Hi Jermaine, Nate, Jack and all...

Been forever since I've posted, hope all you guys are doing well. I've been having a little problem I think is UTEC-related, and I searched and found no answer to this and was hoping for some quick suggestions, so here goes:

I'm still running the Jermaine-adjusted 1.7 Stage II Map, and have been getting severe "stuttering" when cruising at light (under 30% TPS I think) throttle. Basically, I'll be cruising along at around 3400K RPM's, say 70mph, and then this rapid stutter that feels like fuel cut happens, and if I increase throttle there is no power, the stutter just gets louder. If I back off throttle, it goes away instantly. If I increase throttle gently, it often comes right back. If I'm beyond 40% throttle or so, she accelerates like a charm.

Cory at Atlantic Motorsports theorized (and I think he's right) that it was the OLF (Open loop fueling) switchover point sort of "oscillating" between on and off, creating some mayhem between the UTEC and the ECU in which neither knows what to do...anyone else having this problem?

Is there an easy fix? Adjusting the "UTEC Control vs. ECU Control" throttle thresholds in the UTEC? Adjusting my actual throttle position sensor?

I know it's not a fuel pump problem as it happened before and after my Walbro 255 install. There is no trace of knock, and no knock light either that I can find.

Pardon if my searching was just inept and this has been answered before. Help appreciated!

If you guys don't have an easy fix in mind, I'll just go see Jermaine and the boys in Gaithersburg and ask if they can help me out.

Thanks,
Adam

 

Definatly sounds like a cross-over problem. We do a lot of UTEC Subarus out of here and it sounds like what happens to them if it's not tuned out on the street a little bit. PM me and hopefully I can help you out a little more.

 

PM Sent, thanks.

Any other input welcome folks...

Thanks,
Adam

 

What are you Running for plugs, wires, and Ignition

 

NGK BPR7ES plugs, normal gap I think last time I checked, stock wires and ignition.

It was suggested to me that I might have too much timing below 20%throttle, so I'm going to try to log and post results soon.

Thanks,
Adam

 

Ya Do that first, Check the condition of the plugs. I was having the same issue with mine, but it ended up being a wire problem.

 

Although its probably a transition problem, it could also be surge from the turbo, check the vacuum line to your DV make sure its not kinked or something silly like that.. What has changed most recently? has this always been a problem, or had this been something you noticed recently, did you notice it recently in the colder weather? etc..

I do recall when I was first configuring the transition crossover, I had to raise it from 25% to 35%, later I lowered it to 20%, basically if you find your throttle position always hitting that crossover point, you'd probably want to raise it slightly so your not always toggling back and forth into it.

The easiest way to tell is to log data when it happens.. if you see it rapidly jumping from the 0% to 10% load column then its probably the transition point. again, if its that, you can raise or lower that point so your driving habits don't tip into it as frequently.

 

BTW before you transition into the UTEC OLF, your still at the stock ECU's mercy.. so it could be some sort of boost cut, I occasionally would get that on very cold days.. I lowered my transition point to 20% and retuned the car again..

 

Thanks as always Jack for your great suggestions, I'm going to log as soon as I get a chance and will try to replicate the stuttering problem and post results.

Best,
Adam

 

hows the weather down there, When exactly is this happening? Sounds like it might be a Crossover issue. Check and play around witht that setting. change it from 25% to lets say 20% like Jack suggested. Reflash retune if you need to. try it again. See how it reacts. and Post a log. Id like to see the A/F ratio and what its at. at that throttle position. .

Anthony

 

Well guys, I did a little road testing while my trusty copilot watched the UTEC dashboard readout, and unfortunately, the problem repeated while still on ECU timing and boost I think, as the UTEC was not seemingly engaged, around 20 - 23% throttle.

So my guess now is that I may actually have a mechanical air/line/valve problem of some sort as Jack suggested.

Just to be sure though, Jack how do I adjust the OLF transition point? I couldn't find it for some reason in the parameters...and I think raising to 35% would certainly help eliminate UTEC fueling transition as the culprit...

Thanks again all,
Adam

 

There are two places to adjust those settings.. Should be in the config OLF settings, and the standard (I think settings menu 1) its been awhile so forgive me if I'm brain dead. Too busy with the house and upcoming baby..

 

I almost forgot, many warm congrats on the baby Jack! I'm a step or two behind you, planning our fall wedding with my fiancee, but I expect that time for the Evo will get less and less as I move on down the family path too. :-)

Going to try to hunt down the OLF setting tonight. Thanks as always.

-Adam

 

Thanks.. So excited, she's "Due" monday, we've been trying different things to make her go into labor.. Heheh..

 

Was there any resolution to this?