Cameron

Before I open it up to try, can you service the throttle position sensor, sometimes referred to as the WOT switch?

When I did my SharkTuning, I noticed that the switch would rarely but on occassion read 2 (cruise) in a 3 (WOT) situation. I am having a slight surging problem now and want to eliminate the WOT switch as a variable.

IcemanG17

Cameron
You can try to tighten the cable that moves the throttle body.....I also had a WOT fault....but tightening the cable fixed the problem!

jyoon

yes you can service it, check arnnworx.com for some detail

the flyin' scotsman

Adjusting the cables is, as Brian mentions, a surefire way to ensure the throttle plate is opening far enough to trigger the WOT switch. Starting with the most inner cable that is from the 'go' pedal work you way out to the throttle cable, the auto trans. kickdown and the cruise. Set the cables with zero slack or tension.........you'll know if your too tight on the TB cable as you'll increase the idle speed.

John Speake

The cables are critical for the closed throttle switch part to work properly - a nice microswitch that give a definite click when it swicthes either on or off.

I think Cameron is referring to the WOT part of this assembly, activated at approx 2/3 throttle open. It is not a very good design, just two flexible contacts that rub together - no reassuring click...

Cameron

The idle switch is working fine. I am concerned about the WOT functionality. Can I open this puppy up, check/clean the contacts and put it back together?

John Speake

Hi Cameron,
Yes I understand the problem 2-3 .....

You can get the cover off with care, always a risk of breaking little plastic lugs. But the contacts are get -atable -

Cameron

John,

Thanks. That pic is perfect. And I like that word: get -atable-

jyoon

some detail here: http://arnnworx.com/tps-repair.htm

i believe the 944 and 928 are the same part

Cameron

Update

I started leaning out according to AFR a couple of weeks ago. Never had I had that problem since I put in the SharkTuner tuned chip. Long story short:

- WOT switch was fine.
- I swapped MAFs with a known good one to eliminate that variable - thanks Sab.
- We suspected in tank fuel pump and were correct. Shop diagnosed it today based upon my recommendation to check there first.

What are the chances that the external pump has suffered stress and will fail shortly? I have heard that this can be an issue after the internal pump fails.

the flyin' scotsman

I recall reading that the external pump requires fuel for cooling from the internal pump...............without fuel the external pump gets too hot and expires; could save yourself a potential lot of grieve by replacing it.

Gretch

I over tightened my cables and my idle and WOT switch functions took a hiatus. Tweaked them a bit and viola, they are working again.......Takes some time to get it right.....why I do not know.

John Speake

Hi Cameron,
As you only had a "partial weak" condition at WOT, you may be lucky with the external pump.

However you might be safest to change both, especially as you are s/c

The pumps will fail very quickly if totally starved of fuel, even for a short time. I have known this to happen due to hard cornering with a tank low on fuel.

Under these conditions generally the main pump fails first.

As Malcolm says, the fuel cools and lubricates the expernal pump.