Overboost... Wastegate problem possibly?

[PewterCam]

This is my First turbo car and want to be sure I'm diagnosing this correctly. this will get technical but I know we have some seasoned turbo people here that should get what I'm at. Try and follow along.

I started to have an overboost issue today. I swapped CAI from FFTec to the Vargas, changed plugs, oil, and now the car overboosts. I know the problem is not going to be related to the intake, plugs, or, oil at all. I believe its just coincidence and noticed some inconsistent boost the past month anyhow. Now when I get on it it will hit 26+ even at part throttle and reached the 29psi limit once during a WOT run which put the car into limp mode. Car is full bolt on's, DP, FMIC, exhaust, Charge pipes, Spraying water/meth, and currently using a local tunners tune on Cobb. it has 23K on it. The daily drive slot is a conservative 20psi. I still run the stock Wastegate. I also have the tune+ lifetime tune but I think I only sent in one revision and that was a long wile ago and went with a Dyno tune instead to learn more about the car. I have Cobb ATR for the car which I've used only to learn about the car and how this all works. 90% of the time I've been using the Dyno tune from the local tunner with no problems until recently when I've noticed the boost get less consistent and occasionally creep into 23-24 psi on the 20psi tune but didn't think much of it. Now anything past 60% throttle puts it over 25psi.

what I've done thus far...

If I put small amounts of air pressure into the wastegate it opens and closes and appears to operate fine. I don't have a way to accurately metering the air pressure though other than knowing its below 20psi. The actuator rod is not loose and I've not touched that at all. I checked all the lines to and from the Boost control solenoid and those are all fine with no leaks. I checked for boost leaks overall and did find one at the BOV mount which I fixed. Next I made a quick tune using Cobb ATR based on Cobb stage 1 and changed the WGDC on the 2nd slot to WGDC Mode to 3 and zeroed out the cobb wastegate table for that slot also did a TIP limit of 29psi to stay super safe. Basically I kept the car running on the wastegate only with no input from the solenoid. Logs all have the WGDC at 0 the whole time. I took it for a drive and a short WOT in 3rd from 3500-4500rpm and still reached 15psi and hit the TIP limit I set which closed the throttle. When I did this in the past it would only hit 8-9 psi. So something is not right in the boost control of the car.

This seems to point to the wastegate? I think?? What would fail in a wastegate to cause it? I have the Tune+ WGA in the box. I can install that but am not all that confident on what to change in the tune for the high spring pressure WGA but I can drive it on wastegate only until I reach the tunner. I don't want to have to do another dyno tune though. Just want to get a little input on it before I dive into the wastegate more. I might dig around Home Depot and see if I can make a more accurate rig to test the Wastegate pressure. Also I figure the Wastegate should hold pressure as well which I didn't check before.

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[Chef jpd]

I would use a mightyvac type vacuum pump, like the one used to bleed the brakes. It has a gauge and you can see at what pressure the WGA opens and if there is a leak.
I'm thinking that the only way for the WGA to fail is if the diaphragm is cracked or ruptured.
Would it make sense that if it was damaged, the wastegate would not be opening fully and you would get an overboost condition?

Mightyvac mv8000. Amazon has it for $35.

 

[Edkiefer]

What he said ^^

You need to check if it hold pressure w/o any leakage.
mightyvac is best for this, also check all manifold hoses, like the ones to map sensor, a leak here could cause higher boost.
Also check all hoses at boost valve.

I would run stock tune and see if same higher boost shows, if so you then know its mechanical (not tune related)

 

[PewterCam]

Definitely not tune related. I tried stock tune, Cobb stage 1, and I adjusted the tune to run off the wastegate only which should only be 8-9 psi but will still overboost well past that.
Mightyvac is an excellent idea. I have one around here with a broken gauge and I do have a boost gauge laying around and lots of vacc line and t fittings. It will work to see if it holds pressure. Thanks guys for the ideas!

 

[Juben]

I would double check the lines to/from the Boost Control Solenoid (BCS). The BCS lines tend to be kind of fragile and I've seen people fracture them when installing intakes before.

Given what you've described, I too don't think it's a tune issue. I really don't think it's probably a wastegate issue either given the fact that you said that it's opening and closing properly, etc. The BCS would be my main source of attention followed by the wastegate.

In any event though, it's not good to have your boost going out of control like that. Since you already have lifetime tunes with Adam, shoot him an email and see what ideas he might have about it too. Perhaps there's more that you could log and provide to him for better insight on what's happening.

 

[5.0yote]

I would doubt check the lines to/from the Boost Control Solenoid (BCS). The BCS lines tend to be kind of fragile and I've seen people fracture them when installing intakes before.

Given what you've described, I too don't think it's a tune issue. I really don't think it's probably a wastegate issue either given the fact that you said that it's opening and closing properly, etc. The BCS would be my main source of attention followed by the wastegate.

In any event though, it's not good to have your boost going out of control like that. Since you already have lifetime tunes with Adam, shoot him an email and see what ideas he might have about it too. Perhaps there's more than you could log and provide to him for better insight on what's happening.

^ this...... IF you changed nothing other than working around or near the EBC I would check the boost signal line to the wastegate, crack, unclamp it or cut it by accident and you will overboost easy. Since you were near it, it would be my first place to look.

 

[Berstuck]

Did you ever solve your problem?

 

[ronemca]

Did you ever solve your problem?

opcorn:

 

[ronemca]

Resurrecting...

I am still interested to hear the solution to this.

 

[PewterCam]

the issue with mine was a failed spring clamp on the vac/boost line from the WGA to the solenoid. The spring clamp had a chunk stamped out of it. probably a mfg defect. the clamp held fine when cold but ended up leaking after It was hot and in high boost. I actually replaced the hard line with regular vacuum line and 2 stock spring clamps and no problems since.

 

[5.0yote]

the issue with mine was a failed spring clamp on the vac/boost line from the WGA to the solenoid. The spring clamp had a chunk stamped out of it. probably a mfg defect. the clamp held fine when cold but ended up leaking after It was hot and in high boost. I actually replaced the hard line with regular vacuum line and 2 stock spring clamps and no problems since.

9/10 times if its too much boost and easy to hit peak 29psi it will be the wastegate or the signal to it was broken. I hate spring clamps, I changed all mine out for traditional worm gears just feels more secure knowing =)

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