 Service manual;

TPS voltage (ignition switch on, engine not running)

accelerator pedal released approx 0.5Volts

accelerator pedal fully depressed approx 4.2Volts

TPS voltage (engine running at approx 2000 RPM)

approx 0.6-0.7 volts

[too_much_boost]

Its best to adjust the TPS when connected to Nissan Consult. You want the idle position to be below the point where the 'idle closed' switch is activated. You might get this right just by setting via voltages, but you might not

[Stagea_Neo]

Had same issue with my R31 a few years back, drove to Bundalong and back to Melb on one tank, best fuel economy i ever had, although it did shit me each time i lifted of the pedal at 100kmh.

Had to feather the pedal for a less annoying drive.

The old tps died a day or two before i left, so popped down the wreckers got another did a quick adjustment which was

not spot on, hence the annoying drive.

When i got back first thing did was start fixing, I just adjusted by feel / listening to the idle without the multimeter.

I found the adjustment is very sensitive, 1mm and its out.

Even when re-tightening the bolt you can chuck it out, so hold the tps firm when tightening the bolts.

From memory I rotated the the tps anti-clockwise to its full adjustment, then slowly rotated clockwise until it the rough idle disappeared and became smooth but a was a bit high at 900-950rpm.

Re-checked the timing and base idle (which was out 3deg retarded prior to this) and all was good back down at the base 700-750rpm, geez it felt damn good to drive after.

Maybe 60mins of work including test drives.

[sturb25]

no, i think you misread, it should be between 0.3 to 0.5v, not 3.5v. thats why you have an increased idle, because the TPS voltage is way to high. the TPS output scale is from 0-5v, setting it to 3.5v is like telling the ecu you have your foot 3/4 the way on the throttle, hense high idle.

Sorry i stuffed up my decimal points. i meant 0.35volts and its rasing the idle and it was set to start with at 0.51volts

Edited June 19, 2009 by sturb25

[wolverine]

anywhere between 0.3v and 0.5v should be fine

[Race__24]

Another thing that can cause similar symptoms it blocking the BOV. Causes a surge when you come off the throttle. Makes the car a bit clunky.

But in this case I think the guys are on the money.