RX400h Misfire under load

[Philben10]

Hi,

RX400h 2008 65k miles

Have an issue that the Lexus guys say they haven't seen before.

When accelerating hard I get what feels like a misfire. If I continue to push hard the level of charge in the traction Battery starts to drop and shows empty withing 3-4 mins. No service or error lights show. 

On a longer journey last month I did get a service light when I felt the misfire. Lexus did the diagnostics and reset and said it was cylinder 2 slight misfire. Strangely on the journey home the misfire appeared to have gone and the car accelerated cleanly to high speed. Great I thought, its sorted. Sadly not and after 2 days the problem is back. Car drives perfectly in all conditions other than hard acceleration.

Lexus have checked all major components and cant find an issue, so have said to continue to drive and see if an error can be forced.

Has anyone had a similar issue or any ideas? 

Cheers

Phil

 

[ColinBarber]

Sounds like a plug, coil pack, or fuel injector issue but not serious enough yet to make an easy diagnosis.

Other than swapping the plug with another one, and a coil pack to a different cylinder to the plug there isn't much you can do - if the fault occurs again then the cylinder at fault will give you an indication on which component is failing.

[Mara8000]

Hi, Philben10

I know it was in 2018, but I have the same problem with my rx400h. It's like misfire only under heavy load. Already change plugs and coils but did not help. A few guys couldn't find anything. 

Have you solved your problem?

[Barry14UK]

As happens sometimes, drivers come onto this forum, get some advice and can't be bothered to say how their problem was resolved which might have benefited others in due course, you for example.

[Mihanicos]

Check the canister operation  and that all hoses pertaining thereto are sound. Check the fuel filler cap seals the tank.

Chris.

[Mara8000]

The fuel pressure is good. The canister (hose) was pluged for testing. The car runs a bit better when the weather is warm and the engine is cold.

[#Sandy#]

Apart from thinking electrical, could it be a blocked fuel filter, or low pressure in the fuel pump.

[Bergs]

I have a 2008 Rx400h with exact issue. As it happened I managed to find the problem and fix it after replacing plugs,coils and timing belt which didn’t fix the problem.

Turns out it was a split in one of the air intake hoses.

once it was replaced, the problem went away.

Hose was around £50 from Lexus, Job done.

Edited February 2 by Bergs
Price missing

[Greisingel]

Got a picture of the offending hose? How did you do the back bank of plugs? Or was it Lexus service? How much if you don't mind me asking?