alanz123

Thanks John, I will look for any slack. Any suggestions how much of slack there should be on the throttle cable?

John Speake

I am just suggesting you slacken enought ot see if the switch will operate with an audible click.

Final adjustment of the cable comes later once you have identified the issue

alanz123

John - slacking of the cable did not do anything. I am lost here. Also, there seems to be like a humming noise now coming from within my dash only when the car is idleing and when driving. Any thoughts?

cobalt

The Hammer he is using is mine and I had a chance to look at the throttle cables with Alan the other day. I would have to agree it does not appear to be the issue.

John,

I tired using the link you have posted and I get an operation failure notice. If you could PM me with your contact info and or PM me with the cost of the updated module and new battery pack I would appreciate it.

Thanks

John Speake

Hi Anthony
Very good of you to loan Alan your Hammer :-)

The link in my signature seems to be working OK.... PM sent...
Regards

John

John Speake

No -click is mechanical failure. Looks like a plenum off job.... :-(

WallyP

The humming in the dash is usually one of two things:
- The 1" black/blue vacuum check valve located on the brake booster is humming. This is usually due to vacuum leaks in the HVAC vacuum actuators in the dash.
- The small interior temp sensor fan, located behind the small grille on the dash, is humming.

alanz123

Thanks for your input Wally. Will check it out.

I am sending the car off for more diagnostic work next week. I will advise.....

Earl Gillstrom

Alan,

You have TWO threads open for the same problem. If you are not going to respond to the other thread, CLOSE IT.

John Speake: Apparantly there are two styles of the idle switch. The old ones may "click". The new ones do not "click".
The one in my '91 GT does not click. Also, The brand new one that I have in stock does not click.

John Speake

Hi Earl
THat's very interesting, although probably Alan's switch is an old original one.

If someone has changed it recently, then of course they may never have set it up correctly when bolting to the intake on the slotted adjusters.

I haven't seen/heard a silent idle switch yet, but will check out the next one I have here. I sell them regularly, but don't usually take them out of the box and play with them.

alanz123

My switch is brand new and I recently replaced it. I just basically installed it in the same position the original one was. If it needed proper adjustment, I did not do this. Is there a procedure on how this should be done properly?

John Speake

The switch has slots in its mounting lugs. It should be fitted so that as soon as the throttle plate starts to open, the idle contact opens, and when the throttle plate closes, it reliably closes (short circuit).

If the switch never closes, or opens too late then you adjust the rotaion relative to the throttle plate using the slots

Usually in the past it has been easy to listen for the click as the microswitch opened and closed, now it appears you may need to use a meter.

alanz123

I have two brand new TPS switches. And I tell you they are very silent and rotate with the greatest ease. I do not know about the old ones, but these are very silent. However, with the unit(s) in my hand, once I rotate it, you can hear a very tiny click.

My qustion is this, with the unit out, How can I test it via a meter to make sure it is ok? On the unit there are pins labeled "3" "18" "2".

Thanks.

alanz123

On the TPS - What is the correct part number for my 1991 928 S4 (The porsche part is: 928.606.157.00)

0 280 120 320

or

0 280 120 322

Anyone know?

alanz123

UPDATE:

I got a new BOSCH TPS (0 280 120 322) and am now getting the following readings on the switch:

on the Switch Pins 2 & 18
No Throttle - 0.5 OHMS
Throttle - 0.L

on the Switch Pins 3 & 18
Rest/Idle (No Throttle) - 0.L OHMS
3/4 Open and then all the way open - 000.5 OHMS

I believe this is the way it should be now.