I recently returned my IS220d to Lexus so that they could investigate and hopefully cure the erratic power delivery. They re-mapped the ECU claiming that it would “feel like a new car” but I noticed very little change, if anything at all, to the way the engine performs.
The engine delivers almost no power below 2,00RPM, making it very difficult to pull away from a standing start in a hurry.
Example: I have found this unfortunate trait rather dangerous, especially when attempting to join a busy road or roundabout. If the revs to drop below 2,000RPM, the engine immediately bogs down leaving you having to frantically slip the clutch in order to build the revs back up to a level where the engine actually relinquishes some power. As well as being dangerous, this is not very dignified and cannot be much good for the clutch either.
Being an experienced driver and having owned and driven numerous 6-speed turbo diesels, I would say that the 1st gear ratio is simply too high for the job.
Another example: Try driving at exactly 30MPH on the flat then depressing the accelerator to the floor when you reach a derestricted section of road. With my car it takes a full 3 seconds before ANY change in acceleration is felt. What with the power only being delivered from 2,000PRM onwards, when driving in 3rd gear at 30MPH the engine is just below this critical speed ensuring this numb and rather frustrating response on attempting to accelerate.
Having also experienced problems with the useless 6th gear (see my previous post), I can only deduce that, when Lexus changed the final drive in an effort to make a distinction between the “Sport” model and the rest of the range, they have upset the gear ratios to the point that they are now not really practical for the job.
In addition to this, there is a subtle overrun which occurs when gently backing off the accelerator e.g. when moving slowly through traffic, which makes the car lurch forward in a rather embarrassing manner.
I can honestly say that I have never driven a turbo diesel which such strange and un-diesel like power delivery. Where I would normally hope to enjoy the low-down grunt of a torquey diesel engine, I instead find myself having to endure the quirky power delivery which, strangely enough, is not unlike that of the very first car I owned some twelve years ago, a Mazda 626 with a 1.8 petrol engine. Believe it or not I actually got better fuel economy from the Mazda!
Lexus have said that there is no solution to this problem. I mentioned the possibility of changing the injectors to help with the power delivery and they said that this is merely “a myth”.
Does anyone know of a solution to this problem? Your suggestions will be greatly appreciated.