TPS failure

[secondchance]

About 2 weeks ago my Z started to miss badly around 2500 to 3200 rpm. Since I Threw in a set of old FR2LS plugs after the the rebuild, I replaced plugs with NGK Laser iridiums. That had no effect. So, I tried another MAP sensor I had - still no fix. So, I was figuring either bad coil/coils or secondary fuel pump. However, I noticed miss was occurring immediately after cold start before being fully warmed up - may be not a fuel pump issue... What was interesting was that the miss would star exactly at same rpm range - between 2500 to 3200 rpm. This led me to suspect flat spot on the TPS sensor. Replaced it and sure enough, she runs fine!
I will confirm this later when I can hook up Jim's Tech 1 but I suspect voltage reading will start at .54 volts and as accelerator pedal is depressed progressively, voltage increase would drop or go to zero and then pick back up.
Thought I would share this other Z owners for future reference.

[Arctic91]

So, I guess you won't be keeping that old TPS on the shelf as a spare after all.

Scott

[secondchance]

Originally Posted by Arctic91

So, I guess you won't be keeping that old TPS on the shelf as a spare after all.

Scott

Jim and I am going to hook it up and check what happens to voltage as the gas pedal is depressed progressively with Tech 1 hooked up. This should teach us what to look for with Tech 1 when diagnosing a car with stumbling issue to verify TPS functionality.

[XfireZ51]

When you replaced the TPS, did u adjust it to .53-.57v w key ON?

[secondchance]

Originally Posted by XfireZ51

When you replaced the TPS, did u adjust it to .53-.57v w key ON?

Yes. .54 volts.

[Scrrem]

You will have to show me sometime how you set that. I guess a tech 1 will make it easier.
Rich

[XfireZ51]

Originally Posted by secondchance

Jim and I am going to hook it up and check what happens to voltage as the gas pedal is depressed progressively with Tech 1 hooked up. This should teach us what to look for with Tech 1 when diagnosing a car with stumbling issue to verify TPS functionality.

You should get a smooth sweep of voltage as throttle opens. If voltage changes in "jumps" or not at all, then it's a problem. If you have the TPS you replaced, you can just use a DVM to check it. Can also use the DVM to check the one on the car by using jumper wires between the harness and TPS. Feed the 5v reference signal to the TPS,then connect DVM to Ground and TPS signal lines.
With key ON, you can loosen two screws holding TPS to throttle and adjust up or down to set voltage in specified range. Then tighten and re-check. Flip the throttle a few times to make sure throttle is seated properly. Scan tool definitely makes this easier to do.

[rkreigh]

ahhhh the tps

in the old days with my turbo buick these things would forever go out of adjustment and it was important to get the wot volts above 4.7 or the ecm wouldn't give you the full power

we were always grinding out the slots and tinkering with them

then some gent came up with "tps enhancer" boxes that would trick the cpu and change the ramp up curve and max voltage to get more mid range torq from the turbos


never had one go bad, but I sure thought they were

congrats on it being an ez fix

[Billy Mild]

Where can you get TPS sensors at for these old birds?

[secondchance]

Originally Posted by Billy Mild

Where can you get TPS sensors at for these old birds?

Jerry's Gasket.