Volvo V40 ph1 T4: Too much boost after installing MBC

[edang]

Hi,

I'm driving a Volvo v40 T4 MY '98. I'm having a problem with the turbo pressure at higher revs in all gears when full accelerating. Because of the pressure getting too high, the fuel cuts off which results in the T4 shocking and holding back like I was hitting the rev limiter. However, the T4 still keeps going. My boost gauge shows between 13 psi and 17 psi boost.

Too make sure the problem wasn't the Boost Control Solenoid, I tried to bypass it by connecting the red inlet with the yellow outlet, keeping the blue inlet untouched and connecting the turbo outlet directy to the actuator. However, I still got too much turbo pressure.

These problems started today, after I installed a universal MBC on the hose between the actuator and the yellow connection on the BCS. This worked fine, boost builds up fast untill I got the point where I opened up the MBC too much and pressure got too high causing fuel cut off. After I took out the MBC, the problem didn't go away.

My guess now is dat my wastegate actuator is failing. I think it is leaking so there's a lack of pressure to open the wastegate hence pressure in the turbo is getting too high, causing the engine fuel cut off. Would that be plausible? Could installing an MBC cause the actuator to break down?

Thx in advance for your replies,

Ed
The Netherlands

[diro]

dont take it as an offense or insult but installing MBC is a dumb idea tbh.
only a proper chip tuning will do the job. ECU soon or later will start to mess about and you will destroy your engine if keep using mbc. Playing with that u must have a bit more knowledge.
but this is your choice

[edang]

I don't feel offended. But I am a person that likes to try things myself. If it fails, it fails. That's the risk I take. As far as I can tell, MBC's don't necessarily screw up your car. I wasn't hoping for an endless pro-/con- discussion, tho...

[diro]

1. get a hose long enough and appropriate diameter to get fitted one hose end on the wastegate. put another hose end to your mouth and suck an air creating a vacuum. If wastegate is OK you should feel the vacuum all the time. Do the same procedure with TCV. Check the rest of the hoses if no cracks, splits.

2. connect diagnostics tool to identify trouble codes and erase them. It will be trouble codes stored in engines ecu memory definitely. If any chance - watch live data stream.

[edang]

Thank you for this.

[andyv40turbo]

lots of people on here skip the mbc route and just adjust the wastegate actuator, using a boost gauge to calibrate. Dont know if that is any better though!

[edang]

I just tried to suck some air out of the actuator, but the air keeps coming through. I can also blow air in and it almost feels like the air is coming out at the actuator. I think I can tell for sure that the actuator is leaking...

Regarding the adjusted wastegate actuator, I can buy a 1,2 bar wastegate actuator (Kinugawa) from another person who had it installed previously in his T4. I'm thinking about this option. What I can also do is to get the leaking actuator out and try to repair the leak if possible (i've read it can be done properly) with a bicycle repair kit ( ).

[ThroughLou]

I had to adjust the actuator to get it to boost up 19psi. It just takes lots of playin around to get it right

[960kg]

Originally Posted by andyv40turbo

lots of people on here skip the mbc route and just adjust the wastegate actuator, using a boost gauge to calibrate. Dont know if that is any better though!

You have to be careful with the LPT 2litre T3 code at the safe max. is 12psi

This engine is not strong like the `98 T4 1855

Stick to the actuator!!

Originally Posted by edang

I just tried to suck some air out of the actuator, but the air keeps coming through. I can also blow air in and it almost feels like the air is coming out at the actuator. I think I can tell for sure that the actuator is leaking...

Regarding the adjusted wastegate actuator, I can buy a 1,2 bar wastegate actuator (Kinugawa) from another person who had it installed previously in his T4. I'm thinking about this option. What I can also do is to get the leaking actuator out and try to repair the leak if possible (i've read it can be done properly) with a bicycle repair kit ( ).

I would not go the Kinugawa route as there psi is all over the place and you cannot adjust it to get it correct, wildly wrong!....on what i have read over the forums. Soooo take your own chance.

You can`t repair the leak as it is enclosed in the metal cylinder thingy with a folded over flange....then if you do successfully get it out how do you repair the split as it is strong rubber!

Only my opinion but the Volvo repair kit which is the actuator was £210 and add VAT some 6months ago but Forge do an adjustable one for the T4 at about £147`ish without me checking.

The Volvo one is special order from Sweden only so a bit of a wait...

The only other thing is a 2nd hand turbo from ebay!

[edang]

So, at what psi does the fuel cut-off come in?