Installed MBC+A, Still cant adjust boost [Archive] - SaabCentral Forums

: Installed MBC+A, Still cant adjust boost

30th July 2007, 07:26 PM
I have the MBC+A installed perfectly according to all instructions...and no matter where I adjust the MBC to, the car still boosts into the red and hits fuel cut.

If anything, the fuel cut feels when it hit in second gear, my tires chirped.

I am at a TOTAL loss....wastegate? What do I do?

30th July 2007, 08:31 PM
do you have an aftermarket boost gauge?

30th July 2007, 10:12 PM
I do not have an aftermarket boost gauge.

I called Jeff from Smart Performance and we decided that the wastegate had to be sticking. Either from too much oxidation on the wastegate regulator itself, or a failed wastegate actuator.

Tomorrow morning I'm going to take the heat shield off and see if i cant move the wastegate actuator with my bare hands, if it moves and still doesnt work...then its the actuator. If it doesnt move and is seized all together, wastegate is seized shut.

If I can hit it with WD40 and pb blaster and it works.....that would be cool.

30th July 2007, 10:19 PM
keep us updated because I may be going through the same problem

Bummer 9-3
30th July 2007, 10:22 PM
does anyone have the instructions on how to hook up the MBC+A from smart performance because me and my buddy hooked it up and it took us a while and we didnt use a log hose and a short one with a vale on top because he had never seen anything like that because he had only used a Turb XS one, the reason i dont have the directions is because i bought it from someone on saablink but i was just wondering if there were pictures or a site i could go to..

30th July 2007, 10:26 PM
a boost/vacuum gauge might help you adjust the mbc

30th July 2007, 10:39 PM
you need to plug off the old apc and run the line from the t-body hose to the wastegate...

Tweek's Turbos
30th July 2007, 10:56 PM
Compare how you have it set up compared to here:

I think the actuall case is something isn't hooked into the bpc solenoid correctly and thus you are trying to tune something not actually hooked into something.

Try it like above link, only forgo the anticipator portion.

31st July 2007, 12:41 AM
Theres not much you can do wrong when hooking this thing up. The throttle body line runs to the inlet on the mbc, the other side of which is already routed into the Y connector. The wastegate line is run into the open inlet on the Y connector, and the turbo line is run to the APC. I have the short cable blocking off the wastegate and turbo inlets on the BPC, and have left the intake line hooked up to the BPC.

A stuck WG would explain a lot actually. I've always wondered why my stock T5 ecu boosted well into the red.

Has anyone dealt with a seized wastegate or wastegate actuator before?

31st July 2007, 10:06 AM
So I think my nightmares have been confirmed. When i removed the heat shield and tried to move the wastegate arm, it wouldnt budge. I can tell its not the fault of the actuator because i can see the arm moving around inside of the diaphragm.

I think my wastegate is stuck closed internally. Im going to keep hitting the actuator arm and joint with WD-40, but i have a feeling its not going to do anything. No matter how much force i placed on the arm, it would not slide to open the wastegate. I didnt try giving it any I dont want a wastegate thats stuck open either.

Here are some pictures, maybe someone can see something i cant.

The whole assembly

Wastegate side

actuator side.

31st July 2007, 11:23 AM
i really think you should take the waste gate off first, then inspect it. sometimes the internal spring makes it hard to move by hand when its installed. it only takes a few minutes to remove. and once you have it off you can connect a vacume hose with a bike pump on the other end and give it a pump. you should see the actuator arm move outward (and stay extended assuming your holding pressure). or you can pull the actuator out by hand, and put your thumb over the nipple; it should stay extended (holding pressure)untill you release you thumb. good luck Mark.

31st July 2007, 11:45 AM
Im not quite sure what you mean.

Disconnect the wastegate from the actuator arm and use the bike pump to check to see if the actuator is bad?

It only takes 6psi of pressure to move the wastegate, so hand hand pressure moving the arm should be more then enough to activate the wastegate. The actual switch on the wastegate itself is totally wont move at all.

31st July 2007, 12:21 PM
what i meant was , completely remove the "wastegate actuator" from the turbo. (it takes 2 bolts, a clip, and a vacume hose.) once the whole thing is removed then test the pressure of the diaphram. i remember that on my garrett turbo it took a fair amount of force to move the rod when it was intalled. i would have to pull it at least a 1/4 inch to the right just to losen the clip for adjustment. it needs to be under some load to hold the wastegate, in the turbo, shut. and when you remove the clip from the wastegate arm(on the turbo) to the actuator(the rod piece), the waste gate should fall free and move easily. if the wastegate itself is actually rusted shut, you will have an easier time breaking it free when its disconnected

31st July 2007, 12:44 PM
Do you think its safe to attempt to break the wastegate arm free? I have to make a 500 mile trip this saturday, and im really worried that it would get stuck open if i were to try to mess with it.

Or do you think if it breaks open, ill just be breaking the rust holding it shut and be fine after that...

31st July 2007, 01:18 PM
i think its safe if you tap at it and dont try to force it. and a little liquid wrench would help.

all the wastegate is, is a 1 inch rod that connects to the lever that you can see in your second picture. on the other side of the rod there is essentially, an arm connected to a flapper. the rod travels through the turbine housing. its hard for me to imagine where some thing like this could rust solid, and not be tapped loose.

first, i would take the clip off the actuator and then check to see if this lever moves freely. if this shows not to be the problem, then test your actuator.

31st July 2007, 02:27 PM
What is the best way to remove the clip from the actuator arm? It doesnt seem to be very accessible from the top of the engine bay, is this something i have to get from down below?

31st July 2007, 02:32 PM
I think what Mark is saying is a good test. if you can disconnect just the arm off of the wastegate lever, you might be able to isolate the problem. This will either eliminate the WGA arm being part of the problem or identify it. If you just disconnect the arm from the WG lever, you should be able to move the arm freely. You can, at that point test the WGA to see if the diaphragm is okay.

As a side observation, the arm and looks nasty so do the test above and then you can move onto the WS lever.

Here is a picture of mine(with a helper spring) with 180K miles on it.

31st July 2007, 02:35 PM
just use some needle nose pliers/ baby flat head screw driver. you can get to it from the top.

31st July 2007, 02:37 PM
Im going to let the engine cool down for a few more hours, and then hit it with some PB blaster....hopefully that will make it easy to remove that retention pin and break some of that oxidation off of the arm and lever.

1st August 2007, 12:44 AM
The PB blaster worked!!!!!

No more fuel cuts, full boost!

I guess there was so much surface oxidation on the wastegate/arm/actuator that the whole assembly couldnt move.

1st August 2007, 09:42 AM
Now there's a happy ending!

So for the record...was it the actuator or the WG lever?

1st August 2007, 11:36 AM
I know i should be doing this with an actual boost gauge, but about where is 15 psi on the stock unit. Close to yellow? Half way into red?

1st August 2007, 11:45 AM
the stock gauge is very inconsistant, and every one reads diff. but ive seen most,creep into the red before cut off. you should turn it up a little at a time, when you hit cut off, turn it back down.

1st August 2007, 11:53 AM

Tweek's Turbos
1st August 2007, 12:58 PM
1/3 red in my car.

1st August 2007, 01:08 PM
I have been having the same problem on my car after I put my MBC in. I Was hitting red, fuel cut off no matter how much I adjusted it....

I ended up taking the dammn thing off, beacuse it was pissing me off!!!

1st August 2007, 02:55 PM
markm99, was that video you posted of a stock T5, or with MBC installed?

The whole tuning process seems very quirky. Whenever i feel like i can get a higher boost setting...ill get something along the lines of...

1st gear - pulls to redline
2nd gear - pulls to redline
3rd gear - Pulls to 4.5k, studders, and then shoots to redline (at a higher boost setting then 1st, and 2nd)
4th and 5th are fine.

To combat the overshoots in 3rd, i just kept adjusting the APR until i was no longer getting the studdering in 3rd...but this just resulted in longer spool up times.

So at this point, i have the mbc set so im hitting the same boost levels in all gears, which I assume is what im looking for. I have the APR set about one full turn clockwise, and im not sure if its doing anything...but the car feels just fine.

1st August 2007, 05:41 PM

way to go william shatner! lol :cool:

1st August 2007, 11:46 PM
[QUOTE=9600]markm99, was that video you posted of a stock T5, or with MBC installed?

this is from a car with a MBC+A. that was acctually from Super Moderator, "Clevesaabs," car. he just installed his boost controller at the Findley meet, 2weeks ago, and posted his progress for all to see. by the way, a really cool guy to meet.

i think he was saying that he was able to turn it up even higher than ,as was set, in the vid. i used the video to give you a better idea of were to start.

my car is about 2weeks away from a stage5 tune as of now. i have been running water/methanol injection for awhile. with that ive been able to adjust my WG, and hold an almost steady 14+psi. the W/M keeps the compressed air cool, and detonation free. the ECU likes this cool damp air and doesnt perform negative adaption. and if it does, i just do afew hard adaption pulls and its back.

you see, your MBC+A takes this adaption function out of the ECU's hands, and allows you to control when the WG starts to open. having a crossflow intercooler, intake, exhaust,etc.. will add to your engines response and power efficiency, but you will still be limited with the fuel cut-off in the end. eventually if you want more power you will need a tune; this will remove all boost limitations.
mark m

2nd August 2007, 12:36 AM
See, the whole reason i purchased the MBC+A was as a replacement for my BPC valve... a much cheaper replacement and nice way to squeeze some power out of the stock tune. As my problem ended up being solved by PB Blaster, it ended up being a bit of a needless investment, but a fun one thats given me quite the lesson in forced induction.

Right now im just playing the balance game with the air pressure regulator. I seem to be able to get consistent max boost in 1st and 2nd, but im getting irregular boost spikes in 3rd and 4th, only when i shift fast and hit WOT.

I assume this is because of the delay in the ball and spring mechanism of the MBC. I've thought about continuing to increase the pressure on the regulator to eliminate the boost spikes, but without a boost gauge...its difficult to tell when boost starts to taper off and the APR is set correctly.

I think im just going to end up de-tuning the MBC until i no longer hit boost spikes in 3rd and 4th under any conditions. The cons of overpressurizing the APR (increased spool time, loss of boost) just far outweigh the extra 2-3 psi im sure im missing out on.

Once i get a good boost gauge, im sure ill be able to tune the MBC properly.

PS - Is it normal to have your throttlebody tap line blow off the MBC when you hit a particularly rough fuel cut?