fixed my weird part throttle 'miss' problem, it was the TPS board but it was new, and it wasn't a miss Options

[emerygt350]

So... for months I have been fighting what I thought was a lean miss issue (well before I parked it for the winter). It would only happen when I was just barely into the throttle at cruise. It started to get really bad in the past couple days since I brought it out of storage. It was getting so bad I noticed that it wasn't a miss, it was the whole engine losing either spark or fuel. Pulled the TPS cable and the problem disappeared. Last year I had suspected it was the idle circuit but bypassing that made no difference.

I replaced the TPS board 2 years ago. Put the old one back in (looked fine) and all of my problems disappeared. The only thing I can think of is that it was somehow causing the injectors to stop firing when it hit this one spot about a half inch into the throttle.

Here is a picture of the board. It doesn't look great, but it doesn't look bad either.
So, one more thing that might go south on a 914 with weird symptoms. That thing really only works as an accelerator pump and an idle circuit switch. So strange it could have such an effect.

[windforfun]

I had to replace my TPS board too. I was careful to align it just like the old one & it worked fine. Did you maybe have an alignment issue with the replacement? Did it drift out of alignment? Why does the phenolic material (plastic) looked burned?

[emerygt350]

You can see it was aligned correctly from the wear pattern. The color looks worse than in real life but it does make me wonder. There really isn't much current going through that thing. Maybe the contacts were not great?

[SirAndy]

Maybe the contacts were not great?

Sparks would do that ...
(IMG:style_emoticons/default/idea.gif)

PS: 3d print a transparent housing and test at night. Might be a pretty light show.

[emerygt350]

So strange, the contacts were all tight against the board. Well, we will see how the original holds up. I could just pop the cover and see what it looks like in operation I guess.

[emerygt350]

I was trying to fall asleep thinking about this last night, and it occurred to me that the 2.0 doesn't connect all those traces back to the ECU. Due to the wacky armature that shifts contacts depending on which way it is going (keeping from triggering injectors on decel for example) it's hard to know which traces are actually active, but there should be nothing 'heading out' or 'in' from the first trace to the connector, and yet there are 'marks' on that strip, so I think the marks must be either a reaction with the copper or mechanical rubbing due to vibration.