EVAP Purge Valve inop with codes
02-22-2021, 04:43 PM
#1
Registered User
Thread Starter
Join Date: Mar 2003
Location: Louisville, KY
Posts: 449
EVAP Purge Valve inop with codes
I'm getting Codes 443 and 449 on my '95Z with an LS1 PCM. I'm still testing but I am starting this topic to see if anyone has insight on this problem. What I've done:
Using a Mity Vac I've applied a vacuum to the cannister purge solenoid valve. It holds vacuum but it bleeds off slowly. Problem?
In the car, ignition on, I'm getting 12v on the Brn Pin A lead and just slightly less on the grn/wht wire Pin B. Grn/wht Pin B,that is grounded by the PCM, shows open to ground with the car not running and ignition off (as I would expect)
I tried using the Scan94/95 Actuators function to activate the purge valve while monitoring the grn/wht wire that is put to ground by the PCM and I applied the vacuum and watched to see if it was released. The grn/wht stayed at near B+ and the vacuum wasn't released.
I removed the purge valve solenoid from the car, hooked Pin A up to a battery giving B+ to the Brn wire pin (as in the vehicle) and a wire connected to the grn/wht connector (Pin B that is grounded by the PCM). I hooked the Mity Vac to the port connecting to the manifold and drew a vacuum. When the grn/wht plug was momentarily grounded, the solenoid activated and the vacuum was released. I believe this shows the solenoid is working.
I reconnected the solenoid into the car, hooked up a DVM to monitor the voltages and cranked the car. I saw no evidence that the solenoid was activated by monitoring pin B (grn/wht) going to ground. I activated the solenoid with Scan94/95 and watched to see if the car activated; though I may not have given the car enough time.
I checked and replaced the hose connecting at the fuel lines bundle to make sure it wasn't leaking.
I'm feeling the solenoid is good except for possibly the leak down observed.
I'll be tracing Pin B (grn/wht wire) that is controlled by the PCM to the PCM to see if the wire has a break. Pin A - Brn must be good as it has B+ on it.
So looking for other ideas.
Questions:
When/how often does the PCM activate the EVAP Cannister Purge Solenoid Valve?
What else in this circuit could cause this error?
Using a Mity Vac I've applied a vacuum to the cannister purge solenoid valve. It holds vacuum but it bleeds off slowly. Problem?
In the car, ignition on, I'm getting 12v on the Brn Pin A lead and just slightly less on the grn/wht wire Pin B. Grn/wht Pin B,that is grounded by the PCM, shows open to ground with the car not running and ignition off (as I would expect)
I tried using the Scan94/95 Actuators function to activate the purge valve while monitoring the grn/wht wire that is put to ground by the PCM and I applied the vacuum and watched to see if it was released. The grn/wht stayed at near B+ and the vacuum wasn't released.
I removed the purge valve solenoid from the car, hooked Pin A up to a battery giving B+ to the Brn wire pin (as in the vehicle) and a wire connected to the grn/wht connector (Pin B that is grounded by the PCM). I hooked the Mity Vac to the port connecting to the manifold and drew a vacuum. When the grn/wht plug was momentarily grounded, the solenoid activated and the vacuum was released. I believe this shows the solenoid is working.
I reconnected the solenoid into the car, hooked up a DVM to monitor the voltages and cranked the car. I saw no evidence that the solenoid was activated by monitoring pin B (grn/wht) going to ground. I activated the solenoid with Scan94/95 and watched to see if the car activated; though I may not have given the car enough time.
I checked and replaced the hose connecting at the fuel lines bundle to make sure it wasn't leaking.
I'm feeling the solenoid is good except for possibly the leak down observed.
I'll be tracing Pin B (grn/wht wire) that is controlled by the PCM to the PCM to see if the wire has a break. Pin A - Brn must be good as it has B+ on it.
So looking for other ideas.
Questions:
When/how often does the PCM activate the EVAP Cannister Purge Solenoid Valve?
What else in this circuit could cause this error?
Last edited by KYWes; 02-23-2021 at 07:08 AM.
Thread
Thread Starter
Forum
Replies
Last Post
Sandman_97Z
LT1 Based Engine Tech
8
09-22-2005 08:06 PM