Has anyone ever had a pedal sensor go bad. When I’m in the US I can’t get enough drive time in the Bentley, but the last two times I returned this issue sporadically appears out of nowhere.

The accelerator pedal goes completely lifeless and it feels like the engine kind of goes into a limp mode. I normally floor it or pump the pedal and the car just stays around idol level for around 5-15 seconds (feels like an eternity) then everything returns to normal. It has happened at red lights and while traveling at highway speeds (a bit scary).

No codes are thrown so I’m not sure what is going on. Any advice would be appreciated, I’m only back in the states for a month at a time (and I hate it when this car is in the shop the whole time). 2010 GT Speed

 

Doubt this will help but, I once had a similar experience, but with a different car. In that particular case it turned our to be frayed wires to the mass air sensor.

This caused it to be intermittent and also not throwing codes when running ok. Occasional bumps or turns that jostled the wires to short is when this would happen.

 

Thanks Sam, will definitely look at the maf sensor to see how the leads to them are. not sure where it is on this engine... but will dig around.

when power returned for you, was it immediately back to 100% or did it gradually come back?

 

Hi hdc4,

Do you have access to a diagnostic cable to get trouble codes? If so, that would be a big help in pinpointing the issue. My guess is just a complete shot in the dark and so very unlikely to be the same problem.

I don't remember exactly as it was 10+ years ago and in my case, the throttle would do nothing, just as you described, even when repeatedly going through the motions. It would then seem to 'catch' when partially depressed and power would gradually build up for 3-4 seconds until full power was reached. Sometimes it would then be back to normal, other times it would take a few tries before everything was back to normal. This behaviour led me to also believe that there was a problem with the e/throttle, cables, sensor, etc. When the dealer told me it was the plug to the MAF (or was it MAP) sensor, I was duly surprised as I was sure it was related to the pedal function.

The other thing I recall, but not sure if was the same issue, is that when cruising on the highway with part or light throttle (like when you're going an easy 60 and 'coasting' along with traffic on a highway, or in cruise control) it would sometimes just turn off (the engine!) on the highway. I would have to put the car in neutral, then turn the key to restart the engine (was an automatic), and then return to drive.

As you stated, potentially very dangerous, as I would lose power steering, brake boost and all car electronics. There was also a danger in this car of the steering wheel going into the lock position if turned too far to one side with the car engine off. Thankfully, when I found this out, I was coasting into a gas station, turning into it and going at a very slow speed. (I can't quite recall why I unwisely continued to drive the car for a few days after the problem started, other than it was at first, very intermittent, thought it was a 1 time thing, and I had only 1 car at the time. Car died or gave throttle problems on me 3-4 times over those 2 days)

I'm sure you've already also come to the same conclusion to address the issue before any regular car usage (outside of controlled test drives in safe areas.)

 

Sorry hdc4, never mind, I see from your 1st post, you're not getting any codes thrown.

Here's the locations of the throttle body and map sensors.

 

Hello Sam, I really appreciate the effort in trying to help. The last time I was in town I finally got this issue thoroughly diagnosed and it turned out to be bad exhaust temp sensors (codes did not show up on my kiwi). I assume these went bad when I had a engine decarbonization done a few years ago. They changed these and the the issue has not returned...

 

Hello Hdc4,
May I ask why you had a decarbonization service performed on a 2010 W12 TMPI engine, as your 2010 does not have direct injection there is no carbon buildup to need cleaning, our engines from 2003 to the 2014 engine I am working
on all have port injection, NOT direct injection, port injection keeps the intake valves clean, whereas DI sprays directly into the cylinder therefore allowing the intake valves to form carbon build-up.

 

Hello Johnny, when I purchased that car it already had higher mileage than most Bentleys I've seen. Call it ignorance, buying into the sales pitch, or my eagerness to keep the car in top shape, I assumed that there would be some deposits starting to build up. It might be a placebo effect, but if my memory is correct the engine was quieter and seemed to have a little more bite after that service.