st0ppy

Hi there!
Im facing a problem with my 88 951 and was hoping to get a bit of help from the community.

Problem: When I attempt to start the car it starts but really struggles and will just die. Runs very rich. When I unplug the TPS, car starts fine and remains running.
Why don't I just buy a new TPS and be done with it? This is my second TPS (used) in ~1yr as I had the same problem last year so I am wondering if there is something else going on. I am in Canada so ordering a new TPS from Porsche is ~$600 and from ebay ~$450.

Troubleshooting:
- Thinking it may be ISV related (re post I found) I tried jumpering ports B and C, same condition.
- Checked DME resistance

1. 0 closed
2. Infinite at WOT

- Checked KLR resistance

1. Between pins 22 & 23
   1. 0 at Closed and WOT (which I think is bad)

- Checked TPS resistance:

1. between pins 2 &3
   1. 0’s at both WOT and Rest ⁠⁠
2. between 4 & 6
   1. 2.3 at rest
   2. ⁠⁠infinite at even the slightest increase (which I think is bad)

- I do hear the 'click' when I open the throttle

And thats about where I am right now. I really think that something is telling the engine to flood more fuel in than it should, or now thinking about it, not enough air. Given it runs well without TPS it makes me feel like its sensor related but really trying to narrow down the problem.

Appreciate any and all help I can get.

931guru

tps test for turbo cars (from clarks garage workshop manual)For turbocharged cars:

1. Disconnect the electrical connector for the DME control unit. Connect an ohmmeter between terminal 2 on the DME wiring harness plug and ground. This will check the idle contact.
2. With the throttle closed, the ohmmeter should read between 0 - 10 ohms. With the throttle open, the ohmmeter should read infinite (∞). The switch in resistance must occur as soon as the throttle starts to open (approximately 1°).
3. Disconnect the electrical connector for the KLR control unit.
4. Connect an ohmmeter between terminals 22 and 23 on the KLR wiring harness plug. With the throttle closed, the ohmmeter should read between 320 - 670 ohms.
5. Slowly open the throttle to the wide open throttle (WOT) position. As the throttle opens, the resistance should continuously increase to full open resistance without any breaks. Full open resistance is 2.7 - 4.7 Kohms.

CHD

If you need a new TPS I got a Bosch 951 TPS from Partscontainer on Ebay for $244. I've bought several Bosch parts (knock sensors, etc) from them and they're all legit Bosch. It fixed my unstable idle; but I have a rich condition too. Just got a standalone and new harness for more control as I think the old Rogue chip may have failed. AFR stayed in the 10's all the time.