I checked out the cobb forum and Bryan@ GST replied to my thread. Here is what he said.

"fuel cut" and "boost cut" are the same thing, at least in evo ecu land. Boost limit is set in the ecu, based on a load number and how long it's at or over that load. So basically you set a load limit and a time in MS the ecu will tolerate being over that load before it will induce fuel cut.

If you are getting a violent jerk of the car, then you are hitting the boost limit, which is fuel cut. It will not always throw a CEL.

If this is happening more often in the cooler weather, and/or in higher gears, it sounds like the relationship between the wastegate duty cycle tables and the boost target load tables need to be tightened up"

Guys, if you are not getting answers here definately check out Cobbforum.com. They dont reply much for the evo's but when they do the answers are extremely helpful.

Christian - So basically the only way to fix this is to get a protune?

 

I logged mine tonight and it was doing the fuel cut type of thing in 4th gear and it did it serveral times but the funny thing there was no knock at all maybe 1 to 2 counts total so I'm thinking my problem may just be the spark plugs does this sound right to you guys? I'm getting no cell and no knock so I'm not sure what else it could be.

 

If there's no knock, that just means the tune is good except that the boost limit is set too low for the other control boost settings.

 

gonna have a baby next july (our 1st!) so the wifey has got me modification lock down for awhile ........hopefully that will be in the cards for later next year

 

I would assume then that maybe the map just needs a re-tweak....and it would go away?

 

Same here, knock sum is at most 2. I have brand new plugs so I know its not that. I'm sure its the wastegate duty cycle tables and the boost target load tables need to be tweaked.

CPA5- Congradulations!!!!!! Not modding is no fun but you'll have plenty of fun with the new baby.

 

If the car is hitting the target boost levels, and there is no significant knock, then the WGDC tables and boost target load tables can be left alone. Lowering those values would reduce the boost. Just need to raise the values in the load limit table. Its very easy to do in ECUFlash. I would assume its equally easy in ProTuner. I could do it for you with ECUFlash if the AP ROM file is not in a proprietary format or locked. It probably is though.

 

Buy yourself a christmas present CPA. Seriosuly Im gettin pro tuned very shortly and I got GSC s1 cams to maximize my pro tune. You should too!

 

mrfred

In my case though if it was the tune how come it wouldnt do it more often or it would do it on everyones cars all the maps should be the same I would assume and how come I havent seen a code thrown yet? I'm just getting something that seems to be like a misfire. I dont know Im gonna change the plugs today and see if that helps if not I'll be calling cobb

 

How cold was it when you hit fuel cut? I hit fuel cut with my cobb when I was on the race gas map provided and running race gas in 15 degree weather! The climate could have been the reason you hit fuel cut!

 

Could be a couple reasons why it wasn't triggering everytime on your car. 1) Not every WOT run produces the same engine loads. Some runs might produce slightly higher loads than others. One possibility would be that the car was exceeding the load limit only on those runs that produced the highest loads. 2) The load limit feature has different settings at different rpm ranges. It maybe possible that in some rpm ranges the load limit is set too low for your car, and thus, the fuel cut is only happening when you go WOT in some particular rpm range.

Why not every Evo for a given tune? Good question. Pretty much everyone will tell you that not all Evos perform the same for a given set of mods and tune. Some are stronger than others and will hit higher loads. No one has a clear proven reason for this, but it does seem to be the case. Another possibility is the mechanical condition of the car. Load is essentially air flow through the MAF divided by rpm, so one way to produce really high loads is to have a big boost leak. :-)

 

^^^thanks for the response. I guess I have a few things to check out then

 

it was probably in the 30s when it was happening

 

to follow up....my Xmas present this year looks to be a PRO-Tune and Agency Power brake lines ....gotta go on the DL for awhile

MRFRED...thanks for answering some of these ??? and explaining things in detail!

 

Yes, MrFred has been most helpful, my brain is picked. I have no knowledge of this stuff but found it interesting and helpful if/when I choose to buy the Access Port... I think I might buy it but... I'm trying to find a pro-tuner in my area to help out incase something goes wrong or I need testing.