Ok, this is really strange..I use the stage 1 wastgate spring(5-6 psi) on the turbo, and use a Hallman MBC..NOw, if i set boost to around 8-9 psi, boost is great, very steady, NO spike at all. Now, i'm trying to tune for 15 psi,and that sucker will spike to like 18-19 psi! It's only for a second though, and boost falls to 15 steady..Its pissing me off becuase the 034 EIC does not like the spiking very well..making it a PITA to tune..motor will detonate for a second at the spike, or misfire/studder..then runs fine..I'm am starting to wonder if using a MBC to run a much larger boost pressure, over the rated wastgate spring pressure, is causing this spike? I think i read somewhere that you should not run twice the amount of boost as the rated spring pressure..it makes sense, since its spiking over a 10 psi setting...Anyone have any input to this? I've tried all diff boost sources for the MBC also...

13.5 @108 MPH-2.2 60ft(stupid FWD!)
S16G @ 18 PSI/FMIC/Running on MegaSquirt II (Now with sequential
fuel injection)
My webpage: http://eclipsed4evr.home.comcast.net
-1998 Mitsubishi Eclipse RS-T- "Toy"
-1992 Plymouth Laser Turbo AWD(SOLD)
-2000 Honda CR-V(daily)

I've heard the saying not to run double the boost of your wastegate spring also. My wastegate spring is only a 3 psi spring. Well I've had 2 mbc a turboxs one and a hallman. Both for some reason I couldnt get to settle down at above 8 psi. They would hold 6 easy as hell but once i tried to make it 7-8 it would spike to 10 then go down to 8 or whatever. So I finally said screw it and bought an AVC-R I love it so far. I have settings for wastegate @ 3psi, setting B @ 6 psi and setting A @ 8 psi. I really like this thing. It's just a bitch to setup at first but once you get the tuning down you'll like it I guarantee.


1998 Eclipse RS-T
Aim= masterkoronor
Email krwadd02@louisville.edu

The AVCR is nice, I use it in my 2gnt as well. Throw the auto mode out tho, it does not work very well. I picked it up after my MBC would not hold 16 psi very well.

On a side note the avcr can modify boost per gear. I'm running 10 psi in 1st, and 7 psi in 5th. That makes it great for launches at the track and highway driving.

____________________________________________________
four nails four corners four riders and four horses

Yah I love the avc-r. I have all different settings for what I plan on doing. If i just wanna have a little fun I'll just throw it on 3 psi and just have a little fun without owning my gas But when I wanna get down put it to setting A and push 8 psi and have some real fun! hehehe Mr. Mustang GT and Civic SI last night can tell you how fun 8 psi is heahehea.


1998 Eclipse RS-T
Aim= masterkoronor
Email krwadd02@louisville.edu

you have a boost leak. not a spike.

do the usual things.. check all vacum lines, intercooler pipes.. check your exhaust manifold for leaks.

13.5 @108 MPH-2.2 60ft(stupid FWD!)
S16G @ 18 PSI/FMIC/Running on MegaSquirt II (Now with sequential
fuel injection)
My webpage: http://eclipsed4evr.home.comcast.net
-1998 Mitsubishi Eclipse RS-T- "Toy"
-1992 Plymouth Laser Turbo AWD(SOLD)
-2000 Honda CR-V(daily)

I ran a 5psi spring in my car, and 15psi on the MBC. No spikes. Spiking is not a trait of MBCs. it is a trait of bad MBCs.

______________________________
If a sentence found online has 35% misspellings or greater and includes at least two racially charged expletives, chances are it is a YouTube comment.

'95 Eclipse TurboGS (garage deco)
'95 TSi AWD (restoring a survivor)
'97 Talon ESi-T (poor impulse control)
'99 Eclipse RS-T (daily beater)
'13 Evo X (mostly stock)
'17 Sienna (Middle Aged Dad Mobile)



Factory Service Manuals: http://nawdu.de/files/

~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

Megasquirt powered 420A
Custom turbo system

http://www.ms-custom.com

13.5 @108 MPH-2.2 60ft(stupid FWD!)
S16G @ 18 PSI/FMIC/Running on MegaSquirt II (Now with sequential
fuel injection)
My webpage: http://eclipsed4evr.home.comcast.net
-1998 Mitsubishi Eclipse RS-T- "Toy"
-1992 Plymouth Laser Turbo AWD(SOLD)
-2000 Honda CR-V(daily)

Originally posted by XtremeRS

Originally posted by DarkOne I ran a 5psi spring in my car, and 15psi on the MBC. No spikes. Spiking is not a trait of MBCs. it is a trait of bad MBCs.

Yeah..you also use an external wastegate too, which is much better for precise boost control..Could be the MBC i suppose..I have done some searching on the net about spikes, and have read that as you increase MBC tension, spiking can worsen. Spiking is more common on smaller turbos, where the turbo can spool up very quickly(which mine does), and the time it takes for the MBC to open up, pressureize the wastgate atuator, and start to control boost,the boost can spike, then settle down(which its doing). It just can't react fast enough, since the MBC is keeping all pressure from the wastegate, until its set to open. The spiking is the worst when i am on the highway, in 5th, at 70 or so, then drop to 4th and go WOT. Boost is instant, and it just makes sense that the MBC cant control the wastegate fast enough..causing it to spike for a second. Found some interesting info on Saab forum, where someone took an adjustable air pressure regulator, tapped that off of the comressor boost source, then teed the output of that to the MBC's oulet, so both outputs of the APR and MBC go to the wastegate. This lets an adjustable amount of air pressure going to the wastegate actuator, to *slightly* pressureize it, not enough to open it, but enough to pressureize it, then when the MBC opens, boost does not spike at all, since you have decreased the amount of pressurizing time to open the wastegate..sound interesting to try..although the easiest solution is to get the damn EBC haha..trying to Macgyver something is more fun though

__________________________________________
~Chris
03 SRT-4

I'm having the same problems Matt. This is my 4th boost controller. You figured a 90 buck turboxs boost controller wouldn't do that. But it will all eventualy do. I'm going with the dual next. If that fucks up, I'm going all out electronic. Wastegate spring is not a big factor. Afterall it's still being fooled by the boost controller no matter what spring you have.

intricatelines.com/ -graphics and vinyls

"Tell them of us and say,
For their tomorrow,
We gave our today."
-- The Kohima Epitaph

Whooo hooo! I think I fixed it..with a little internet help and searching..Somone on a Saab forum figured out a way to prevent boost spikes or "overshooting". Basically, you use an adjustable Air Pressure Regulator, getting its pressure input from the compressor. You use manifold pressure for the MBC inlet. Then, on both the APR and MBC outlets, you tee them togheter and run to the wastegate. So what does this do? Well you set the APR to "prime" the wastegate with a few psi of air pressure, whenever there is boost. Then, when the MBC's ball/spring mechanism is lifted off its seat at your set pressure, it makes the wastegate much, much more responsive. The spike is caused by a delay really. Since this turbo spools so quickly, esp using a MBC, the MBC cannot react fast enough to open the wastegate to not get any overshoots in pressure. Now, with the wastegate being slightly pressurized, the time it takes to open it, is greatly reduced, and no spikes. I tried it out tonight, and preliminary testing reveals it works, and works quite well. I didn't have much time to play with it, but a little tweeking gave excellent results. This is a very good read, if anyone wants to get more info on the setup. Its called a "MBC Anticipator"

http://www.saabnet.com/tsn/bb/9-3/?bID=73160

http://www.saabnet.com/tsn/bb/9-3/index.html?bID=69576

http://www.saabnet.com/tsn/bb/9-3/index.html?bID=84683

13.5 @108 MPH-2.2 60ft(stupid FWD!)
S16G @ 18 PSI/FMIC/Running on MegaSquirt II (Now with sequential
fuel injection)
My webpage: http://eclipsed4evr.home.comcast.net
-1998 Mitsubishi Eclipse RS-T- "Toy"
-1992 Plymouth Laser Turbo AWD(SOLD)
-2000 Honda CR-V(daily)

EXCELLENT find.

I forget that not everyone runs a manly turbo with an external gate.

______________________________
If a sentence found online has 35% misspellings or greater and includes at least two racially charged expletives, chances are it is a YouTube comment.

'95 Eclipse TurboGS (garage deco)
'95 TSi AWD (restoring a survivor)
'97 Talon ESi-T (poor impulse control)
'99 Eclipse RS-T (daily beater)
'13 Evo X (mostly stock)
'17 Sienna (Middle Aged Dad Mobile)



Factory Service Manuals: http://nawdu.de/files/

Originally posted by DarkOne
I forget that not everyone runs a manly turbo with an external gate.

__________________________________________
~Chris
03 SRT-4

+7, 8?? for MBC suckage.

I doubt its a boost leak if your holding that 15-16 steady after the spike. Normally w/ a boost leak you will fall off a psi or two and its really unpredictable.

400whp or bust.

Sounds to me like you are in the realm of EBC land. A nice EBC will anticipate and learn the charactaristics of the boost curve, and would actually anticipate such a spike. It would know to open the solenoid before that spike, pressurize the wastegate lines. Also, a bleed style MBC might work better than a ball and spring MBC with these boost levels. A Ball/Spring type MBC will keep all pressure out of the wastegate until the ball-bearing pops up and opens the valve (peak boost), while a bleed valve will constantly pressurize the wastegate lines, but bleed off a certain ratio of air pressure to achieve higher boost.


1996 Eclipse RS / 5-Speed / Aerogear Body / Coated in Magnetic Red Metallic rev.2 / T3 Turbo Intercooled @ 8 psi / More at http://home.insightbb.com/~mgalyan/
Mark Galyan - Indianapolis, Indiana