I have an 08 low mileage (7,200 miles) MS3 which suddenly had the Scanguage showing boost levels of 22+ psi WOT. Interestingly, no fuel cut but I didn't let it stay at this boost level for more than a second just to confirm it was a recurrent event.
After a fair amount of visual inspection, I found that the rubber hose from the top of the WG actuator to the solenoid switch had a crack at the top kink part where it attaches to the nipple of the solenoid. I took it off and that area of the hose was hard as plastic and cracked in two when I was flexing it to see how big the original crack was...basically the WG actuator was bleeding off boost to atmosphere allowing it to remain closed longer.
New piece of hose obviously fixed the problem. Of course, when I took the broken hose to the Dealer to get an new OEM piece (car well under Warranty and not modded) I got a fascinating discussion from the Service Manager on how it would be impossible for Mazda to give me this piece without them installing it, like I want them touching my car in view of past dealing with them (Skyland Mazda, Asheville, NC). My argument on how making an appointment, driving 2 cars 50 miles round trip twice to drop off my car and then pick it up for such a simple problem which I had diagnosed and fixed already seemed too much for this guy to fathom. Apparently this Dealer needed to make the money from charging for the "complete" R & R more than making me, the Scum customer, happy by only making off with their reimbursed charge for the part...you'd think they'd show some imagination and pad the bill like they probably do with some Warranty claims.
Anyhow, those of you with MS3's might want to reach down there and feel up that hose and see if it has heat hardened, especially if you don't have an aftermarket boost guage to alert you to overboosting.
After a fair amount of visual inspection, I found that the rubber hose from the top of the WG actuator to the solenoid switch had a crack at the top kink part where it attaches to the nipple of the solenoid. I took it off and that area of the hose was hard as plastic and cracked in two when I was flexing it to see how big the original crack was...basically the WG actuator was bleeding off boost to atmosphere allowing it to remain closed longer.
New piece of hose obviously fixed the problem. Of course, when I took the broken hose to the Dealer to get an new OEM piece (car well under Warranty and not modded) I got a fascinating discussion from the Service Manager on how it would be impossible for Mazda to give me this piece without them installing it, like I want them touching my car in view of past dealing with them (Skyland Mazda, Asheville, NC). My argument on how making an appointment, driving 2 cars 50 miles round trip twice to drop off my car and then pick it up for such a simple problem which I had diagnosed and fixed already seemed too much for this guy to fathom. Apparently this Dealer needed to make the money from charging for the "complete" R & R more than making me, the Scum customer, happy by only making off with their reimbursed charge for the part...you'd think they'd show some imagination and pad the bill like they probably do with some Warranty claims.
Anyhow, those of you with MS3's might want to reach down there and feel up that hose and see if it has heat hardened, especially if you don't have an aftermarket boost guage to alert you to overboosting.
