WhyEye

10 hours ago, Bigchad said:

With regards to the power loss this is usually the start of dpf saturation even if you do 300 miles a day you need to keep the revs up for a continuous burst,manual boxes allow this much easier than autos,if you hit 80mph in 5th or 6th the engine isnt working the dpf effectivley as it needs heat to work the soot out,The loss of power can feel like a petrol engine misfire causing the car to judder this happens when the ecu decides to regen the dpf but if you come of the gas the exhaust fills with fuel intended for the regen but isnt burnt of properly which creates backpressure and the juddering effect,The dpf egr oil fuel system is a wicked circle if one starts to suffer its downhill unless you take action its no good cleaning the egr and hoping for the best,its blocked for a reason,poor fuel,incorrect oil type,city driving or low rev motorway driving,, A good indicator of it all going wrong is to keep a check on your mpg,if it starts to drop give it a good run 2300/3000 constant for 15/20 mins return to normal driving then re check your mpg it should improve if the ecu has regened the dpf,use good fuel not supermarket Bp ultimate and the like use catalysts which allow your dpf to burn soot at half the normal operating temperature,yes they cost more but they maintain a healthy circuit saving you money in the long run,If not using Lexus for your oil service buy your own oil something good like mobil 1 etc and ask a local garage to change it while you watch it going in!! and every now and then make it perform,give it a bit of pedal..hope this helps!

Really useful comments here BigChad - thanks. In my case the EGR valve was replaced fairly early on but seemed to make very little difference really - an expensive experiment! I was also not doing myself any favours - my mileage has dramatically reduced in the last couple of years so opportunities for a good blast to burn off rubbish were also reduced. Additionally, although the car was always serviced by Lexus (so I assume the correct oil, etc.) I was consistently using supermarket fuel. A casual comment from the Lexus Service Manager suggested, like yourself, that non-supermarket fuel might help so I changed and the difference was staggering - over the course of a couple of weeks the problem disappeared almost completely and continues to improve to the point where, today, it's pretty much completely gone. I had no idea saving a few pennies on fuel would end up costing so much and was convinced fuel was fuel, no matter where it came from - I won't make that mistake again.

Thanks again for your comments and input, and apologies to anyone following this thread for not keeping it up to date.

That's excellent news - mine goes back in on Monday and I'll be sure to mention your experience. Fingers crossed - keep us updated.

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Just had the local garage connect up their diagnostic computer to see if any error codes were showing up but there weren't any - clean as a whistle. The mechanic did think he'd heard of a similar problem being caused by the air mass meter/mass airflow sensor and felt that disconnecting the device should show if this was the cause - we did disconnect then tried a test drive but it was impossible to rev the engine beyond around 1500 RPM and certainly there was no power available so he believed this indicated the air mass meter is not the problem - anyone concur?

Hi, I'm new on here but hope someone can help identify a solution to an odd problem with my IS220D.

The car is a 2010 reg with around 80k miles on the clock. Fully serviced on schedule by Lexus. Recently needed to have the EGR valve replaced but since then, and progressively getting worse, when the engine is warm there is a marked hesitation when accelerating beyond around 2000 rpm and a complete loss of power. When the car is stationary the engine can be revved throughout its range without hesitation but the problem always occurs when the engine is under load. I can accelerate away from a junction in 1st and through 2nd gear with no problem but when the car is on the move and a similar maneuver is attempted then the problem occurs. It feels like a misfire but I'm at a loss to understand why it would only happen while driving and not when stationary or pulling away.

Any thoughts or suggestions?

Many thanks