Slow building boost

[uNVme]

Hey guys. I'm new obviously. Just took possession of my protege today actually. Here's my issue. Normal driving, the car doesn't build boost at all. Barely even gets to zero on the gauge. It seems like it has to be at wot to begin building any pressure. Drivability is fine and I checked up and down for leaks. I know these cars are set to barely make any psi but it shouldn't be that bad. Maybe map sensor? Idles fine, drives fine. No sputtering. Just seems sluggish. Ideas? Thanks in advance.

 

[uNVme]

And of course as soon as I post that I see a section at the bottom that pops up with four similar questions. Off to read those. Sorry to ask a repeat question.

 

[JDMazdaFamilia]

You shouldn't be building boost under normal driving. I'm running a big turbo so I have a little more lag but I'd say you should be atleast at half throttle and in the mid to high rpm range to build boost. If its really that bad then you're looking at a boost leak somewhere between the turbo and intake manifold, a stuck open wastegate, or an exhaust leak before the turbo. The map sensor has absolutely no effect on building boost so you can get rid of that thought

 

[jdwk]

A stock MSP builds positive pressure pretty much off idle at full throttle. I had to uninstall my AEM software on my laptop so I can't go get specifics, but the car is definitely at full boost by 3krpms, probably sooner.

I believe the last time this issue popped up, it was a bad boost guage. The only other possibility is that your wastegate is stuck wide open. Test the boost gauge with a pump, if it works then your wastegate it stuck open. It's rare, but it can happen. You'll need to determine if it is just gunked up and can be cleaned or whether the spring actually broke.

With the car off and cool, reach down and grab the wastegate actuator rod and see if you can pull the wastegate closed or push it open. You should be able to feel the resistance from the spring as you push it open.

BTW, there is no MAP sensor on the MSP aside from the EGR boost sensor, but that is only for emissions regulations and nothing to do with tuning or the issue you are experiencing.

 

[IshSonP5]

A stock MSP builds positive pressure pretty much off idle at full throttle. I had to uninstall my AEM software on my laptop so I can't go get specifics, but the car is definitely at full boost by 3krpms, probably sooner.

Isn't that with WOT though.....and 3k seems a little soon to be at full boost....

OP if you are daily driving nice and easy you probably won't see boost. I can drive an entire day with my gauge at 0 by just crusing around, maybe 1psi or 2. but thats it. Is your car a MSP? or is it a protege with a speed setup....or what? do you have a boost gauge? do you have an MBC or EBC? are you using a msp ecu for your tune and thats it? more info and you can get more accurate answers.

 

[hornsfan10609]

The small T25 in the MSP spools quickly, it absolutely is at full boost by 3krpm if not sooner. Sounds like a boost leak.

 

[mazdaspeedp]

Are you just running factory hotside and coldside intercooler pipes? If so maybe one of them or even both are cracked.

 

[IshSonP5]

The small T25 in the MSP spools quickly, it absolutely is at full boost by 3krpm if not sooner. Sounds like a boost leak.

10-4 now I know for future. I am unsure as to what the OP is running though.