Odd Rev Issue High Rev when low speed

[richard-]

Hi,

Is this normal for a CT to be in high revs at 40mph. For example, i’m driving at about 70-75mph and I take my foot off the gas, or break it starts to decelerate however the engine is still running at 4200rev at 60,50,45mph. Only at around 40mph it will drop to about 1500rev.

Is this normal, as I drove a brand new CT and it didnt’t have this issue.

[ColinBarber]

No that isn't normal. I assume you have it in D and not B?

[stormchaser]

Not normal. I haven’t noticed this.


Sent from my Iphone using Tapatalk

[richard-]

Yes I have it in D, I have the following video, this is with the foot off the gas, and not on brake.

I told lexus when they had the car and they said this is normal for a CVT gearbox. But I have only just recently  noticed it.

It’s difficult to get a video however this is to 75 to 60mph. It seems to do it more when the engine is hot

 

 

[200h]

obviously Richard you had your phone on a mount and you used your voice to start & stop the recording,

as you wouldnt dream of breaking the law would you :-)

as you only have to have your phone in your hand whilst the engine is running nowadays to be fined & get points

[richard-]

That is not me holding the phone, it is my partner, does that look normal from that video?

I will have to try and get anothrr when it does it from 70 to 40mph but sometimes it does it, sometimes it doesn’t.

[Britprius]

As Collin has already asked are you sure your in D and not B mode. I found when I drove both the Prius, and the Ct it was easy to accidentally knock the leaver, and enter B mode. This gives engine braking for long downhill runs, and just this effect..However the dash display clearly shows your in D mode. 

If the HV Battery is fully charged "all green bars" you can also get this as the electricity generated has no where to go so power generated by MG2 goes to MG1 to spin the engine at speed to give engine braking. 

John.

[ColinBarber]

Does it do it if you aren't in Sport mode?

[richard-]

For sure I was in D, it is very rare I use the B mode.

It does do it in normal mode too, here is what lexus wrote when I asked about it.

 

[stormchaser]

Mine has never done this and I don’t believe what Lexus say about it.


Sent from my Iphone using Tapatalk

[ColinBarber]

The reply from Lexus just seems a generic one from someone who hasn't bothered to understand the issue.

Yes the CVT transmission allows engine speed and vehicle speed to be completely independent, however there is no reason why the engine rpm would remain high when it isn't required. In Sport mode it will maintain a higher speed so that power is more quickly available should you need it, hence my question whether it still does this in standard mode.

[richard-]

Yes I still hear the engine running at high speed when in Normal mode as well, the same noise in Sport mode so I assume it is also doing it. 

Anybody know what could be causing this

[richard-]

I’m back with a new video, sorry the girl is not too good at this filming. It definately has the sound of a blocked egr valve or something (not sure if the CT even has one of these)? It hangs onto 4000rpm, and it unecessary using the wrong gears 75mph all the way to 40mph in 4000rev. Mpg is down 5mpg aswell. So does anyone elses do this? Happens in all modes eco/standard and sport

 

 

[rayaans]

7 minutes ago, richard- said:

I’m back with a new video, sorry the girl is not too good at this filming. It definately has the sound of a blocked egr valve or something (not sure if the CT even has one of these)? It hangs onto 4000rpm, and it unecessary using the wrong gears 75mph all the way to 40mph in 4000rev. Mpg is down 5mpg aswell. So does anyone elses do this? Happens in all modes eco/standard and sport

 

 

Could be an EGR valve yes. There are some reports of EGR problems on the Prius and CT which both share the same internals. 

Get the fault codes checked if there are any

Try using premium fuel and a bit of redex, see if that works a bit. 

Also, give it the absolute beans. And I mean it, get the revs to hold at 7k for a bit see if that works

[richard-]

Done it about 5 times (cant get it to 7k only 5k) booked it in at lexus next week and also for a drive with them. Already use redex. They said when I called the CT doesn’t have a EGR?

[Farqui]

The CT does have an EGR valve, ref; http://australiancar.reviews/2ZR-FXE-engine.php

[Britprius]

29 minutes ago, Farqui said:

The CT does have an EGR valve, ref; http://australiancar.reviews/2ZR-FXE-engine.php

Thanks Lee. There is a paragraph in that article that confirms something I had suspected, but not found any proof of regarding the Toyota/Lexus VVT system.

The cold start rattle many have been complaining about is due to a pin failing locking the sprocket to the cam at engine shut down. At start up "after the oil has drained from the VVT sprocket" the sprocket should be locked to the cam by a spring loaded pin stopping any movement. Once the sprocket has filled with oil the oil pressure rises it pushes the pin out of it's locking position and allows camshaft advance.

This pin on some GS's is either seized or it's spring is broken or weak not pushing it into the locked position. The result is the start up rattle many of us are getting after the car has stood for a while. Lexus say this is not a problem for the GS450H, and put up with the noise. In the US the GS, but not the GS450H has a recall for this because it can cause the cam retaining bolts to fall into the timing chain. They say it does not happen with the GS450H because of the different starting method, but there has been a report on LOC of this happening.

The cure is to replace the timing sprockets involving removing all 4 cams at considerable expense. Alternatively a prelube system that pressurises the system before the engine turns over eliminates the problem.

I will shortly as promised give details of building such a system at very low cost.

John.

[Farqui]

Well spotted John @Britprius 

[richard-]

19 hours ago, Britprius said:

Thanks Lee. There is a paragraph in that article that confirms something I had suspected, but not found any proof of regarding the Toyota/Lexus VVT system.

The cold start rattle many have been complaining about is due to a pin failing locking the sprocket to the cam at engine shut down. At start up "after the oil has drained from the VVT sprocket" the sprocket should be locked to the cam by a spring loaded pin stopping any movement. Once the sprocket has filled with oil the oil pressure rises it pushes the pin out of it's locking position and allows camshaft advance.

This pin on some GS's is either seized or it's spring is broken or weak not pushing it into the locked position. The result is the start up rattle many of us are getting after the car has stood for a while. Lexus say this is not a problem for the GS450H, and put up with the noise. In the US the GS, but not the GS450H has a recall for this because it can cause the cam retaining bolts to fall into the timing chain. They say it does not happen with the GS450H because of the different starting method, but there has been a report on LOC of this happening.

The cure is to replace the timing sprockets involving removing all 4 cams at considerable expense. Alternatively a prelube system that pressurises the system before the engine turns over eliminates the problem.

I will shortly as promised give details of building such a system at very low cost.

John.

Thanks Lee & John for the info and that useful link. I did think the car had a EGR as i’ve had diesels before and it makes the exact same noises when blocked or needs cleaning. 

I too have noticed on start a rattle especially when the engine is cold or in winter. Would this be also something I could ask lexus to investigate and rectifying under warranty? I have still the extended warranty in the UK.

 

 

[Britprius]

7 hours ago, richard- said:

Thanks Lee & John for the info and that useful link. I did think the car had a EGR as i’ve had diesels before and it makes the exact same noises when blocked or needs cleaning. 

I too have noticed on start a rattle especially when the engine is cold or in winter. Would this be also something I could ask lexus to investigate and rectifying under warranty? I have still the extended warranty in the UK.

 

 

I would certainly get the car into Lexus for them to investigate. I know the CT had problems along with the Prius for occasional very rough, and noisy start up, and Toyota redesigned the inlet manifold to cure the problem. If you can Video the problem with your phone, and take this along as evidence.

John.

[richard-]

Lexus has fixed the problem by replacing the EGR valve and now it is back to normal. Also they did a software update. 

[Wass]

On 4/28/2018 at 7:36 PM, richard- said:

Hi,

Is this normal for a CT to be in high revs at 40mph. For example, i’m driving at about 70-75mph and I take my foot off the gas, or break it starts to decelerate however the engine is still running at 4200rev at 60,50,45mph. Only at around 40mph it will drop to about 1500rev.

Is this normal, as I drove a brand new CT and it didnt’t have this issue.

Beware the shark sales rep who tells you that they all do that except for the latest models which Lexus have managed to fix!