To make this as short as possible, I have a 2003 stage 1++ XEDE car with ~20Kmiles. Car was tuned last sunday in Atlanta by Shiv. According to Shiv, the poor car just would not boost past 20psi even with boost bleeder.

In the end, shiv pulled a best 278whp @20psi on 93 octane and 299whp @20psi on 110 octane. Torque, as you would expect, was also low. The numbers may be good for near-stock boost (Are they?) but for stage1++????.

I've tried working this out on my own and have not gotten anywhere. So, here is what I need to figure out:
Why am I only boosting 20 psi with a custom map that should be pushing 24 psi? Could stock turbo be tired after 20K miles? Could it be the stock diverter valve?

No one--including Shiv--thinks it's the motor, so it is something with the turbo and/or supporting parts. I have checked all tubes and hoses and all expected pills are in place. Intercooler hoses are tight with no discernible leakage. I have more plans for this car but it would be unwise to spend more money until I resolve or at least understand this issue.

Any ideas???? Anyone had or have a similar issue? ...getting quite frustrated, so I'd appreciate any thoughts or suggestions.

Later...

 

it could be the wastegate actuator, a cut in a rubber hose or the turbo itself.

 

Last time when I changed to Forge recir. bov, it held 2 more psi. but don't know about the MR bov though.

 

Also check your cam gears. I know it sounds silly but if you are just one tooth off you will have similar power robbing results. I can tell you all this from experience, it was the problem on my car.

 

True. However, isolating the root cause is the challenge. Is there a systematic way that I could eliminate potential culprits to reduce the number of suspects?

 

How much boost were you "holding" prior to changing the valve? When you say hold, I imagine you are not refering to peak psi but sustained boost at higher rpms, correct?

Can a purge valve really cause low peak psi like I'm experiencing?

Open Question: Is there a particular boost pattern (curve on dynograph) that will suggest a particular cause for my boosting issue?

 

Take off the Forge and put your stock dv/bov...I never have liked the forge design. They stick open and leak if not periodically cleaned and relubed.

Wastegate actuator can be visually inspected for cracks on the body. If you can reach in, see if the spring hold the rod tight.

You need to pressurize the charge side to see if there are any hose leaks.

Remove the turbo inlet pipe to inspect the turbo

 

I had the same exact problem at dyno4mance a couple months back accept my car wouldn't make more that 21psi without a bleeder and more than 23psi with a bleeder.

I tried and tried to figure out what was wrong, with NO luck. I finally decided to put a pill in the wastegate line between the boost source and the T. I think some solenoids just can't hang with upping the boost, IDK what else to think.

Try what chronohunter said, let andrew check out your car if you are close to ATL and see about the cam gears. Other than that, my fix worked and it actually made my car a freaking beast. i can now hold 22psi to redline

 

Hmmm... Wouldn't a timing issue result in low power output relative to boost as opposed low boost? Wil you describe my hp numbers as low for 20 psi peak boost?

 

I don't have the forge valve, mine is stock. I'll try your suggestions for checking the wastegate. Maybe I should know this but how can I presurrize the charge side?

 

what are your cam gears set at? mine are -2/-2. was the stock airbox recommended? when I had a cone intake, I had to replace the MAS as the cone messed it up somehow, boost was down, running rich. The mitshu dealer can hook it up to see if its messed up. Are you getting any Balooning of the hoses? mine was leaking at the bend by the battery, squees it see if its "gushy" in the bend. the outside appearence looked fine to me, but bad internal hose. did you spray starting fluid around the hose endings?if it bogs, you have a leak (If you catch on fire, you sprayed too much starter fluid) Is the diverter BOV upside down? I had it backwards. have forge BOV now red spring. I can hold 25psi of boost till I run out of road.

 

The thing is, Andrew installed the cam gears three months ago.

 

1. Cam gears are -3/-3
2. I think Vishnu typically frowns on aftermarket intakes (could be wrong)
3. Would the MAF situation have been detectable on the dyno?
4. No balooning that I could find
5. "Gushy"?
6. No starter fluid around the hose endings
7. No

I'll go squeeze the hose... Pun intended!

 

The cam gears are correct on your car....
Boost can be made the way gsujeff suggested although I would be happier finding the cause first and then take that route if we really need to
Hope you find the problem......I am still dreaming about your bike, coolest I have seen in a while

 

yes I believe he does frown on the aftermarket intakes.
im not sure if it would be detected.even with all my mods, i still got the car plugged into a machine at the mitshu dealer and the readings were off the chart for the maf sesnsor, once changed no more problem!
you cant see ballooning with the car off. you have to shove alot of psi thru the hoses, they will expand and not let the air thru full force ( kinda like an anerysm)
you have to spray the starter fluid/brake fluid around the hoses with the car running. if it boggs down when sprayed, it is leaking there
gushy is a tough one. I could feel under the "braided" stock hose and detect a crack under the braid. got a new hose and cut the old one and sure enough! bad hose.