P0235 fault code

[Bren]

Our vectra is regularly flagging up the above - boost pressure negative deviation.

Put op com on the car tonight - it showed the above as well as cyl no1 misfire and dpf saturated.

 

Cleared codes and wrung cars neck. Spanner light came on - P0235 was stored. Cleared it and took it for another run.

 

Car does'nt smoke much and turbo does provide boost however arouns 2000 rpm is when spanner illuminates. Does'nt appear to be any leaking boost pipes so I am not sure where to go from here.

Thoughts?

[cobblers]

If the DPF is clogged then it's going to restrict the exhaust flow.

That'll prevent the turbo spinning up properly, which will mean the thing provides less boost than the ECU requests at a particular throttle/rpm, hence your fault code "Boost pressure Negative deviation" = Less boost than it was expecting.

 

 

Disclaimer: I've never been under the bonnet of a vectra and the last time I went in one was in 2005 and it was a taxi

[tommotech]

I've known the EGR valve to cause this by staying slightly open. Boost pressure leaks away and less exhaust gas flow to turbine, i.e. not achieving expected boost.

[Bren]

Time for Mr. Muscle?

 

Ben

Been there done that.

[sierraman]

This is why I got rid of a diesel, I was sick of coming home from work to deal with stuff like this

[Bren]

This will be our last.Because it is the V6 parts are expensive and it is amare to work on - even the local vx specialist will not touch it.

[DodgeRover]

Could you remove the tail pipe/ DPF to see if that fault code goes away?

[red5]

DPF /Turbo. Or both. :-/

 

Try cleaning etc etc and clearing faults. As I'm sure you know.

 

Lovely when running right.

[Bren]

DPF /Turbo. Or both. :-/

 

Try cleaning etc etc and clearing faults. As I'm sure you know.

 

Lovely when running right.

When being the word. Sadly I am not sure it will get sorted - a 55 plate car is worth nothing.

[SiC]

This will be our last.Because it is the V6 parts are expensive and it is amare to work on - even the local vx specialist will not touch it.

Good luck with that! Unfortunately with the rush to diesel, the vast majority of cars newer than 10 years old in this size are diesels. This has been the case for ages and as everyone avoided petrols, you could get a petrol as a bargain. However due to everyone running scared of diesels now, those petrols are being snapped up quickly. Leaving mostly only diesels left.

 

This is the exact problem I'm having at the moment looking for a newer modern as the trusted long term, reliable hack.

[Bren]

Apparently there are a number of "field remedies" (ECU upgrades) for the car which I would imagine the car has never been treated to.

 

I have emailed local vauxhall specialist to see if he can do the flash but i'm not holding my breath. He refuses to work on diesel fuel systems.

[Tamworthbay]

Can you get to the egr valve easily? Even small amounts of dirt build up can cause gremlins.

[SiC]

Main dealer should be easily be able to do the updates too.

[Bren]

EGR is about a 90 min job to remove. I will give it a clean - if I ever get chance.

[Bren]

Does negative deviation mean too much or too little boost?

[SiC]

iirc less Boost than it was expecting.

[Bren]

Could stuck vanes cause this?

[Bren]

 

I wonder if anyone has messed with the stop?

[Bren]

The issue is with the turbo. The compressor wheel is touching the housing. The housing and blade tips have marks.

 

It cannot keep up due to wear/damage and goes into limp mode.

[chatsharris]

Ebay for one being broken and get a replacement? 

[SiC]

You really need to get rid of this liability. Must be able to get a spare turbo easily enough given how many of these Isuzu V6 engines have xasploded over the years.

[New POD]

Could stuck vanes cause this?

 

The Vanes are designed to be closed at low revs so that when you apply throttle, the velocity of the exhaust creates FASTER flow, turns turbine wheel and hence the shaft quicker and therefore more boost achieved  at compressor wheel. In order to keep up  the vanes then gradually open so  they do not become a bottle neck in the system.  The Turbine wheel is sized so that it is bigger than the max exhaust flow, so that you can't overboost at high revs, and therefore don't need a waste-gate.  

The fail safe for the vanes is fully open IIRC - so less boost at low revs, but max boost at high revs, and lots of nasty lag.

[SiC]

Often limp mode on variable vaned turbos limits maximum revs (often 3k ish) so it can never boost.

[New POD]

DSC_0665.JPG

 

I wonder if anyone has messed with the stop?

 

I'm going back 16 years to when I was the manufacturing engineer  who introduced the VNT to The Garrett Skelmersdale plant, just before they shut it and moved it to other parts of the world.

I can't remember having a stop. We set the actuator arm based on a flow rate at a particular exhaust pressure, with a particular actuator vacuum.  But they were developing electronic actuators, and commercial diesel used pressure from air brake system which was regulated by a control unit.  

I think the stop is irrelevant to your problems.

[New POD]

The issue is with the turbo. The compressor wheel is touching the housing. The housing and blade tips have marks.

 

It cannot keep up due to wear/damage and goes into limp mode.

 

The only way to stop the centre housing bearings being destroyed is to ignore long oil change intervals and do it much more often, and also allow a cool down at the end of a run. And no short journeys with cold oil.

You are lucky that blades have not gone into engine. Do NOT run it like this.  

[Bren]

I'm going back 16 years to when I was the manufacturing engineer  who introduced the VNT to The Garrett Skelmersdale plant, just before they shut it and moved it to other parts of the world.

I can't remember having a stop. We set the actuator arm based on a flow rate at a particular exhaust pressure, with a particular actuator vacuum.  But they were developing electronic actuators, and commercial diesel used pressure from air brake system which was regulated by a control unit.  

I think the stop is irrelevant to your problems.

Correct - but I had to consider whether or not somebody has altered it.

I will get an estimate for a recon unit, however if it goes bang in the meantime it's one more vectra off the road.

[Bren]

After doing some research it would appear I have been a bit hasty in condemning the turbo.

 

The shaft has some movement (not front to back) I have been advised that with oil pressure much of the play would be elimated.

 

The fault code relates to too much boost - which means gummed up VNT. I tried Mr Muscle when we bought the car but due to it's location it is nigh on impossible to get it in.

 

I have ordered two bottles of forte turbo cleaner - if it does'nt work then it's a recon turbo.

 

I must admit I am enjoying the fault finding process even though I am not getting anywhere quickly. But on the plus side it has cost me £20 for a cheapo op com and I have sorted egr and dpf faults.

[cpjitservices]

After doing some research it would appear I have been a bit hasty in condemning the turbo.

 

The shaft has some movement (not front to back) I have been advised that with oil pressure much of the play would be elimated.

 

The fault code relates to too much boost - which means gummed up VNT. I tried Mr Muscle when we bought the car but due to it's location it is nigh on impossible to get it in.

 

I have ordered two bottles of forte turbo cleaner - if it does'nt work then it's a recon turbo.

 

I must admit I am enjoying the fault finding process even though I am not getting anywhere quickly. But on the plus side it has cost me £20 for a cheapo op com and I have sorted egr and dpf faults.

There's a video on youtube where some guy drills a hole in the back of his turbo to get in with the Mr Muscle. Sticks a nut in it when hes finished.

 

I really didnt think it was a serious video, but apparently it is serious. This is on the 2.0 TDCI mind.

 

Heres the link:

https://www.youtube.com/watch?v=SFDMd8eVVXo&t=366s

[bigfella2]

If the compressor wheel has touched the housing, then then the turbo has had a overspeed situation, where the fins of the compressor wheel touches the housing. So deffo overboosting, I would be tempted to take it off and get it looked at by a turbo specialist. Had overboost before on a previous car but no damage like you have mentioned, infact current car is currently overboosting, but only if I go above 95