Hi guys, so I made a thread about having boost problems past 3k rpm from 3rd-5th gear a couple weeks or months ago. I was told to get a boost gauge to diagnose the problem. I finally finished the gauge install(hopefully i installed it right). The boost seems to be fine. It goes to 10psi and 8 then back to 10. Sometimes when i first boost itll hit like 12 or 13psi then go down to 10. However in 3rd,4th, and 5th gear it goes to 15psi? Then after that i hear the noise "brrr" and the car doesn't want to accelerate or boost anymore so i have to let off the gas. I'm not sure if the psi drops down at that brr sound because i bring my head back to the road. Is that fuel cut? I don't understand how the car can boost to 15psi when my car is completely stock besides a strut bar and a catback. There's no way it could be doing that right? I also notice sometimes in 2nd and 3rd gear when im already passed 3k rpm and i decide to boost, it will boost only at 5 psi. What does this seem like?

 

It does sound like fuel cut. The only thing you have is a catback? I find it hard to believe that you are hitting 15 psi with only a catback.

 

Not everyone experiences overboost due to mods lol. Things do fail on 20 year old OEM parts LOL

thewird

 

Yeah I was confused too. I have no idea what to do to fix this problem. I always thought I was boosting not enough or something of that sort. I also hear air leak when i'm starting to boost. I believe its coming from my stock bov(or bypass valve). Can a bov failure lead to incorrect boost? I'm confused and stump.

 

+1

may be time for a vacuum hoses/valves check/job?

 

Oh okay, I'll get to the vacuum hose during winter break after i finish all my college apps.

 

ever figure out what your problem was?

 

Boost control module maybe bad. Goto non sequential and make it all simpler lol.

 

I still havent found out the problem. My car hasn't been running since novemeber haha. I've been doing the vacuum hose job... I'm really lagging though. I only have a couple hoses left and then it's on to putting everything back into the car. I'll let you guys know if that solves the problem. Where can I find the BOost control module?

 

Let us know if you find the problem! Mine does almost the same thing and I was thinking know it might be plugged up main cat!

 

Okay I will, My car should be running by this week if I don't have much homework. Have you done the hose job on your car yet?

 

Yes, vacuum hose job and new custom solenoids and still having same issues!

 

if the solenoid switching system is working, then perhaps the mechanical end of the sequential control needs some adjustment.

is the precontrol/wastegate opening all the way? actuators functional? lube the gate bearing/bushing/hinge?

 

Are you planning to replace the checkvalves too I would recomend to do that allso.

 

Status?

 

The car still isn't running yet. I have been really busy with school. I was wondering if a new fuel pump would fix this issue. http://www.racingbeat.com/mazda/perf...-pressure.html It seems like a fuel pump might work according to this

 

since your car is down take the time to verify that your boost gauge is accurate.

I have experienced boost cut due to over revving and it feels exactly as if you were to take your foot off the gas. Except your foot is on the wot position lol.

I have also heard detonation on a friend's car. He was relatively stock and hence his car was on the quiet side (I would never hear it mine too damn loud). Anyway as my friend wot'ed on third we heard this continous 'click' sound, we thought it sounded like a relay clicking. Anyway a couple of days later I mentioned it to my mechanic and he said it was detonation. He describes it as marbles... I guess the cliking can also be described as when marbles collide.

If you determine that your boost gauge is accurate it could be that the 'brrr' sound be detonation, prior to going into fuel cut. Or as the weird pointed out the system is just old and as fuel cut is engaged it makes that weird noise. But whatever it is you shouldn't be hitting 15 psi on higher gears.

 

Yeah my boost gauge is accurate. the "brrr'' sound doesn't sound like marbles colliding. it's like a low growl, i can't really describe it. It's like the sound goes on and the car loses its boost like how you described your foot was on wot but it wouldn't boost. If I hold the gas pedal down still. It will switch off between "brr" and boost and "brr" and boost. I don't know it's a weird thing. I really hope the vacuum hose job does it.

 

I would recommend getting a hand vacuum pump, it'll help diagnoise your problem. I was having problems with my car boosting past 4.5k, i bought a vacuum pump to diagnois the problem and found it in a few hours...was caused by the charge control solenoid sticking. If i were you, i'd follow this troubleshooting guide and make sure everythings working. http://www.autosportracetech.com/RX-...leshooting.htm

 

Was the problem fixed with a new charge control solenoid? I'll start testing all my solenoids.

 

I should probably buy a new solenoid, but I actually just shot a little lubricant in the charge control solenoid (I didn't think it would work) but to my surprise it worked and my car boosts perfectly now ...What i looked for was the charge control actuator (when you turn your car on, it should be pulled in, then turn your car off and it should stay in by the vacuum in the vacuum chamber, however with my car when i turned it off it open up, caused by the solenoid being stuck closed...sorry if that was a bad explanation but ya i'd check your solenoids.