My car as begun to stall after i shift under boost, and coast. i thought a bad vacuum could have been the issue but ive checked and double checked them, to me this problem seems like one someone with a bov would have if not set up properly. but after every shift the bpv dumps the charge back into the intake system after the maf, which mine is doing, and like i said this is a new problem with no physical changes to the car from before. I can easily make this happen by just drivng up to 5000rpm in second shfting into third and letting off the gas completly and the car will die, but if i give any throtle input it is fine. I city drive quite a bit, so i coast quite a bit, and latily have been stalling qute alot. i need help!
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car stalls after shifting under boost if no gas is given after
- Thread starter Prohero
- Start date
powderider87
Member
- :
- 03 MSP
Wastegate. You'll see a vac line that goes into the wastegate, leave that hooked up to the wastegate and unhook the other end. Then blow in the vac line with your mouth as hard as you can. If you are able to blow air thru the line into the wastegate fairly easily then you more than likely have a bad wastegate, which casues stalling issues you are describing.
what? wastegate either you over boost or you dont. if you have a vacleak thats another deal. This is happening due to the bypass/bov staying open to long. You have two options
1-maf relocate
2-new bypass or bov thats adjustable so you can dial it in.
1-maf relocate
2-new bypass or bov thats adjustable so you can dial it in.
papadock73
Member
- :
- 2003 Mazdaspeed Protege Yellow Mica
mine does the same thing and i have a non adjustable ssqv.should i change the bov and you think that would take care of it?
maf relocate would fix for sure. But if you cant do that you need a bpv that shuts quckly but in either case it may stall eventualy. if you think about it where is your maf. Your maf being point (A) throttle being point (B) the (X) factor is two things-distance and volume beng released by the bpv/bov.
This is all Theory
Senerio 1-to much piping/distance.
Registerd information from point (A) to point (B) wll be off. I Cant say by how much, Im assuming the guys at mazda had a formula for the ecu saying that with the stock piping point (A)signal takes .75 sec to Travel to point (B) that is unless you dump the air then x amount of volume is lost and the ecu will have a buffer zone for that lost amount of volume so it wont stall. so if you change the distance between point (A) to point (B) you get a delayed reaction same thing will happen if you increase the amount of volume released. So you can see that by changing piping and bpv you have effected the formula causing stalling during recovery.
So how do we fix it
*Maf relocate-better signal responce (throttle responce)
*smaller diameter BPV -look at the diameter of your current bpv versus the stocker. Thats why maybe people have had good luck wth the forge.
*tighter spring for bPV- shuts valve quicker but you get surge
*smaller pipes- smaller pipes could work but it may cause the turbo to work a tad harder due to restriction.
This is all theory and assuming you dont have vac leaks you also have to consider enviroment, air temp becuase that would change air volume as well.
good luck.
This is all Theory
Senerio 1-to much piping/distance.
Registerd information from point (A) to point (B) wll be off. I Cant say by how much, Im assuming the guys at mazda had a formula for the ecu saying that with the stock piping point (A)signal takes .75 sec to Travel to point (B) that is unless you dump the air then x amount of volume is lost and the ecu will have a buffer zone for that lost amount of volume so it wont stall. so if you change the distance between point (A) to point (B) you get a delayed reaction same thing will happen if you increase the amount of volume released. So you can see that by changing piping and bpv you have effected the formula causing stalling during recovery.
So how do we fix it
*Maf relocate-better signal responce (throttle responce)
*smaller diameter BPV -look at the diameter of your current bpv versus the stocker. Thats why maybe people have had good luck wth the forge.
*tighter spring for bPV- shuts valve quicker but you get surge
*smaller pipes- smaller pipes could work but it may cause the turbo to work a tad harder due to restriction.
This is all theory and assuming you dont have vac leaks you also have to consider enviroment, air temp becuase that would change air volume as well.
good luck.
My car just started doing the same thing. It would run fine until the car was warm. When the car was warm, if I was driving along and started coasting, the engine would die. When I stopped at a light, the car would idle very rough between ~200-700 rpms and almost die.
The only difference is that it did not do this last week. I changed my oil cooler gasket and put some thread lock on the oil sender, then on the way back home is when the car started doing this. And again, this only happens when the car is WARM. So is this caused my the MAF as well?
The only difference is that it did not do this last week. I changed my oil cooler gasket and put some thread lock on the oil sender, then on the way back home is when the car started doing this. And again, this only happens when the car is WARM. So is this caused my the MAF as well?
its the tune bro you can relocate the maf it will help but the fact is the hotter it gets the worse it will be. The tune is not right for hot days. The ecu realy doesnt compensate for temperature. I noticed that once i swapped my thermostat the car runs leaner. I wenr from 14.5-15.2 to 15-15.7 the only thing I can say is that i hope at least i save some gas.
papadock73
Member
- :
- 2003 Mazdaspeed Protege Yellow Mica
seeing as mines doing the same thing and i have an ssqv,where do i relocate my maf to? closer to the throttle body or where?
hornsfan10609
Certified Mazda Tech
- :
- 2003.5 Mazdaspeed Protege x2
It has to be after the BOV, at least 10 inches after the BOV is preferred to limit air turbulence through the MAF.
papadock73
Member
- :
- 2003 Mazdaspeed Protege Yellow Mica
well my bov is right after my throttle body and my maf is after that,should i just flip flop the pipes around and see if that works? i have an altered customs front mount
hornsfan10609
Certified Mazda Tech
- :
- 2003.5 Mazdaspeed Protege x2
As long as the MAF is after the BOV the car will run fine.
papadock73
Member
- :
- 2003 Mazdaspeed Protege Yellow Mica
sooo pretty much put my maf after my throttle body then pipe with blow off valve after that?
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