TPS testing results - bad?

[mallard ducks]

Hi, anybody that can help, I'd sure appreciate it!

I've followed the test values at the TPS given in Clark's:

"The 16V N/A cars use the same TPS as the early cars."

"Idle speed contact. With the throttle closed, the ohmmeter should read 0 - 10 ohms. With the throttle open, the ohmmeter should read infinite (∞). The switch in resistance must occur as soon as the throttle starts to open (approximately 1°). "

>My switch tests good for the idle speed contact.

"Wide open throttle (WOT) contact. With the throttle closed, the ohmmeter should read infinite (∞). With the throttle approximately 2/3 open, the ohmmeter should read zero (0) ohms. "

>My switch does not change over to 0 ohms until the throttle is virtually full open

Is this an issue/does it indicate a bad TPS or a misadjusted TPS? I positioned it so it clicks immediately upon moving off the throttle stop and on the way back clicks just before it hits the throttle stop.

The problem I'm chasing WAS a high and cycling idle: always cycling between 1,000 and 1,100 rpm hot or cold.

All my vacuum lines, hoses, intake boots have been changed out and I resealed my throttle body (again) last weekend.

So NOW the problem has changed to a steady but high idle:

Car idles at a steady 1,000 rpm on cold start-up, but as the engine warms-up the idle goes to a steady 1,100 rpm. So cold I'm steady at 1,000 rpm with no cycling; and warm I'm steady at 1,100 with no cycling.

???

[Outback Porsche]

Your TPS is Good, according to the workshop manual.

Pin 2 to Ground - throttle closed: 0 Ohm, throttle open: infinite Ohms. Switching must take place when throttle is slightly open (1 Deg). Pin 3 to Ground - Throttle closed: infinite Ohms, Throttle wide open: 0 Ohm. Switching must take place immediately before full throttle.

There's a good chance you've fixed your vac leak and all that needs to be done is an idle adjustment. I think clarks has a procedure for this if you don't have the workshop manual.

Cheers

[mallard ducks]

thx. no idle adjustment screw on "S" throttle bodies.

I'm resigned to my fate. At least the idle doesn't cycle anymore.

[bearone2]

the tps is mis adjusted.
you should be able to hold the throttle cam and barely moving it should hear a "click"(the 1 deg)which isn't happening until wot.

loosen the screws and adjust the tps until the values are correct.

throttle closed should be "0", anything beyond the 1 deg should be infinity on the ohm scale, hope you're using a decent meter.

[mallard ducks]

thanks.

The TPS is adjusted so that it clicks as soon as you move the cam so that it's just off the throttle stop, and on the way back it clicks just before it hits the throttle stop

The idle speed contact test is good: throttle closed = 0 ohms, as soon as it opens/clicks = infinite.

The wide open throttle contact test is not quite right according to Clark's: it doesn't change from infinite to zero until the throttle is almost all the way open (according to Clark's the change should come at about 2/3 open)

But Outback Porsche has the test specs from the Workshop Manual which says that this is actually okay.

[marky522]

Originally Posted by bearone2

the tps is mis adjusted.
you should be able to hold the throttle cam and barely moving it should hear a "click"(the 1 deg)which isn't happening until wot.

loosen the screws and adjust the tps until the values are correct.

throttle closed should be "0", anything beyond the 1 deg should be infinity on the ohm scale, hope you're using a decent meter.

There are two switches in the N/A TPS an idle switch and a WOT switch, both of which are working fine by his diagnosis. Any meter should be able to test reistance like this.

Mark

[marky522]

To further diagnose i would smoke the intake, but i doubt you have access to a smoke machine? You would be surprised where a vac leak can be, a higher idle would indicate a vac leak, I would double and triple check vac leaks before adjusting your idle.

Mark

[mallard ducks]

thx Mark

For maintenance purposes I've replaced all hoses, boots, o-rings from under the intake manifold, AFM, throttle body, AOS, dipstick tube, fuel injectors, etc. and there has never been any effect on the cycling/idle speed except for the throttle body reseal, which eliminated the cycling between 1,000 and 1,100rpm at idle.

No smoke machine in my cupboard so can't do a smoke test immediately. I remember reading a past thread about taking ISVs apart to replace an o-ring that after 20+ years of service is more than likely shot. That's something I haven't done.

This is getting ahead of myself, but if the issue is a vacuum leak and that's where it's coming from and I wreck the tabs that secure the ISV housing trying to get at the o-ring - I'll be so PO'd... these things cost something like $370(!!!) for the 16Vs. That is just so outrageous.

Don't want to sound like I'm going to skip a troubleshooting step, but does anyone know of anything independent of vacuum leaks that would cause a high idle condition? Specifically, cold idle = steady 1,000 rpm; hot idle = steady 1,100rpm

[Tcrate]

So I am not having the exact same problem. Does anyone know what the solution was. I have replaced vacuum hoses and run a smoke test so onto the TPS and the ICV. Thanks.