Mazdaspeed 6 low boost issue

[arnold600]

I have a 2006 mazdaspeed 6 with a corksport srt + tip, Cobb apv3, corksport hpfp, and some other mods. anyway, I only get 13 peak psi of boost and the most ive ever seen was 14.1 on the cobb. I looked all over my pre and post turbo connections and everything seems tight and secure. Ive also tried unplugging the battery and doing a re-flash of the cobb ots stage 1+sf 93 map. still not hitting over 13psi. my idle is smooth. However, my wastegate duty cycle on the cobb seems to be a bit suspect and starts to kick in around 10 ish psi. Thoughts?

[GroceryGtr]

do a boost leak test, a visual inspection doesn't do much.

[Vansquish]

You need a real tune. Cobb's OTS maps are pretty shitty.

[MSMS3]

Originally Posted by Vansquish You need a real tune. Cobb's OTS maps are pretty shitty.

You're right, but he should be seeing 15 psi or a bit more, even with that shitty map.

He does need to do a true boost leak test. He may also want to check vacuum lines on his elrctronic boost control. They get hard and get little splits almost invisible over time.

[Jeff23spl]

IMo, you don't play with the tune before being sure the mechanic is in shape.
-Boost leak test
-Engine compression/ leak test
Then if everything is fine, you can start to play with it.

It could be a cheap intake/bad maf (or bad maf cal. in the tune) that read too much g/s and drop the boost because the target load number is reached...But if you fix it by a tune and then find and fix a leak, you will need another tune to avoid overboost.

[Jeff23spl]

Originally Posted by MSMS3 He may also want to check vacuum lines on his elrctronic boost control. They get hard and get little splits almost invisible over time.

Yes but usually a leak would just increase boost. WG duty create a leak thru the solenoid valve to reduce the pressure seen by the WG actuator. So any added leak, is just like more ''hydraulic wg duty''
(Drilling tiny holes in the vac lines was a cheap and easy trick in the old days to increase boost with cars without boost control...)

[arnold600]

FOUND THE ISSUE.
So I unplugged my boost control solenoid to diagnose where the issue was. I.E., if unplugging the solenoid still yealded low boost, I would have a turbo piping leak, but if I made boost, I would have a bad boost control solenoid. So, sure enough, a small pull generated 20lbs of boost. DEFINITELY engine destroying territory. So im going to measure the resistance of the BCS, and if its in spec im going to do some wire hunting.. Thanks for everyones suggestions and help.

[Fstrnyou]

Unplugging (electrically) the BCS should result in spring pressure boost (about 10-12psi).
Unplugging either hose to the wastegate is an easy way to go really fast for a very short period...read ZZB.

[arnold600]

Originally Posted by Fstrnyou Unplugging (electrically) the BCS should result in spring pressure boost (about 10-12psi). Unplugging either hose to the wastegate is an easy way to go really fast for a very short period...read ZZB.

Definitely, It was just a quick test. I unplugged the BCS wire and only got 8psi, I also did a data log with it plugged in and i see a signal being sent and received. So i believe the wiring is good. I ordered a new BCS, so hopefully the issue gets resolved.

[Jeff23spl]

what do you mean by login a signal being sent and received ? How did you confirmed the feedback ?

[Fstrnyou]

Originally Posted by arnold600 Definitely, It was just a quick test. I unplugged the BCS wire and only got 8psi, I also did a data log with it plugged in and i see a signal being sent and received. So i believe the wiring is good. I ordered a new BCS, so hopefully the issue gets resolved.

I would agree that 8psi (with unplugged wires) comfirms the electrical is good, but 8psi is too low for spring pressure. Unless that falls within manufacturing tolerances of wastegates and Mazda said "IDGAF, the ECU can figure it out."

[MSMS3]

Spring pressure should be maxing at 10-11 psi.

I still think he has a boost leak somewhere.

OP should post that data log he did. Might prove helpful, depending on which parameters he was monitoring and how he did the log.

[mituc]

We can only tell if you post a log. It may be a boost leak, or it may be the turbo (it was the case for a local which I was tuning, he bought the car with the wrong chinese turbo replacement).