I just took a drive in my MINI this afternoon and when I went to get on the freeway a floored it or would have been run over. Well it went up to 20lbs and once it 3krpm the boost just dropped off to around 4lbs.

Just a little back ground I have an intake, piping, IC, catlless DP, and catless exhaust and I am also running Alta's stage 3 right now. I am going to back off and drop it back down to stage 1 till I get this sorted out.

Does anyone have an idea of what it could be causing this?

 

Sounds to me like your MAP sensor freaked out and held the wastegate open as a "SAFETY" measure.

Mike @Tech Division will know more, he does a lot of R56 stuff.

 

I was thinking wastegate problems but, I am not quite sure.

 

That's the boost cut that has been discussed at length on numerous threads. There's nothing wrong with your car.

I don't run Stage 3 just because of this very issue. My advice, run Stage 2....it feels just as quick (in my opinion) and it still boosts 20+, but you wont have to deal with the boost cuts.

 

Like Thumper said you went into soft limp most likely do to the aggressiveness of the stage 3 map. This can happen under heavy acceleration and is exasperated by any added load. If the on ramp was up hill this might explain why it happened at that point and not another time you pushed it.

BTW did you get that manifold on yet?

 

This certainly seems like the famous "boost cut" most of us have experienced.
Thumper's suggestion to run a less aggressive is the remedy, but bear in mind that this phenomenon is temp related as well. So for instance, if you run a map with 20psi overboost, when the temperature goes up the ECU is compensating to reach the target load, which means higher boost, and voila "boost cut" again. From my personal experience, I run a 19psi overboost map which is "boost cut" free as long as the outside temperature is below 85.

 

This happens to me with stage 1 (91 octane TPS map). I've asked Alta for a less aggressive map (19psi). They told me it's normal for stage 1 to hit 20+ psi.

-JL

 

Ok cool I was going to drop the Map down to Stage 2 anyway. Thanks for the help. I did search this problem but, as everyone knows the search feature on this forum sucks so I couldn't find it. Also I found out it was only under full throttle too. I will data log it and see if Alta will adjust it to run better. I thought I broke something cause I was running it hard the night before and it was fully boosting before. BTW no Manifold I miss judged what was requried and was not prepared. I will be doing though soon once I am moved into my house.

 

The boost cut is a strange phenomena, I have had it intermittently even while stock, ran unichip for a year and had it on and off, and now even on AP stage one it happens now and then. One similarity I have noticed is the exhaust becomes louder and raspier every time it happens. Since I finally have the capability to datalog I will try to make some more sense of it once I am done with the aesthics

 

Swithced to Stage 2 and still having the problem but it seems only to be under a load like going up hill. Also I have noticed when it does it the exhaust does get louder but I figure that is because it is running motor then turbo so I am not worried about that part. I guess I need to do some data logging to see if I can get it tuned up a little better.

 

Did you install that new manifold?

 

Once again no I did not install the new manifold. I underestimated it and was not prepared to do it.

 

must have skipped that part.. my bad..

 

The base stage 2-3 maps will do this. We adjusted the load targets on some cars and eliminated this for most driving conditions. It's still not a perfect fix it helps quite a bit. If you were local I'd say come by and we could mess withbrhe map. For now hit up Jeff and see what he can do.

 

It's fine. I kinda over reacted a little.


I do plan on calling Alta for some help but, won't do that till tomorrow though. Too late right now.

 

one problem is people floor the dam car under 3k...I only have the problem with high load under 3k, try hitting it AFTER 3, it isnt a v8 with alot of low end tq lol....

 

Happens to me anywhere from 50-150 miles after loading a map onto the ECU. USUALLY doesn't happen in 1st or 2nd, but I've seen it happen in 2nd. The requested load/targets in these gears usually don't require boost to compensate that much.
As for 3,4,5,6, I can be at 2k,3k,4k,5k,6k rpm's and go WOT and it still happens.

Oddly enough, its not ALWAYS IAT dependant. Sometimes I'll have 90*F IAT and romp on it and its fine, over and over no problem, even as temps reach 120*F. Above that it starts pulling timing and such, but usually if I'm running that hard I'm not as focused on my IAT's and more focused on whats ahead and around me. Then again, usually when I see this not cutting even with high IAT's is when the ambient is lower, aka at night with 50-60's *F. Could be with the recovery or air thats passing the TMAP thats not ACTUALLY that hot and possibly the TMAP becoming heat soaked may be a possibility..

I tried cleaning my MAF and it seemed to help a bit as I went 250 miles with no cut, but it happened again, so inconclusive there. Some still say an open intake can affect this, I haven't tried my stock intake back yet.

The way the ecu/tune file requests boost/power also makes a difference. One map I have is a 18/19psi holding and that'll run fine for the first 50-150 miles, then once it hits that first cut, it'll cut much more often than my other map which has a target 16/17 psi holding. The later map requests boost much more linearly, whereas the first map can request full load at only 50% throttle. Thus, I can hit boost cut not only at WOT, but partial throttle as well. Uphill/downhill doesn't matter.

 

Considering peak torque starts at ~1600rpm...I'd say you are wrong. Our cars are ALL low end torque.

 

I just recently starting running a stage 3 map after getting my FMIC in, and I've had this happen to me a few times. I'm glad I saw this thread, now I know why it does it...

 

We all know why it does it. To protect the engine. However, what we dont know is, why there isn't a perfect fix for that problem?
Is it that difficult?
In my opinion, if a map is going to throw a "boost cut" it is useless.
What's the point of driving a car which is occasionally dangerous?
I have experienced these boost cuts soooo many times with various maps and my conclusion is that this engine is unrealably tunable, which is such a shame.

 

Porthos, try Google to search this site. Just add "Site:northamericanmotoring.com" to your other search terms to restrict the results to NAM.

Try this.

Cheers,

Charlie