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  #16  
Old 06-23-2003, 11:42 PM
gl1674 gl1674 is offline
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I think I know a temporary fix for this problem - all it takes is removing the heads and scraping the carbon deposits off the heads, valves and tops of cylinders.
Unfortunately the effect only lasts for a thousand miles or so...
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  #17  
Old 06-24-2003, 05:56 AM
nikkihorz
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Carbons....???

Now by carbons, do you mean hydrocarbons?

Because from what I understand, high hydrocarbons are the result of bad knock sensors.

Do you feel this could be the cause of the carbon deposits?
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  #18  
Old 06-24-2003, 01:15 PM
gl1674 gl1674 is offline
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As far as I remember, there were some black brittle (crumbling) deposits on the valves, heads and pistons. Call them carbon, charcoal - whatever the name, they do take up some space and increase compression as the result.
One theory is that the increased compression caused detonation and pinging and that forced ECU to retard timing. The problem with this theory, it does not explain why it happens when engine is cold and why it goes away when it warms up (should be the opposite).

All I know scraping the deposits off did help for a while (although I cannot eliminate a second factor - ECU had been disconnected and had to relearn it's bad habits).
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  #19  
Old 06-24-2003, 06:03 PM
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Surging is almost always caused by a lean condition. Now, whether or not the lean condition is a result of a problem or a programming glitch is another story. A vacuum leak, poor fuel pressure or flow, bad ECT, etc. can contribute to the cause.
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  #20  
Old 06-24-2003, 10:49 PM
jsvxstyle jsvxstyle is offline
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option

find a shop that has the smoke machine to find intake manifold leaks, when the engine is cold cap off the air flow meter, put plugs in the exhaust tips, start the machine and youll see that on the intake box were the tube join the box to the valve covers, or ventalation tube will leak smoke, all i did was put clamps on the hose and , since then i dont have the surge, i thought it might been the baramic pressure sensor, when the engine is cold unmetered air goes in past the air meter, the o2 sensor sees extra air but air flow says it perfect, so then the ecu start adjusting or i should say fighting its adjustment till it goes into closed loop. where all sensor play the role of tunning.
think this is right beav.
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  #21  
Old 06-24-2003, 10:59 PM
gl1674 gl1674 is offline
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One minor correction - when engine is cold, O2 sensors do not work. This is the main reason for the open loop mode existence.

Does anybody have any ideas about DIY smoke machine???
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  #22  
Old 06-24-2003, 11:58 PM
jsvxstyle jsvxstyle is offline
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only after the o2 heater rises in temp then the o2 starts monitering after afew minutes of idling in the svx
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white leathers, h.i.d, ecutune S/C stage 4, 14 inch 2piece rotors big brake kit., , msd ignition, c/f dash kit, front spoiler,carbon fiber jdm rearc wing,19 inch rims, nos, , aem fuel regulater, koni-gc package, ported cylinder heads, supercharger cams,solid buck and shims,wrx sti intake valve and exhaust valves,& valve springs, gas analizer,water injection, exhaust temp gauge, idiglo gauges, shift kit, , remote start, all automatic windows,2.5 inch true dual exhaust system with crossover, and 2 borla stainless steal muffler,air filter velocity air stack 3inch to 6 for air filtre, group n mounts, momo steering wheel, dyno will happan soon
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  #23  
Old 06-25-2003, 12:00 AM
jsvxstyle jsvxstyle is offline
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smoke machine

yes i have them at my shop, works great for audis problems. and all sorts of other problems, got it from my mac dealer
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  #24  
Old 06-25-2003, 04:07 AM
SVXdriver_007
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I nhad this surging problem at especialy at idle and durin intial driving, the problem mostly went away after a few days with the new IAC and letting the car run for like 2 minutes before driving it. I'm not sure if this would help since I was clearly throwing a CEL for the IAC in the first place?

ahh well for what its worth
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  #25  
Old 06-26-2003, 08:44 PM
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Check around IATN for home-made machine topics. I know several people there were making them a few years ago, but I don't know if they got them to work well enough to warrant the effort.
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  #26  
Old 06-27-2003, 12:58 AM
gl1674 gl1674 is offline
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IATN as www.iatn.net? The automotive technician network?
Unfortunately it requires subscription and has some requirements to join - like ASE certification or 4 years of employment as automotive technician. I do not think tinkering with SVX qualifies (be it good or bad).
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  #27  
Old 06-27-2003, 06:00 PM
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As long as you don't post to the groups (would probably tip your hand) and just use it for research I don't think it would be a problem. But you didn't hear that from me... ;-)
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  #28  
Old 06-28-2003, 12:59 PM
gcookaustin
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Quote:
Originally posted by gl1674
One minor correction - when engine is cold, O2 sensors do not work. This is the main reason for the open loop mode existence.

Does anybody have any ideas about DIY smoke machine???
Is this why my I got an error code for the O2 sensors when it was really really cold out this winter?
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  #29  
Old 06-29-2003, 12:20 AM
gl1674 gl1674 is offline
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Yep. There is a glitch in the ECU logic - sometimes it expects sensors to warm up faster than they do and it throws code and CE light for a few seconds/minutes. It is required to throw code and illuminate light by law, I'm not sure if the law specifies maximum time for sensors to warm up. The sensors have built-in electrical heaters to speed up the warming.

The problem happens to many people on this board - on my car it does not need to be really cold. It seem to depend on the usage pattern - it is more likely to throw a code after a ~ 20 minute stop, when engine is still warm, but pipes cooled down.
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