The z3 diagnostics thread instructions, experiences, discussions, experimentation – page 25 v gas station

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Crunchiness in the pedal is likely a hardware problem – maybe a bushing knocked out of location and binding or a walnut shell getting pulverized under the pedal… but most likely is what Randy said, the linkage somewhere. Particularly on the M52 I would be checking the cables. On one of my cars my cruise control cable was binding, presented as a roughness in part of the pedal travel and occasional revving when off-throttle (cable was binding and preventing throttle plate from closing)

I’ve had 3 pedals fail on me, and 4 TPS sensors fail on me in my various cars. Never felt a "crunch" or anything out of the ordinary. When the sensors fail, they just fail, there aren’t bearings or anything in them that start to go out. It’s an electrical failure, not mechanical. If you don’t have a CEL and EML I would have not reason to think the TPS or pedal is bad. Check the physical "hard" stuff… have someone go through the throttle travel where its crunchy (should be fine with engine off) while you poke around following the cable seeing whats going on. Not to say its not possible, just would be out of the norm to fail in way that the sensor becomes crunchy…

A lot of the m54 throttle behavior is programmed to be that way. Actually so is the M52tu behavior. That is why I learned how to tune both, because some of that programming is a bit interfering with driving dynamics. I can make the M52tu and M54 throttle behavior brutally direct.

There’s no feedback mechanism to the feel of the pedal.I did Portland to Redding in under 6 hrs on Saturday evening, and found the unanalogue behavior annoying… but I also felt what I’d call crunchiness in the pedal… and since on the e39 there is zero cable, ie, purely electronic: I’m going to see if I can remove that, or simply replace the mechanism… then I may hit you up for a more linear feel to it… but let me get mechanical aspects sorted out first… and it sounds like from your comments: that the ADC is at least 8 bit, so there should be zero "pixilation" effect – right now it feels like it’s 5 or 6 bit, and the steps between the values are noticeable and too large. Many thanks. … and get the elbow healed up 🙂

Crunchiness in the pedal is likely a hardware problem – maybe a bushing knocked out of location and binding or a walnut shell getting pulverized under the pedal… but most likely is what Randy said, the linkage somewhere. Particularly on the M52 I would be checking the cables. On one of my cars my cruise control cable was binding, presented as a roughness in part of the pedal travel and occasional revving when off-throttle (cable was binding and preventing throttle plate from closing)

I’ve had 3 pedals fail on me, and 4 TPS sensors fail on me in my various cars. Never felt a "crunch" or anything out of the ordinary. When the sensors fail, they just fail, there aren’t bearings or anything in them that start to go out. It’s an electrical failure, not mechanical. If you don’t have a CEL and EML I would have not reason to think the TPS or pedal is bad. Check the physical "hard" stuff… have someone go through the throttle travel where its crunchy (should be fine with engine off) while you poke around following the cable seeing whats going on. Not to say its not possible, just would be out of the norm to fail in way that the sensor becomes crunchy…I would just add the comment: that how a sensor fails, depends on how it is intended to operate… a Hall sensor: yes, probably will just die. Even a theroswitch – although the resistance across the closed switch was probably getting larger over time, there would be some point when the resistance crossed some value, so that the logic it drove would nolonger see it as a closed switch, and would appear to "just die."… But like on the accelerator pedal assembly [where this is no connection to the world beyond an single cable], where you have a plunger driving a gear driven potentiometer – the gear vs plunger could get crud in their interface, causing "crunchiness"; one could also have the resistor element of the pot start to wear through, giving a non-linear both feel and or output. In this case I suspecting the plunger/gear is the source of the felt crunchiness… but since it’s a sealed unit, I’m guessing that it’ll be a replacement.. but bottom line: how they appear fail, has a lot to do with how they were designed to work.

On all the failures I experienced, the first symptom was intermittent "bogging" while accelerating. Then it would be a hard "cutoff" when accelerating, like you suddenly went off-throttle (but you didn’t). Then the CEL’s and EML’s started coming… one after another… they just didn’t stop. It was relentless… I’d buy a new sensor, no EML for a day or two. Then BOOM – right in your face – EML and dead throttle. All around me, everywhere I looked – EML. I’d be riding my bike and suddenly see it – an EML light…

It’s certainly possible some crud got into the pedal assembly and messed some stuff up. I’d take it off and inspect before replacing though, as it could be a simple fix (could just be a tortilla chip under the plunger… who knows). The pedal on my car is a different design than the M54 you are talking about. The one in my car was basically an afterthought – a "how do we make DBW from a car designed for cable throttles" and the result is a motor with an arm, instead of pulling a cable that goes to the engine, the pedal pulls linkage that pulls the motor arm down. I believe the M54 pedal assemblies are self-contained in the pedal, like the E46 M3.