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Old 01-24-2008, 09:57 AM   #1
phoenix_wrx
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Default Fuel Cut? Boost creep? Help with stutter

Hello All,

Since i went stage 2 (well kinda) with a catted TBE from Buschur and a tune from them as well (done by DynoFlash) i have noticed that if i am 4th or 5th at low RPMS and push the throttle down, my boost goes up to about 18 psi. Everything is running fine, but if i suddenly release the gas, I get a hard stutter out of the engine.

If i release the gas slowly, no issue. I have pmd DynoFlash, but didnt get an answer. If i am revving higher (say 3500+) it doesnt do it either. I am thinking boost creep, but Buschur swears it is not an issue with the td04 and his exhaust. I have researched the heck out of it, and am now more confused than ever.

I can easily avoid the issue just by being careful how i pass and such, but i didnt think i would have to worry about this.

My only other mods are an SPT intake (dont start with intakes please. I like the sound and know it doesnt really do any other good) and of course the AP V2.

I am tempted to try using the Cobb stage 2 map and see if i still have the issue. Other than this little issue, i am happy as a pig in crap with the power i get now.

Help a (somewhat) noob out here. Should I buy a tactrix cable and try to map it out? I dont know if this is a simple tuning issue, or a physical one due to the exhaust.
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Old 01-24-2008, 10:01 AM   #2
sluflyer06
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is this a mail/email tune or dyno tuned?

I used to have a map by dynoflash through buschur that was mail in, i used it for about a day the car was pulling timing every time i got on it and was way too aggressive for a non protune. If this is your case I could not recommend using it. Al also has the worst customer service known to man, good lucky ever getting something done through PM or email with him.
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Old 01-24-2008, 10:12 AM   #3
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I'm having the same problem with my tune from xx. It's not boost creep or anything. Your WGDCs are probbly to high. That means your overshooting your boost targets and the ECu is compensating by pulling boost. that's causing the stuttering.

Watch your boost gauge, it probably fluctuates.

If you want to do some logging you don't need a tactrix. You can get EcuExplorer to read properly using your AP cable. It's not plug and play, but the direcitons are easy enough to follow to get you the data you need. (if you don't want to spend $80)
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Old 01-24-2008, 10:24 AM   #4
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Also, here's something I found with my tune.

When I reset the ecu, it nixed the realtime map and that left my car running on the basemap, which didn't have any problems at all.

I'm not sure what other parameters were changed between the base and realtime map, but I'm probably not making the same power. The base was probably more conservative and the tuner used the realtime map to be more aggressive.
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Old 01-24-2008, 10:31 AM   #5
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ok. going to try the cobb map and see if that is better. This was an email tune. I did stage 1 on Buchurs dyno, as i was in OH, but the stage 2 is a mail in.
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Old 01-24-2008, 10:37 AM   #6
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Quote:
Originally Posted by sluflyer06 View Post
is this a mail/email tune or dyno tuned?

I used to have a map by dynoflash through buschur that was mail in, i used it for about a day the car was pulling timing every time i got on it and was way too aggressive for a non protune. If this is your case I could not recommend using it. Al also has the worst customer service known to man, good lucky ever getting something done through PM or email with him.
how do you know you are pulling timing? I have not logged anything with the accessport yet. I am going to look into the ecuexplorer to try this.
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Old 01-24-2008, 11:02 AM   #7
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Quote:
Originally Posted by phoenix_wrx View Post
how do you know you are pulling timing? I have not logged anything with the accessport yet. I am going to look into the ecuexplorer to try this.
because i was datalogging after being advised to make everything was 'kosher'. I also noticed the Igntion advance multiplier was not wanting to stay at '1' which is bad.
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Old 01-25-2008, 11:06 AM   #8
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ok. i switched to the OTS cobb stage 2 map last night. and everything is MUCH smoother. I notice that i am hitting their boost targets, and with no stutter any more. but i also have WAY less "butt dyno" power. It doesnt pull nearly as hard as it did with the buschur tune. I take it this OTS map is much more conservative?

I am going to leave the cobb map in for a couple tanks and see if there is any improvement after the computer learns a little.

perhaps a pdx tune might be a better middle ground?
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Old 01-25-2008, 11:07 AM   #9
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a protune is definitely in my future, when i am near someone in the mid south who can actually dyno awd and tune subies. where that would be i have no idea.
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Old 01-25-2008, 11:10 AM   #10
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Your best bet would be to tune it yourself. Email tunes are like arranged marriages. You could get lucky and everything works out, but you never know.

You best bet would be to tune it yourself. Sell the AP, get a wideband and tactrix, read tea cup's threads, and go to town
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Old 01-25-2008, 11:17 AM   #11
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i thought about that, but am scared to death to goof something up. then again, if some of the jokers on here can figure it out, there is no reason that i cant.
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Old 01-25-2008, 11:24 AM   #12
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Quote:
Originally Posted by phoenix_wrx View Post
i thought about that, but am scared to death to goof something up. then again, if some of the jokers on here can figure it out, there is no reason that i cant.
Honestly, I was in that camp for a while, but after 3 protunes and $1750 (700 for Ap and 1050 for tunes) later I learned that $80 tactrix and $145 wideband will get you much further.

The catch is that you need to read a but load of documentation so you understand what's going on.
But on the good side, it's really not that complicated, there's lot of info available, and if you post logs people on here will be happy to help.

The other good side is that you know exactly what's happening with your car. That's something a protune will not help you with because tuners don't want to give out their open maps for fear that you'll start trading or selling them.


A protune isn't worth it unless it's opensource
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Old 01-25-2008, 05:37 PM   #13
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ok. cobb stg2 ots is running ok. tried the low rpm push in 5th today, no stutter. My boost is noticeably less with the cobb map. I am betting wgdc as well. I dont really have the time to put into learning tuning and going opensource on this.

Do you think i would have any luck talking to Buschur or DynoFlash about fixing the tune they gave me? I mean, i think it was too agressive, but the power it put out was noticeably more than the cobb map, but it wasnt really smooth in delivery, and i am guessing not very safe in the long run. i do have the buschur map still on the ap, but i am starting to think it might do more harm than good (the odd kick in my pants on an on-ramp)
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Old 01-29-2008, 11:21 AM   #14
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i got two replied via PM from Al. He basically told me i need a protune. Not much help. I guess i am going to just wait until i can get a protune, and just stay with the cobb map for now.
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Old 01-29-2008, 11:54 AM   #15
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said it sounded like compressor surge.

Compressor surge wouldnt translate to a physical hesitation when i am in gear would it? This only happens at low RPM and high boost if i let off the gas too quick. BAH! I guess will just run with the Cobb map which is much less boost, and be safe.

Last edited by phoenix_wrx; 01-29-2008 at 12:03 PM.
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Old 02-02-2008, 07:02 AM   #16
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if your boost gauge shows fluttering that is surge. boost should be pretty solid. What you are describing sounds like surge being caused from duty cycle on the wastegate. One option is putting in a boost controller if you want a little more boost but at the same time run the more conservative CObb map. You'll stay run less timing.
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Old 02-02-2008, 10:15 AM   #17
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surge didnt sound right to me either. the boost didnt flutter at all. I just build 18 psi and its almost like the BPV isnt relieving fast enough. Like i said, its only at low RPM and lifting off the throttle quickly that this was noticeable. Perhaps an aftermarket BPV would fix the issue? I am leaning towards tuning it myself, otherwise it will have to wait until the end of the year when i am back in Canada, or on the way to Ohio to get on Buschurs dyno again for a protune.
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Old 02-04-2008, 10:26 AM   #18
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How much boost will the stock BPV hold? I know it was holding OK, but it seems like it may not relieve the pressure fast enough.
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Old 02-04-2008, 10:49 AM   #19
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The BPV shouldn't be an issue since your studder is RPM dependent. If the stocker couldn't hold x psi, it would always leak anytime you're past x psi reguardless of gear or rpm. x psi is x psi
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Old 02-04-2008, 11:28 AM   #20
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i read unabombers faq again, and realized my last was a stupid comment.

What could the stutter be? I love the power of the buschur map, but dont want to worry about the reliability.
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