I have had the JB+ for probably about 4 months now and everything has been fine for the most part except for one thing. Every once in a long while I will get a weird boost cut...total loss of power. The first time I noticed it was when leaving MOTD. I was only there for one day and had the JB+ turned up to 7 (stock being 5) because I had just installed colder plugs and I was running a strong octane booster. My friend who installed the plugs also reset all of the adaptives in the DME and off to the dragon we went. All was well that Saturday but on the way back home I had a weird boost cut when I tried to accelerate in 4th gear at about 60mph. The JB+ came off for the rest of the trip and the problem went away. My friend blamed it on aggressive learning from running the dragon and having the JB+ turned up which caused a hiccup of sorts. I turned the dial back down when I got home, reinstalled the JB+ and all was well.

It happened one other time a couple of weeks later when I had the JB+ turned up to 6.5 or so but never again after that even though I left the dial in that position. I have been monitoring afr and timing and everything seems ok.

Two weeks ago it happened again but that was when I tried to sort of "hypermile" the car on the way home when I was low on gas the night before. Last night it happened again but it seemed completely random. I had been assuming that my friend was correct about the aggressive learning and that my foot is partially to blame. The past boost cut occurrences seemed to support this theory. This time was different. I was on an on-ramp and tried to go WOT in 3rd at about 3500 rpm and the car fell on it's face again. Not once have I had a CEL for this issue and the car always picks right back up and never goes into limp mode or anything.

I need a little input from the JB+ peeps out there! What's going on with my car?

Just to be clear::::::JB+ between 6 & 7 on the dial....BP 93 octane... I am NOT running meth....and I have never seen timing pulled on my SGII with the cold plugs. Car is at 60K miles and other mods are in my signature.



**Sorry for the lengthy post...just wanted to paint a clear picture.

 

I have experienced these side affects before. First off, if you remove the JB after a hiccup, be sure you removed same as you installed. Let DME sleep. Drive it like hell for 50 plus miles after removal. If symptoms still occur it's not the JB+.

As far as running your JB+ any higher than stock, take it from my trial and error: not worth it unless you are running Methanol or E85. I tried using a high octane booster, Fail! I've heard Torco is the only reliable product, but never used it.

I am currently running my JB+ at 2 o'clock, but I'm pushing a 50/50 W/M Boost cooler @ 8 psi and up.

IMHO, the JB+ is perfect for the plug n play user who is happy with a little bump in power. If you are a HP junkie, move on to a full tune, it's not worth the hassle and risk.

Just saying...

 

How long does this boost cut last? Mere seconds, or are we talking about the rest of the drive?

 

Roxspin72 :: Good to hear I am not the only one. The problem went away the first time as soon as the JB+ was removed. The other few times it has been a one time occurrence and there was not point in removing the JB+ to trouble shoot. I am certain that the JB+ is to blame...I am really just curious as to why. I am going to turn the dial back down and just wait until I can get a Manic tune and see if it happens again. BTW is there any info on how us N18 North Carolinians go about getting a real tune?

Grizld700 :: It goes away instantly. If I let off of the throttle and ease back into it then it's fine. If I keep my foot on the gas it will stumble until I let off.

 

One thing I noticed with mine was it happened only when I would stomp on the gas during low rpm when in 4th or 5th gear... Seemed the DME would add to much boost due to the setting I had the JB+ tuned to.

We have a couple options for Manic:

1) Ship DME to a tuner
a) Mario Palza (currently weighing his options for Bench tuning, but has a good grasp on the process and has the OBD port tuning capability) MTF on this...
b) there are two businesses, 1 in New Mexico and the other in Jersey.
c) there is also a member on NAM, Paul. He is starting a Group rate, but same as the others we must ship our DMEs.

2) Cerenkov is having talks with a Raleigh based tuner. They are known for their work on BMWs and MINIs. Not sure if they will bite.

Biggest issue is demand. Not everyone is in it for the Power and speed. And or not ready to commit due to warranty clause, etc...

I'm at the point where I'm willing to ship if no tuner is found locally.

Good luck.

 

http://www.weavermotorsportsinc.com/

They are DNA approved tuner. Check it out

 

On your boost cut issues, were by chance monitoring boost and/or timing?

I'm guessing one of two things happened:

During my logging, I've seen that sometimes when I go WOT in 3rd, 4th or 5th and lowish RPM, I can get boost spikes then the boost will quickly come down to a reasonable level. Boost cuts on the MCS happen at 22 psi (IIRC).

With your setting of 6.5-7, I can see this happening, especially with the warmer temperatures. Like Roxspin said, be careful with anything over default on the JB+ without some sort of octane booster such as torco, E85, meth, race gas, etc. I have a new 32 oz. can of torco, if you're ever close to NC State Univ. let me know and you have have it.

The other thing that could have happened was that timing could have been aggressively pulled. Some people have described it like you have.

On another note, I did stopped by Euro Motors in Raleigh last week to see if they were interested in becoming a Manic rep. I'll follow up with them this week. If they aren't, I might ship my DME out since I'm going on vacation in 2 weeks anyways.

 

I'll go see them. Maybe they would be interested in being a Manic rep too.

 

Cerenkov is correct. On the MCS boost cut occurs at 21.75psi due to the fact that the MCS is equipped with a 2.5bar MAP sensor. One bar is atmospheric pressure at sea level and since the sensor is manifold ABSOLUTE pressure you subtract one bar and that is the max the sensor can read (for simplicity this is ignoring variations in altitude)

There are two ways around this. The best method is to install a JCW 3.5bar MAP sensor and have the car tuned so the linearity of the MAP sensor table is adjusted. The output from both sensors range from 0 to 5 volts and follow a linear progression between boost and voltage. The map sensor table is adjusted so that 5 volts with a JCW sensor represents 36.26 psi instead of 21.75 and scales down accordingly.

The second method is a work around that disables boost cut at 5 volts and calculates injection quantity and timing based on MAF. A simple and elegant solution but not perfect. If your using an OBD device to read boost pressure two things can happen depending on the skill of the tuner. Normally you will only read a max of 21.75, perhaps 22 if it rounds up. The second option and I don't know if Nick at Manic has done this or not, but if anyone can it would be him, is to recode the executable to return values based on MAF after 5 volts. But the results will not be as accurate as a true sensor, else the engineers wouldn't have used them in the first place.

The other possibility is a MAP sensor that is failing. It doesn't happen often but like any sensor they can fall out of calibration.

 

Looks like what I need to do is turn the dial down and watch my numbers closely whenever I am hitting full boost. I havent been watching the boost and timing every time it happens, but I don't recall the boost ever going higher than 19 even on over boost.

As far as tuning goes I am not really interested in a bench tune but as soon as OBD tuning is available I will be the first in line. I can't wait to see what you guys come up with!

 

OBDII won't be available for a longer time. Like via Accessport, Group4autosports is taking that into consideration with Lenny from RennTech.

For a side note, I seen 19.6psi at 50% default setting. But don't forget it's not always about how much you push boost wise, it's how effectively is power being put down.

 

Thanks for all of the input, guys. I definitely learned a lot here. I have the JB+ turned back down and I have to admit the car seems much smoother even after about 40 miles or so. If I notice the boost cut again I will try to monitor everything and see if I can see some boost and timing numbers. Without a way to datalog it is difficult as everything seems to happen so fast.

I will definitely be keeping a close watch on what happens with getting a Manic rep in the Triangle area. I would love to have a "real tune" but until then it looks like I will be playing it safe with a stock JB+.

 

If you are hitting 21psi with the JB+ then turn the dial down! It's not meant to be operated at the edge of the boost sensor's ability to read boost. Shoot for around 18psi with it.

 

I removed the JB+ a few days ago to let everything adapt back to stock readings. The car is back to stock boost now so I will put the JB+ back on soon and leave it on 5 this time! No more turning the dial up with out meth or ethanol.

 

Guys, does anyone can help me?

I'm from Brazil, have a MCS n14 with Manic stg2+ remap.

When my car goes over 22psi, than the boost start cutting until it gets 18psi. This topic was openned by myself, inf someone can read:

https://www.northamericanmotoring.co...ml#post4161168

The best solution for this problem is to change the map sensor? I really don't want to change my remap for one that don't go over 20psi.

Thanks a lot.