Volvo V40 ph1 T4: Too much boost after installing MBC

[gazO2V40T4]

Check the forum but I think someone posted that 95 Ron fuel can burn the valve seats if used for a long period of time !!!

[bigyin85]

when i first got my t4 i ran it on the 95 ron fuel, ran ok but when i found out that the t4's should be ran on v power, i changed it to that. what a differance it made, i found my t4 starting better, the engine runs better, more power and the car just sounded alot healthier.

give it a try, it might help your problem mate

[edang]

My tank was almost empty so I threw in Shell V-Power for a change

Ok, today I disconnected the hose (that comes from the actuator) from the BCS, so no air pressure controlling the actuator. Result: it seems the turbo's building up more pressure (going 19 psi), but the engine still keeps stuttering.

I disconnected the MAF sensor and then I experienced a clear loss of power, engine holding in. Totally different story. Dashboard showed lambda warning (which would be normal I guess) but also DSA warning (why?). I reconnected the MAF sensor, but my lambda warning is still showing. Is that normal and should it be reset at the garage? The DSA warning light disappeared by itself.

So, is it safe to say that the MAF sensor is not the cause of my problems?

Too bad, I can only have my ECU read next week Thursday

[Dean1985]

Not sure about the DSA light coming on when unplugging the MAF but after 4-5 starts the engine light will go by itself. Just a thought for you though, have you checked the connection plug going onto your coil packs is not corroded? On the bottom of the plug you can unclip and release the bullet connectors and check the wiring for corrosion.

Dean

[edang]

I have just been searching on the internet, untill I stumbled upon topics about the DSA module failing. What happens is that the DSA module limits torque. Could it be my DSA module failing by constantly intervening, causing the stutters (torque limiting) while in full acceleration? Though, the DSA warning sign doesn't come on when stuttering.

Edit: Nope, at least switching off the DSA by holding the DSA button down for a few secs doesn't change a thing.

[960kg]

So your getting there gradually.....

Because the boost was greater when you took off the red hose it shows that the BCS/TCV is faulty.

Although you say the "plugs look ok"....that isn`t sufficient really on a fussy engine like the T4......how many miles have the plugs done?...if over 10,000 replace them although Volvo recommend 34,000 in reality the performance drops right off if you do this.

If you don`t put new Volvo plugs in then at least adjust the gap to .75mm as they will of worn wider over the miles.

If it were my motor i would just do plugs first as they are the cheapest thing to get correct, these in there self are the most likely cause of misfires also check the leads and coils for cracks.....on the coil pencil tubes make sure the spring on the end protrudes 5mm from the tube.

The BCS is about £53, i wouldn`t buy 2nd hand as that will probably be duff as well, you can`t tell by just looking at it, so the chances are money wasted unless your lucky!!

If after the above it still stutters then fit a new large fuel filter by the rear wheel and then if no good a new fuel pump.

[edang]

960kg, why would the bcs be faulty when the turbo pressure gets higher when the hose is disconnected? You mean like air is escaping from the bcs when all hoses connected normally?

[edang]

I just took off the heat shield so I could take a look at my turbo. I noticed that the wastegate valve (the one the acuator rod is attached to) can be slightly moved vertically, it feels a bit loose. Is this normal?

I also checked what happens if I push the throttle without load. Just before hitting the rev limiter, I can clearly see the actuator rod slightly move forward.

[960kg]

Originally Posted by edang

960kg, why would the bcs be faulty when the turbo pressure gets higher when the hose is disconnected? You mean like air is escaping from the bcs when all hoses connected normally?

The BCS controls the boost in 1st and 2nd gear to about 10/12psi approx.

when you get moving WOT in 3rd, 4th and even 5th the boost will be the max.the actuator is set at 14psi or with 3turns of the actuator 17psi and 4turns 19psi.
So if you are set at standard about 13/14psi and when you disconnect the hose it reaches 19psi or more the BCS is then faulty as it is not allowing full boost!

Originally Posted by edang

I just took off the heat shield so I could take a look at my turbo. I noticed that the wastegate valve (the one the acuator rod is attached to) can be slightly moved vertically, it feels a bit loose. Is this normal?

I also checked what happens if I push the throttle without load. Just before hitting the rev limiter, I can clearly see the actuator rod slightly move forward.

Up and down movement of the large pin on the wastegate does not really matter it will even be worn elongated which is worse as the boost will leak somewhat until all is expanded and really hot like a motorway drive.

You shouldn`t really rev. the engine to the limiter with no load on it and as with the turbo no load equals no boost just a flicker of the actuator rod.

[edang]

Ah ok, I got it, totally clear now.