SaabCentral Forums banner
1 - 9 of 9 Posts

Discussion Starter · #1 ·
I have been having a couple of issues with the mbc+a set up. I have recently installed the Viggen IC so since then a few things have crept up. Like getting a fuel cut 5 weeks after installing the IC and in warmer weather 34C.
So I started from scratch to set up the mbc+a last night,
1. I closed off the anticipator.
2. Adjusted the mbc until I got fuel cut.
3. Backed off the mbc and did runs with no fuel cut. So ok.
4. Started to open up the anticipator.
5. (anticipator) at 1 3/4 turns the boost was 1/2 way on red and stayed there. At 2 full turns the boost was 1/2 in red but settled back to start of red. At 2 1/4 turns the boost was only to start of red. Q? The optimum setting is the one with the boost staying in 1/2 into the red even at high rpms? If boost drops to start of red, this is not good. Am I correct???
6. On one of the runs with 2 turns I got fuel cut in 2nd & 3rd gear!! wtf?
7. So I backed off the mbc just a hair.
8. Seemed to be fine after and I have been doing this for an hour so I went home.
9. This morning I set the anticipator back to the "1 3/4 turns position" to try and hold more boost. I was not even able to get in the red!!!
10. I then set it back to where it was at 2 turns, and it boosted 1/2 way in the red. What's going on here???
11. Just shaking my head here at work. help!

Any advice on set up. Am I missing something?

· Registered
2,297 Posts
Sounds a little like a boost adaptation problem.
Onc you have established stable boost through three adaptation runs, you might find a more stable setting. The droop could be a number of things. vac line leaking boost, BPV(if not upgraded) IC heatsoaking, turbo reaching its flow limitations, etc...

CCW is fully closed on +A and that is where you started from right?

You using WOT to tune the MBC?
WOT and partial throttle have different effects on boost and how fast the MBC reacts. The stock gauge is alos not the most accurate thing either.

Best to find the setting using WOT and go from there.

Discussion Starter · #3 ·
Should have posted before...engine/intake mods:
3" Flared Tube Airbox
K&N Air Filter
Dawes MBC+A
viggen Intercooler
Viggen Bypass Valve
Smoothed inlet on TBTC

Don't think this mornings problems was IC heatsoak since only driving 5 min before WOT.
Yes, the APR was fully closed.
I have been using WOT to tune.
Don't think I have any leaks. All seems tight. No splits in hoses.

The object is to hold 1/2 in red? right?

It's lunch time so I'm gona go find some open roads at the side of the city and report back.


Discussion Starter · #4 ·
Well, it went better but I think I may have to start from scratch again. I have a feeling I'm not doing the adaptation runs correctly, so the initial mbc setting could maybe be greater.....

How should I be doing the adaptations runs? WOT 2nd 3rd 4th 5th gears. 3 times?

Discussion Starter · #6 ·
Oh....I tried to keep the car cool by driving normal in between runs last night. But with all the stopping, the IC could have been warmed up.
I will try again with your methods.
Thanks for all the help.

· Registered
164 Posts
about 2 hours ago i got home adn installed it
and heres my review
THe device installed extremely easy except that i could not remove the wg hose formt he bpc to use the smaller hose to loop the wg to th turbo.. instead i used the hoses already there.. would this make a difference. Anyways first run noticed red ont he left hand side of the needle for the first time ever. but spool wasnt great. . twisted the apr a bit and finally got it to go about 1/4 red and spool quickly... I didnt notice a reduce in lag off of the line though.. it still seemed to take its time.. im waiting to take a colder run though tonight

Its sitting at almost fully on the mbc and about 1 1/2 to two turns on the apr... IM thinking the reason that i am not seeing half into the red is because or my stock filter/box and dirty filter. i also have a return flow ic aka 99 9-3 ...

I would appreciate some comments or suggestions

Discussion Starter · #9 ·
Well I set up the mbc+a a few days ago (27C and humid). It was frustrating setting up the base boost on the mbc. I would adjust until I get fuel cut, then turn down and still get fuel cut, and turn down and still get fuel cut. wtf? :evil: I guess the weather and IC heatsoak was messing up things....

Worked fine until this morning (21C not humid), had big fuel cut in 2nd gear and minor fuel cuts in 3rd. I hate this big fuel cuts as it really jerks the car and I feel I'm abusing the heck out of it.:cry: (the anticipator is adjusted correctly)

I assume the outside temperature makes a difference in the setup of the mbc. But the anticipator is supposed to deal with it? All my vac and IC lines are tight and not split.

I decided to go a head and install a boost gauge so that I can see what the mbc is really doing. I assume Autometer gauges are the most popular and accurate? Looking at # 3301. Any Canadian sources for online or local sales?
1 - 9 of 9 Posts
This is an older thread, you may not receive a response, and could be reviving an old thread. Please consider creating a new thread.