Low Boost, what to check.

[FreeFlyFreak]

I have thought that I had a boost problem for a while.

Just got an AP, loaded the map that Christian gave me and took it for a drive yesterday drove very well a big improvement, BUT....

I checked the boost using the AP and although it shows a brief spike to the boost called for by the map (17.5), it drops in 1/2 sec to low 12's psi and then drops to 11.8 psi, where it stabilizes, basically I only hold 11.8-11.9 psi during acceleration after the initial spike.

Now I know there must be a leak, I also know it will probably be hard to find, its not like its loosing all the boost just a bit.

I have checked and tightened the hose clamps on the turbo inlet/outlet, intercooler inlet/outlet, and intake inlet. No change.

What else could it be and what is the best way to check?
Should I just take it to the dealer?
Im guessing the stock bpv may be the problem any way to test it?

Thanks

Steve

[mdogg]

maybe try flashing back to stock and logging your boost? (to rule out AP map issues)

[phillyb]

do you have another valve to put on the car by any chance?
have you gone to the stock map to see how much boost you hold?

[FreeFlyFreak]

Originally Posted by mdogg maybe try flashing back to stock and logging your boost? (to rule out AP map issues)

If I flash back to stock, I cant look at the realtime data, I would have to use the stock style map.

Originally Posted by phillyb do you have another valve to put on the car by any chance? have you gone to the stock map to see how much boost you hold?

No other valve, I'll try the stock style map and see what happens.
What should the boost hold on the stock map. 15.6??

I am going to flash stock and take it to the dealer though in the meantime, and see if they find anything amiss, I have suspected a boost leak for a while, just had no way to check until now.


Question: a boost leak to atmosphere would affect the LTFT correct?

I ask because the LTFT while using the AP yesterday was very good under any kind of acceleration, anything more than light throttle was +1. (-8 idle, -4 very light throttle, +1 anything higher than very light)
+1 LTFT under boost would seem to indicate that the loss of boost is not being vented, which would indicate a bpv leak...... correct?
Just thinking out loud.

[phillyb]

i don't know about that theory. but you are correct that you should hold around 15.6 psi.
i'm curious to see if this problem persists with the stock map

[FreeFlyFreak]

Dealer said "car runs fine", but that is what I expected them to say, no trouble code, no problem.
They said there were some computer updates that they flashed.

According to the MAP I should be holding 17.5 psi

I am only holding 12psi, with all clamps tight.

That is a lot of air to lose, LTFT is normal, that tells me I am not altogether losing the air, by deduction I figure leaky BPV, the lost pressure is being recirced hence no out of whack LTFT.

Im guessing the initial psi spike is enough to open the valve and then it doesnt completely seal again.
Anyway I went ahead and ordered a forge BPV seems the most popular, but mainly I wanted the stock look and fit, should have it by Friday I paid for expedited shipping. I want to get this solved before I go to Laguna Seca on the 10th

I'll post again with my findings when I get it installed to let everyone know if it cured my psi problem.

If it doesnt I'll get a leak tester and pressurize the system, see whats what.

EDIT: Sounds just like my problem here: STOCK BIPASS VALVE tested. - Mazda Forums

[phillyb]

ugh, with the stock style map, you can do real time logging.
can you please use the stock style map (copied from the ecu, yes?) and monitor your boost?

furthermore, if the dealership said it's fine - stock - it makes monitoring the boost on the stock map even more important.

if it's your valve, you'll be leaking even with stock map. keep us updated

[FreeFlyFreak]

Originally Posted by phillyb ugh, with the stock style map, you can do real time logging. can you please use the stock style map (copied from the ecu, yes?) and monitor your boost? furthermore, if the dealership said it's fine - stock - it makes monitoring the boost on the stock map even more important. if it's your valve, you'll be leaking even with stock map. keep us updated

Yes I realise that, and I understand why you are suggesting it, to rule out the map.
There are a few reasons I didnt go that route yet
1)I am trying to keep the flashing to a minimum
2) I dont think it is the map, I thought I had a boost problem before I even got the AP, my car was definately lacking under boost compared to another stock MS3 I test drove.
3) Finally this thread sold me, sounds like my problem exactly STOCK BIPASS VALVE tested. - Mazda Forums

I am going to see if the forge fixes my problem first without adding a bunch of flashes, I think it is the most likely suspect at this point.

If the valve does not solve it then I will try your suggestion of monitoring the stock style map at that point.

Thanks

Steve

[desertrat]

Altitude could also be an issue? I live in the high desert of NM and I spike about 16 psi and hold about 12 psi. Mods are COBB SRI, OCC, and Ground wires.

[FreeFlyFreak]

Originally Posted by desertrat Altitude could also be an issue? I live in the high desert of NM and I spike about 16 psi and hold about 12 psi. Mods are COBB SRI, OCC, and Ground wires.

Good thought, but....
Nope, Im about 50' above sea level.....
And Cool 65 degrees.

I'll find out tomorrow, when I get my forge BPV