How important are TPS fine adjustments

[trd_st184]

Hi all,
This probably looks like quite a general question but i'm really curious how these variables below for adjusting TPS on a 4age effect the motor.

For example the chart below states that with the Throttle fully open, the resistence between VTA and E2 should be between 3.3kΩ and 10kΩ

There is 6.7kΩ between those 2 values, i'm wondering how the car would respond differently on WOT if the resistence was 4kΩ as a pose to 9kΩ? I have a feeling the ecu is designed to be able to read between 3.3kΩ and 10kΩ.

I just did the TPS adjustments for the first time on my 4age 16v, and got all measurements within spec as per below, except for the measurement with .35mm clearance which states I should have less than 2.3kΩ. In my example I got 0Ω, which I would have thought was correct but I was expecting a value above 0 and below 2.3kΩ.

[jondee86]

IDL > E2 is effectively an open or closed switch. It should have low resistance when closed (zero is good) and infinite resistance when open. The factory ECU has a lot of tolerance built-in to allow for "creep" in the values due to deterioration of components and wiring, connectors etc over time.

As it happens I was also taking measurements yesterday. Here are the resistance values (from full closed to full open in kOhms) that I pulled off a spare throttle body with my $10 analogue multimeter...

E2 > IDL Zero to infinity (sudden change)
E2 > VTA 0.75 to 3.8 sweep
E2 > VCC 4.2 constant
IDL > VTA 0.75 to infinity (sudden change)
IDL > VCC 4.2 to infinity (sudden change)
VTA > VCC 1.0 to 3.9 sweep

Cheers... jondee86

[trd_st184]

Thanks for the help mate
Its interesting that since doing the adjustments within spec, the engine response seems more flat, in a bad way. Seems like there are more flat zones which I am attributing to the TPS adjustment. Maybe I might have to try adjusting it again. Strange though as all my values were within spec after adjusting.

[dumbass]

Those specs are to see if tps is working ok and not connected
To properly test a tps u need it connected to ecu and power to be on and then find the voltage specs for it

[trd_st184]

Those specs are to see if tps is working ok and not connected
To properly test a tps u need it connected to ecu and power to be on and then find the voltage specs for it

I couldn't see any notes in the workshop manual to describe testing the TPS with it connected and power to be on. Do you know of any good resources that may describe the testing method?

Thanks for your input

The motor feels like its been down on power, and it bucks at 1/4 throttle or so. Strange thing is that my TPS resistence settings were all in spec after adjusting it

[DX20VT]

From my experience the TPS voltage itself does not matter than much on the early 16V 4AGE's.

What does matter is the idle contact which is required for idle speed control and also must work to correctly set ign timing,

and the the voltage changes smoothly when opened as the ECU uses rate of change more than actual voltage for acceleration enrichment.

At WOT it should in theory make next to no difference.

[timbosaurus]

I had an issue on my 20v that I guess u could describe as bucking. Steady throttle out very light throttle would violently hesitate and jerk. Measured all sensors (including tps) to be within spec. Completed head rebuild, rebuilt injectors, checked a million times for air leaks. Replaced AFM and 02 sensor.

Through desperation, I fitted a wideband 02 to see what the mixtures were d, and it turned out they were going fully lean whenever it was jerky.... Like it was going into deceleration fuel cut when it shouldn't be.

So I tweaked the tps fully in one direction, and problem is solved. So it obviously can have an impact on a 20v.

[jondee86]

The setting of the TPS is critical to a smooth off-idle transition, as the IDL switch on the TPS tells the ECU when the engine should be operating on the IDLE map or on the RUN map. At very low throttle openings on the 20V, if the TPS is not adjusted correctly, the IDL switch can be hovering on the changeover point, so that the ECU is switching between maps.

On the 20V the ISCV passes all the idle air when the throttles are closed. So if the ISCV changes position when the IDL switch opens/closes, you could get substantial changes in the amount of air entering the engine, and this would give you lean spikes. My 16V runs 20V ITB's and ISCV on aftermarket management, and I know that just cracking the throttle open a fraction when the engine is idling, gives a big lean spike.

Cheers... jondee86

[masterofsinanju]

I think I need to adjust the TPS on my 1g and came across the video below

http://www.youtube.com/watch?v=k7jS1y70S98

I thought it was a fair explanation for the 4age but was wondering if it is the same procedure for a 1g. Does anyone know?

[Suavemechanic]

dumb question but have you adjusted the cable ? are you getting full throttle when your foot is flat to the floor ( you need a helper and a torch ) and a tiny bit of free play at idle ?
and maybe give the connectors a clean ,sounds like somethings not right.....
cheers

[masterofsinanju]

There is some play (more than a tiny bit) in the cable and I do get full throttle.

it is more about the transition from idle to gentle throttle is quite abrupt/jerky that made me think the TPS might need adjusting.

[CrUZida]

The IDL-E2 contact is really the only important one.

Make sure the throttle plate is closed 100% properly (ensure its completely clean and completely closed).
Set the IDL-E2 changeover to occur as soon as the throttle plate opens.

As for the rest, as long as they are close to spec its ok.
If the car is jerky at very light throttle cruising (ie, 50kph), then you have the IDL-E2 changeover set too close to closed throttle, and it will need some tweaking

[masterofsinanju]

Thanks CrUZida. You've given me something concrete to check.

[wiso]

The IDL-E2 contact is really the only important .

Make sure the throttle plate is closed 100% properly (ensure its completely clean and completely closed).
Set the IDL-E2 changeover to occur as soon as the throttle plate opens.

As for the rest, as long as they are close to spec its ok.
If the car is jerky at very light throttle cruising (ie, 50kph), then you have the IDL-E2 changeover set too close to closed throttle, and it will need some tweaking

Sorry to dig up an old thread but I am having some serious trouble on this topic.

On light throttle at sydney traffic crawling speeds the engine violently jumps kicks and bucks. Very hard and punishing to drive. Also at 3000-4200 I have a big hesitant spot. Where while accelerating it feels like its kicking in and out. It is also using a fair amount of fuel for a stock 4age just rebuilt. About 10L/100km

I have been playing with the tps but no matter what I do I cannot get rid of this jerkyness. All settings I am easily getting in spec with the new TPS.

The bgb says at .35mm its less than 2.3kohm. Mine is ~80ohms. And at 0.59mm it shows open. Cruzida above is saying the change from a reading to open should occur as soon as the throttle open. Should I try setting the change over closer to stop than 0.59? Or should I make the stop larger? I have tried a stop changeover at 0.63mm and it drives smoother on low speed but feels really flat still at mid revs.

I have un plugged the TPS to try and the revs increase by 300rpm and it runs sooo bloody smooth. Revs free and easy. Cruising has no jerking and no hesitation at 3000+rpm.

So has anyone got any advise on setting the tps e2-idle for changeover or should I just ditch it? Does this sound like normal operation when the TPS is disconnected?

Sorr about the novel hope someone can help. Its not fun to drive like this.

[jondee86]

The setting of the TPS gives you the two feeler gauge sizes to use. The IDL switch should definitely be closed when the throttle opening is less than 0.35 and definitely be open when the opening is more than 0.59mm. That means the changeover point should be somewhere between those two values.

The throttle arm should hit the throttle stop just the tiniest fraction before the throttle butterfly bottoms out in the throttlebody.

When crawling in city traffic, the throttle is barely cracked open, and if that happens to put the throttle opening at around the changeover point of the TPS IDL switch, then jerking will occur. Try setting the TPS changeover point close to 0.35 and see if it makes a difference. And make sure your warm idle is around 850 rpm.

Cheers... jondee86