Hey everyone I’m looking for some help with a possible boost issue I’m having. I have an evo 7 that is tuned to boost to 1.6 bar. Lately it has been getting to 1.2 bar as fast as it normally does but once it gets there, it takes some time to get to 1.6 bar which the car holds well once it gets there. Before this started the car would get to 1.6 bar very quickly and hold well. I have done a boost leak test and found some small issues that I fixed. I also replaced the throttle body shaft seals since they were leaking too. I have replaced my aftermarket boost control solenoid with another one, I replaced the wastegate actuator, replaced all the couplings as well as all the clamps with t-bolt clamps. The only seals I haven’t replaced yet have been the fuel injector seals but I have them ready to go with a new fuel rail ready to go when I have time to replace it. I’m just seeing if anyone has run into something like this or if anyone could give me some other ideas of things I could look at.

 

Perform boost leak test by pressurizing the plumbing to boost pressure range

make sure to disable crankcase air venting return pathway (on compressor inlet) to avoid pressurizing crankcase

 

i already performed a boost leak test and nothing major showed up except minor issues and throttle body shaft seals that I ended up replacing.

 

You filled all the plumbing from the compressor cover to the engine with air pressure using and air compressor? And it held tightly for 30~seconds at least?

If so you may have a chipped/damaged turbine wheel or something like that.
Or an issue with the boost controller.

Boost is a result of resistance to flow, flow which originates at the compressor outlet. So either the compressor isn't outputting what it used to, or the engine isn't receiving the output (its leaking out), or the controller isn't doing itsj job. I can't think of anything else... hmm... I Mean there are exotic issues such as maybe a camshaft suddenly retarded 20* or something like that.

 

I went back in and performed another boost leak test and found the injector seal that meet at the intake manifold were leaking under higher pressure. I popped them out and saw they were cracked/dry rotting away. I replaced them and my boost is back up to where it should be. I am going to be replacing the exhaust manifold gasket along with the turbo to exhaust manifold gasket since they are original parts. It’s more for peace of mind at this point but I’d rather know I replaced everything I could short of the turbo.

 

told ya lol. its usually a boost leak... the simplest things, the last thing you check, the cheapest thing, always do those free tests first
happy motoring and I hope this learned you a thing or two