Mongo

I have 152,000 miles on my car and i'm wondering when does the throttle position switch decide to take a sh*t? what are the symptoms too????

<img src="graemlins/burnout.gif" border="0" alt="[burnout]" />

Skip

Should have done it by now... most are good for at least 100k. Symptoms for your model would include improper return to idle on deceleration. The TPS signals the DME to shut down the injectors when the throttle is closed - the DME will fire the injectors once a preset RPM is met (~1200 in your case).

TPS failure in your model does not disable the car, it's simply annoying.

Good Luck!

Mongo

mmmmmm i think i'll definitely pick a switch up since i read about throttle hesitation and that being linked together. the injectors and fprs checked out...must be the throttle position switch.

<img src="graemlins/burnout.gif" border="0" alt="[burnout]" />

Ken

[quote] TPS failure in your model does not disable the car, it's simply annoying. <hr></blockquote>

I'm gonna have to disagree with you there Skip. My TPS failed and the car was undrivable. It would start, but wouldn't rev past 1200RPMS. Try driving like that! Its easy to replace, and pretty cheap and I would recommend it to anyone with odd throttle activity.

jim968

Mine failed in the '88 na at around 105K, on the idle side. Symptoms were poor idle, rough under engine braking, and .. odd, this... the upshift indicator light would come on at inappropriate times. That was my major clue when I started troubleshooting.

Jim, back to the attic & insulation...

Steve Lavigne

On another note, my '86 951 seems extremely sensitive between off throttle and slight throttle in slow speed traffic. It takes quite a bit of effort to get on the gas smoothly after idling along in first gear. Has anyone had this extreme sensitivity rectified by replacing the tps?

I have adjusted my tps so that it just clicks when the throttle butterfly is shut.

Skip

[quote]Originally posted by Ken:
<strong>I'm gonna have to disagree with you there Skip. My TPS failed and the car was undrivable. It would start, but wouldn't rev past 1200RPMS. Try driving like that! </strong><hr></blockquote>

You're absolutely correct - my bust, and good catch. The main failure mode is that the switch does not make contact, which causes the slow let-down when the throttle closes and instable idle. Ken describes the other failure of the switch being stuck closed... that's a real problem, though happens with far less frequency, thankfully.

Skip

Skip

[quote]Originally posted by Steve Lavigne:
<strong>On another note, my '86 951 seems extremely sensitive between off throttle and slight throttle in slow speed traffic. It takes quite a bit of effort to get on the gas smoothly after idling along in first gear. Has anyone had this extreme sensitivity rectified by replacing the tps?

I have adjusted my tps so that it just clicks when the throttle butterfly is shut.</strong><hr></blockquote>

It could be the switch, but try backing the sensitivity off just a bit more - to the point where it may not seem to trigger the microswitch. With the trigger set too high, you are opening the throttle and rushing the engine with air before the DME can react - then the DME senses the volume and tries to compensate... that's the rush you feel when the engine seems to buck.

Good Luck!

Ken

[quote] You're absolutely correct - my bust, and good catch. <hr></blockquote>

Woohoo! Now do i get a "Proceed directly to guru" card or something?

I do think replacing or adjusting(as Skip mentioned) the TPS is a good place to start whenever there are odd throttle problems. On our old cars, its probably never been replaced. Its a cheap and easy job too, so if you question your the condition of your TPS, replace it! It can solve all sorts of problems!(my friend had an 89 Sable with what we thought was a busted transmission. After many trips to the shop, and many replaced parts, the $12 TPS was the culprit! It confused the computer and caused the shifting to be out of sync with the engine revs causing rough shifts, which we thought were a problem in the tranny.)

sean bartsch

I think mine needs replacing to. i have 158,000 miles and im having the same symtoms you guys are. I just called my local Porsche dealership and they said the TPS would be $125. could this be right. If so, anyone know of a place with a better price?

sean
86 951 tial WG, SFR 3"exhaust, Apexi AVC-R, t04 turbo

sm

While we're on the subject of throttles and such...

When I let off the gas in 1st or 2nd gear around 2000 RPMs, the car feels like it hit a wall. The car feels like the brakes have been applied and usually causes me to jerk forward slightly. Then when the RPMs lower to 1500 or so, the car juts forward a little as if the imaginary brakes have been released. I heard about the TPS causing the fuel injectors to shut down until idle speed has been reached, but can I make it a little smoother for my passengers?

Skip

[quote]Originally posted by sean bartsch:
<strong>I just called my local Porsche dealership and they said the TPS would be $125. could this be right. </strong><hr></blockquote>


[list is only $78 - maybe try some other place]

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Skip

[quote]Originally posted by sm:
<strong>When I let off the gas in 1st or 2nd gear around 2000 RPMs, the car feels like it hit a wall.</strong><hr></blockquote>

Stop driving so hard in mall parking lots.

[quote]<strong>The car feels like the brakes have been applied and usually causes me to jerk forward slightly. Then when the RPMs lower to 1500 or so, the car juts forward a little as if the imaginary brakes have been released. I heard about the TPS causing the fuel injectors to shut down until idle speed has been reached, but can I make it a little smoother for my passengers?</strong><hr></blockquote>

Old Car Syndrome - as I call it. Happens more often than it should, but seems common. A couple of things to check/replace are most of the common tune-up stuff... plugs, cap, rotor, wires, filters, etc. Also, this can be caused by dirty fuel injectors (get them cleaned/tested) or improper fuel pressure (replace FPR and check-valve).

One of the major causes of this - drivetrain backlash... caused by the worn components to include the transmission, differential and CV joints.

The cure is out there, but it costs time ,money, and patience.

Good Luck!

sm

[quote] Stop driving so hard in mall parking lots. <hr></blockquote>

Why do you think I'm buying the M030 sways???

[quote] The cure is out there, but it costs time ,money, and patience <hr></blockquote>

I have the patience, but may I have your time and money?

I'm about to replace the cap, rotor, plugs, wires, and *maybe* coil. Will report back if it solves the problem.

If not, I'm sending the injectors out to be cleaned.

Will the Blaster 2 coil be a good item for the 951? I see mostly N/A's with that mod.

Skip

[quote]Originally posted by sm:
<strong>Will the Blaster 2 coil be a good item for the 951? I see mostly N/A's with that mod.</strong><hr></blockquote>

That's a good upgrade for any car - if for no other reason than it's nice to have a fresh coil.

S