Surging Idle

[BrandonDouglas]

are you sure you checked the right wire?  were you using wiring diagrams?? maybe you read them backwards or something.  Check the other wires and you should find one with around .4-.7 volts with the throttle closed.  that will be your tps signal wire...  Unless that wire is shorted to the 5v refrence voltage... but if that happend im sure a CEL would come on...

I seem to remember checking every wire. But no we don't have a wiring diagram, if someone could post one that would be sweet!
I do get a CEL but its P0300 and I believe its different.


Update for a good portion of today it was idling at 2000rpm and going off throttle the wideband was still registering, but then later on it started idling normal again.

AAAAAAAAAAHHH I hate chasing gremlins

[BrandonDouglas]

So I did it again today, set it between continuity and non. Put key to full on with car not running.
All the pins were showing 0v

Took it for a test drive, car no longer idles high and I can feel the throttle actually closing this time when I go off throttle, so driveability has defintely increased.
Still got a 1000 to 1500rpm surge again though.

My biss and components arrive soon, as well as my FIAV seal (bypass plate arrived yesterday)
Why would the pins not register any voltage though? Do I have a faulty TPS?

[Brett Haviland]

did you confirm that your tester was working properly by checking it on the battery using the same ground u used to test the TPS.

[BrandonDouglas]

did you confirm that your tester was working properly by checking it on the battery using the same ground u used to test the TPS.

Yeah I checked it on the battery and I would get 11.7V.
I checked the plug pins and on 2 of those I would get about 4.5V, but none on the TPS

[BrandonDouglas]

I followed these steps:

1. Disconnect the connector of the TPS.
2. Connect ohm meter between terminals 3 and 4.
3. Insert a feeler gauge with thickness 0.45mm (.0177 in.) between the throttle stop and the throttle lever.
[Fold a piece of paper in half 4 times if you don't have the feeler -Ed.]
4. Loosen the TPS mounting bolts. Turn the TPS all the way counter
clockwise.
5. Check for continuity in this condition.
6. Slowly turn the TPS clockwise until the point where continuity and
non-continuity is found (pins 3 and 4). 
7. Tighten the TPS mounting bolts.
8. Check the voltage between pins 2 and 4 of the TPS with the ignition
switch on, but the engine not started.
9. Standard value: 400 - 1000 mV
10. Remove the feeler gauge.

Now, this might be a dumb question....but I was checking all the pins on the TPS with the plug unhooked, how would the TPS get any voltage anyways with the ignition on, but the plug undone?

[GlenMartin]

I followed these steps:

Now, this might be a dumb question....but I was checking all the pins on the TPS with the plug unhooked, how would the TPS get any voltage anyways with the ignition on, but the plug undone?

your not checking for voltage per say. your checking for resistance (correct me if i am wrong). my guess is your volt meter is not set to the right settings. 

[John Hartman]

resistance checking is useless in this setting unless you suspect your TPS is completely borked.

you need to run voltage thru it while you are testing for changing voltages.

you need to run small pins into the two wires at the connector so you can hook up a volt meter to the lines.

at closed throttle it should be near 0v and at full throttle it should be near 5v

Don't stab the wire, you can introduce other problems later.  Push the pins/thin metal rods into the back of the connectors, past the weather seals carefully so they contact the metal inside the connector.  Then these pins now act as points to hook your DVOM up to.

Key on, engine off, read the voltages.  SLOWLY move the throttle plate from closed to open and back.  If its glitchy in its movement,and this can be repeated, replace the TPS.  If its not close to 0 and close to 5 at the other end, replace it.  Set it according to VFAQ, but it should be about half a volt at idle.

[daniel Dee]

DSM ISC motor testing & Replacement
http://www.youtube.com/watch?v=KibYz21IMA0

ISC Check
http://www.youtube.com/watch?v=6t4-K69d3LE&feature=channel_video_title