I have a '94 TS Magna 2.6L fuel injected. I have been having idle problems and in the process I have fiddled with the idle speed screw. I have ordered a new ISC on ebay (cause the old one tests bad coils - although it was OK initially), and I believe that the ISC will try to compensate for a wrongly set idle speed screw.

Does anyone know how to do the initial adjustment for the idle speed screw? I recall seeing some instructions on the net somewhere, but I can't find it.

Hi Mate,


I did my adjustment as it was off quite alot.
My TR was idling too low- it was dropping down to 500RPM and stalling quite often when in drive gear).

Idle speed screw is found in part of the throttle body assembly, close to the TPS (Throttle position sensor)

I set mine at between 750-800RPM approx in drive gear.
To do this i had the car in Park and turned the idle screw until it was sitting at approx 1100-1200 RPM. When i then jump back in the car and change to D (drive gear) it dropped down to about 800 RPM. You may need to adjust it a couple of times to get it right on the RPM.

A warning in that you dont want to set the idle too high or too low. To my suprize i found that the idle shaking when sitting at traffic lights etc.. was reduced a bit (it was really getting annoying hearing the dashboard of my TR shaking & vibrating)

When you turn the idle screw clockwise it reduces idle and when turned anti-clockwise it increases the idle speed.

Before you do this it is worth checking that the electrical connections to the TPS (Throttle Position Sensor) is not clogged or dirty (Ii found my TPS connector was full of chalky green stuff as adjusting the idle screw at the time did not solve my issue.

I hope this helps.

Im sure you can find some more posts on here on the subject if still unsure (i found the posts on this here when i had idle issues)

Cheers

Is there a way to set the initial adjustment? I think i may have turned the wrong screw to adjust idle speed, since it now idles in gear at about 500 after I had the battery disconnected. Its higher when cold, and is about 800 in N at the traffic lights. Never stalls, but the shakes annoy me...

that could be the idle speed controller relearning to idle the car... give it a couple of days driving aroung it will come good.
dont touch the idle screw.

I am not sure if we are talking about the same screw. The one I adjusted is at the end of the throttle cable. It is basically a stopper that prevents the idle from going too low. Turning it clockwise increases the idle speed.


Hi Mate,


I did my adjustment as it was off quite alot.
My TR was idling too low- it was dropping down to 500RPM and stalling quite often when in drive gear).

Idle speed screw is found in part of the throttle body assembly, close to the TPS (Throttle position sensor)

I set mine at between 750-800RPM approx in drive gear.
To do this i had the car in Park and turned the idle screw until it was sitting at approx 1100-1200 RPM. When i then jump back in the car and change to D (drive gear) it dropped down to about 800 RPM. You may need to adjust it a couple of times to get it right on the RPM.

A warning in that you dont want to set the idle too high or too low. To my suprize i found that the idle shaking when sitting at traffic lights etc.. was reduced a bit (it was really getting annoying hearing the dashboard of my TR shaking & vibrating)

When you turn the idle screw clockwise it reduces idle and when turned anti-clockwise it increases the idle speed.

Before you do this it is worth checking that the electrical connections to the TPS (Throttle Position Sensor) is not clogged or dirty (Ii found my TPS connector was full of chalky green stuff as adjusting the idle screw at the time did not solve my issue.

I hope this helps.

Im sure you can find some more posts on here on the subject if still unsure (i found the posts on this here when i had idle issues)

Cheers

Time for you to read the manual, or perhaps research here how the ISC and ECU work together. If working properly the hot idle should not vary more than 200 rpm at any time, from a base of 800 (and then only briefly) neutral to drive, lights on/off, aircon on/off. Cold start should give you 1,200 approx and settle down to normal idle within a minute or 2. Fiddling with the 2 screws will do very little if the ISC is stuffed.

I have no idea which screw i adjusted, it was when I first had the car, and it has a nut on it to prevent it turning. e.g. wind nut up, adjust screw, wind nut down to lock.

Thats the throttle stopper screw. It is set at the factory. Its job is to stop the throttle plate from binding on the throttle body bore when the throttle is closed. It only needs adjusting when the throttle plate binds on the throttle bore, which it can do with age. It should not be used to set idle speed, that is the job of the ISC, cold air bypass and ECU. Its all in the manual. Try reading it. Its not like a carby engine where you can fiddle and by luck hit a combination that works for you. Muck around with that screw and the ISC/ECU will go mental trying to get a stable idle speed.

I have a '94 TS Magna 2.6L fuel injected. I have been having idle problems and in the process I have fiddled with the idle speed screw. I have ordered a new ISC on ebay (cause the old one tests bad coils - although it was OK initially), and I believe that the ISC will try to compensate for a wrongly set idle speed screw.

Does anyone know how to do the initial adjustment for the idle speed screw? I recall seeing some instructions on the net somewhere, but I can't find it.


Get the new ISC in first. Idle rpm should settle after a while.

I don't have a manual. How should the screw be adjusted so that the throttle plate is not binding on the throttle bore. Can you see the throttle plate when the air cleaner hose is removed? Can you feel if it is sticking?

Thats the throttle stopper screw. It is set at the factory. Its job is to stop the throttle plate from binding on the throttle body bore when the throttle is closed. It only needs adjusting when the throttle plate binds on the throttle bore, which it can do with age. It should not be used to set idle speed, that is the job of the ISC, cold air bypass and ECU. Its all in the manual. Try reading it. Its not like a carby engine where you can fiddle and by luck hit a combination that works for you. Muck around with that screw and the ISC/ECU will go mental trying to get a stable idle speed.

If its sticking you can feel it by moving the throttle lever on the engine by hand. The main symptom is that you push the throttle pedal with your foot, and it doesn't move. You then push harder and the engine suddenly revs up too high. Makes the car hard to drive if it is a manual gearbox. lol The workshop manual is readily available on this forum, have a search.

If you fiddled with it back the screw off until the throttle plate binds, then screw it in a quarter of a turn, and lock it with the nut. My TS had the screw completely missing when I first got the car, and the ISC was stuffed. Previous owner obviously "fiddled" with it.

If you fiddled with it back the screw off until the throttle plate binds, then screw it in a quarter of a turn, and lock it with the nut. My TS had the screw completely missing when I first got the car, and the ISC was stuffed. Previous owner obviously "fiddled" with it.

Don't you just like it when people just fiddle and THEN decide to come out to report a problem. lol There's an old post (2006) from Madmagna on TB maintenance and the oinline manuals also help to diagnose the various bits of the TB. If all else fails, take it to a mechanic who knows.

I guess there is nothing wrong with fiddling, as long as you keep at it, and reseach the problem, to the point where the problem is fixed. That's how you learn. I just hate it when people fiddle, make things worse, then walk away. lol

Cheers for the help Madmax. I have posted on this forum before in trying to sort out my idle issues, and what I have done is as a result of replies to those posts. Not every little problem requires a mechanic, but often a bit of helpful advice can resolve a problem easily (like testing and swapping an ISC).

I think I have the idle screw set correctly. Thanks.

Have a hunt around the site, I don't have the link but there is a 1312 approx page factory manual in .pdf format that is about a 40mb download and it leaves a Gregory's or Haynes $50 manual for dead
Maybe someone here could post the link ?

http://www.lisho.net/?page_id=3

Thanks a million!

I got the new ISC installed and that has fixed my idle problems. Thanks everyone for your contributions.