Ok, first some general info. I have very bad power over 6000 RPM. If I take the UTEC out, it runs fine up high. Map 0 doesn't run as good as with the UTEC removed. It seems to run a bit stronger with

My mods: JWT intake, Crawford plenum, UR crank pulley, DC headers, Helix test pipes (with O2 spacers).
Car is a 2005 non-revup.

Here is my AFR chart as it sits now. This was logged from my factory wideband O2s with Cipher.


I know its not a great tune, but the problem I'm needing help with is above ~5750. The AFR bounces around too much for me to tune it smooth being I only have 250 RPM precision. But besides that, it is slow up there. It runs pretty good up till that point, where it just dogs.

My ignition timing right now is like this:
5750 = 24
6000 = 25
6250 = 25
6500 = 26
6750 = 27.5
7000 = 27.5

I had it more agressive (based on stock + 1 degree), but this seems to pull a little harder on the UTEC for some reason.

I'm showing no knock anywhere in the rev range, btw, and without the UTEC my AFR isn't so jumpy (between the 250 RPM points that is; its much more controlled).


Does anyone have any suggestions? I've tried flashing the UTEC, using both version 2.3 and 2.6 (it came with 2.6). I'm out of ideas here... I just don't get why its so slow up top.

 

Ok, so I was reading a lot about EFI, everything I could get my hands on, and I figured I'd give something a shot.

O2 sensors only detect gasses, they cannot detect unburnt fuel in the exhaust, so there are situations (see: very rich or bad combustion) where pockets of gas in the cylinder will not burn and seriously hinder performance.

With this thought in mind and loggers running, I set the UTEC to go much more lean at and above 6000 RPM. Off to a pull and low and behold, it runs much stronger up top, yet the AFR charts are hardly changed (but smoother). Guess that was the problem.

I haven't tweaked it much more, but I have made a lot of progress up there. O2 sensors can lie and it sucks.

Still seems very odd as I have seen no other mentioned cases of a problem like this, but hey, such is life.

 

I can not make any sence of that Cypher log..but if you are running 27 degrees of timing, your probably knocking and the UTEC is pulling timing based on knock..Can you post a data log of your utec on a WOT run?

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yeah bro, do a datalog with the utec and post it and see what we can figure out, your AF ratio is all over the place...

 

That log is a lil old and wasn't very tweaked, and the UTEC is not showing any knock, wasn't before, and infact I have now advanced it slightly more up top with noticable results. I have the knock constants at very reasonable values.

I'm going to get it dyno tuned soon, but I wanted to get it running at least decent first.

Edit: Here is a UTEC log from a run earlier (3rd gear)
http://www.inventedexistence.com/utec/dl.TXT

AFR isn't on it, that's in Cipher, and I'd make a graph but I'm running off to meet someone for dinner.

 

Well, I did another run, and the AFRs are really jumpy again. I dunno what the deal is with that. Its definatly a lot stronger than before (before I couldn't get to redline... like I lost all power progressivly as I went over 6000 revs), but my AFRs on the 2 banks still split apart and get all jumpy up there. Its too bouncy for me to fix with the UTEC (its not terribly consistent and it happens too often to fix with 250 RPM adjustments). I wonder if the stock ECU is doing something to it or what, I'm tricked at this point.

On a side note, if I take the UTEC out, the car is plenty strong over 6k and the AFRs are more stable.

 

well the log doesnt show anything out of the ordinary. hmmm it would have to be something internal on the utec that is not causing something to fire right.

especially if it works fine with the utec out...


there are a few utecs with problems, TXS is pretty good about changing them out i believe. i only know one person that had a problem but they exchanged it for him

good luck bro, let me know what happens, i feel your frustration though

 

Well, I sent TurboXS an e-mail about it as at this point I'm running out of ideas. I just cannot get the AFRs to quit jumping around so much up there.

 

That is because, and dont take this the wrong way, but you are not an experienced tuner..It is nothing wrong with the UTEC 99.5% of the time, just the end user.

 

I know, but I'd like to get it running well before I take it to a pro for fine tuning... mostly just for the learning experience.

You have any idea why the AFRs are so jumpy? I just don't see how I can tune that out with the UTEC with 250 RPMs of precision. And the jumpyness must be the UTEC, as it doesn't do it with the factory ECU alone. Not to say its broken, but what could make it do that?

 

What are your mods again?

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AIM: SALESMRC
Authorized dealers for: APS, Greddy, Turbo XS, GT-Spec, Strup, Unlimited Tuning, HeadGames and more.
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I have a Crawford upper plenum, JWT intake, DC headers, Helix test pipes(with the O2 spacer trick), and UR crank pulley.

 

With the O2 sensors spaced out of the pipe they can't possibly give an accurate reading.

 

Its the post-cat (secondary) O2s, not primaries. They arn't being read, nor are they used to control the motor. They are narrowband sensors, anyway. I'm reading the primary O2s (the widebands).