logrythm for purging evap
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Joined: Apr 2002
Posts: 217
From: Hurst TX
logrythm for purging evap
Does anyone know how and why the PCM decides to purger the evap canister? I tried other places and no one seems to know. My PCM seems to think anytime I'm cruising it's times, ie not WOT and speed = >0 . My logs
are showing a very heavy use and it is usually opening egr when this occurs to compensate for the rich condition caused by purging.
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Adam in Hurst TX
95TA M6 Borla Cat Back
!TB,!MAF,Ripper,Tuner Cat
HP160, !UD pulley,CAI
Best 1/4 13.79 101.4
are showing a very heavy use and it is usually opening egr when this occurs to compensate for the rich condition caused by purging.
------------------
Adam in Hurst TX
95TA M6 Borla Cat Back
!TB,!MAF,Ripper,Tuner Cat
HP160, !UD pulley,CAI
Best 1/4 13.79 101.4
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Posts: 71,094
From: Hell was full so they sent me to NJ
How do you know its running rich when it purges? The canister will only absorb so much vapor. If there is purge air pulling through it most of the time - I am assuming you are seeing a 100% PWM on the EEC purge - it doesn't mean that the air is saturated with vapor.
And, I don't know how the EGR would know to respond to a rich condition by opening up. When you think about it, the exhaust gas would just be replacing fresh air that would normally be coming in through the intake, and the PCM would not be adding the fuel for the displaced air, because it knows the EGR valve is open. It wouldn't solve a "rich" problem.
I honestly don't know the (I believe you meant) algorithm (or maybe more appropriately, "logic") for the EEC purge operation. I would suspect it is just like the EGR and there is a table somewhere that sets PWM for the EEC based on throttle position, load and rpm. Just guessing though.
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Fred
94 Formula A3+1: 381/TH400+OD/N2O
Advanced Tech Posting Guidelines
Detailed Mod's List
11.513@115.59 on motor; 11.162@127.67, 1.643 60' on a 125-shot. Going with a 275-shot this year
And, I don't know how the EGR would know to respond to a rich condition by opening up. When you think about it, the exhaust gas would just be replacing fresh air that would normally be coming in through the intake, and the PCM would not be adding the fuel for the displaced air, because it knows the EGR valve is open. It wouldn't solve a "rich" problem.
I honestly don't know the (I believe you meant) algorithm (or maybe more appropriately, "logic") for the EEC purge operation. I would suspect it is just like the EGR and there is a table somewhere that sets PWM for the EEC based on throttle position, load and rpm. Just guessing though.
------------------
Fred
94 Formula A3+1: 381/TH400+OD/N2O
Advanced Tech Posting Guidelines
Detailed Mod's List
11.513@115.59 on motor; 11.162@127.67, 1.643 60' on a 125-shot. Going with a 275-shot this year
Thread Starter
Registered User
Joined: Apr 2002
Posts: 217
From: Hurst TX
<font face="Verdana, Arial" size="2">Originally posted by Injuneer 94FormM6:
How do you know its running rich when it purges? The canister will only absorb so much vapor. If there is purge air pulling through it most of the time - I am assuming you are seeing a 100% PWM on the EEC purge - it doesn't mean that the air is saturated with vapor.
And, I don't know how the EGR would know to respond to a rich condition by opening up. When you think about it, the exhaust gas would just be replacing fresh air that would normally be coming in through the intake, and the PCM would not be adding the fuel for the displaced air, because it knows the EGR valve is open. It wouldn't solve a "rich" problem.
</font>
How do you know its running rich when it purges? The canister will only absorb so much vapor. If there is purge air pulling through it most of the time - I am assuming you are seeing a 100% PWM on the EEC purge - it doesn't mean that the air is saturated with vapor.
And, I don't know how the EGR would know to respond to a rich condition by opening up. When you think about it, the exhaust gas would just be replacing fresh air that would normally be coming in through the intake, and the PCM would not be adding the fuel for the displaced air, because it knows the EGR valve is open. It wouldn't solve a "rich" problem.
</font>
is purged to 100% I see the int go to 118-122
rich then it will open the egr a few secs later to bring it back to around 128.
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