Intermittent misfiring

RK1975 · February 22, 2023

2013 CT Advance with 160k on clock. Starting a couple of days ago and very occasionally there's been a juddering at low speeds, around 15 to 20 mph then clears. At first I thought the juddering was going over rough surfaces but it's not. No loss of power or warning lights and its fine at higher speeds. Today it started misfiring when idling so I've called RAC who couldn't diagnose - no fault code showing but maybe because problem not lasting long enough. The misfiring was totally random.

RAC suggested may be spark plugs or coils, but said that would normally result in more consistent misfiring and would happen at higher speeds. I saw another thread with a similar problem possibly caused by clogged EGR and suggested this, but he said there's no way I'd be able to do 70 mph if that was the case (he followed me for a bit on motorway). There's been no other problems with it and spark plugs were (supposedly) changed 3 months ago.

Anyone have any ideas what may be happening? My normal garage cant see it til at least a week away so I'm going to try and get it into another garage tomorrow. Meanwhile, would it be safe to drive? Any advice or suggestions much appreciated.

Las Palmas · February 22, 2023

Is your "normal garage" Lexus or independent?

Not that Lexus are the only company that can fix cars, but maybe they know more about Lexus than many other garages. They supposedly have all needed tools to fix whatever happen to the cars.

Lexus has the bad habit of being stupidly expensive, but they have fine expensive workplaces and hopefully competent people working and nothing is easy or free.

Maybe some competent member here can tell what it might be, but unfortunately, I have no idea, except I would go to Lexus to have the car examined.

RK1975 · February 23, 2023

Thanks for replying, appreciated. Tbh, Lexus garages are my choice of last resort (Lexus quote for loose heatshield repair: £185 + VAT + parts. Indi: free. Effect: same). My garage is an indi and anything he can't fix, he sends me to another indi (electrics specialist, also fully booked) who can. This is going totally off topic, but I came across a post about changing batteries in key fob and any suggestion to me about using a Lexus dealer to do this.... it seemed OK with some and i found that weird. My 8 year old niece worked out how to do it on my fob without prompting. As I say, that's all off topic, but I hatevthat car manufacturers tie you in to their brand. As a saying might go... Its not because I love Lexus repairers, its because I've got no bloody choice but to use the buggers! Anyways, that's all besides the point and I don't want this thread to go off topic. So, anyone have ideas about the misfires?

Las Palmas · February 23, 2023

2 minutes ago, RK1975 said:

Tbh, Lexus garages are my choice of last resort. My garage is an indi and anything he can't fix, he sends me to another indi (electrics specialist, also fully booked) who can. This is going totally off topic, but I came across a post about changing batteries in key fob and any suggestion to me about using a Lexus dealer to do this.... it seemed OK with some and i found that weird. My 8 year old niece worked out how to do it on my fob without prompting. As I say, that's all off topic, but I hatevthat car manufacturers tie you in to their brand. As a saying might go... Its not because I love Lexus repairers, its because I've got no sodding choice but to use the buggers!

For some it will be a problem, but only if not having a screwdriver that is tiny enough. Your niece needs a big hug.

RK1975 · February 23, 2023

Just had a mobile mechanic out. He thinks that the dual mass flywheel may be misaligned. The car started shaking on startup for a couple of seconds then stopped which he said was a classic sign of it. Does this sound plausible to anyone?

Spock66 · February 23, 2023

10 minutes ago, RK1975 said:

Does this sound plausible to anyone?

Yes, because an actual misfire should result in a fault code being generated.

RK1975 · February 23, 2023

1 hour ago, Spock66 said:

Yes, because an actual misfire should result in a fault code being generated.

Thanks, I really wasn't sure as I know little of cars. Phoned round a few reputable garages who've all said it's a main dealer job and probably going to cost a couple of thousand quid to fix. Think I might just trade it in for whatever I can get for another car. As much as I like the car, the running costs are outweighing the enjoyment I'm getting out of it.

Spock66 · February 23, 2023

4 hours ago, RK1975 said:

Thanks, I really wasn't sure as I know little of cars.

Can't be certain, but at 10-years and 160k you are probably at the tipping point of where maintenance and repair costs can ramp up significantly.

LexusDave · February 23, 2023

8 hours ago, RK1975 said:

Just had a mobile mechanic out. He thinks that the dual mass flywheel may be misaligned. The car started shaking on startup for a couple of seconds then stopped which he said was a classic sign of it. Does this sound plausible to anyone?

I may be wrong but I think a dual mass flywheel is normally only fitted to a manual transmission! So no it doesn’t sound plausible.

RK1975 · February 23, 2023

11 minutes ago, LexusDave said:

I may be wrong but I think a dual mass flywheel is normally only fitted to a manual transmission! So no it doesn’t sound plausible.

OK thanks for the response. If we assume it's a normal flywheel that was meant, would it make sense then? He did admit he wasn't fully au fait with hybrid automatics, but did say what he saw is very typical of a flywheel misalignment. Given the other circumstances in my original post, the initial suspects seem to be ruled out.

LexusDave · February 23, 2023

No, I think he’s barking up the wrong tree. The mechanics of a hybrid with the CVT drive, I think, is very different to a “normal” drive system.

From what I read on the subject your symptoms do sound like the EGR problem. If you do a search on this forum you’ll find a lot information on it.

diabolik · February 23, 2023

Any differences in behaviour between cold and hot engine?

RK1975 · February 24, 2023

10 hours ago, LexusDave said:

From what I read on the subject your symptoms do sound like the EGR problem. If you do a search on this forum you’ll find a lot information on it.

With EGR though, the RAC said there's no way I'd be able to do 70 mph on the motorway? I'd agree otherwise as my problems do sound very similar to those in other posts.

7 hours ago, diabolik said:

Any differences in behaviour between cold and hot engine?

I'd say it happens more when hot, though more recently it's been happening when starting up. I would still describe it as happening randomly but only at low speed or when idling.

RK1975 · February 24, 2023

It's been suggested to me that I can get the EGR valve blanked off (whatever that means) which will remove this problem (apparently for good). Has anyone heard of this or tried it? I've asked Prof Google and the results are....mixed.

Spock66 · February 24, 2023

I have had an EGR fail (not a Lexus though), other than the MIL light there was no discernible issues.

RK1975 · February 25, 2023

Just had an opinion from a local mechanic who has said it's more likely a faulty EGR valve. He said if it was blocked it'd be shaking all the time, not just intermittently (it started fine when he looked at it). He's suggested I just buy a valve from eBay and pay someone to fit it. He said he could blank it off if I wanted, ten minute job and there'd never be an issue with it again. I'm just really confused now.

Djwbiker · February 25, 2023

I would let your nearest Toyota dealer look at it given the that the Prius and the Ct200 are one of the same. They will have a better understanding if its EGR, spark plugs, leads or coils. Or use and Lexus/Toyota independent if one near enough to you.

Lexus Indie Garages.docx

RK1975 · February 25, 2023

29 minutes ago, Djwbiker said:

I would let your nearest Toyota dealer look at it given the that the Prius and the Ct200 are one of the same. They will have a better understanding if its EGR, spark plugs, leads or coils. Or use and Lexus/Toyota independent if one near enough to you.

Lexus Indie Garages.docx 10.99 kB · 1 download

Hi, thanks for that list. I've found an indi hybrid specialist in the meantime, but there's a repairer on there near work if my one doesn't can't help.

RK1975 · March 6, 2023

Just had the flywheel diagnosed as the problem and told whole clutch system needs replacing. EGR is working fine, valve opening and closing OK. Emissions are good. Been quoted around £3k to replace. Think I'll just trade it in for whatever I can get. I'm never buying a hybrid again!

wharfhouse · March 6, 2023

26 minutes ago, RK1975 said:

Just had the flywheel diagnosed as the problem and told whole clutch system needs replacing. EGR is working fine, valve opening and closing OK. Emissions are good. Been quoted around £3k to replace. Think I'll just trade it in for whatever I can get. I'm never buying a hybrid again!

Very unusual problem to encounter on a Lexus or Toyota hybrid - was that a Lexus dealer diagnosis - if not maybe worth getting a diagnosis from them before getting rid of the car and IMHO for such an unusual problem I wouldn't let it put you off another hybrid - there are many out there running happily with 2x or 3x your mileage.

I had a Honda Accord about 8 years ago that had very similar symptoms to yours - slow speed hesitation but nothing at higher speeds. Reading the codes did indicate a faulty coil and once I tracked down which one it was and replaced it all was well. Also had a car with overdue spark plug replacement some time back and that again showed similar symptoms - didn't try and read any codes with that but changed the spark plugs (you could see the tips were well worn on pulling them out) and all was well.

It may be worth checking spark plugs - were they changed to schedule - could even be faulty one. Coils should throw an error code but I guess there's a possibility they may not. Buying one coil and replacing each in turn should rule that in or out?

wharfhouse · March 6, 2023

If you want to know a little more about the damper and flywheel assembly on a hybrid this video shows you what it is and what it does:

RK1975 · March 6, 2023

5 hours ago, wharfhouse said:

I wouldn't let it put you off another hybrid - there are many out there running happily with 2x or 3x your mileage.

its not the mileage or anything, it's finding someone to repair it. Even indy hybrid specialists are refusing to do the work. Lexus want the best part of 500 quid just to look further at the damned thing. And to add insult that's just to test for one issue they said. Of course, they want to hook it up to diagnostics thing even though 3 others have done so and no error code show. I'm not good with my hands or with practical stuff otherwise I'd take the damned thing apart myself.

Where exactly do these Prius taxi drivers take their cars to, cos I'm betting its not a Lexus dealer...

Las Palmas · March 6, 2023

2 hours ago, RK1975 said:

its not the mileage or anything, it's finding someone to repair it. Even indy hybrid specialists are refusing to do the work. Lexus want the best part of 500 quid just to look further at the damned thing. And to add insult that's just to test for one issue they said. Of course, they want to hook it up to diagnostics thing even though 3 others have done so and no error code show. I'm not good with my hands or with practical stuff otherwise I'd take the damned thing apart myself.

Where exactly do these Prius taxi drivers take their cars to, cos I'm betting its not a Lexus dealer...

Here taxi drivers take their taxis to Toyota/Lexus as they usually do not keep them longer than warranty is on them, and they want to sell them when they get money for them so they can buy new with warranty. They probably get good service as Toyota want them to be returning customers. Not like us that just want to keep the car while hybrid Battery is warranted.

But you are right. Lexus is not a friendly company when it comes to money.

wharfhouse · March 6, 2023

2 hours ago, RK1975 said:

its not the mileage or anything, it's finding someone to repair it. Even indy hybrid specialists are refusing to do the work. Lexus want the best part of 500 quid just to look further at the damned thing. And to add insult that's just to test for one issue they said. Of course, they want to hook it up to diagnostics thing even though 3 others have done so and no error code show. I'm not good with my hands or with practical stuff otherwise I'd take the damned thing apart myself.

Where exactly do these Prius taxi drivers take their cars to, cos I'm betting its not a Lexus dealer...

If it is the flywheel / damper then I can understand indys not wanting to do that. I'm surprised Lexus want that much for a diagnosis though - usually around £150 for that - they will of course hook it up to check - if the people who have run the diagnostics to date haven't used the full Lexus / Toyota diagnostics though they may have missed something more easily fixed. Coils and plugs are relatively easy things to check and troubleshoot - I don't do a lot on my cars but have done those. If you have a friend or family member who can do it worth a go for not much outlay - just a set of spark plugs and one coil that you can use to replace each in turn and see it there is any change. Might even be able to get a second hand coil from a breakers to do the checking - that's what I did on the Honda and then bought a new one to replace the offending one and kept the second hand one as a spare.

wharfhouse · March 6, 2023

Just re-read the thread and you don't say whether the problem is there when the car is on EV mode only or after it has started up the Internal Combustion Engine (ICE) - knowing that might help with a diagnosis - did the others who checked it test in both modes.