VP D4 possible turbo problem?

[Nick Wight]

We've only been out a couple of times so far this year, but I have noticed that with a wide open throttle the engine will not rev above 3000rpm , speed will not rise above 20knts and fuel consumption is up by almost 30%. Unfortunately I did not think to check the turbo boost reading, as I assumed that all of this might be due to bottom fouling. She is booked in on the 30 April for a lift out to sort that.

However, yesterday I started the engine on the berth to let it run for a while and I noticed that with throttle only (gear disengaged) the engine would not rev above something like 1700rpm. The turbo boost was zero at 700rpm tickover and very reluctantly increased to around 70kpa, accompanied by a significant whining/moaning noise from the engine bay.

I seem to recall previous posts of similar problems and the possibility of a faulty sensor (IAT??) being talked about??

Before I get our usual engineer to take a look, I wondered if anyone has any thoughts about this, as I also recall that to replace the sensor is a straightforward "DIY" job.

Nick Wight.

 

[julians]

There's is a built in rev limit that won't let the engine rev past something like 1500rpm in neutral. So your lower rev limit in neutral is a red herring.

 

[julians]

Does your boat have one engine or two? I presume just one engine, but If two are Both engines affected the same?

From the description it could well be due to fouling,can you see the Hull, does it look dirty?

 

[Nick Wight]

Hi Julians -- wow that was a fast response!

It's a single engine and I think that there will be a fair amount of fouling, but I can't really see it -- bit cold to jump in at the moment!

Thanks for the info about rev limit in neutral and it does sound like that's a red herring. I think I'll wait now until she's lifted out and review the situation after that.

You know what it's like: almost all post winter jobs completed, so there must now be a new issue to deal with!

Nick.

 

[Andy Bav]

We've only been out a couple of times so far this year, but I have noticed that with a wide open throttle the engine will not rev above 3000rpm , speed will not rise above 20knts and fuel consumption is up by almost 30%. Unfortunately I did not think to check the turbo boost reading, as I assumed that all of this might be due to bottom fouling. She is booked in on the 30 April for a lift out to sort that.

However, yesterday I started the engine on the berth to let it run for a while and I noticed that with throttle only (gear disengaged) the engine would not rev above something like 1700rpm. The turbo boost was zero at 700rpm tickover and very reluctantly increased to around 70kpa, accompanied by a significant whining/moaning noise from the engine bay.

I seem to recall previous posts of similar problems and the possibility of a faulty sensor (IAT??) being talked about??

Before I get our usual engineer to take a look, I wondered if anyone has any thoughts about this, as I also recall that to replace the sensor is a straightforward "DIY" job.

Nick Wight.

Fouling likely an issue.

In Torquay, on the way back from a service in Darthaven with clean everything, we managed 22 knots at c2,200 revs and were burning c55 LPH (twin engines). 6 months later, to achieve the same speed we were close to WOT and burning over 100LPH, and she just felt sluggish. After a few days of blatting about we were somewhere between the 2.

Are your props clean also - that was also highlighted as an issue for us, as well as fouling on the legs which will literally drag your performance figures down.

 

[Irish Rover]

On my last boat I had a similar problem on two separate occasions about 5 years apart on my VP D4 and both times it was a faulty oil pressure sensor.

 

[snowbird30ds]

At idle I wouldn't expect to see any boost and not much at 1700 so that is not enough to start paying out on turbos, if it's coming out for a clean anyway wait to see what difference it makes.

 

[volvopaul]

We've only been out a couple of times so far this year, but I have noticed that with a wide open throttle the engine will not rev above 3000rpm , speed will not rise above 20knts and fuel consumption is up by almost 30%. Unfortunately I did not think to check the turbo boost reading, as I assumed that all of this might be due to bottom fouling. She is booked in on the 30 April for a lift out to sort that.

However, yesterday I started the engine on the berth to let it run for a while and I noticed that with throttle only (gear disengaged) the engine would not rev above something like 1700rpm. The turbo boost was zero at 700rpm tickover and very reluctantly increased to around 70kpa, accompanied by a significant whining/moaning noise from the engine bay.

I seem to recall previous posts of similar problems and the possibility of a faulty sensor (IAT??) being talked about??

Before I get our usual engineer to take a look, I wondered if anyone has any thoughts about this, as I also recall that to replace the sensor is a straightforward "DIY" job.

Nick Wight.

Start with a clean hull , I don’t think you have an issue other than a dirty hull .

 

[Nick Wight]

Thank you all for your comments and information and I now feel confident that it is most likely to be a dirty hull problem and I will now wait and see what she's like after the hull clean. I fooled myself into thinking that there must be another serious problem somewhere!!

Nick.

 

[[2068]]

Thank you all for your comments and information and I now feel confident that it is most likely to be a dirty hull problem and I will now wait and see what she's like after the hull clean. I fooled myself into thinking that there must be another serious problem somewhere!!

Nick.

I've found that propellor fouling can also make a massive difference to D4 performance.
That could be because they are relatively small and fast spinning (at least, they should be fast spinning ).
Get the props really smooth too ...