Boost fluctuations

[dreadedboost]

As most of you know I'm new here and to the MSP's. I've had turbo cars for many years now and having just recently installed my boost gauge to see what I'm running at I have a question. These cars are supposed to run around 6-6.5 psi if what I've searched for is right well with my car is not the case and I just wanted to see if this was pretty common. If I go from a 3rd gear roll around 2.5k to redline I see boost all over the place. Peaking at 7psi around 3k then falling quickly to 3psi for a moment, back up to around 4psi up until 5k. At 5k it feels similar to vtec, is that the butterflies opening? Then it steadies itself to 5 psi to redline. I know my car has a stock ecu tune, no reflash, because it hesistates regularly. I just wondered if it has that much affect on boost levels?

 

[gimpo2]

you prolly have a leaky WGA

 

[Brian MP5T]

Do you have a manual boost controller? If so, remove it, put it in the garbage and buy an Electronic Boost controller.

If you do not then I suggest looking at the lines running to the WG as well.

 

[BOOSTR]

Stock boost is 6.9, some have less and some have more. The lack of a flash should not effect the boost. I hated driving my car unflashed. Too much hesitation and dead power for me. I recommend getting yours flashed and have the wastegate checked out. Good luck.

 

[dreadedboost]

Do you have a manual boost controller? If so, remove it, put it in the garbage and buy an Electronic Boost controller.

If you do not then I suggest looking at the lines running to the WG as well.

No boost controller of any kind, only had the car for a week now and I've just done normal maint. I looked at all my vac. lines yesterday before my boost gauge went in. Everything was connected solidly, no tears, everything was good.

 

[Brian MP5T]

Wow, I'm not trying to insult you here at all but I feel you should check again...

You say that they are all solid... It's either

1. Bad Wastegate actuator or
2. The Lines..

Kinks are just as bad as leaks..

 

[dreadedboost]

Stock boost is 6.9, some have less and some have more. The lack of a flash should not effect the boost. I hated driving my car unflashed. Too much hesitation and dead power for me. I recommend getting yours flashed and have the wastegate checked out. Good luck.

Yeah I need to get mine flashed but closest mazdaspeed dealer is like 6+ hrs away. It feels fine driving around town 1-3k but inbetween that and 5k its totally lame power delivery. Anyone know what I was talking about with the power being so much better and harder pulling at 5k to redline?

Another thing is I went to re-clamp my intake tube to my turbo and pulled off the hotpipe and when I did there was a considerable amount of oil built up inside the vertical section of the hotpipe. So I checked shaft play and it seems to have Alot, especially for a BB center section.

 

[Brian MP5T]

^^^ How many miles?? Shaft Play could be a new turbo from Mazda...

 

[dreadedboost]

27k and change.
I've never had a stock turbo with this much shaft play. Even with my old talon's 14b with over 130k and ragged everyday it was better than this. Are these turbos known to be failure prone.

 

[Brian MP5T]

Wow, That's Nothing...

Free play..

In and Out

or Up and Down??

 

[dreadedboost]

Yeah, tons of free play. In and out i'd estimate at 2-3mm, up and down about the same, I don't know how it hasn't taken a total s*** on me.

 

[Brian MP5T]

Yeah, tons of free play. In and out i'd estimate at 2-3mm, up and down about the same, I don't know how it hasn't taken a total s*** on me.

That is totally odd for a BB turbo..

A Journal B turbo, I can see it.

Is there any binding in the rotational motion?

 

[dreadedboost]

That is totally odd for a BB turbo..

A Journal B turbo, I can see it.

Is there any binding in the rotational motion?

I know it troubles me too, my past 3 BB turbos were never like this and they got beat to hell and never missed a beat. I agree on the journal bearings also and when in that condition they went pretty soon after but they were run at a much higher pressures and durations, not to mention age. The only thing I could figure is that maybe this one was a lemon and what life is there is short.

 

[Brian MP5T]

If it's a lemon, it's been like this since day one..