WOT: how does one confirm wide open throttle?

rbogh901 · 07-11-2012, 10:49 AM

Where do you look to see the butterfly position to check? I've searched a bit and don't see it previously outlined. My Webers are easy, just look down the venturis and adjust linkage until vertical.

Any good links out there?

993Speedster · 07-11-2012, 11:38 AM

From what I understand, WOT ignition timing and fuel tables are activated once a little microswitch on the throttle body is activated. To make sure you are indeed hitting WOT, have a friend mash the gas and check to make sure it clicks when the pedal almost reaches the floor. Might also be a good time to clean that area and make sure nothing is gummed up and sticking.

TMc993 · 07-11-2012, 06:51 PM

993 Speedster: Are you from south of the Mason Dixon line?

LouZ · 07-12-2012, 05:36 AM

There's no butterfly that's easily visible. Look at the linkage on the T.B. and you will see a black microswitch at the lower end (electrical plug will be attached to it). From the engine bay (with the engine OFF), pull down on the linkage and see if and when it makes contact, it is supposed to be at 78% open.

To verify, pull the plug on the microswitch and hook up an Ohm meter, and see that it is actually closing the contact on actuation.

If the switch does not make contact, you will have to adjust the throttle cable at the pedal and/or in front of the tranny by pulling up the slack a bit.

993Speedster · 07-12-2012, 10:11 AM

Quote:

Originally Posted by TMc993

993 Speedster: Are you from south of the Mason Dixon line?

I'm not to great with geography, but I think so? Why you ask?
I'm in the NW Indiana/Chicago area. Car is from Los Angeles though...

rbogh901 · 07-12-2012, 07:22 PM

Quote:

Originally Posted by LouZ

There's no butterfly that's easily visible. Look at the linkage on the T.B. and you will see a black microswitch at the lower end (electrical plug will be attached to it). From the engine bay (with the engine OFF), pull down on the linkage and see if and when it makes contact, it is supposed to be at 78% open.

To verify, pull the plug on the microswitch and hook up an Ohm meter, and see that it is actually closing the contact on actuation.

If the switch does not make contact, you will have to adjust the throttle cable at the pedal and/or in front of the tranny by pulling up the slack a bit.

thanks Lou.

There is a switch on the side there and I seem to be activating on WOT but I should do a continuity check. Aren't there 3 blades there on the connector? Can someone say which is which?

LouZ · 07-13-2012, 04:54 AM

Here's the wiring diagram of the Idle and WOT switches.

rbogh901 · 01-23-2013, 11:13 AM

Does a Hammer/ scantool interrogate the wide open throttle switch?

Bill Verburg · Bill Verburg's Garage

Quote:

Originally Posted by rbogh901

Does a Hammer/ scantool interrogate the wide open throttle switch?

Mine does on my 993, it is found under the "Actual Values" menu and reads the current opening angle of the the throttle plate 0° is auto selected at idle and full throttle is 84° +/-3°

the 964 system is somewhat different but I'd guess that it reads similarly

cgfen · 01-25-2013, 05:39 PM

Quote:

Originally Posted by 993speedster

i'm not to great with geography, but i think so? Why you ask?
I'm in the nw indiana/chicago area..

lol

Hamptonsam · 01-26-2013, 12:10 AM

A Hammer (kts300) does as well as the scantool.

rbogh901 · 02-01-2013, 07:14 PM

Quote:

Originally Posted by 993Speedster

From what I understand, WOT ignition timing and fuel tables are activated once a little microswitch on the throttle body is activated. To make sure you are indeed hitting WOT, have a friend mash the gas and check to make sure it clicks when the pedal almost reaches the floor.

Yes it appears to activate. And scantool shows this in the right upper corner, with engine off, accelerator pinned to the floor. Does this confirm WOT switch function? Note that idle the "idle" appears correctly off in this screen capture.

LouZ · 02-02-2013, 03:35 PM

Quote:

Originally Posted by rbogh901

And scantool shows this in the right upper corner, with engine off, accelerator pinned to the floor.

It shows that it is working!

However, you state "pinned to the floor", as I posted earlier, it should kick in around 78%. Slowly depress the go-pedal, and watch when the scantool's WOT switches, then make sure that there is additional travel before it hits the floor.

rbogh901 · 06:47 PM

Quote:

Originally Posted by LouZ

Slowly depress the go-pedal, and watch when the scantool's WOT switches, then make sure that there is additional travel before it hits the floor.

Good idea. When the snow melts I'll see where the WOT switch activates, hopefully this week.

How do you interpret the MAF sensor and the O2 sensor readings here? I'm assuming the O2 sensor reading is meaningless as the engine is off but the MAF sensor should still be accurate representing a voltage from the MAF dependent on flap position, but I really don't know that. And technically, being a 964, it's not a MAF but and AFM, correct?

Anyway, an MAF voltage of .25 at WOT is what is reported here. What are normal MAF readings for a 964? Do I check MAF voltage at various throttle positions or just remove the AFM, clean it, and reinstall?

rbogh901 · 02-07-2013, 05:51 PM

Quote:

Originally Posted by LouZ

However, you state "pinned to the floor", as I posted earlier, it should kick in around 78%. Slowly depress the go-pedal, and watch when the scantool's WOT switches, then make sure that there is additional travel before it hits the floor.

In the name of furthering this topic should anyone in the future ever want to know, I did run scantool again this afternoon. Indeed, as per LouZ, the WOT switch activates before the throttle is fully pinned to the floor. I would estimate that it does so around 75-80% wide open, as advertised.