Who is overboosting and to what?

[Craighjr]

I have a Speed 3 thats boosting to 21.5psi. This is according to my Prosport gauge with memory recall. Mine is modded with a Mazdaspeed CAI, Corksport down pipe, and VIBRANT Exhaust (single hi-flow cat). I keep hitting some sort of hard fuel or boost cut which dumps power for a second or two then surges back up. It happens on balls to the wall hard pulls in 3-6 gears. What is the solution to this? I will not use an ATP device because that will allow the boost to spike even higher. I believe my car is pulling back and it would be boosting more if not stopped by the ecu. This is done while tricking the ecu into thinking its ok. So I know a few people have tuning ecu's done and it seems like alot of people have exhausts, intercoolers, intakes and such. Is everyone just babying their cars and not opening them up?

 

[madeye moody]

What have you done to cause an overboost if anything?
I don't think a catback nor an intake pipe would cause that.
The only reason for an overboost is wastegate opening too slow, boost controller being used and set too high or shiddy design.

If the wastegate is unplugged then you could also get the same issue, check the vacuum line to the wastegate control solenoid.

If you are boosting to 21psi you are probably way out of the turbo's efficiency range and the intake temps are going way up, consequently the system could be opening the bypass valve to reduce boost until the temps drop back down.
Not positive but just a thought.

 

[mrlilguy157]

weird. sounds like the electric boost solenoid is whacked out

nothing should allow you to boost higher if you havent adjusted boost with a manual boost controller, but boost spikes are likely to occur with all of the better flow you have going on now...

 

[Craighjr]

Open intake, open down pipe, and open cat back all allow the turbo to spool faster. The ecu can't control the fast spool up giving me a boost spike all the way to 21.5 when the car senses overboost and shuts the whole thing down. I would appreciate if suggestions are accompanied by your set up. If your not running this set up and aren't some turbo guru I don't know if your going to help (ie telling me what will or will not cause this).

 

[mrlilguy157]

Open intake, open down pipe, and open cat back all allow the turbo to spool faster. The ecu can't control the fast spool up giving me a boost spike all the way to 21.5 when the car senses overboost and shuts the whole thing down. I would appreciate if suggestions are accompanied by your set up. If your not running this set up and aren't some turbo guru I don't know if your going to help (ie telling me what will or will not cause this).

this is my setup.

a manual boost controller, ATP boost cut killer, intake, turboXS hybrid blow off valve.

yes, like i said, boost spikes will occur with better flow, but they're not going to force the turbo to hold those boost pressures at that level. if 21.5psi is seen, then fuel cut occurs if anything over 18psi is held for about a second. (because it occurs at 18psi and up without the MAP sensor hack, aka the ATP boost cut killer)

i'm not a guru, but i'm pretty close

 

[MS3ICA]

mine does this too spikes up to 20psi in 5th and 6th, im planning on buying xede i herard this stops the spike, not to mention 60hp 70thq!!!

 

[mrlilguy157]

mine does this too spikes up to 20psi in 5th and 6th, im planning on buying xede i herard this stops the spike, not to mention 60hp 70thq!!!

don't buy the xede - get a PnP standback from CP-E or cobbtuning accessport, hopefully available at the end of september. its cheaper and programs the ECU via OBDII port

 

[Craighjr]

this is my setup.

a manual boost controller, ATP boost cut killer, intake, turboXS hybrid blow off valve.

yes, like i said, boost spikes will occur with better flow, but they're not going to force the turbo to hold those boost pressures at that level. if 21.5psi is seen, then fuel cut occurs if anything over 18psi is held for about a second. (because it occurs at 18psi and up without the MAP sensor hack, aka the ATP boost cut killer)

i'm not a guru, but i'm pretty close

Ok thanks. I'm not sure what my car holds boost wise. I would like to keep it at the stock level for now and in my opinion its not good to be hitting that cut alot. Did you run with out the mbc, I'm gunna assume that if you did you didn't hit cut with just the intake. How high will you spike before your mbc holds boost and are you holding over 18?

 

[mrlilguy157]

Ok thanks. I'm not sure what my car holds boost wise. I would like to keep it at the stock level for now and in my opinion its not good to be hitting that cut alot. Did you run with out the mbc, I'm gunna assume that if you did you didn't hit cut with just the intake. How high will you spike before your mbc holds boost and are you holding over 18?

i spike about 21 psi, hold 20psi, and then it starts to taper off in the top end back to 17psi

i never hit cut with just an intake. that's weird honestly.

 

[Craighjr]

I guess the downpipe and cat back are getting the same spike with out the atp tricker on my map or a mbc. Well good input thank you.

 

[CaSHMeRe]

don't buy the xede - get a PnP standback from CP-E or cobbtuning accessport, hopefully available at the end of september. its cheaper and programs the ECU via OBDII port

neither will be out by then. cobb has not released a date, and CPE stated atleast 4-6 months. Personally, i would wait for the CPE PNP. The Gen2 is supposed to be excellent!

the next available PNP will probably be the xede, but for $1000 bones, pretty rough (headshake

the xede also won't control the throttle plate. both the cobb ap and CPE standback will have full control.

my .02 cents.... wait for another PNP besides teh Xede.

 

[civic si hb]

neither will be out by then. cobb has not released a date, and CPE stated atleast 4-6 months. Personally, i would wait for the CPE PNP. The Gen2 is supposed to be excellent!

the next available PNP will probably be the xede, but for $1000 bones, pretty rough (headshake

the xede also won't control the throttle plate. both the cobb ap and CPE standback will have full control.

my .02 cents.... wait for another PNP besides teh Xede.

Yeah I can't wait for some plug and play to get going. I have alot of friends with suby's that are very happy with the cobb AP. I hope it does well for this car also.

 

[Craighjr]

neither will be out by then. cobb has not released a date, and CPE stated atleast 4-6 months. Personally, i would wait for the CPE PNP. The Gen2 is supposed to be excellent!

the next available PNP will probably be the xede, but for $1000 bones, pretty rough (headshake

the xede also won't control the throttle plate. both the cobb ap and CPE standback will have full control.

my .02 cents.... wait for another PNP besides teh Xede.

Cash do you have an exhaust yet? How does your car run with the maf moved for the fmic? I don't know if I can wait out the year to the new stuff is out to contol this. I really wanted an AP but by the time it comes out other better stuff will be right around the corner.

 

[MS3ICA]

cpe is very creditable and i beleive they do quality work, but at the same time look at the reputation of xede with the evo's and the sti , to me there something to be said for a reputation., im still open to getting a cpe stanback, im just really lading to xede cuase of the rep. and becuase its availible

 

[CaSHMeRe]

cpe is very creditable and i beleive they do quality work, but at the same time look at the reputation of xede with the evo's and the sti , to me there something to be said for a reputation., im still open to getting a cpe stanback, im just really lading to xede cuase of the rep. and becuase its availible

uum...reputation with STI's and EVO's. hmmm.... and what does that have to do with mazda?

just because i can tune hondas like the back of my hand, doesn't mean i can tune a completely different ecu platform.

XEDE = $1000 = No throttle plate control
AP/CPE = $700 range = Full Throttle Plate Control

patience is a virtue.

 

[MS3ICA]

good point.....??????.....

 

[funkyman]

Subarus and EVOS are not front wheel drives,DI Turbo,no sophisticated electronics to manage torque and two fuel pumps so its not the same.This is a very new technology and not even Exede can easily manage a good tune.

 

[TorqSpeed5252]

Insted of messing with the ECU, why not just run a manual boost controller in parallel with the solenoid valve/ wastegate?

Set it at 15.6 psi and your done. A little bit of plumbing work, but that's the only hard part. No more boost spike.

Can't say one won't get fuel cut from a MAF sensor issue, but that's another ball of wax altogether.

 

[Craighjr]

Insted of messing with the ECU, why not just run a manual boost controller in parallel with the solenoid valve/ wastegate?

Set it at 15.6 psi and your done. A little bit of plumbing work, but that's the only hard part. No more boost spike.

Can't say one won't get fuel cut from a MAF sensor issue, but that's another ball of wax altogether.

A mbc bleeds off pressure to the wastegate making it open later and hold more boost if im not mistaken. That would probably be the exact opposite of what I want to do to keep my car from blowing apart.

 

[TorqSpeed5252]

A mbc bleeds off pressure to the wastegate making it open later and hold more boost if im not mistaken. That would probably be the exact opposite of what I want to do to keep my car from blowing apart.

Only if it's ran in series. That won't happen if run in parallel. kind of like an electrical circuit where the ground is the atmosphere.

The wastegate would be the end of one of two lines. The wastegate line is controlled by the solenoid, which is controlled by the ECU, which can't respond fast enough due to your faster spool-up.

The other line would only be a MBC venting to atmoshpere set at 15.6 psi

See attached sketch. Please excuse the crudeness

This way the ECU control is unchanged (something I think you said you wanted), and you still control boost spike.