Boost is stuck pretty low

thewumpus99

thewumpus99

Donating Member
My boost won't go higher than 7 or 8 psi, even at WOT.

I took the attached .CSV log using TunerPro RT:
https://docs.google.com/file/d/0B0w-JDdb37U2MG9PRUkzMTdHdms/edit?usp=sharing
Chip came from Waller when he rebuilt my engine, and should be matched to the build. I'm pretty new to TunerPro, so not sure which of these things is normal vs. which is cause for concern. Hopefully you guys can help with that! Anyway, the things that seemed weird were:

1. It seems like “MAP 3-bar kPa” is stuck at 2.2 the whole time, whether idling or WOT on the highway. This matches the “Base Desired Boost Pressure 3 Bar (kPa)” value, but... shouldn't it be changing? The “Desired Boost PSI” of zero likewise seems bad.

2. Why is “Desired AFR” always 0? This should be a closed-loop chip, so shouldn't this value be in use?

If the “Desired Boost” values aren't the problem, any thoughts on what I should check/try next?

Thanks!
 
atkonkler

atkonkler

Is this your bush?
Re: Boost is stuck pretty low

My truck did this also a couple of weeks ago. Pulled off the cold air, adjusted the wastegate rod. Put it back together and it was back to normal. Wtf? I just coughed it up to electrical gremlins and called it a day and didn't feel like chasing my tail. Check vacuum lines or do the bicycle tube test hooked up to the upper intercooler and fill it with air to find the leak. Good luck if u need any help let me know!
 
neildemo

neildemo

Administrator
Re: Boost is stuck pretty low

Boost Solenoid. Or reversed Vac lines on boost Solenoid. I had the same problem. Base boost is 8psi if you bypass the boost solenoid and run a vac hose directly to wastegate that is. Or you could have a bad Boost Solenoid they do go bad and your only getting base boost. Just my 2 cents on these turds.
 
thewumpus99

thewumpus99

Donating Member
Re: Boost is stuck pretty low

It looks like a previous owner deleted the boost solenoid. There is just a vacuum line from the turbo down to the wastegate.

So, in a truck where the solenoid has been removed, how does boost normally get controlled? Just wondering where to look next. (Also, could it be a leak in the vacuum hose I mentioned?)
 
NJ93TY

NJ93TY

Donating Member
Re: Boost is stuck pretty low

"There is just a vacuum line from the turbo down to the wastegate."

There is your answer. The spring will open at 7-8lbs so you won't be able to build anything more then they unless you install a manual Boost controller or get the stock boost solenoid back into play. The way it is set up now you have no way to control boost pressure.
 
atkonkler

atkonkler

Is this your bush?
Re: Boost is stuck pretty low

Just buy a ebc and call it a day! I love my truboost by aem! You.Can fiddle all day with the spring pressure and duty cycle its great!
 
ajt86

ajt86

Member
Re: Boost is stuck pretty low

I was going to ask the same thing- I looked into getting a tru boost for better spool up
 
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