Disconnected Evap Purge Solenoid = Very Happy LNF
05-21-2010, 02:26 AM
#155
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I've gone back to just unplugging the electrical connection to the solenoid, and leaving everything else alone. Yes, there's a CEL, but the car feels awesome with my 23 psi Trifecta tune. I talked to Vince about disabling the evap purge solenoid in software as part of the tune and keeping the long-term fuel trims, but he's worried about the safety and liability issues of doing that, which I can understand.
Still, I've had my evap purge solenoid disconnected (with a few reconnections for testing) for about 3 months with no problems, other than the CEL, and my car has never felt better, so it does seem pretty safe... stupid emissions controls...
Still, I've had my evap purge solenoid disconnected (with a few reconnections for testing) for about 3 months with no problems, other than the CEL, and my car has never felt better, so it does seem pretty safe... stupid emissions controls...
05-21-2010, 07:49 AM
#156
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Just did this last nite and much to my surprise the car runs like a raped ape. Its just a mind **** how disabilin a evap componet can produce this kinda result. The draw back is the mil coming on pretty much rite away.
05-22-2010, 08:42 AM
#159
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I am afraid I may be developing a similar symptom on my SS Sedan. With the GMS1, Catted 3" DP, and modded air box/KN filter. I'd noticed it's not quite as smooth at idle as it was stock. I'd also noticed like someone said, it was backfiring occassionally when shifting from 1-2nd at light - moderate throttle. And now with a recent dyno tune, I had a P2237 off and on. I'd traced it down to only when it has a hiccup/cutout at cold start then follow with this code after a few miles that last for a day or so then it goes away. The car knock occasionally at initial part-throttle input only. I will be getting an updated map soon to remedy these symptoms. I may just try disconnecting the EPS to see if this makes a difference? We need to find a true fix for this.. 
05-22-2010, 04:46 PM
#160
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I have this going on in my car right now. it will be at 14.7 at cruising and then go to 13 steady and then to 15 steady then go back to normal. I got the "P0420 - catalyst system efficiency below threshold" CEL code. I thought that it was my DP with cat causing it and that's what the dealer said too but maybe it's from this?
06-16-2010, 03:26 PM
#161
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LTFTs freeze, but not necessarily at zero.
So as an update:
It appears that the electrical disconnection method freezes LTFTs... but freezes them at whereever they are at the time.
I've been doing some intake tests and had the LTFT off of zero. In between logging drives, I turned off the car, disconnected the Evap Solenoid, and continued on another logging drive. My dashdaq was still picking up the LTFT as it had changed to during the previous drive, while the STFT was still changing. This is further backed up by the fact that the STFTs were much smaller (STFTs would have become much larger again if the LTFTs had gone back to zero).
So, it seems that the LTFTs will be frozen, but not at zero unless they were already at zero or you reset the ECU. In a way this is good news.
I've also been monitoring the Evap System vs AFR/Fuel Trims. There is definately a connection between the AFR swings and the system. Still trying to isolate what part exactly. Currently monitoring purge flow/pressure, Evap Solenoid percentage open, fuel tank vent, fuel tank pressure, etc.
People that were worried about tank pressure building up will be happy to know that no tank pressure is shown to build up at all, and the fuel tank vent remains open at all times (even with the system enabled, I found that it still stays open a lot).
It appears that the electrical disconnection method freezes LTFTs... but freezes them at whereever they are at the time.
I've been doing some intake tests and had the LTFT off of zero. In between logging drives, I turned off the car, disconnected the Evap Solenoid, and continued on another logging drive. My dashdaq was still picking up the LTFT as it had changed to during the previous drive, while the STFT was still changing. This is further backed up by the fact that the STFTs were much smaller (STFTs would have become much larger again if the LTFTs had gone back to zero).
So, it seems that the LTFTs will be frozen, but not at zero unless they were already at zero or you reset the ECU. In a way this is good news.
I've also been monitoring the Evap System vs AFR/Fuel Trims. There is definately a connection between the AFR swings and the system. Still trying to isolate what part exactly. Currently monitoring purge flow/pressure, Evap Solenoid percentage open, fuel tank vent, fuel tank pressure, etc.
People that were worried about tank pressure building up will be happy to know that no tank pressure is shown to build up at all, and the fuel tank vent remains open at all times (even with the system enabled, I found that it still stays open a lot).
06-30-2010, 10:56 PM
#162
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bringing this back.
i don't have a wideband to test this on my 2.2 07 l61 but I wonder if this capping would have the same effect on it.
is this becoming a common thing that lnf owners notice? meaning is it something every ss/tc ss/sc ss and 2.2 technically encounters, since we all share essentially the same evap system?
i don't have a wideband to test this on my 2.2 07 l61 but I wonder if this capping would have the same effect on it.
is this becoming a common thing that lnf owners notice? meaning is it something every ss/tc ss/sc ss and 2.2 technically encounters, since we all share essentially the same evap system?
07-23-2010, 04:15 PM
#163
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So can you just cap it and leave it plugged in? Somehow i got kind of confused. Or would you cap + resistor.
I dont want to just unplug it and get a CEL. And i want the LTFTs to not be frozen.
I dont want to just unplug it and get a CEL. And i want the LTFTs to not be frozen.
07-25-2010, 10:19 PM
#164
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1) Leave it alone (seems obvious, but it's an option lol).
2) Disconnect the electrical connection: Will freeze LTFT at whatever it's at when it's disconnected. After an ECU reset, I keep the evap enabled until LTFT adjusts and then disable it.
3) Cap it: Disconnect the hose going to it but keep the electrical connection. This keeps LTFT, but may still result in an eventual CEL.
4) #2 + #3: Because if it's disconnected then what's the point of having it still connected.
5) Tune the evap purge to disable it or set to 0 purge. Approached Vince about this a couple times and he's not interested in pursuing that.
09-20-2010, 11:27 AM
#165
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When I hook up hptuners and check for dtcs, it also
Tells you what systems are complete like catalyst, and stuff. Well my evap system always shows incomplete. Also upon doing a log, my stfts are all over the place(+7+10 to -7-10) my ltfts are always stuck into the negatives (-3 to -8). I have a kn intake, dejon pipes, synapse ic and gm stage 1. Could these be symptoms of a bad evap solenoid?
Tells you what systems are complete like catalyst, and stuff. Well my evap system always shows incomplete. Also upon doing a log, my stfts are all over the place(+7+10 to -7-10) my ltfts are always stuck into the negatives (-3 to -8). I have a kn intake, dejon pipes, synapse ic and gm stage 1. Could these be symptoms of a bad evap solenoid?
11-02-2010, 03:25 PM
#169
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11-02-2010, 03:45 PM
#170
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