|
|
|
|
Thread Tools | Display Modes |
05-25-2002, 11:57 PM | #1 |
Scooby Newbie
Member#: 404
Join Date: Oct 1999
Location: socal
Vehicle:2000 Audi S4 endless.night |
Studdering on boost?
As you guys know i had a lot of trouble with my turbo after TRI installed it. Anyways ive started to have another problem creep up here.
About 2 weeks ago i would get some hesitation and stutter at around 4000 rpm when on boost. This gradually got worse and worse, and this past weekend i put in the svx fpr and did the parallel fuel mod, and now its horrible. Once i reach boost past about 3 or 4 psi the whole car just stutters and it doesn't really pull. The boost will climb to 6 psi like it should but the EGTs drop way down to like 1200 and it just doesn't pull. The thing thats weird is that at about 1/2 throttle i can keep it at 3 psi and pull nicely. Its just once i go WOT the car stutters. I am possibly thinking its my plugs, and one or more aren't firing under boost. They are still the stock champions (i know, i know, im replacing them this week ). I have tried adjusting my rrfpr every way i can and it doesn't really seem to make that much of a difference. I talked to Tom over at ludespeed and he said check that, and then if worse comes to worse get a compression check (which im really scared to do). You guys (and gals) have any other possibilities to check? Jason
* Registered users of the site do not see these ads.
|
05-26-2002, 12:01 AM | #2 |
Scooby Guru
Member#: 6551
Join Date: May 2001
Chapter/Region:
MWSOC
Location: Carol Stream, IL
Vehicle:'01 GC8 Dinged STM '09 Concours 14 ABS Black |
sounds like whatever you are using to clamp the Map sensor is failing.
jeremy |
05-26-2002, 12:11 AM | #3 |
Scooby Newbie
Member#: 404
Join Date: Oct 1999
Location: socal
Vehicle:2000 Audi S4 endless.night |
Yeah, thats also what i thought. So i hooked up a voltmeter to the actual map wire running into the ECU and it never breaks 4.7v. I set the SS voltage clamp intentionally a little low to try and make sure that wasn't the problem. I have even tried lowering it to around 3.9 and still have the problem.
Jason |
05-26-2002, 03:35 AM | #4 |
Scooby Guru
Member#: 6551
Join Date: May 2001
Chapter/Region:
MWSOC
Location: Carol Stream, IL
Vehicle:'01 GC8 Dinged STM '09 Concours 14 ABS Black |
hmmm...odd, it's acting like fuel cut, have you tried to watch the knock sensor during all of this, that's right about the time the ECU goes to open loop.
jeremy |
05-26-2002, 06:55 AM | #5 |
Scooby Specialist
Member#: 1109
Join Date: Mar 2000
Chapter/Region:
MAIC
Location: Reston, VA
Vehicle:1999 Suzuki Samurai Blackish |
I'm thinking O2 sensor.
|
05-26-2002, 03:36 PM | #6 |
Scooby Newbie
Member#: 404
Join Date: Oct 1999
Location: socal
Vehicle:2000 Audi S4 endless.night |
How can i check to see if its the knock sensor? And when does the ecu go into open loop, like 50% throttle?
Also which 02 sensor do you think it is, front or back and how can i check if its dead or not. Its probably the front since i was running extremely rich for a while. Jason |
05-26-2002, 04:44 PM | #7 |
Scooby Specialist
Member#: 1109
Join Date: Mar 2000
Chapter/Region:
MAIC
Location: Reston, VA
Vehicle:1999 Suzuki Samurai Blackish |
Probably front.
You could always unplug it, drive it, and see if it makes any difference. |
05-26-2002, 05:09 PM | #8 |
Moderator Member#: 922
Join Date: Feb 2000
Chapter/Region:
MWSOC
Location: Schaumburg, IL
Vehicle:16 WRX (white) 04 FXT (red) |
It can't be the O2 sensor if it only happens in open loop. It's not reading off it at all then... if it only happened in closed loop, then it'd be a very good possibility, though.
What does the studder feel like? Does it feel like a lack of boost, a lack of fuel, a small ignition cut, some unidentifiable hiccup? Do you notice anything going on with your EGT's, A/F's, or boost when it occours? I would doubt it being a compression problem if the car runs just fine at idle, where you'd notice it the most. At WOT, the car has very little chance to lose boost out the rings (due to, say, a common crown breaking off), and at idle the vacuum and rotation of the motor is so low that it'd be much more likely to run roughly (BTDT). How are you controlling timing? It's possible that it's at the threshhold where the ECU may hear detonation and pull timing, causing a dip there. Wish there was a simple knock-link circut that could be made to test this... I'm going to guess that it's detonation due to low/lack of fueling and advanced timing. |
05-26-2002, 09:17 PM | #9 |
Scooby Newbie
Member#: 404
Join Date: Oct 1999
Location: socal
Vehicle:2000 Audi S4 endless.night |
Hey 8,
The studder feels like a lack of ignition or a lack of fuel. The boost stays solid at 6 psi and really doesn't move. When i get on the throttle the EGTs drop real quick, to around 1200 where they are usually around 1400-1500. As for timing i am using the J&S ultra safeguard. I have it retarding 1/2 degree per boost starting at i guess 3 psi or 5 psi (whatever the start knob all the way clockwise is). I will try disconnecting the J&S this week and see if that changes anything. I do think that the ecu is either pulling fuel or retarding the timing. I am definitely going to invest in a fuel pressure gauge to make sure im fine, but im pretty sure im getting plenty of fuel. So what should i do or test?? |
05-26-2002, 09:22 PM | #10 | |
Moderator Member#: 922
Join Date: Feb 2000
Chapter/Region:
MWSOC
Location: Schaumburg, IL
Vehicle:16 WRX (white) 04 FXT (red) |
Quote:
Are you throwing a CE light? If so, what is it? This would be a very important piece of the puzzle. Could be fuel, could be detonation, could be MAP voltage. |
|
05-26-2002, 09:30 PM | #11 |
Scooby Newbie
Member#: 404
Join Date: Oct 1999
Location: socal
Vehicle:2000 Audi S4 endless.night |
Ha, yeah good idea about the J&S. I have had a CEL for like 2 years now. Can't get rid of it. This was even before the turbo, it was 02 sensor, i replaced it and subaru could't even figure it out. So i basically just ignore it. I can run up to subaru sometime and check the code or is there an easier way?
Also i was looking at getting the Nordskog digital fuel pressure gauge, just something cheap to check my fuel while i tune and then hide in the glovebox or something. Is this an decent gauge, my friend uses one in his conquest tsi. Anyways, what are the possible things that would throw a fuel cut or retard the timing? |
05-26-2002, 10:47 PM | #12 |
Scooby Specialist
Member#: 351
Join Date: Oct 1999
Location: NE
Vehicle:97 Legacy GT White |
i know that a friends wrx had a problem with maxing the injectors out, that resulted in a similar studder feeling when on boost. or is it possible with the low egt's that youare running very rich bogging a bit due to all the fuel. i know my friend but a set of sti injectors in and no longer has the problem, not it just runs rich as all hell.
kevin www.subee-sound.com |
05-28-2002, 01:07 AM | #13 |
over boosted again
Moderator Member#: 1458
Join Date: May 2000
Chapter/Region:
RMIC
Location: Colorado Springs CO USA
Vehicle:2017 WRX Limited 15 Forester XT, 21 Ascent |
When I had that problom, I had a bad #3 plug wire and was dumping unburned fuel out of #3 cylinder, EGT's dropped to 1200, and I fouled the plugs and O2 sensor.
|
05-28-2002, 01:14 AM | #14 |
Scooby Newbie
Member#: 404
Join Date: Oct 1999
Location: socal
Vehicle:2000 Audi S4 endless.night |
Thanks for your help, i haven't gotten a chance to really take a look at anything yet as i was at my girlfriends graduation. On the way home i basically discovered this, as soon as the boost hits like 2 or 3 psi, or the MAP voltage coming in reaches 4.85 or so the studdering happens. I have the SS voltage clamp in there and i can read the voltage going to the ecu and it is below 4.85 so im not really sure.
It really feels like a fuel cut, the motor just doesn't pick up eventhough there is plenty of boost. The EGTs drop which makes me think its pulling fuel and the timing. I will take a look at all of my wiring tomorrow, maybe something came loose. I'll let you know. Jason |
05-28-2002, 09:00 PM | #15 |
Scooby Newbie
Member#: 404
Join Date: Oct 1999
Location: socal
Vehicle:2000 Audi S4 endless.night |
Well i went out today and replaced the plugs with bosch crap, just the stock heat range since i couldn't find the NGK BR8ES's i wanted anywhere around.
Cleared up the problem completely. Thanks for your help, i love you. Jason |
05-29-2002, 12:08 AM | #16 |
over boosted again
Moderator Member#: 1458
Join Date: May 2000
Chapter/Region:
RMIC
Location: Colorado Springs CO USA
Vehicle:2017 WRX Limited 15 Forester XT, 21 Ascent |
Doh!
I knew it was a spark problem, just not in all 4 cylinders... |
05-29-2002, 05:39 PM | #17 |
Scooby Specialist
Member#: 1440
Join Date: May 2000
Chapter/Region:
South East
Location: Keeps Bumpers Fresher, Longer!
Vehicle:05 LGT Wgn; 04 FXT BDSM -- Birmingham, AL |
I've had and still do have a similar problem.
Keep and eye and an ear on it dyswtric27, I bet it comes back. When I bought my car (already turboed and tec'd) he was still running the Champions (W.T.F?) I changed out the plugs and it ran great! Now it is doing it again. I know that I am running rich, but I am still too timid to pull back some fuel. I guess I'll have to take the risk! -Nathan |
Thread Tools | |
Display Modes | |
|
|
Similar Threads | ||||
Thread | Thread Starter | Forum | Replies | Last Post |
5k rpm studder on my 07 tr...please help | boostdog | Factory 2.5L Turbo Powertrain (EJ Series Factory 2.5L Turbo) | 34 | 07-09-2007 03:06 PM |
VAC on boost gauge reads zero, boost 30PSI stock!!! | xS2k | Electrical & Lighting | 12 | 10-23-2005 12:06 AM |
problem! showing no boost on boost gauge | Benjamin Tang | Factory 2.0L Turbo Powertrain (EJ Series Factory 2.0L Turbo) | 6 | 08-26-2004 11:22 PM |
92 Legacy Studdering on starts | TheShadowWRX | Normally Aspirated Powertrain | 2 | 07-09-2003 06:34 PM |
buzzing from Subaru Boost gauge on boost? | Cosworth | Factory 2.0L Turbo Powertrain (EJ Series Factory 2.0L Turbo) | 3 | 06-29-2001 11:47 AM |