MR2 Rev2 Boosting issues

[Major combover]

Ever since i got a boost gauge fitted, my car is struggling to boost, sometimes it will hit full boost but then as soon as I change gear it either doesn't boost at all or only reaches around 5 psi. Boost seems to be very temperamental.
I also have an MBC

Any ideas?

[super]

Did you fit the MBC at the same time? Was it OK before if not?

[Major combover]

The MBC was fitted before and was totally fine, this has all started since the gauge was fitted. I have even fastened the vacuum hoses with cable ties.

I have tried adjusting the MBC but but it doesn't make a difference. Boost is still being temperamental

[Pauln]

Assuming it's an electronic boost gauge, it's sounds like a vacuum tube or sender issue. I'd be tempted to revert to your setup before fitting the gauge to see if the problem goes away.

Paul

[Major combover]

Should I unplug the vacuum hose from the sender and block that off with a screw? Since I don't have the stock vacuum hose anymore.

[Pauln]

I'm not sure how you've connected this up at the moment. But if you had it all working OK with the mbc, that's what you want to get back to.

This will then eliminate everything you've done since. If the problem goes away, there's something wrong with how the new gauge is connected. If it doesn't then you've a different issue and it may just be coincidental that this happened at the same time as you fitted the new gauge.

Just removing the sender will only show if that's likely to be the problem.

Paul

[2mad]

Very odd it would start playing up after fitting a boost gauge , if the sensor leaked the turbo would make up the difference by pushing harder (and hotter .. bad)

Mbc has more that likely picked up a fault .

[Major combover]

I have tried unhooking the vacuum hose from the sender and plugging that. Didnt make a difference.

I have ordered myself a new MBC. I do hope thats the issue.

I never thought an MBC could drop the boost pressure to below standard?

[2mad]

I have tried unhooking the vacuum hose from the sender and plugging that. Didnt make a difference.

I have ordered myself a new MBC. I do hope thats the issue.

I never thought an MBC could drop the boost pressure to below standard?

Its ball and spring , if it fails you could get no extra boost (like your getting) or massive creep .


Stock boost is 5 to 7 psi iirr

[Major combover]

Im guessing if there is no tension in the spring there wont be any boost?

And if I had a boost leak, would I still be producing the correct amount of boost?

[2mad]

Im guessing if there is no tension in the spring there wont be any boost?

And if I had a boost leak, would I still be producing the correct amount of boost?

If the mbc has failed .. that would explain no extra boost.


If you have a boost leak that could explain it to .. its very difficult to diagnose faults over the net .. if the new mbc does not help look for leaks and resell it .


Wish i was more help , doing this over the nets not ideal

[Major combover]

Fingers crossed the new MBC will sort it

Going to take it to Pacific Works on Saturday anyway.

Just no fun without boost

[2mad]

Hope so mate .. or a hose clamp just needs nipping up , it happens.

[Major combover]

It turned out all the plumbing was fine, the actuator was getting caught on the downpipe. Sometimes staying stuck open and sometimes closing. Thats the reason for temperamental boost. Swapped the ebay special downpipe for a standard one with gutted cat

[2mad]

That is such a common problem .. glad its sorted