96 R850R Bogging Down

PGlaves said:

So it is running way too rich. Or the spark is very intermittent. The trick is to figure out which and why.

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In attempting to adjust the tps with the zero=zero procedure on ibmwr the value on the multimeter never changed from .006 while rotating the sensor: to me this indicates a faulty tps, but I'm not sure.

apalm_r850r said:

In attempting to adjust the tps with the zero=zero procedure on ibmwr the value on the multimeter never changed from .006 while rotating the sensor: to me this indicates a faulty tps, but I'm not sure.

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Do you have signal voltage and ground continuity?

To expand on D'Yoda's question - it sounds like you don't have a good connection to the proper places at the TPS plug.

First verify that your DVM actually goes to Zero when you short the test leads together - I've seen many cases where those leads have broken internally, typically where the wire connects to either the banana plug or the probe itself. Even some broken strands can cause a bit of grief: the measurements won't be repeatable. Also verify that the battery in the DVM is known to be good - it's not used "directly" for taking a voltage measurement, but it still has to reliably power the display.

You need to make certain that you have good contact to the white wire with the red runner (Pin #1 is rearmost), and to the brown wire that bolts to to the throttle body (ground, also Pin 4, frontmost). You can use a fine needle to gently pierce the #1 wire's insulation with minimal damage, or gently snake it up alongside the wire & pin until you make contact. A couple of small alligator clip adapters can be useful here.

It would also be worthwhile to disconnect the TPS plug and inspect the mating pins in the connector and on the throttle body for distortion. Make sure it's fully seated and the spring clip goes back into position when you put it back on to take the measurement again.

Apalm, I have to ask --- are you certain this is not still the HES ???

When the problem first occurred the HES was definitely bad. From your pic it looks like you added some insulation, but still the problem persists.

ALIENHITCHHIKER said:

Apalm, I have to ask --- are you certain this is not still the HES ???

When the problem first occurred the HES was definitely bad. From your pic it looks like you added some insulation, but still the problem persists.

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The part of the insulation that suffers the most damage is in the splice behind the plate itself.

Pauls1150 said:

You need to make certain that you have good contact to the white wire with the red runner (Pin #1 is rearmost), and to the brown wire that bolts to to the throttle body (ground, also Pin 4, frontmost). You can use a fine needle to gently pierce the #1 wire's insulation with minimal damage, or gently snake it up alongside the wire & pin until you make contact. A couple of small alligator clip adapters can be useful here.

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I was measuring the voltage originally with the ground directly on the battery, I switched it to the brown wire to try again. There is still no change in voltage when rotating the TPS. I have verified that the DVM is working properly

As for the HES, I ran the new wires all the way up to the pink/green wires behing the splices; the insulation on those looked fine. I suppose it is still possible that it may be causing the issue, however with the TPS test going the way it did makes it seem unlikely to me.

https://imgur.com/gQ2OSKh

You could see if you can pull a code: http://www.largiader.com/articles/motronic.html

Don't get too caught up if you have a code, the TPS is pretty robust.

Thanks to Anton and many others for their dedication posting relevant information.

Here's a schematic of what's inside the TPS:



Older oilheads used wirewound resistive elements, but this was changed to a resistive film later on.

It would be interesting to unplug the TPS and set up the DVM for a resistance check - see if you can get a change of resistance between pins 1 and 2, pins 1 and 4, and pins 2 and 3, while turning the throttle (the wiper of the unit is a snug slip fit on the throttle plate shaft). If you have an Open or No Change, that would point to a bad TPS.

Uh oh

Hi everyone, I finally got around to getting a new (used) tps. The problem with the throttle seems to be fixed, however while doing a TB sync I noticed a leak from the valve cover gasket area. When I took it off the oil was murky and thin and smelled of gas. I'm not even sure what to make of the situation, as the original problem appears resolved but I'm pretty convinced I seriously broke something in the fall it seems.

apalm_r850r said:

Hi everyone, I finally got around to getting a new (used) tps. The problem with the throttle seems to be fixed, however while doing a TB sync I noticed a leak from the valve cover gasket area. When I took it off the oil was murky and thin and smelled of gas. I'm not even sure what to make of the situation, as the original problem appears resolved but I'm pretty convinced I seriously broke something in the fall it seems.

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Drain the oil immediately and put in fresh oil and change the filter. A bad HES can cause injectors to continuously fire, dumping raw gas into cylinders which makes its way into the oil.

Resolution

A new TPS appears to have fixed it for good (not sure how/why).