Cut issue..a little help please!!

wunuvaknd

Member
:
2008 MS3
Ok ive read about all of the posts on here and cannot find a solid answer. Im hoping that i can get some kind of help here..

At around 5k to 5.5k i am getting a major jolt, fuel cut is what it seams like. Its not sputtering, its a dramatic cut. its happening in about all gears except for 1+2. I am getting frustrated and cant seem to find hammered down answers anywhere..too much differing in opinion.

I have the turboxs tbe, cobb ap and aem intake. I hadnt had any problems with the first two and now am getting this problem after my install of the cai.

Ive seen people getting the fuel pump upgrade from protegegarage, and some say that that wont cure my problem. I gave cobb a call and they said the fuel pump as well. I'd rather not spend hundreds if it can be fixed easily, but will if necessary. I was running the Stage2+MSCAI map and went to the stock style mode to see if that did anything, but it did not help.

Can anyone give me an honest opinion on how to fix this problem? I would really appreciate it.
 
I got occasional fuel cut with my dp/rp, but since the cold hit I get it constantly. Unfortunately, temp dropped like mad the day after I installed my tmic, so can't be sure it's the intercooler as this is my first winter with my speed.

Sounds like boost cut to me. I'm moderately modded up and I've monitored the situation. That's why I am confident in saying it's BOOST cut, not fuel. Either I creep above 16psi and cut, or I spike high and don't fall (or not fast enough) and cut. Dashhawk maps are showing fuel pressure is fine and then the wastegate opens and the boost goes bye bye.

I am untuned, but would say that it may be your ap maps. The map I am planning on flashing to moves the boost cut to 20psi.... do have any way to monitor your parameters?? Where do you live, if you are close you can certainly come use my dashhawk to get it straightened out.
 
cut issue..a little help please

Well my ap shows that i am spiking to up to 21.2 psi of boost. i am getting an over boost cel and it shows up periodically(guess i should have put that in there to fully diagnose my prob..).

There is an option to run the ap map of "Stage2+SF 91 Octane FMIC LWG--Stage2+SF for Stock Vehicles with COBB Tuning SF Intake System, LOW WASTEGATE VERSION FOR VEHICLES THAT ARE OVERBOOSTING. Requires turboback exhaust with a catalytic converter. +18.2% HP / +19.2% lb. ft." Ive yet to update my ap due to the lack in 64bit vista compatibility..should be able to try that out this weekend while at my familys home.

I just assumed that this cell was due to the ap map. I don't understand why the stock map is still giving me jolts though..I get what you are saying and makes sense, but why after I reverted back to the stock map would it act like this. Another thing I am wondering is if I should just sacrifice a bit of hp by opting for a hf cat and hopefully cure the problem. I thought about doing this anyway due to the barbecue-like smoke coming from the tail at idle! Maybe that'll help that issue too!

Live in IL near Rockford...but thanks for the offer man
 
What you are experiencing is boost cut...

Boost cut is a violent jolt, while fuel cut is a little smoother...

Anyway, there are many things that can trigger boost cut. If you say you are really spiking to 20+ PSI, then there is your problem. Also, you don't necessarily need to be spiking above 20 PSI to cut, you can just hold 16 PSI a lot longer and trigger boost cut.

Basically, the ECU monitors your boost curve, and if it deviates from the stock curve, you get boost cut.

The only way to get rid of boost cut is a MAP Clamp, Standback, or an AP; which is kind of odd your AP is not tuning out boost cut.

Another cause could be temperatures...how cold was it when it happened? Any temps below 30* will trigger boost cut; if the MAF temperature sensor sees a certain temp, it will trigger boost cut.

Currently there are no solutions at the present time other than wiring a potentiometer on the MAF temp sensor...but I doubt thats your problem unless your temps were below 30*.

I hope that helps... I just quickly summarized...
 
cut issue..a little help please

I think that helps! I am wondering though...all of my ap maps show that I need to have a hf cat to run the maps. Is it possible that I am running my exhaust so clean through that I am giving the turbo the opportunity to boost all the way it wants to? Do you think that if i take out the clean flow and add a bit of back pressure with the use of a hf cat that it will resolve some of my issue? I'd rather not solder in a map clamp but if necessary i will just to cure my problem.

I also was planning on getting the GT2871R Bolt On Turbo Upgrade from protegegarage..That way I dont run the risk of my turbo blowing up and creating a whole mess in my engine bay.. Tell me what you all think

Thanks again to all who are helping. I do appreciate it
 
you may have to go with a different tuning solution if you decide on upgrading the turbo. Cobb still hasn't come out with their tuning software, so the other options for custom tuning are piggyback EMS's, like the Standback or Xede.
 
Back