Hi. You guys are my last hope. My 1993 Bentley Turbo R (RHD) after a stay at a local Bentley 'expert' (who overall did a good job on various other problems) managed to create what seems to be a misfire. It only happens in 'top' gear between 1500-2000 revs when the accelerator is barely being touched. If I take my foot off completely or press down, it goes away. Doesn't happen at the same revs in 3 or 2 gears. I have had new distributors/plugs/cables etc replaced. The mechanic that 'caused' it seems to think he has tweaked the gas mixture too weak, but can't get it to go back to a slightly richer mix, for some reason. Any thoughts?

 

Just a wild guess as I know nothing of the Turbo R, what it sounds/feels like specifically, what your mechanic worked on, or other symptoms.

Not sure what type of mass air sensor is on the 93 Turbo R, but if it's a mechanical type or sensor, make sure they're thoroughly clean and test functional through out their range.
Also, might check all the vacuum lines and if there's a wastegate that's 'sensitive' in that load range or a boost protection circuit that might be getting falsely triggered.
If there's a spare computer to try out might also be something to help narrow it down.
Finally, the turbo(s?), wastegate, exhaust and 02 sensors are in good shape?

 

Thanks for this, I am no mechanic, but I will forward this on to the guy who has worked on it for me and see if he knows what to do...really appreciate your time.

 

Good luck, hope you get this sorted.