TPS Idle Switch

[Toysrme]

Past 4am, I tend to wander...
Notice that there is overlap between the minimum VTA throttle angle output, and when the IDL signal. This is for a reason. The basic premis of the IDL in the tps is to let the ECU know when the actual angle position (VTA) has reached an idle state. Over time it can varry, and slides out of adjustment.

[JetspeedCamry]

Well, i tested the TPS and it is completely within spec. The resistnace values are all spot on, and so are the continutity adjustments of the IDL switch in the TPS. So, i'd say that this problem isnt with the TPS malfunctoning...because its doing exactly what its supposed to.
What im after is a way to remove the fuel being dumped in at 0 throttle. With the engine now being bolted to a manual tranny, this fuelling causes the the motor to jolt. You can feel it quite easily....just by releasing the throttle slowly...at about 1% TPS, bang...the engine note gets louder and the motor jerks. I assumed this to be the IDL switch in the TPS.

American manual models came with a thing called a Dashpot. Maybe this has something to do with it? It seems to be bolted to the throttle..and is vacuum controlled.

[3sgte]

Yeah, my TB doesn't have anything like that on it. On the NT V6's with manual tranny, they have something called a "dashpot". Im not 100% sure what it does, but it attatches to the throttle in some way, and has a vacuum line or to connecting to it. Any idea what that is for? Its specific to only MT version in US.



Hehe, yeah, the last thing i want is to stuff something! So i think ill just leave it alone. There must be another way to fix this problem, and as stated, im doubting too that the idle switch is the problem.

The "dashpot" would be the vacuum diaphragm "thingy" that I mentioned to you.

I don't see any harm in trying an adjustment of the TPS, I did have one M/T that I needed to adjust the idle switch turn off earlier than spec to avoid a light throttle surge.

With the idle switch on, at above a specified RPM (say 1200), the EFI cuts fuel on deceleration for fuel economy and emission reasons. The EFI senses closed throttle via the IDL contact. If your very light power demand (light throttle) isn't sufficient to turn off the IDL switch, then the EFI thinks you are decelerating.

The AT ECM and the MT ECM likely have different control characteristics in this regard. One more thing you have noted in the quote above is that the MT version has the dashpot (used to control final few % of throttle closing).

If you don't have the dashpot, then I would try the TPS adjustment (IDL SW off sooner when opening throttle)

[JetspeedCamry]

^ Thanks for that info..makes it quite clear..and you seem to know the problem im having..."light throttle surge" as you put it is spot on.

Ill give the TPS adj. a go and see where it takes me. As i said, the TPS itself isnt "broken", its working fine, but for an auto trans.

[o_man_ra23]

Again I repeat that the powerchip should be able to compensate for this change to a good enough degree. Failing this, look into a similar motor which has the dashpot (maybe a 1JZ or a 3SFE or something would have this) and pinch the dashpot and install into your motor.

Cheers, Owen

[JetspeedCamry]

Well, the powerchip is an ignition computer. It advances/retards the ignition timing in steps through the RPM range. What would i be looking at doing to the map to "compensate"?

[Toysrme]

I think they're under the impression it was tuning fuel.