R33 - Setting Throttle Position/closed Switch

[hardsteppa]

hey all

been having trouble with my s2 R33 gtst, idling low at around 550-700rpm and generally sounding a bit off.

Checked the throttle sensor readings on consult and when I set it to 0.4 volts closed throttle, the closed throttle switch shows as off (as in, reads as the throttle is open), and it also idles wayy too high, 1200-1600rpm. To get the closed throttle switch to show as on (throttle closed) i can only get the throttle sensor to read around 0.2 volts, and then it idles low/rough. Thought it might have been a faulty tps but have put a brand new one in, and has exactly the same issue.

This was happening ages back on and off but hadn't had it for a while, now is like it all the time.

I also noted when playing around with the tps adjustment (ignition on, engine off), when the throttle position sensor is turned between approx 1/3-2/3 open it makes something in the area underneath the intake manifold towards the rear of the engine start buzzing (like a solenoid clicking but heaps faster). It does not make this noise in first 1/3 or so of throttle opening, or when throttle is almost fully open.Not sure if this is normal, or related to the crappy idle issue?

I have searched on here and googled away on it but can't find the answer, only alot of posts about what voltage the tps should be reading at closed and full throttle....nothing really about the closed throttle switch readings or what might be causing the problems.

Open to ideas n suggestions about this, thanks!

Edited March 12, 2013 by hardsteppa

[Plattsy]

Yep I get the same issues.

[AGROV8D]

Did you try adjusting the idle via AAC once you've set the TPS?

[hardsteppa]

i haven't no, because I believe the issue is caused by something not switching right (as in, something that relies on the open/closed throttle switch that doesn't seem to be operating correctly). When my car wasn't having this issue it was idling perfectly so don't want to go adjusting the idle to compensate for an error, if that makes sense...

[AGROV8D]

i understand where you're coming from, went through a similar idle issue and as a result I can tell you that male pattern baldness is not hereditary, it's caused by troubleshooting Skyline idle issues.

My suggestion to you is, take out the AAC valve and give it a good clean with throttle body cleaner.

Clean the throttle body with... ahem… throttle body cleaner.

Set the TPS to 0.45V after you’ve cleaned it. Adjust it with a multimeter connected to the TPS directly.

Take out the MAF and resolder the connector pins.

Check all the hoses to and from the intake manifold for air leaks.

Once you’ve done all of the above, reset the ECU and reset/adjust the idle.

If you're still having issues, compare the readings you’re getting directly from the sensors against the consult readout for any variances.

[hardsteppa]

thank you for your suggestions, I do appreciate it. All of the above have previously been done apart from using a multimeter to set the tps, I did that via consult. As mentioned in the original post I can see on EcuTalk (consult) gauges that the open/closed throttle switch is not reading right, and showing as open, even though the throttle is closed, whenever I try to set the TPS to 0.45 volts. This to me would seem to be the issue, the ecu sees that the throttle is open and so would not be controlling idle like it would do with a closed throttle. That's what I'm trying to figure out, why it's doing that. Will clean the throttle body again on the weekend, throttle plate might be sticking open slightly? although doubtful, it seemed pretty securely closed when checked it previously

[Plattsy]

yep. my thinking is the tps is knackered. there are two seperate parts too it inside. one for the voltage and one for the throttle closed. if i turn my voltage above .02 on ignition the throttle shows as open.....

ive just had my emanage tuned and that seems to have got around the problem. the tuner said something about tricking it into thinking its working.

still id try swapping out the tps. see how that goes.

[hardsteppa]

so, progress of sorts I guess...turns out I have been chasing a ghost with this throttle on/off switch. After playing round with it more last night, set the throttle to 0.48v when closed, still wasn't reading as "closed" though. Unplugged tps, revved, plugged back in, and now showed as throttle closed, and reading 0.48v still. Sweet. Still have an idle issue though, runs ok then slowly idles lower/shitter 'till sputtering away at 550rpm. AAC, afm readings were all in spec as per nissan workshop manual; did notice though that the 02 voltage goes down to 0.2v and sits there very evenly when it did this though, which I believe shows it running lean? Plugs are all very evenly colored so don't think it's any one injector playing up, and they were all reco'd less than 3000k's ago. So thinking it is either blocked fuel filter causing flow to drop at idle, or faulty fuel reg....Any thoughts?

[Plattsy]

as you idle speed is droping is your aac % dropping too? could be that your screw is in too far if thats the case.

[scotty nm35]

How is the BOV return plumbed? Is everything stock including the intake?

[hardsteppa]

BOV is plumbed back into intake, not atmo. Stock ecu but usual, fmic, exhaust, cam gear, custom metal pipe/pod intake. Have pressure tested in the past and no leaking under boost.

Thinking more about regulator may be stuffed, as Tomei fuel pump which used to make a higher pitched sound when priming sounds a little lower (working against less pressure?) Have ordered a fuel pressure gauge so will fit that and see what is. New fuel filter didn't make any difference.

[hardsteppa]

still waiting for fuel pressure gauge to arrive but crimped the fuel return hose last night to increase pressure, and idle picked up back to normal sort of level...so would say fuel regulator not holding pressure properly, anything else this could be?

[kosmo90]

Im having exactly the same problem, .2 closed anything above is open.

Ordered a new TPS but that didnt look like it was your problem hardsteppa?

I've tried unplugging but that didnt do the trick, see what the new one does i guess.