Under boosting

[CrazyM]

just a question....Is there a problem\is it hurtful to run less than stock boost?

 

[Shigun]

I don't see why it would be. As far as I know, the way the turbo works, it will push more on the turbo the more you press on the accelerator past a certain RPM. That's why (at least as far as I am with driving), I can keep the foot on the accelerator to hold it at around 0, but when I want to push it, I can pretty much press down to get however much boost I want, be it 3, 5, or 7.

Essentially, to sum it up, I would figure it would not pose any sort of problem. Just like pushing on the accelerator less.

 

[Loewen21]

I dont see how less compression on the engine could cause problems. But why is your car running less than stock boost is the question.

 

[Calan]

just a question....Is there a problem\is it hurtful to run less than stock boost?

You do it all the time when your foot isn't through the floor

But seriously folks...

If you had the car tuned for a specific amount of airflow at WOT, and you are now not pushing that amount of air (boost), your car could run rich... but it depends a lot on all the other factors such as what the ECU is seeing, injector duty cycles, what/how you are tuning AFR at WOT, etc.

My car was running pig rich.. stuttering and blowing black smoke like crazy at WOT when I first got it. Simply turning the boost up a bit to around 15 PSI leaned out the AFR some and made a big improvement (it already had the supporting mods and an MBC, but wasn't tuned at all). So I don't see why the same effect couldn't happen in reverse.

 

[ilikespeeding]

You do it all the time when your foot isn't through the floor

But seriously folks...

If you had the car tuned for a specific amount of airflow at WOT, and you are now not pushing that amount of air (boost), your car could run rich... but it depends a lot on all the other factors such as what the ECU is seeing, injector duty cycles, what/how you are tuning AFR at WOT, etc.

My car was running pig rich.. stuttering and blowing black smoke like crazy at WOT when I first got it. Simply turning the boost up a bit to around 15 PSI leaned out the AFR some and made a big improvement (it already had the supporting mods and an MBC, but wasn't tuned at all). So I don't see why the same effect couldn't happen in reverse.

We have Mass Air Flow sensors, Oxygen sensors, and sometimes MAP sensors that determine airflow. You might have had a faulty air flow sensor or something. Turned up the boost to 15? That's not that much above stock, I dont see how that could possibly correct a:f, and you dont really need supporting mods to run 15 psi. Running under boost will not hurt your motor. However, there really isnt a way to add pressure to the wastegate line, so unless your turbo is ####ed, you're gonna be boosting factory.

 

[KazooGS-T]

Unless you shim the wastegate acutator.

 

[ilikespeeding]

Unless you shim the wastegate acutator.

Why would you want to do that? Plus, I think he would have known if that was done.

 

[Calan]

We have Mass Air Flow sensors, Oxygen sensors, and sometimes MAP sensors that determine airflow. You might have had a faulty air flow sensor or something. Turned up the boost to 15? That's not that much above stock, I dont see how that could possibly correct a:f, and you dont really need supporting mods to run 15 psi. Running under boost will not hurt your motor. However, there really isnt a way to add pressure to the wastegate line, so unless your turbo is ####ed, you're gonna be boosting factory.

The car has a GM MAS/MAF-T setup, and had boost leaks, etc... and had every backwards-ass ghetto trick in the book done to it. So based on how fubared it was, yeah... bumping the boost about 4 psi made a difference.

That was my point, although maybe I didn't make it very well. Depending on a gazillion factors and what state of tune the car is in, a change in airflow at WOT could (did) make a difference. Maybe it shouldn't with a good tune and proper operation... but it can otherwise

EDIT:

Now that I think about it, it was probably closer to 17 or 18 psi. The WG arm was initially hooked to home-made welded "boost controller" and basically limited to stock boost, because of the crappy tune. I installed a proper MBC, set it for around 15-18 psi (I forget exactly) and test drove it, and saw an immediate improvement.

The car had leaks at both TB gaskets, shaft seals, and the injector seals (all post MAS). My theory is that by turning up the boost, I was able to force more air past the leaks which allowed the car to run leaner in open loop mode. But I dunno...

 

[CrazyM]

Sorry If I was not clear. I was not meaning my car is underboosting. it boosts perfectly fine, but was wondering, say I turned the MBC down to say 5Lbs of boost...Don't wanna get flamed for this question, no i have no done, no im not doing it, but just wondering for a more knowledgeable outlook on the car.

 

[KazooGS-T]

You can't turn the boost down past what the gastegate spring is set at, with a boost controller. Hence the idea of shimming the wastegate actuator, allowing you to lower the boost.

 

[CrazyM]

ahhh I see. That's the kinda answer i was seeking..Thanks