Rx450h rough idle

[darrude]

Hi Wifes RX (2012/450h) has got a bit of a rough idle, just approaching 80,000 miles.

By rough idle I equate that to be just a small vibration / bouncing when stationary with the engine running. 

I can't find any evidence in the history for the spark plugs been changed, so going to do over Christmas, just wondering peoples thoughts on this, or if it could be something more (ie a coil pack failure).  Does the check engine light come on for a coil pack failure / missfire.  I can't myself believe the spark plugs could be so bad that it would cause this on is own.  Other than a rough idle car seems to run fine.

Going to change the 12V as well, although this is showing 12.3V on a cold morning.

Just ordered an OBD diagnostic (lost my old one), just to check for codes, but trying to plan so I can get everthing ready for when I tackle the job.

Thanks,

 

Darren.

[Herbie]

3 minutes ago, darrude said:

Just ordered an OBD diagnostic (lost my old one), just to check for codes, but trying to plan so I can get everthing ready for when I tackle the job

Have you not got an old laptop that you could use Techstream on? A generic OBD reader will only catch generic stuff, nothing that's Lexus-specific such as hybrid codes etc.

I've never experienced anything like what you're describing so I'm afraid I can't help there.

[m4rkw]

Could be a worn motor mount. When I had a coil pack go out on a BMW it threw a CEL.

[m4rkw]

Does the rev needle move when it's "bouncing"?

[Stefan213]

I have the same vibration on my 2011 and i was thinking of changing the spark plugs as i dont have a service history... 

You cant see it in the rev needle but can feel it

 

[darrude]

3 hours ago, Herbie said:

Have you not got an old laptop that you could use Techstream on? A generic OBD reader will only catch generic stuff, nothing that's Lexus-specific such as hybrid codes etc.

I've never experienced anything like what you're describing so I'm afraid I can't help there.

I bought tech stream when we got the car and completely forgot, as have just put a new hard drive in an old work laptop.... Good call. I'll get it installed and plugged in tomorrow. I've been meaning to sort for ages.

[darrude]

3 hours ago, Stefan213 said:

I have the same vibration on my 2011 and i was thinking of changing the spark plugs as i dont have a service history... 

You cant see it in the rev needle but can feel it

 

I'll let you know if it makes a difference.

[darrude]

3 hours ago, m4rkw said:

Could be a worn motor mount. When I had a coil pack go out on a BMW it threw a CEL.

Does feel more like engine hesitation. Just of that is fine when under load.

[m4rkw]

14 minutes ago, darrude said:

Does feel more like engine hesitation. Just of that is fine when under load.

Could be a slight vacuum leak.

[Herbie]

4 hours ago, m4rkw said:

Does the rev needle move when it's "bouncing"?

Doesn't have a rev needle, or at least my 2013 RX450h Advance doesn't.

[m4rkw]

14 minutes ago, Herbie said:

Doesn't have a rev needle, or at least my 2013 RX450h Advance doesn't.

Really? Damn I thought it was weird that my wife's Nissan Note didn't have a temp gauge but no rev needle is just weird.

[darrude]

25 minutes ago, m4rkw said:

Could be a slight vacuum leak.

Good thinking I'll check for that.

[darrude]

Just an update. I never actually changed the spark plugs. We bought at 62,000 miles, but although was told this service was done, no stamp or service invoice was handed over. Turns out he did post it on, my wife never told me (I had it serviced locally just after purchase as believed it never came through).

Anyway this showed spark plug change at Lexus main dealer so seemed pointless me changing).

 We live reasonably rural, and on my last car I stopped using the local (attended service) petrol station as I was convinced my car didn't like the fuel from there.  While trying to think what could be at fault if not the spark plugs it suddenly dawned on me. I bet with the cool weather she is filling up there so she didn't have to get out of the car. 

Turns out she was, back on fuel from a mainstream garage and the issue has gone away. 

So my advice, don't fill your Lexus up from a petrol station that makes its money primilary from red diesel sales....!

[m4rkw]

2 hours ago, darrude said:

So my advice, don't fill your Lexus up from a petrol station that makes its money primilary from red diesel sales....!

It may just be that they don't get loads of traffic so the fuel wastes away in the pumps a bit more than a busy station.

[Passerby]

Its an old approach but, if the car is doing mostly rural mileage, take it for a blast down a motorway and maybe engage sport mode to get the revs a little higher. Used to be referred to as the 'Italian Tune' - gets the internals nice and hot and clears out the cr*p.

[Gliderpilot]

On 12/19/2019 at 7:45 PM, m4rkw said:

Really? Damn I thought it was weird that my wife's Nissan Note didn't have a temp gauge but no rev needle is just weird.

All Lexus/Toyota hybrids don't have a rev counter, they have a power display in its place as you can be powering the car just from the traction Battery and the ICE will not be running.

[Zotto]

18 minutes ago, Gliderpilot said:

All Lexus/Toyota hybrids don't have a rev counter, they have a power display in its place as you can be powering the car just from the traction battery and the ICE will not be running.

Totally WRONG. You can set (in many Lexus) if having power display or rev counter. In my RX I have just decided to leave in HUD power line and rev counter on dash.

Besides, rev counter is automatically shown switching in sport mode.

 

 

[Silversalmon]

Our old CT200 changed to a rev counter in sport mode, my RX doesn't however. Meaningless with a CVT transmission anyway.

 

[olliesgrandad]

9 hours ago, Zotto said:

Totally WRONG. You can set (in many Lexus) if having power display or rev counter. In my RX I have just decided to leave in HUD power line and rev counter on dash.

Besides, rev counter is automatically shown switching in sport mode.

 

 

Gen 3 RX450h doesn't have a rev counter at all, unlike the later model. 

[MrChemist]

I only looked at this thread because I thought it might give a clue to my VERY rough running for the first minute. Like, rattling everything underneath rough. No help there.

 

I wasn't expecting capitals, Mr. "TOTALLY WRONG", gen 3 RX450H doesn't have a sport mode, either. The OP says 2012 model, gen 3 was 2009 to 2015, IIRC.

 

[ColinBarber]

2 hours ago, MrChemist said:

I wasn't expecting capitals, Mr. "TOTALLY WRONG", gen 3 RX450H doesn't have a sport mode, either. The OP says 2012 model, gen 3 was 2009 to 2015, IIRC.

Luigi's reply was against the assertion that no Lexus hybrids have a rev counter - and that is wrong as the CT, IS, RX series IV etc. provide that functionality. Just not the RX series II or III.

I don't believe any rudeness was intended, just someone who is from a different country where English isn't their native language. 

 

Rough idle on the RX450h is potentially a fuelling issue, and there have been a few reports of injector issues. Might be worth trying a fuel system cleaner as a first attempt to resolve the issue, something like this:

https://www.amazon.co.uk/Liqui-Moly-Injection-Cleaner-300ml/dp/B0096Y6OII?ref_=ast_sto_dp