So I just had my car tuned and everything is great for about a week or two. I am on the highway, downshift to pass, and suddenly I hear my BOV and it feels like I have lost ALMOST all of my boost. I have had some problems with the couplings on my UICP not holding but but have made adjustments but figured that must have been it. I was wrong. All my piping seemed fine when I pulled over. I didn't see anything obvious but the car seemed to run decent enough for me to get home. The thing I did notice, was the when all my boost kicks in it was pretty underwhelming. I tried to stay way out of boost though (except for my initial test to see if it was just a fluke).

When I got home and opened her up, I found that the hose from my boost controller (AEM) was not connected to the wastegate actuator. I reconnected it and figured that must be the problem. I reconnected it and still wondered why it had come off but reasoned that I must be all better.

Well I was wrong and it is still driving the same way it was with the hose disconnected.

This is my first turbo'd car so the wastegate thing is new to me. I know what it does, just not how it does it and more importantly, how it can fail.

TLDR: Can anyone suggest how to check the Wastegate actuator/ Wastegate to verify everything is working corectly?

 

Check to see if your wastegate arm is still connected to the flapper door thingy.

 

So I read around and checked the wastegate. It opened at what seemed like the right pressure. Looks all good. So back to the drawing board. The last thing I had not replaced (from the previous owner) was the "HKS" bov. Well I got suspicious and pulled it apart and low and behold, (A) I think it is a knock off and (B) had a broken plastic piece on the vacuum side.

I replaced it with a new REAL HKS BOV 4 (I already had all of the flanges and parts to make it recirc). Hooked everything up and took it for a test drive, and BAM, same thing.

To reiterate the problem, when I am WOT in max boost the revs will still climb, but I will not really accelerate (if I am accelerating, I don't notice it). If I back off just a little bit it jumps back to accelerating for that amount of throttle.

I am stumped.

 

Spunds like the wastegate arm is not keeping the wastegate flapper shut causing the really late spool. Check your wastegate arm that when the wastegate is closed fully you are barely able to pull the arm over the hook.

 

So if I apply pressure to the actuator, and the arm moves out, it is opening right? Basically, what it is like now, if i remove the arm, it is difficult to put the arm on. If it is closed with no pressure applied then it seems like it is keeping the flapper shut.

Is it possible my AEM boost solenoid is not holding the boost when it gets too high?

I am really grasping at straws.

 

Sounds like a boost leak. Have you tested for a leak?

The confusing part is you say you hit "max boost." What is max boost? Then you say your revs continue to climb, but you don't really notice any acceleration.

If you're hitting your regular boost numbers and the revs continue to climb normally, you should accelerate normally unless you are driving on a treadmill.

My guess is the boost isn't as high as it was before, or the boost curve is flat.

Since the hose popped off the wastegate actuator, perhaps there was some sort of backlash that forced it off? Maybe the backlash broke the actuator? Was the test you ran on the wastegate a reliable test?

Another thing I've seen happen that's produced similar symptoms is a stuffed catalytic converter.

 

Yea sorry about not being clear. By max boost, I mean acording to my tune, I should be hitting maximum boost at about 5500 RPM (I think but I am pretty sure it was something like that) at WOT. I do not have a boost gauge installed so I don't know for sure, but I am fairly confident that I am not hitting the same boost numbers.

I am going to read up on doing a boost leak test.

As far as the test on the wastegate goes, I think it was pretty reliable. I hooked a pressure gauge in line with a manual pump, then pumped it up slowly until it moved. It looked to be around 11psi or so and seemed to move fully. I did it without the wastegate flap attached then again with it attached and it seemed to work correctly.

As for the cat, I dont have one. I currently have a test pipe installed.

 

That sounds like a slipping clutch to me. If you have tested your wastegate and it's holding fine, and you're hitting your target boost, than it's gotta be something else. Does it only "not accelerate" when you jam on the throttle? What if you roll into it softly or only go 70% throttle?

 

Dont stock wastegates have a 6lb spring?

 

12

 

I don't know if I am hitting my boost numbers since I don't have a boost gauge. That my bad. What I mean by "max boost" was at that point, my tune should be at max boost. I am going to do a boost leak test and hope I just need to tighten something. Otherwise I think you are right, the next thing seems like it would be the clutch slipping.

 

ok so install boost gauge 1st and check the boost when the issue occurs. Be sure to check all vacuum hoses going to intake manifold, BOV and actuator. if you dont have one already, get a datalogging cable and log the car so you can see what is really happening.

Then post back

In the mean time do a proper boost leak check and post numbers

 

Whatever you happen to "mean" by "max boost" is not worth a whole lot in the greater scheme of things. So, get a gauge, dude!

It is a cardinal sin on EvoM to be attempting to adjust boost level w/o a boost gauge. This is true on an Evo or any other forced induction conveyance. You are batting in the dark. Get serious, puhleeze! .