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Old 08-16-2004, 01:05 AM   #1
waploom
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Default STI UTEC (Do I have a problem?)

hey all, maybe u can shed some light on what is happenining with me. My car is essentially stock. All I have is a perrin short ram intake and I just had the UTEC installed. The guy who installed it appeared to do a good job. However, I am noticing some weird behavior from the car. While the CEL does not go on, every so often, at varying speeds, the car seems to hesitate/buck forward in a very weird feeling way as if the ECU is fighting with the UTEC in a tug-o-war. I am not sure why this is happening and it seems to be happening quite often, especially at high speeds and low rpms (usually about where i am starting to use a little boost) I am wondering if this is a bad sign (e.g. defective utec) or normal or what. I plan on taking it to a tuner to have it checked out, but I am curious if anyone is aware of what is going on. When i go WOT (which I have cut out since feeling the hesitation quite often) the car seems to rev real smooth and nice. HOwever, at regular speeds, the car hesistates often enough as to make daily driving a bit annoying. Ne ideas guys?
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Old 08-16-2004, 06:09 AM   #2
TheMadScientist
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First take a look at your boost map. If you only have one # in the entire map that can cause saome of the hesitation. I like to ramp boost with throttle position, incresing # from left to right. Also a lot of hesitation is caused by the low load fuel and timing YOU have to tune those.
I would try to find someone in your area that has an Sti Utec that knows how to tune it. Check your local forums I am sure you can find someone to take a look at your maps and help get it tuned some what.

TMS
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Old 08-16-2004, 07:13 AM   #3
Abe Froman
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This is very common. Do you have logs?

Look at what timing the UTEC is using when it takes over and what the ECU wants to run in that same line, make them similar and that will go a long way towards lessesning that hesitation.
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Old 08-16-2004, 08:37 AM   #4
happasaiyan
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the problem is the fuelling and timing. easiest thing ive found was to let the ECU control timing up to the 30 col, then play with the low load fuelling to get it to match as well as you can.

i just recently took a step backwards and now have more hesitation than i did a week ago or so...now i have to remember what were the values i had before. doh. looks like ill be saving my maps everyday now. lol
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Old 08-16-2004, 03:59 PM   #5
yeager
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there is also a utec software update, i believe (v 1.1c) that takes care of 100% IDC misfires/stumbles. may be worth investigating.
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Old 08-16-2004, 07:08 PM   #6
Abe Froman
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Quote:
Originally Posted by happasaiyan
the problem is the fuelling and timing. easiest thing ive found was to let the ECU control timing up to the 30 col, then play with the low load fuelling to get it to match as well as you can.

i just recently took a step backwards and now have more hesitation than i did a week ago or so...now i have to remember what were the values i had before. doh. looks like ill be saving my maps everyday now. lol
I have the UTEC running near stock timing in those areas but I still get it once in awhile. I'll try letting the ECU run timing down there. But of course you might give up some spool up if you have a good tune in those areas(not that I do)...in any case I'm gonna try it.

I save everything, I have dated folders with morning, lunch, and evening maps...
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Old 08-16-2004, 07:14 PM   #7
zimm
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If it's at light throttle around 3k, I changed the boost map to be on ECU all the way up to 30% (20% is what it comes with). That helped a little bit. I tried ramping the boost up and it seemed worse for me. I can't wait until I can get this thing on the dyno and get it really fixed.
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Old 08-17-2004, 04:06 PM   #8
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My Utec does the same thing. I'm afraid I will make it worse or screw up my car by tuning it myself. I'm going to wait until I get more mods and get a good tune. My car runs great except for the hesitation at 2800 rpms. With exhaust, Utec + Turboxs boost controller, I out ran an
M5 from a 20 - 95 mph roll. So the car is fast. But the hesitation is a little annoying.
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Old 08-19-2004, 01:09 PM   #9
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I don't believe the UTEC comes programmed to work with the Perrin Short ram. I believe that intake is significantly bigger in diameter than stock. If so, you are LEAN. One one hand it's great that the Suby's use the MAF "stick" because you can throw it into any intake. What you need to remember is the sensor part is designed to be in the center of the intake tube. If you put it into a bigger intake tube the sensor is now "above center". There is more air going "under" the sensor now. If you have not had the car tuned with a wide-band O2, or even just make sure that the stock front O2 is showing rich enough, you are likely in a dangerous situation.

Do a log immediately. Make sure that it is showing rich. The last STi Utec with an intake I did was running (or trying to) 15 to 1 afr at 8 psi. NOT GOOD.

SS
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Old 08-19-2004, 03:27 PM   #10
Abe Froman
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The front 02 sensor readings are not logged on the STI UTEC, althought I wish they were...
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Old 08-21-2004, 09:33 PM   #11
BOOSTi
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same thing on my car from 2k-3k rpm, and my car has been tuned, and i even upgraded the software i dont know what else to do.

Last edited by BOOSTi; 08-22-2004 at 01:18 AM.
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Old 08-22-2004, 03:12 AM   #12
kenlee
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I'm sure Nathan will jump in here shortly to help shed some light.
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Old 08-22-2004, 03:51 AM   #13
waploom
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Default ok, i got the car dynoed

just to let everyone know with a follow up. I got the car tuned at axis power racing in St. Louis. So far, I am quite pleased. Just to remind everyone, the engine was stock with just the utec and perrin short ram. The dyno was a dynamics dyno I believe (check axispowerracing.net) The dyno reads low and the stock reading was 215. After dyno tuning, the car registered 253 hp 263tq to the wheels at 18.5 pounds of boost. The car runs fantastically. So well, actually, that the car is insane on wot. As to the hesitation, it is still there (supposedly a flaw/piggyback issue with the utec) but it appears to be much less of an issue, iow, it happens far less frequently. I will see how it performs over the next couple weeks and let everyone know. I think my next step will be suspension/brakes. (eibach springs, ferodo pads, rear sway, front tower strut brace). If anyone wants to see the graphs, I will post them.
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Old 08-26-2004, 02:30 PM   #14
DISCOPOPE
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Quote:
Originally Posted by Abe Froman
The front 02 sensor readings are not logged on the STI UTEC, althought I wish they were...
i'm not getting the fron 02 to show up on my logs either.
but folks keep saying that it does...
what gives?
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Old 08-26-2004, 03:27 PM   #15
happasaiyan
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on the STi UTEC, they arent.
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Old 08-26-2004, 03:29 PM   #16
Abe Froman
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Quote:
Originally Posted by happasaiyan
on the STi UTEC, they arent.
WRX UTEC = AFR
STI UTEC = no AFR

Abe Froman =
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Old 08-26-2004, 03:58 PM   #17
DISCOPOPE
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ty for the info
btw, how did you guys start working up your boost maps?
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Old 08-26-2004, 04:49 PM   #18
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I dont understand this issue. I have a STI UTEC and a tuna and I get both AFR in my log. The UTEC is obviously collecting the data and passing it to the tuna.

So my question is was this a clever method to increase tuna sales?
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Old 08-26-2004, 07:15 PM   #19
Abe Froman
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Quote:
Originally Posted by DISCOPOPE
ty for the info
btw, how did you guys start working up your boost maps?
Slowly, take a log of the stock boost curve and try to match that taper(the shape), then start rasing the midrange and work your way up 10-15 at a time. I only raised my taper 1-1.5psi near the top so it's not much more than stock but I have much higher boost in the mid range.

I have several maps that I use, depending on the weather, this gives me from 16psi to 20psi in the mid but all taper to 13-14ish near 7k.

Quote:
Originally Posted by bikerboy
I dont understand this issue. I have a STI UTEC and a tuna and I get both AFR in my log. The UTEC is obviously collecting the data and passing it to the tuna.

So my question is was this a clever method to increase tuna sales?
The issue is the stock O2 sensor not the O2 sensor that comes with the tuna. The tuna uses it's own wideband sensor and actually passes the info the UTEC(not the other way around), the UTEC then puts that reading it into the log with the other info and then gives it to you.

For those of us w/o wideband sensors(ie tuna) we would like to see the stock O2 sensor which is a semi wideband(only good down to 12:1ish) and the STI UTEC does not report this in the logs. This reading can be used to tune pre-spool and the hesitation in transition.
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Old 08-27-2004, 08:47 AM   #20
ride5000
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i don't see any earthly reason why they wouldn't include the stock front o2 sensor reading.

do you get any indication of it in the dashboard screen?

it does seem suspiciously like a ploy to "encourage" users to purchase a tuner.

ken
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