Boost drop normal for MS3 - DashHawk log attached

[Parkeway]

OK. For all the boost junkies out there (from a MS3 noob) -

I am used to the land of superchargers where my boost was generally constant relative to 100% throttle.

I have attached a log in an effort to see if my litttle MS3 is "normal" with the spike-drop off and not a boost leak.

http://img87.imageshack.us/img87/3354/boostlogjp1.th.gif (http://img87.imageshack.us/my.php?image=boostlogjp1.gif)

Is this par for the course?

TIA

[Bravnik]

No that is not normal at all. Yes you can have a spike and it drop fast, but never drop then spike back up like in your log. I would suspect a boost leak of some type there. You're spiking to 16psi dropping to 14psi quickly then building back to 15.6ish then dropping off as normal. You should not be seeing that drop to 14psi. You should see a spike that drops down a bit, settles then drops off slowly from there.

Check all your clamps (4 on the boot tubes and 1 on the Turbo Inlet) and ensure they are all tight. Your stock BPV could be leaking also (if you have a stock one).

[Zimmer]

what gear are you pulling in?
Can you feel the surge and drop off when driving?

I have been suspicious I have a leak ... sometimes I can feel the turbo kick in and I swear it kicks off then builds back up .. only happens once?

[Silver Ecstasy]

Would be nice of mazda to equip us with stock boost gauges hehe.

[Parkeway]

No that is not normal at all. Yes you can have a spike and it drop fast, but never drop then spike back up like in your log. I would suspect a boost leak of some type there. You're spiking to 16psi dropping to 14psi quickly then building back to 15.6ish then dropping off as normal. You should not be seeing that drop to 14psi. You should see a spike that drops down a bit, settles then drops off slowly from there.

Check all your clamps (4 on the boot tubes and 1 on the Turbo Inlet) and ensure they are all tight. Your stock BPV could be leaking also (if you have a stock one).

Those pulls were from rolling in 1st through 5th (the RPM peaks are shift changes) and the car just feels lathargic without much "oomph" - but then I drove a 280rwhp Miata track monster for 2 years ;)

Anyway, do I take this car to the dealership (still under warranty but *just barely*) and tell them boost is dropping like a hammer?

-And would any more information be valuable to you guys? Not sure how to best log the 3...

[Bravnik]

Here is a copy of a recent DH Log I took. You will note that I spike then drop down and then slowly lose boost. There is no Dip at all. The Dip is not normal and as I mentioned above, I would suspect a boost leak.

<a href="http://img214.imageshack.us/my.php?image=8808yr4.jpg" target="_blank"><img src="http://img214.imageshack.us/img214/6600/8808yr4.th.jpg" border="0"/></a>

This is a 3rd and 4th gear pull.

If you had a 280whp monster Miata then you should know a bit about cars. Tighten your clamps then run your test again. See if it fixes the problem. If not, then I would suspect a leaky BPV that can't hold boost.

[SuperStretch18]

Those pulls were from rolling in 1st through 5th (the RPM peaks are shift changes) and the car just feels lathargic without much "oomph" - but then I drove a 280rwhp Miata track monster for 2 years ;)

Anyway, do I take this car to the dealership (still under warranty but *just barely*) and tell them boost is dropping like a hammer?

-And would any more information be valuable to you guys? Not sure how to best log the 3...

If you take it to the dealer, don't even mention the dashhawk. They don't like anything that attaches to the OBDII port.

I would check all your clamps to make sure that they are tight. Quite a few have mentioned that they were leaking due to lose clamps...

[Zimmer]

Those pulls were from rolling in 1st through 5th (the RPM peaks are shift changes) and the car just feels lathargic without much "oomph" - but then I drove a 280rwhp Miata track monster for 2 years ;)

Anyway, do I take this car to the dealership (still under warranty but *just barely*) and tell them boost is dropping like a hammer?

-And would any more information be valuable to you guys? Not sure how to best log the 3...

thanks I see my fault miss-read the plot.

[mckraut]

Hmm, I was pretty sure spike was normal, just not at that level. When I really get on the throttle mine spikes to 18-20psi for a split second and then levels out between 15.50 and 16.00psi.

Brav, are you saying that my spike is not normal, or am I misunderstanding?

Edit: NM, I think I understand now. Wasn't taking the other charted data into account.

[Parkeway]

Here is a copy of a recent DH Log I took. You will note that I spike then drop down and then slowly lose boost. There is no Dip at all. The Dip is not normal and as I mentioned above, I would suspect a boost leak.

<a href="http://img214.imageshack.us/my.php?image=8808yr4.jpg" target="_blank"><img src="http://img214.imageshack.us/img214/6600/8808yr4.th.jpg" border="0"/></a>

This is a 3rd and 4th gear pull.

If you had a 280whp monster Miata then you should know a bit about cars. Tighten your clamps then run your test again. See if it fixes the problem. If not, then I would suspect a leaky BPV that can't hold boost.

WOW. So *thats* what it supposed to look like! I will check for leaks at the IC and BPV because in 8 or 10 runs, I look nothing like that.

Of course when I built-up the Miata, I turned every nut and bolt on the way up. I also had eManage with a laptop logging e v e r y t h i n g (Inj duty cycles per RPM for example) Thus I could only blame myself and my wrenches when something was amiss.

But I bought this MS3 with 30k on it and as my first turbo car, can claim ignorance (till an engine swap!!!)

Thanks for all the info - back out to the car (inout)

[Bravnik]

WOW. So *thats* what it supposed to look like! I will check for leaks at the IC and BPV because in 8 or 10 runs, I look nothing like that.

Of course when I built-up the Miata, I turned every nut and bolt on the way up. I also had eManage with a laptop logging e v e r y t h i n g (Inj duty cycles per RPM for example) Thus I could only blame myself and my wrenches when something was amiss.

But I bought this MS3 with 30k on it and as my first turbo car, can claim ignorance (till an engine swap!!!)

Thanks for all the info - back out to the car (inout)

Don't forget to check the Turbo Inlet clamp. Mine was so lose I could pull it off :confused:

T-Bolt Clamps are one of the first things I would recommend getting with the first thing being a MM :)

[Parkeway]

what gear are you pulling in?
Can you feel the surge and drop off when driving?


There is a *kick* but the car just doesn't pull...just sort of hit and miss if that makes sense. But my only boost experience was an Eaton sc and tiny pulleys :)

I just have a steeper learning curve here b/c I didn't build it myself!!!

[Zimmer]

ah man I need to get me one of these dash hawks!!!!

[Bravnik]

ah man I need to get me one of these dash hawks!!!!

Yah the DH was one of the best investments I have ever made car related. You can just get so much information from them.

[Bravnik]

There is a *kick* put the car just doesn't pull...just sort of hit and miss if that makes sense. But my only boost experience was an Eaton sc and tiny pulleys :)

I just have a steeper learning curve here b/c I didn't build it myself!!!

Park - Just a question. Did you go and download the latest build for your DH? If not, I would highly suggest it as I swear they update the build once a week :)

[Parkeway]

Park - Just a question. Did you go and download the latest build for your DH? If not, I would highly suggest it as I swear they update the build once a week :)

Flashed the 2.5 final build almost immediately upon receiving the DH. Love it (just hate the work it is creating for me!)

[Parkeway]

Here is an updated log taken this afternoon. Managed a pull through 4th gear only with a bit more data:

http://img177.imageshack.us/img177/992/boostlog4rw7.th.gif (http://img177.imageshack.us/my.php?image=boostlog4rw7.gif)

To say the run was "uninspired" would be an understatement. I've either got a leak or the world's weakest MS3 :(

Any thoughts?

[mckraut]

You've encouraged me to post my own log. I'll do a run on the way home and post it up when I get here. Curious to see what people think about it.

[mckraut]

This is a brief run from on my way home tonight. Highway driving.

[Parkeway]

This is a brief run from on my way home tonight. Highway driving.

Ok. That settles it...my MS3 is slower than my Land Cruiser...

Your log looks like fun...I wonder what that feels like...?

So, where's the culprit? Are these little things prone to BPV failure at 30k?

[Parkeway]

...and...after further review:

Checked hoses at I/C, line from BPV, and every other clamp or hose I could put my hands on and all were solid.

- this is a BPV issue, no?

(and thank goodness for the DashHawk...otherwise I'd have no other way of knowing I was driving a plain ole Mazda3)

[mckraut]

Sounds like a leaky BPV, yes. Is yours stock? Might want to look into a Forge.

[Bravnik]

...and...after further review:

Checked hoses at I/C, line from BPV, and every other clamp or hose I could put my hands on and all were solid.

- this is a BPV issue, no?

(and thank goodness for the DashHawk...otherwise I'd have no other way of knowing I was driving a plain ole Mazda3)


Ok just a few questions - The big one, did you put a wrench to the clamps or just pull on the hoses? Reason I ask is that mine felt just fine too, but when I put a wrench to them I got at least 20 cranks on it before they were tight :eek:

Second - What are your mods? The Stock Airbox just kills this car. A Simple CAI will give you 20WHP if that tells you anything. I saw this first hand at a Dyno day for Mazdas in my local area. CAI equipped mazdas pulled 18-22 more WHP than ones with stock airboxes.

Third - Keep in mind that I'm modded pretty good thus my car will hold Boost longer and higher than a stock one.

Forth - The stock BPV is knows to hold boost very bad. At 16PSI it has known to leak. Forge makes a really good and cheap BPV for our car.

If you're stock then I would assume that is your issue. Do some runs shifting at 5500RPM's and see what happens. Do a couple pulls from 3rd through 4th and see what you get.

Also the odds of someone not modding the MS3 is rare. Thus when the original owner put the old parts back on they might not have done it right or half assed. Something to think about.

If you think this is the case then I would check a couple things. First I would look for the MBC How Too and then check the hoses it refers too on your car to see if they are factory or after market/tampered with. If it looks like it was tampered with, I would check your wiring harness to see if any of the wires are taped which would indicate a Map Clamp being installed.

Both of those would be my biggest concerns as the person may not have hooked them back right.

After that I would get a CAI of some sort (if you don't already have one) to get that noose around your cars neck off.

Anyway, I hope this helps. If your car is stock don't panic. A few hunder dollars will get you up to speed pretty quick :)

[Parkeway]

Brav - youdaman! Thanks for taking the time to follow-up - I am taking notes on all the feedback here with the goal of getting this car to (mis)behave :)

I made ONE MORE RUN tonight and with the temperature in the low 80's, it seemed to run a bit better. Most runs I've made in the short two-weeks I've owned this car have been in the 95-100 degree afternoons here. And while temps did affect my SC'd Miata, the oversized FMIC and eManage made quick work of the heat (ran strong with 160deg track temps at VIR one year)

The Speed3 on the other hand, in my bone-stock trim, seems a little "moody". What this means, of course, is that I will waste no time slapping the mods on it to unleash the beast.

Thanks again to everyone here trying to zero-in on the issues.