unstable idlling-stalling im going nuts

[Ensoniq5]

Leadfoot6, you're missing my point. The idle switch MUST switch on precisely at the point that the throttle valve completely closes. Moving the TPS may mean the idle switch triggers before the throttle valve is fully closed (if the TPS is rotated one way), or the valve will close before the idle switch triggers so the ECU never switches to idle mode (if the TPS is rotated the other way). The TPS cannot be adjusted without affecting the idle switch trigger point, as they are integrated.

[leadfoot6]

Leadfoot6, you're missing my point. The idle switch MUST switch on precisely at the point that the throttle valve completely closes. Moving the TPS may mean the idle switch triggers before the throttle valve is fully closed (if the TPS is rotated one way), or the valve will close before the idle switch triggers so the ECU never switches to idle mode (if the TPS is rotated the other way). The TPS cannot be adjusted without affecting the idle switch trigger point, as they are integrated.

I did not miss your point, as you have suggested.

My comprehension skills are reasonably well developed.

Rather, I disagree with your point.

Today, after doing some further internet research and finding a few websites that treat this matter(which admittedly are few and far between that deal with 4 wire TPS) , I contacted via telephone(and subsequent email) a trusted transmission workshop.

The workshop concerned is DS Jones, which I referred to above.

It is now owned by a tradesman who was a senior apprentice at that business when I made reference to the episode I referred to in post #34 above.

I should have more to say about this shortly, depending on how long it takes for the workshop to reply.

Stay tuned.

[Ensoniq5]

Stay tuned.

No problem, staying tuned. I would be very interested to know how to adjust the throttle position sensor on a 3rd Gen Magna without affecting the integrated idle switch.

[leadfoot6]

Stay tuned.

I am interested in the process of adjusting these sensors for best idling.

No problem, staying tuned. I would be very interested to know how to adjust the throttle position sensor on a 3rd Gen Magna without affecting the integrated idle switch.

Below is a full text copy of the email that I sent to the current proprietor, Graeme, of D.S. Jones Automatics on Wednesday 04 December 2019:

The Proprietor

DS Jones Automatics

Anvil St

Seven Hills NSW 2147


Dear Graeme(please forgive me if I have got the spelling wrong),

Thank you for taking the time earlier today to discuss via telephone the basic functioning and adjustments of Throttle Position Sensors.

Would it be possible for you to, very briefly, review the discussions on the internet that I will link to below prepared primarily by owners of Lexus 6(SC300 Supra type) and 8(LS400 type) cylinder vehicles manufactured mainly between 1990-2005 and using a 4 wire TPS?


https://www.youtube.com/watch?v=n3-DfW2ouGA


https://www.clublexus.com/forums/per...hifting-2.html


https://www.lexls.com/tutorials/EFI/tps.html

They are discussing primarily the possibility of adjusting cars with 4 wire equipped TPS in order to reset the correct settings after replacing a faulty TPS, or wishing to alter the shift patterns to make operation of the automatic transmissions more positive.

Most of the comments made are that it is possible to adjust the TPS without necessarily using feeler gauges to do a "final" adjustment, and carrying out small adjustments to the TPS without suffering any adverse effects or having an error code registered.

Also, these discussions note that the "idle" speeds do not become objectionable or present problems.

They may not necessarily be exactly what is specified in official workshop manuals, but a small variance after making adjustments to the TPS seems to be OK.

Some people suggest that an error code will register in vehicles equipped with a similar 4 wire TPS setup if the "feeler gauge" method is not strictly adhered to.

Your comments about the need to strictly adhere to such a procedure would be appreciated.

In our telephone conversation earlier today I described the very positive outcome achieved 10 years ago by the former owner of your business, Dave Jones, in adjusting 3 wire TPS equipped vehicles(1990 Nissan Skyline and TR Magna).

You also suggested that such a procedure is still an option on later 4 wire TPS vehicles, and that in the case of later Mitsubishi Magna vehicles, minor adjustments to TPS settings can be made by your workshop using a scan tool to improve the shift function.

You also relayed to me the very reasonable cost that a customer would pay to have this procedure carried out by your workshop.

I will not repeat this figure online so that you can quote on an individual basis.

Once again, I appreciate the time that you have taken to discuss this matter with me, and I want to repeat to you my assurance that all dealings that either myself, my brother and my friends that have used your workshop are always positive, and I hope that I can refer more customers to you.

I look forward to receiving brief comments from you about these matters when convenient for you.

Kind regards,

John Giles.

This afternoon, Thursday, I made a telephone call to establish if he was still able to provide a suitable written reply.

Graeme told me that he did receive my email and is more than happy to provide a detailed written reply when time pressure allows a fully researched reply.

I do know how busy that workshop is, from past use of it by my brother(just a few years ago having a full rebuild done on his Jeep Cherokee auto transmission), and myself when I used to live nearby in Northmead in Sydney.

I asked him if he could provide me with some brief comments in the interim, and said that, in essence, it is possible to adjust the TPS on late model Mitsubishi Magnas without the problem of upsetting the idle suggested by AMC member "Ensoniq5".

He did point out that the range of motion through which the TPS can be adjusted on later 4 wire systems is less than that on earlier 3 wire systems, but that adjustment AWAY FROM THE MANDATED FACTORY SETTING OF THE "FIXED" TPS POSITION IS POSSIBLE, TO OVERCOME AGE AND WEAR.

He also indicated that I have presented him with a thought provoking exercise and that he looks forward to completing a suitable written reply when he has time.

I did not press him to commit to a time.

That is the best I can do for the present, other than to point to the sources relating to Lexus 4 wire sensors which I linked to above, and which I asked him to comment on when able.

I will just have to wait for his reply.