aright 3sgte homies....as u all know i just got my twos r us MBC this week, installed and set to 12 psi. tonight i ran the car pretty hard in some races and twice my boost spiked to 14psi and i hit boost cut. prolly 2 out of 10 times that i full boosted i hit boost cut. had to pull over on the shoulders and restart the car to get that CEL off ive checked all my hoses and piping and everything seems to be a-OK. this happen to anyone else?

btw i ran against an s2000, wrx, and a pretty modded audi tt...no loses on my part

bboy

Nice! Time for an FCD?

nice ruel, yo at 440 it was pretty wack tonight but there was a chase as sson as we got there red integra was about to get hassled by a cop and right there from the dunkin doughnuts parking lot the chase was on.

>

Thats what I want to hear... 3sgte power
Makes me want to do an engine conversion now.
I hope you get this boost cut sorted for some more
a$$ whopping

yeah ma friendds ae86 turbo was doing the same when we put the boost controller, (i wanna know the problem) if your not wanting it to hit 14 psi then your boost controller might be really sensitive and need to tweak it slowly becuz ma friends was hitting boost cut at 20 on a little 1.6 gze turbo and so we took the boost controller off and is gonna buy a new one (turbo X's) and if the prob is the boost cut then yeah get after market ems

exactly what boost controller is it and have you disabled the tvsv?

im so proud and feeling tempted to get a 3s swap

Of course, all this racing was done on a track or private road wasn't it?

>

Those simply 3 letters - M B C - are the cause of the overboosting issues. MBCs are renowned to causing overboost as they simply can't react quickly enough to keep the boost under control. I have never and will never fit one to a turbo car for that reason. Overboosting can potentially wreck an engine as you may well be aware of. EBCs may cost more, but will control boost much better and are still cheaper than an engine rebuild.
Gary

hmmm didnt know EBC were better than MBC in controlling boost...so theyre just not as responsive huh? and yah i know overboosting = blown engine thats why i havent gone FCD yet. the feeling of hitting that boost cut sucks but its better than my engine blowing up. anyway in any case ive heard really good stuff about the TwosRUs MBC and i thought id give it a shot. anyone else with 3sgte swaps having overboosting problems?

and yes all racing was done away from public traffic at 3am in the morning

bboy

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its the twos r us MBC and yes the tvsv has been disabled

bboy

an mbc will not cause overboost if adjusted correctly and locked off. the big advantage of ebc's is the boost will cut in quicker as it will hold the wastegate closed until full boost it reached and obviously you can adjust it more easily and accurately

>

Sorry, but completely disagree with you there. MBCs are notorious for causing overboost.
Gary

explain??? i know a fair few ppl who have no overboost problems...

i agree with the over boost issues as i use a TURBOXS MBC on my jetta and they surge pretty easily

i never experienced a surge? even with my homemade MBC. it was like that oven thing.
just set it and forget it. id never go over 13psi. (unless i did it intentionally)

wow some mixed experiences...anyone else have experience overboosting on MBCs? i think ill go EBC but that wont be for awhile til i get some serious upgrades...the thought of setting a certain boost level for each gear is real tempting

bboy

methinks some of you have mistaken the overboost for a leaking pipe

>

could be a possibility but ive checked all of my piping and anything/everything related to this without finding anything lose or leaking...hmmm

bboy

The reason you are overboosting is because your waste gate door is hitting the flange on your down pipe, and getting stuck closed. You need to take off the downpipe, grind down the flange alittle and reinstall. Then your over boost problems will go away.

You'll see where you need to gring once you remove the DP.

DEF

damn you guys have some pretty crazy ideas....lol


BBoy.... fuel cut happens right at 12psi. if you set it at 11-12ish, you might be fine one day, but hit fule cut the next day because the weather got colder by a few degrees. all you have to do is disable fuel cut. there are 2 ways of doing it....

1, disconeect the vac line that goes to the turbo presure sensor and put a vac cap on the sensor and a cap on the vac line that used to go to it. this will give you no fuel cut protection. just keep an eye on your boost gauge and make sure it stays under 15psi. i have had my car like this, with the same mbc for almost 2 yrs... never had a problem and the boost stays were i put it.

2. buy or build an FDC and set it up to fuel cut at around 16 psi. this will just bump your fuel cut back so that it happens later. in 93 toyota changed the fuel cut on the 3s to 16psi , so youll be doing the same thing, just with an aftermarket box.

even if you buy an ebc, youll still hit fuel cut after 12psi if you dont disable it.

ebcs are great for in car control and keeping the wastegate closed till the last second, but for what you are doing, a good dual ball and spring mbc will work great...and is used by 75% of the mr2 guys with no issues

This post has been edited by lagos: Jan 24, 2006 - 12:48 PM

lagos does this apply to the 3rd gen motor too?

yah thats the same thing alltrac.net told me lagos...lol and i was thinking the same thing. in any case i will be getting an FCD pretty soon

bboy

Get a piggyback ECU or a full aftermarket ECU. That way you can tune your ECU for your mods, and also bypass fuel cut

gen3 motor has fuel cut at around 17-18psi. (stock boost is 13psi)

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yah i plan to get a full standalone within a year or two along with some major upgrades (soon as i get myself a beater ) ur so damn lucky to have a gt4 bud lol

bboy

hehe thanks I saved up for it... actually I wasn't planning on getting a GT-Four but I just came across it one day when I was looking for a car - saw it Friday afternoon, checked it out, and within four hours, negotiated and signed papers. Picked it up the next morning
Got it from a Toyota dealership, thinking it was stock... but turns out a lot has been done to it, including SMT6 piggyback ECU, hiflowed CT20b turbo, camshafts, cam gears, custom SS downpipe/midpipe, and there might be more, for all I know...