10lbs no mbc, mbc all the way out 16lbs

[danyz250f]

I have a 16g turbo with an internal waste gate and the least amount of boost i can run while still getting a fast spool is 10lbs. I would like to run 12-13lbs but when i hook up my mbc screwed all the way out the boost goes up to 16lbs. I have stock injectors and a motor with 105,000 miles on it and i dont want to go more than 13lbs. But i notice a huge increase in power from 10-13lbs. I have tried taking coils out of the spring in the mbc and that didnt help. I have screwed in the waste gate arm and have to really pull on it hard to get it to hook back on to the flapper, and saw no change.

how do i get that extra 2-3 lbs, do i not run an mbc like i am currently doing and tighten up the wastegate more or what. I have spent alot of time and have popped the hood many of times trying to fix this problem.

 

[1993eclipseGS]

If you run the car at 16lbs, That is fine... Unless, You're motor is in really bad condition. Miles do not mean anything, It's how well the car is maintained. Just buy a logger if you don't already have one

 

[Iceman90]

Looks like standard boost creep to me. A full 3" turbo-back exhaust with no cat is definately going to cause a non-ported 16g to creep. A simple solution would be to just add a cat, but you will lose some power. If you don't want to lose power you can port your turbo inlet to eliminate the step and port the wastegate chamber so the wastegate arm can open at a full 90 degree angle. You should be able to hold whatever psi you set your mbc to all the way to redline after that.

If you think you can port it yourself here's a good article on it:

http://www.dsmtuners.com/forums/showthread.php?t=186525

 

[danyz250f]

I have a logger and an safc. I seem to hit fuel cut at 15lbs thats why i want to run lower boost, untill i get the $300 for 650cc injectors that i hope will fix the problem. I have the safc on the high throttle set at -5% all the way till about 5800 rpms then up to positive 20% from 5800 increasing gradually till about 6500 then leveling off till 7000 rpms. I had to go this high to get rid of knock from 6200 rpms to redline. This was tuned at 10lbs, and the piggyback tuning guide said that it is easier to tune a couple of lbs lower than what you want to run.

 

[1993eclipseGS]

That's strange that you're getting fuelcut at only 15lbs, Since you have the pump and injectors. Did you check your whole system for boost leaks?

 

[danyz250f]

Yes and I had a small one where somewhere on the back of the motor. I used to run 14lbs easily before my fmic install.

 

[oldman]

Yes and I had a small one where somewhere on the back of the motor. I used to run 14lbs easily before my fmic install.

1. You have more than just a small leak, boost leaks is most likely the cause of your fuel cut. What were the results of your boost leak test after fmic install? If the answer is "I have not done one yet" then your fmic installation was never finished.

2. I don't think it's boost creep, if so, it should happen with or without the mbc though I wouldn't rule it out just yet. When boosting to 16psi, does it pause at 10 then creeps to 16?

3. Which mbc and how is it hooked up? I bet it's off the BOV line. When you remove the mbc, how is your actuator hooked up?

 

[danyz250f]

Ok after I did my fmic install I went over to my friends cabinet shop to use their huge rotary air compresor. I found that my bov had cracked in half while tightening it to tight to the flange i welded to the intercooler piping because when I welded it I didnt let the metal I cool (weld a bit let it cool weld some more ect.) and it warped a little. So i made a rubber gasket and didnt tighten the spare 1g bov down so tight. Fixed that leak. Then one pipe simply came out of the coupler, I repositioned it and reclamped it. That just left the leak on the trottle body I asssume the gasket on the block. Haven't fixed that leak yet because i don't know how.

The MBC uses the pressure source nipple of of the J pipe. When the MBC isn't hooked up the hose goes straight from the wastegate to the J pipe nipple.

When the MBC is hooked up the boost hits a full spool of 16 lbs at 3500 rpm. No hesitation at 10 lbs. I even tried hooking up a tetra valve in line to see if that would reduce the pressure a little that the wastegate sees. That didnt do anything at all.

P.S. it is a ball and spring ebay special that work fantastic with my stock 14b

 

[oldman]

1. Boost leak test: How much was the boost gauge registering after you fixed the leaks? A leak test isn't finished until you're able to pressurize the intake up to 20 psi and allow no less then 30 seconds before it bleeds down to zero. When you retest, spray soapy water every where, make sure you cover the injector seals, TB BISS and both sides of the TB shaft. Once you locate where the leaks are, I will be able to help you fix them.

2. SAFC: I suggest zeroing out the safc because any adjustments you make to it with the stock injectors are just bandages to other problems you're ignoring. Am I right that you're still on the stock injectors and MAF?

3. MBC : I suspect that the spring in the mbc is too long, take apart the mbc and make sure that with the adjustment all the way out, the ball is not blocking the path to the wastegate. If so, remove the spring and clip off the amount which will allow the wastegate path to be exposed when the adjustment knob is all the way out.

Hope this helped.

 

[danyz250f]

thank you for your help i will let you know the results. Yes they are stock maf and injectors

 

[oldman]

You're welcome, good luck.