Boost Issue

[djx11b]

Doing my head in so couldn't leave it back out for a tinker on my break at work

Found the vacuum pipe going from manual boost controller to the turbo had came off so 4 new hose clips all round. This has now cured my overboost issue 1.1 bar and no more no matter how hard I push it. One thing off the list

Higher Revs boost issue still there

Noticed when in 2nd gear will go up to about 5500 rpm before boost drops but when in 3rd or 4th gear boost drops at 4000 rpm.

Car running great apart from this high end boost goes really well so might just live with it as unless racing up at crail or knockhill which I don't do to often then I will never go up over these revs with my normal day to day driving

any other suggestions on what to change or do before i give up ??? ( codes and dump valve is my last two things to try)


Have ordered a new dump valve fitting kit so I will be able to move it to the front pipe as the fitted one is to small tried to do that this afternoon.

[960kg]

You cannot splice O2 sensor wires!!

You have something badly wrong as 1.1bar is only a c*ck over standard and you are forcing it by using an MBC to get it

You should be able to get 1.3 easy without a MBC if the engine and components are running properly.

You can`t jump any procedures to get a result you may even get engine damage over a short time because of the wrong AFR`s the MBC is giving you.

Still everyone to there own!

[djx11b]

It's 1.1 bar as I have set it at that if I want it to go higher I can adjust my mbc and it will go higher but I'm happy at 1.1 bar and it is not over boosting now. I believe the volvo bcv was not holding the extra pressure from the uprated actuator 0.8 bar one and that is why I fitted a mbc to limit it to the 1.1 bar I wanted and to stop overboost which it has now.

I looked at the posts you sent about lambda but my chassis number doesn't seem to match any of them it is all original wiring and positions so I will need to contact volvo to make sure the new one I get will be the same and not the short underneath one that won't work on my model because of length.

[960kg]

Originally Posted by djx11b

It's 1.1 bar as I have set it at that if I want it to go higher I can adjust my mbc and it will go higher but I'm happy at 1.1 bar and it is not over boosting now. I believe the volvo bcv was not holding the extra pressure from the uprated actuator 0.8 bar one and that is why I fitted a mbc to limit it to the 1.1 bar I wanted and to stop overboost which it has now.

I looked at the posts you sent about lambda but my chassis number doesn't seem to match any of them it is all original wiring and positions so I will need to contact volvo to make sure the new one I get will be the same and not the short underneath one that won't work on my model because of length.

Sorry, if i misunderstood but that is how you wrote it!

[mitchyboy01]

Originally Posted by 960kg

You cannot splice O2 sensor wires!!

You have something badly wrong as 1.1bar is only a c*ck over standard and you are forcing it by using an MBC to get it

You should be able to get 1.3 easy without a MBC if the engine and components are running properly.

You can`t jump any procedures to get a result you may even get engine damage over a short time because of the wrong AFR`s the MBC is giving you.

Still everyone to there own!

Of course you have to force it to hit 1.1bar! It's a 0.6bar actuator!! The BCS has to force it to hit 1.1bar too! He brought a MBC to keep the boost DOWN as the BCS can't control the new stronger actuator well enough. If he bought the 18psi actuator as you suggested he'd be struggling not to hit 2bar using BCS as the ecu is mapped for the BCS duty cycle on a stock actuator and wouldn't be able to control it. He is hitting 1.1bar with MBC easily, he's not forcing it at all. He could run a lot more boost if he wanted too. He has SET it to 1.1 bar as this is where he wants it.

As for wrong AFRs? What are you on about? The ECU fuels as per MAF values based on airflow on WOT. MBC will not change this.

[960kg]

Originally Posted by mitchyboy01

Of course you have to force it to hit 1.1bar! It's a 0.6bar actuator!! The BCS has to force it to hit 1.1bar too! He brought a MBC to keep the boost DOWN as the BCS can't control the new stronger actuator well enough. If he bought the 18psi actuator as you suggested he'd be struggling not to hit 2bar using BCS as the ecu is mapped for the BCS duty cycle on a stock actuator and wouldn't be able to control it. He is hitting 1.1bar with MBC easily, he's not forcing it at all. He could run a lot more boost if he wanted too. He has SET it to 1.1 bar as this is where he wants it.

As for wrong AFRs? What are you on about? The ECU fuels as per MAF values based on airflow on WOT. MBC will not change this.

I knew you would poke your nose at me as soon as i wrote it!

Why do all your post`s dig at me when i am talking to the OP??

He said absolute max at what he adjusted boost to READ HIS POST

so i replied, then he says it will go more if he re-ajusts so WTF does that mean?

The ECU does not just fuel on MAF readings it needs the O2 sensor readings as well to give the correct AFR and not ONLY WOT and we all know you can get almost full boost at 3/4`s full throttle so at what opening do we get CLOSED LOOP. If the O2 sensors are not reading correctly the ECU together with the MAF input cannot give the correct AFR and may do damage at higher revs.

It is well known that an MBC tends to give very weak mixtures at a high psi , why don`t you ask your friend with the fastest T4 in the world?

To get the correct Boost you need the ECU to receive the correct fuel amounts from the O2 sensor readings and the air volume readings from the MAF.

So get off my back!

[mitchyboy01]

Originally Posted by 960kg

I knew you would poke your nose at me as soon as i wrote it!

Why do all your post`s dig at me when i am talking to the OP??

He said absolute max at what he adjusted boost to READ HIS POST

so i replied, then he says it will go more if he re-ajusts so WTF does that mean?

The ECU does not just fuel on MAF readings it needs the O2 sensor readings as well to give the correct AFR and not ONLY WOT and we all know you can get almost full boost at 3/4`s full throttle so at what opening do we get CLOSED LOOP. If the O2 sensors are not reading correctly the ECU together with the MAF input cannot give the correct AFR and may do damage at higher revs.

It is well known that an MBC tends to give very weak mixtures at a high psi , why don`t you ask your friend with the fastest T4 in the world?

To get the correct Boost you need the ECU to receive the correct fuel amounts from the O2 sensor readings and the air volume readings from the MAF.

So get off my back!

Get off your back? I'm just sighting look further than your own nose fella.

Where did I mention O2 sensors? I was talking about your vendetta against the MBC when if you look at the options it's the best for the OP without spending 100s.

You said a MBC will mess up AFRs! It won't! A bad O2 will but I never mentioned the O2 so why get on my back about that? My point was about the MBC. I ran 20psi on a bigger turbo through a MBC and the AFRs were steady if getting a little richer nearer redline which is no bad thing even without a map. And I'd hardly call the OPs 1.1 bar high... as you said it's not much more than stock. Do you have an AFR gauge? Has your car been near a rolling road? How do you know the HLM map isn't lean, plently have been. I admit, an MBC is not IDEAL, but given the OPs situation, if he wants to stick with the actuator he has it's the only way to control his boost without a custom map. MBCs are not the devil you say they are, they are just not IDEAL.

[scoobysn7x]

TO be honest I don't understand why you don't pop it in to one of the two garages I mentioned and let them diagnose the issue rather that keep swapping out/ buying new parts, my T5 was in voltech today for a wheel bearing and it was only £40 labour charge so I'm sure it'll be cheap enough for them to have a butchers, Paul (ex volvo mechanic) knows his stuff and is reasonably priced, just my thoughts, I had issues when I first got my T5 was back to the garage I brought it from twice and once to another garage in the same franchise, they couldn't solve it couple of hours at volvomax and that was it sorted....

I enjoy working on my car and do what I can (I replaced the gear knob and steering wheel on my T5) but at the end of the day I'd rather pay someone who knows what there doing and that I trust to sort any big/complex issues, I had a problem with the ambient temp sensor and voltech sorted it for £30, & £15 of that was the part, now I probably could have done it (swapped the sensor) but it probably would have taken me 3 times as long and I probably would have broken something..

[djx11b]

Thanks for all the input don't want to make anyone fall out

blanked dump valve off tonight and took it out 5 miles ran like a dream then when up to higher temp it started again

going to scan it for codes when my reader comes then if nothing after that will be trying the garage you suggest as ran out of ideas

would like to fix it myself but doesn't seem to be happening so will let someone else have a crack at it

[mitchyboy01]

Dont worry mate. Me and Keith always fall out but at least it makes for good reading lol. Always say we need to meet up but I'm scared we will have a punchup haha

Good luck with the car mate. Keep us posted.