Stg 1 hic-cups at WOT (jumpy acceleration)
01-06-2005, 01:47 PM
#1
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Posts: n/a
Stg 1 hic-cups at WOT (jumpy acceleration)
Alright, so i just got my car running and everything is great in 1st and 2nd gear WOT. Car pulls hard. But i get a slight hesitation in gears 3-5 when giving it partial throttle. Accerleration is a little jumpy, although nothing too bad.
However, when I am WOT in 4th or 5th, the car will pull for a second, hit full boost, and then all of the sudden start bucking like I'm hitting a fuel cut. WTH is going on and is there anything I can do to fix it? Oh yeah, and there are no CELs...
Engine Mods to the car are:
Gutted Up-Pipe
TurboXS Stealthback (cat-less)
TurboXS Unichip with a Stg 1 map (i know, but i can't afford a UTEC)
K&N drop-in filter
Silencer Mod
Blitz SS BOV <----- could this be the problem?
All the mods on the car are the exact same as the previous owner whom I had bought them off of. He had gotten the Unichip when they first came out and had no problems with it. From what I was told, it was tuned for the Turboback, up-pipe, and panel filter, and i don't think a atmo. BOV would cause a problem like this.
1st gear i get a steady pull and the car hits ~12 psi
2nd is just the same, pulls hard right to and holds ~12-13 psi
3rd pulls well until full bost, which is set at 16 psi, hits, then the car starts to stutter
4th stutters pretty bad and at WOT I'll hit what feels like a fuel cut
5th is the same as 4th
Also, if i try to roll onto the throttle into full boost, i get the same damn hesitation
However, when I am WOT in 4th or 5th, the car will pull for a second, hit full boost, and then all of the sudden start bucking like I'm hitting a fuel cut. WTH is going on and is there anything I can do to fix it? Oh yeah, and there are no CELs...
Engine Mods to the car are:
Gutted Up-Pipe
TurboXS Stealthback (cat-less)
TurboXS Unichip with a Stg 1 map (i know, but i can't afford a UTEC)
K&N drop-in filter
Silencer Mod
Blitz SS BOV <----- could this be the problem?
All the mods on the car are the exact same as the previous owner whom I had bought them off of. He had gotten the Unichip when they first came out and had no problems with it. From what I was told, it was tuned for the Turboback, up-pipe, and panel filter, and i don't think a atmo. BOV would cause a problem like this.
1st gear i get a steady pull and the car hits ~12 psi
2nd is just the same, pulls hard right to and holds ~12-13 psi
3rd pulls well until full bost, which is set at 16 psi, hits, then the car starts to stutter
4th stutters pretty bad and at WOT I'll hit what feels like a fuel cut
5th is the same as 4th
Also, if i try to roll onto the throttle into full boost, i get the same damn hesitation
01-06-2005, 02:25 PM
#2
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Join Date: Nov 2002
Location: Longing for my ol' white '02 WRX :(
Posts: 3,639
Car Info: 2016 Acura RDX ... meh. Um, nice subwoofer?
You're prolly hitting fuel cut for overboost.
Is it just sorty jerky or is the car really lurching? If its just sorta jerky, you're prolly getting timing pulled, especially if it feels sluggish afterwards at the same loads. If its really lurching around, you're hitting fuel cuttoff for over boost.
Your boost gauge might be saying 16, but there's 2 problems 1) guages are not as accurate as what your ECU really sees and 2) if you are just using your eyeballs with no peak hold, esp no digital peak hold, you really have no idea. If you had a way to log stuff, this would be even better.
The BOV would not becausing this problem.
jason
Is it just sorty jerky or is the car really lurching? If its just sorta jerky, you're prolly getting timing pulled, especially if it feels sluggish afterwards at the same loads. If its really lurching around, you're hitting fuel cuttoff for over boost.
Your boost gauge might be saying 16, but there's 2 problems 1) guages are not as accurate as what your ECU really sees and 2) if you are just using your eyeballs with no peak hold, esp no digital peak hold, you really have no idea. If you had a way to log stuff, this would be even better.
The BOV would not becausing this problem.
jason
01-14-2005, 07:35 PM
#3
Registered User
Join Date: Nov 2002
Posts: 152
is this a pre-flashed unichip? if so, they cause more problems than give results IMO.
I went the stage 1 /stage 2 unchip route a long time ago and the results were not a smooth increase of power across the rpm band. In fact, i had increased and smoother power up through the midrange with just an mbc.
warning..anything higher than 14.5~15psi on an untuned car will result in possibly a burnt out uppipe cat or in my case, a melted stock egt probe.
If you want to play safe, remove the unichip and save for a custom tune.
The unichip is still a good piggy back for those who dont plan to tune often or switch gas ..but again it has to be tuned. My result with a unichip tuning with supporting mods was 283whp on 93 octane.
If you are in the north east, feel free to pm me and i can refer you to two tuners.
I went the stage 1 /stage 2 unchip route a long time ago and the results were not a smooth increase of power across the rpm band. In fact, i had increased and smoother power up through the midrange with just an mbc.
warning..anything higher than 14.5~15psi on an untuned car will result in possibly a burnt out uppipe cat or in my case, a melted stock egt probe.
If you want to play safe, remove the unichip and save for a custom tune.
The unichip is still a good piggy back for those who dont plan to tune often or switch gas ..but again it has to be tuned. My result with a unichip tuning with supporting mods was 283whp on 93 octane.
If you are in the north east, feel free to pm me and i can refer you to two tuners.
01-27-2005, 06:20 PM
#4
Registered User
Join Date: Jul 2003
Posts: 5
The unichip will not flash the check engine light like the utec will. You are running too much boost and the factory knock sensor is pulling your timing. Turn your manual boost control all the way down and see if it still does it. Then start turning it up a quarter turn at a time, but I would not go over 2 full turns.
01-27-2005, 09:03 PM
#5
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Join Date: Nov 2002
Posts: 152
Originally Posted by 123wrxguy
The unichip will not flash the check engine light like the utec will. You are running too much boost and the factory knock sensor is pulling your timing. Turn your manual boost control all the way down and see if it still does it. Then start turning it up a quarter turn at a time, but I would not go over 2 full turns.
The stock computer still has its saftey parameters enabled when it sees trouble, ..of which you pointed, the factory knock sensor may be signaling the computer. The MAF sensor will also be signaling the computer to flash the CEL due to a leaning condition when your boost is too high. Remember you are introducing more air when running more boost, the fuel map on your unichip may not be optimal.
01-29-2005, 01:07 PM
#6
Registered User
Join Date: Jul 2003
Posts: 5
I had the unichip first and now I have the utec, so I know the unichip will not flash the cel when the engine knocks. I put in a knock-link when I put the unichip in so I would have some way of determining if the car was knocking. Still have the knock-link in and it lights up the red l.e.d.'s every time the utec flaches the cel for knock. I Like to play around with different maps alot!!!
01-30-2005, 12:03 AM
#8
There are several issues with the unichip/mbc setup.. especially the older ones. First, if you set the MBC too high, you'll encounter serious detonation and the ecu will pull a lot of timing... this is probably what's happening to you. I suggest turning the MBC down so you don't see anything over 15psi in any gear untill you can get a custom tune.
The second issue has become known as Part Throttle Full Boost. This occures with MBC's in general when you're at less than 64% throttle and running more than 8-9psi. In this condition the ECU stays in closed loop mode (14.7:1 a/f). This is too lean for this amount of boost and causes high EGT's and detonation. Unichips never addressed this problem and require secondary devices to be run to handle the open loop/closed loop switchover.
-- Ed
Equilibrium Tuning
EQTuning.com
The second issue has become known as Part Throttle Full Boost. This occures with MBC's in general when you're at less than 64% throttle and running more than 8-9psi. In this condition the ECU stays in closed loop mode (14.7:1 a/f). This is too lean for this amount of boost and causes high EGT's and detonation. Unichips never addressed this problem and require secondary devices to be run to handle the open loop/closed loop switchover.
-- Ed
Equilibrium Tuning
EQTuning.com
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