Boost leak?

[1326]

I have a 2003 mazdaspeed protege and a problem, cheap glo shift boost gauge reads -11 to -12 at idle and goes to +5 to +6 at full throttle, is there a boost leak? It hits fuel cut when cold out some times every thing is factory other than injen cold air, and a crap diy bov on the factory plastic cold pipe, it doesnt leak were the bov is.

 

[pbarton14]

If you have a boost leak big enough to make it feel like a fuel cut then it'll be a dime sized hole somewhere or a big bad leak lol take it pipes off and put then back on . Inspect them .

 

[pbarton14]

If it's a huge vacuum leak then your car will idle horrible.

 

[1326]

Feels like fuel cut when I turned the boost to 7 to 8, idle is fine, I took the cold pipe off and made shure it wasnt leaking, but the hot pipe wouldn't come off, didn't want to pull to hard and break it, its my only means of transportation.

 

[njintau_fsd]

Just to be sure, what would a fuel cut actually feel like? I'm asking cuz I'm also having some weird issue which I suspect is a boost leak...

 

[pbarton14]

for a fact you will not hit a fuel cut at 8 lbs of boost . i run at 10 sometimes and even in the coold i have no fuel cut. when i had my stockplastic pipes on i accidentally brok the bpv nipple on the hot side and that made me have a "fuel cut" when i gradually went into boost. that is my example of a bad boost leak causing the "fuel cut" feeling

 

[1326]

Well the harsh deceleration would be fuel cut right, my cold pipe and hot pipe have been rigged with jb weld the bov is jb welded in and the bpv bung or whatever has been done also. The cold pipe does not leak I have checked it. So this is a leak, though what vacuum should it be pulling at idle?

 

[BOOSTR]

At idle, depending on atmospheric conditions and altitude your readings should be -20 to -22. Some gauges read lower but your reading is too low if correct. So I would obtain a vacuum gauge and hook up to get a correct reading.

As far as the cut goes, its temperature based and not psi based. I don't doubt that up in NC overnight and in the morning its cold enough to cause that.

 

[1326]

so does this mean i have a leak or some thing else is wrong? My torque app says the ecu is reading -25 hg.

 

[BOOSTR]

Like I said, hook up a reliable gauge and get an idle reading. I wouldn't trust what either one of yours are telling you. And if your asking if you have a problem because you are experiencing a cut under boost, with the current temps, then the answer is no. If it happens even when warm, then yes. A higher than normal vacuum reading could be caused by the condition of your engine, worn parts, incorrect timing etc.

 

[1326]

Il get a timing read today, should get a manual boost gauge in a few days.

 

[1326]

What should the timing be?

 

[BOOSTR]

In mentioning timing I mean that depending on your mileage and condition of your belt, tensioner and spring you may be off.
You cannot check and set the timing like on an engine with a distributor. Its all handled by the PCM and making sure that the timing marks on the cam sprockets are correct.

Answer this, does the car hold boost and boost normally in non-freezing like conditions?

 

[1326]

Yes it does.

 

[BOOSTR]

Well than you have a normally functioning MSP. Only way to stop that from happening would be to go full stand-alone which is several thousands of dollars. In the meantime try applying less throttle pressure when its cold outside.

Hopefully when you install your new gauge it will also show that you have normal vacuum readings.

 

[jdwk]

Fuel cut in our cars is actually spark cut and if feels like someone shut off the car. It is violent and horrible, you won't ever guess if you hit it or not, you'll know.

It happens when the PCM calculates 100% injector duty cycle or higher to prevent you from blowing up your engine. This could be because of a bad MAF (highly unlikely), a bad WGA (very likely), or a vacuum/boost leak (incredibly likely).

When my WGA went bad very early on in my car's life, I ran into spark cut because without a working WGA, the turbo is free to boost to its heart's content. The MAF is going to read all that air and once the injectors are maxed out, the engine cuts spark. It's more likely to happen in cold weather because colder air is more dense.

 

[1326]

Got a new boost gauge and put on a fmic and got rid of the jb weld factory pipes. All is well at 10psi unless it its cold out. Now I pull a little over -20 at idle. Thank you mazda247 members made all the work allot easier still was hard to mount fmic under base model bumper cover