GTM Stage II TT - Possible issue hitting max boost?

[DIGItonium]

I recently installed a Hallman MBC, and it's not working at all. The boost source was initially connected to the intake pipe, and today it was relocated to the back of the intake plenum where the boost gauge is tapped into. It still doesn't work, so I'm waiting to hear from Hallman to see if it's a defective unit.

Anyhow, I notice I don't hit 5 PSI until after 4-5k RPM. Is this later than usual? It just seems like I'm not building up boost as fast as before, but it's steady around 5 PSI.

We looked around for leaks, but couldn't see or hear anything odd. Engine idles and revs fine. Every once in awhile it would raise idle and fall back (like only seen it 2-3 times since September).

So sad.

[tower74]

It almost seems like these cars don't like better being FI.
Do you have a boost controller on your system?
On my system I'm still fighting the gremlins but for the most part they are gone.
good luck and hope you can get it resolved by next weekend!!

[DIGItonium]

The boost controller is the Hallman MBC. O&G has one as well, but he has the custom single turbo setup.

Man, it shouldn't be this difficult. I'm tempted to leave the WG port open to see if I can get more than 6 PSI on partial throttle haha. Too risky.

[tower74]

My boost controller is a simple switch
One is set at 5psi and the other can be set by a dial back by the turbo.
Does seems odd you can only get 5psi

[Zat_Zuma]

I found my vacumn/boost leaks by using starter fluid. Visual inspection wasn't enough. I searched high and low and didn't find one but the log data from Cipher showed that I wasn't getting up to MAF voltage (air flow) but the starter fluid found everyone of them. I had 4 in total. Like you, my boost pressure just wasn't up to snuff. 6.5 psi VS 8.5 If you can't use starter fluid, use electrical contact cleaner .... less volatile and almost just as effective.

The idle speed will increase indicating a leak.

Good luck with your search

[Deadman]

Originally Posted by DIGItonium

I recently installed a Hallman MBC, and it's not working at all. The boost source was initially connected to the intake pipe, and today it was relocated to the back of the intake plenum where the boost gauge is tapped into. It still doesn't work, so I'm waiting to hear from Hallman to see if it's a defective unit.

Anyhow, I notice I don't hit 5 PSI until after 4-5k RPM. Is this later than usual? It just seems like I'm not building up boost as fast as before, but it's steady around 5 PSI.

We looked around for leaks, but couldn't see or hear anything odd. Engine idles and revs fine. Every once in awhile it would raise idle and fall back (like only seen it 2-3 times since September).

So sad.

Hrmm..
The, mbc needs a boost reference which cant come from the intake. It needs to come from post throttle body no?

Edit: nvm you are correctly hooked up... I was reading your initial thread and typing this up Haha

[DIGItonium]

Yea, it was rerouted to a barb connector on the back of the intake plenum. This is where the boost gauge sensor is connected to as well. So it's currently a post TB setup.

Just talked to Sam@GTM, which lead me to text my installer at Baker Tuning. One possibility is the wastegate preload. If it's too lose, then I won't be able to raise the boost. So I'm waiting to hear back from him as well as Hallman tech support.

@ZatZuma, were your leaks found in the intake piping or the vacuum lines? Most of my lines are still zip tied.

[EDIT]
I'm going to leave my car with the tech. He's going to take a look at the wastegate actuator and tighten it up. He also has a boost controller that he can test if mine still doesn't work.

[SharpByCoop]

One thing I've learned about an electronic boost controller is the difference in how much quicker the boost comes up when regulated by this.

When I turn it off and only have waste gate pressure, it's lazy. Turn it on, and even at the same boost setting it jumps up. It really holds the waste gate closed tight till it's ready.

I get boost 6-8 lbs of boost @ 3500. FYI. (EVC-S Boost controller)

Coop

[DIGItonium]

Thanks, Jim. I just notice things are a bit funky lately, but that's probably because I've been boosting more often. We should've done it this morning while the car was on the lift, but he's going to double check the wastegate actuator rod to make sure it is tight and is keeping the exhaust flap closed.

Other than that, it completely baffles us that the MBC wasn't doing anything useful after giving roughly 7 full turns. Boost held steady at 5 PSI, but man it boring in 3rd gear. I didn't see full 5 PSI until 5k or so regardless of the MBC setting.

BTW, what does this mean? I'm loading the car under boost in 3rd gear to about 4k, quickly let go, and the revs jump to 5-6k as the BOVs open up.

[edub370]

If you are having issues with boost dying off up top theoratically u would need to loosen the wg rod (unless its already extremely loose). AKA make it longer. i believe tightening the rod = quicker spooling but possible boost fade up top.

could the rev jumping be your SRM and FI not playing well together? have u tried turning that off? only other thing i could think of would be the tune you are running having something to do with it. dyno time may be your best friend here

[Dembflyr]

Originally Posted by DIGItonium

Thanks, Jim. I just notice things are a bit funky lately, but that's probably because I've been boosting more often. We should've done it this morning while the car was on the lift, but he's going to double check the wastegate actuator rod to make sure it is tight and is keeping the exhaust flap closed.

Other than that, it completely baffles us that the MBC wasn't doing anything useful after giving roughly 7 full turns. Boost held steady at 5 PSI, but man it boring in 3rd gear. I didn't see full 5 PSI until 5k or so regardless of the MBC setting.

BTW, what does this mean? I'm loading the car under boost in 3rd gear to about 4k, quickly let go, and the revs jump to 5-6k as the BOVs open up.

Have you checked the BOV's? One could be stuck open just a bit. I had a issue with mine where one was stuck just a little bit open. It was causing some weird issues. Took mine apart and cleaned and lubed them and it was good to go.

[DIGItonium]

Alright guys, here's a quick summary. I'm an idiot (maybe). :P

However, I learned a lot about how my FI system works over the past few days. This is great because I have a bit more confidence working on this stuff on my own as long as I don't have to get underneath the car. Earlier the tech rerouted the MBC boost input from passenger intake pipe to the intake plenum. Made almost 7 turns and did not see more than 5 PSI in 3rd/4th at WOT. It was steady, but felt sluggish.

I got the call from support at Hallman. I was told to take the MBC out and blow through the inlet while tightening it down. If I felt restriction, then the MBC works. It was confirmed working! Interesting because I started having a better idea how this thing works.

The next suggestion was the unthinkable. Plug everything and leave WG hose open. I took the car around the block and loaded it at 4k at half throttle, and I was able to get past 6 PSI (almost 9!). The car felt so good!

So I put everything back, used bigger zip ties, and made sure to tighten the hoses correctly without slipping over the barb lip. I did a quick test with the MBC disabled and boost was steady at 5 PSI past 5k RPM. It took 7 full turns to start noticing steady 6 PSI, which was familiar. At 8-9 turns, it was steady around 7 PSI. At 9-10 turns, it wanted to exceed 8 PSI at 5k RPM WOT so I dialed it back by half a turn.

Afterwards I drove casually to test response. Wow, it is so much better! I was able to get out of vacuum easily and push about 3 PSI. At half throttle, something felt different. What's nice now is boost appears to be very steady. Boost gauge wasn't wiggly and confusing. It was a clean sweep to 8 PSI.

Anyhow, I'm going to take it in to revert to the old setup to be safe with the wastegate hose. I just need to dial past 7 full turns to see results!

[O&G]

I noticed better boost response after installing my MBC as well. Glad you got it figured out. Remember once you get it to the point it's actually adjusting the psi(7 turns +) it won't take as many turns to increase the psi. Have fun!

[Deadman]

Nice Grats on getting it all sorted out ! I really want to turbo the car one day just seems like little gremlins are always on the prowl if its not one thing its another hehe. Enjoy the car now !

[DIGItonium]

Originally Posted by O&G

I noticed better boost response after installing my MBC as well. Glad you got it figured out. Remember once you get it to the point it's actually adjusting the psi(7 turns +) it won't take as many turns to increase the psi. Have fun!

Definitely. It takes little effort to get out of vacuum, and the car sounds different. IMO, the turbos are starting to wake up now haha. The drive to work is great now that it feels more responsive.

Originally Posted by Deadman

Nice Grats on getting it all sorted out ! I really want to turbo the car one day just seems like little gremlins are always on the prowl if its not one thing its another hehe. Enjoy the car now !

Thanks. I freaked out when I only made 5-7 full turns, but it could be the combination of double checking and tightening the vacuum lines and dialing past 7 full turns (in my case).