Hey guys,

I'm not much of a poster, but I read quite a bit on this forum. I just recently installed the UTEC into my car. It's an '03 Evo, Buschur Stage 1 through 4, GSC 272 degree duration cams, Buschur 20g-9 turbo.....anyway- My tuner and I were working with the UTEC this past weekend and were having some hesitation issues when switching from closed to open loop. We have the switch-over occuring at around 35% throttle. It seems as though when changing from reading from the MAF back to tuning with throttle position, a very rich condition occurs. I'm running a stock MAF sensor at the present, is there any way to get rid of this problem by tuning? Otherwise, I read of people using a blow-through MAF sensor, and also switching to MAP, would this rid the car of this problem? I greatly appreciate any help.

Thanks,
Matt

 

Well, you have a choice, work from MAF or MAP.. If your transitioning and getting a rich condition, then you have to tune the 10% column to more closely match your closed loop tune.. and you'd likely have to tune the 0% column so the tune in closed loop is closer to the transition, thats the only way to eliminate most of that.

There aren't many people using a blowthrough meter, and it wont solve what your describing, only time and logging/tuning will get you through it..

Right now, you need to determine how much of a jump your making from your closed loop to open loop fueling, and then try to smooth it out.. once you can do that the hesitation will all but disappear in most instances..

 

word, malibu lol


also, watch the timing transitions more closesly, most people that dont spend alot of time on the utec, wont properly match the transition timing, you get a nice transition hesitation....

but as malibu stated, make sure your 0% load is tuned properly that way it doesnt dump.

cb

 

Yeah thats a really good point.. Low load timing is different than high load timing, so you will see a different jump, and the hesitation you are feeling is likely due to part throttle light load driving, so you need to log alot of that data so your not making 1-3 degree jumps at 2500-4000 rpms.. This is one of the most common issues that nobody ever addresses. Only you have to do this as your transition in the 10% column, you don't want to fix your 0% column timing if at all possible since that will affect the car's day to day drivability.

 

I appreciate the help with the matter. Another question, at what throttle position do you guys have your switch-over set to? It seemed like, on my car, that the lower the value, say, 25% compared to 35% throttle, the more noticeable the hesitation is. I have it at 38% at the present, but I'm starting to get worried that I'll start boosting when tuning by throttle position, and experience a lean condition. I appreciate all your help guys, I know the mechanical side of my car, but the tuning side is new to me.

 

mine is 35% it seems to cross over least frequently in daily driving.. Anything lower and it happened in highway driving all the time.

You really aren't tuning at all by throttle position, the load sites are a calculated factor of MAF (or Map) and throttle position, the only map that uses throttle position exclusively to determine load site is the Boost control map.