Hello everybody. I have an Evo 7. Can someone describe me how boost leak affects driving? I noticed that when turbo is starting to work, the car starts to shaking, like wants to jump to front. It is not noticeble in the 1st gear, but in 2nd and 3rd gear before shifting in 4000-6000 rpm it is doing it. I changed my spark plugs and it did not change. I am thinking now maybe it is boost leak. But i do not know how it is affecting. Please i am waiting for your replies. It is very disturbing problem.

 

In my car when I was suffering from a boost leak the car would have a drop in power. The turbo would spool but the car would fall on its face.

 

The car has a drop in power. Like it wants to go, but it doesnt get enough air and it starts to jump forward. And also black smoke comes from exhaust. The catback is all black. I do not think it is because of spark plugs.

 

You will run rich if you're not getting air because of the boost leak.

In my car I could hear the air escaping when I was trying to build boost.

 

Thank you for reply. The problem is that i am not hearing anything maybe because of engine noise. But i think if the car is jerking like this, there must be serious boost leak.

 

The boost leak test is done with the car's engine OFF. Just making sure you are aware of that.

Could be possibly clogged injectors, coil packs or plug wires..what are your plugs gapped to?

 

Get an SD conversion and free yourself from such issues in terms of driveability.

 

Yes before cleaning injectors, i was pretty sure that it was because of injectors. But after cleaning injectors, it did not change. I was using ngk iridium and i changed it to stock spark plugs. My car is just slightly tuned by boost controller and gets roughly 340 hp. After these changes, still same thing. I am wondering, is it a serious problem or not. I read threads, it seems like it is not serious one but i do not know what to do.

 

No i meant while i am driving i am not hearing any leak noise.

 

Sorry but i am quite new on these things. What is sd conversion and what is relation of it with boost leak?

 

SD (Speed Density) has nothing to do with boost leak... sort of...

A boost leak will occur whether it's the traditional MAF setup or a SD setup, it's just where the ECU gets its readings is where it differs.

With an SD conversion, even with a HUMONGOUS boost leak, the car will still drive as if there is no boost leak, and you won't have the judder and shudder of a MAF setup with a boost leak. In that sense, the SD is a much more effective and reliable option.

 

You would have to have one hell of a boost leak to be able to hear it while driving.

What I'm trying to say is you cannot hear a boost leak while driving... Hence my statement that a boost leak test is done with the car/engine off so you CAN hear/see the leak with soapy water and pressurized air.

What did you gap your oem plugs to?

 

I sure did.

 

I stand corrected!

 

Ok. But if it is not that big leak, can it affect the that much? I mean car is not going, losing power at some point and i forgot to say, it blowing up like explosion from the exhaust. Can a leak cause those problems?