PMO Individual Throttle Bodies - Sensor issue?
 

Anyone else running PMO ITBs? The throttle position sensor on mine is giving my Motec and I issues.

Basically, I think the potentiometer might be a bit dirty or faulty, and it is giving a false reading to the Motec. When the throttle is at 0 (i.e., butterflies shut), the pot sometimes gives a reading of 10 degrees open (shows on the Motec readout), but when I work the throttle through it's full sweep a couple of times and restart, the sensor is recalibrated to 0.

Has anyone else had this problem? The TPS is a GM part, so I'm inclined to point the figure at it, haha.

Pull out the sensor, keep it hooked up to the ECU. The hook up the laptop, & move it full sweep & see what the reading are.

Vibration, single noise, & a incorrect adjustment can all lead to this.

Yes, it can be a bad sensor, after all it is a GM part!

Any ideas/suggestions for (non-GM) replacement parts?

Nope sorry, best would be to contact PMO, or MoTec & see what they say.

Giving this thread some CPR, in case others have encountered similar problems with the PMO ITB kits in their applications.

First, a recap:

I have now had the throttle position sensors that come with the PMO ITB kit fail on two separate occasions. On both occasions, the sensors in question were new out of the box.

For my particular application, the primary symptom of a failing sensor was a faulty reading by my Motec based on the sensor's output. Typically, I found that the Motec was reading the sensor angle/position to be fluctuating, when in fact it was static. This led to my Motec adjusting the fuel mixture richer to compensate for what it thought was more air coming in. The engine then ran too rich, eventually leading to the engine fouling the spark plugs to the point that the car wouldn't start at all.

Finding a solution:

I ended up taking the sensor out to give it a really good look over. First crucial bit of information: this is not a GM/AC Delco part, despite what PMO says (at least twice) on their site, and I quote: PMO High Performance Porsche 911 Carburetion

- "Integral Boss to Mount Delco Throttle Position Sensor (EFI only)"
- "Delco Throttle Position Sensor"

The PMO ITB kits come with a CTS series 514 contacting rotary position sensor as the throttle position sensor.

The guy who built my engine tried contacting Richard Parr of PMO, though I haven't heard any feedback on this. He also contacted Motec, who said they had a replacement part, which subsequently turned out to be the same CTS part. So I have now gone ahead to contact CTS to see if they have a better version of this flimsy part (I use CTS potentiometers in my guitars that look more robust than this thing).

Stay tuned...