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  #1  
Old 06-20-2014, 07:16 AM
Witsend Witsend is offline
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Default 99 Buick Century P1441 system flow during non purge

The purge solenoid can be actuated by scanner fine and holds vacuum, not stuck open , Freeze frame data showed fuel trims to be negative at the time (rich) and Baro reading was 35.4 psi! . Car drives fine and baro reads 14.5 psi now , but I'm thinking with all the rain and high humidity lately, maybe the MAF sensor might actually been malfunctioning and PCM is blaming it on the purge flow I'm going to take a TSB look at the wiring loom near the accumulator, because I also have an ABS code for a right rear wheel sensor that seems to be agreeing with the other 3 wheels speeds. So Why did Baro show 35.4 PSI during freeze frame event if not a MAF problem, unless the PCM just defaults to that value when running too rich , Any better ideas ?

Last edited by Witsend; 06-20-2014 at 07:57 AM..
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  #2  
Old 06-20-2014, 08:05 AM
Crusty Crusty is offline
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Use the purge and seal function and check the fuel tank pressure sensor.
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Old 06-20-2014, 09:15 AM
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Yup, do what Crusty said....check the FTP operation. This code wont run if there are MAP codes set so the PCM though 35psi was ok. the 1441 is for FTP below -11" H2O during the evap diag test.This is over 4volts, make sure the signal and reference wires arent shorted together. The canister and vent valve are back behind LR wheel, make sure the vent isnt clogged or hose collapsing. Make sure the purge solenoid hoses arent swapped and that there isnt any canister carbon in it. Skewed/erratic sensors are fairly common, I do a few a month
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Old 06-20-2014, 09:36 AM
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Default Solved

Thanks Crusty and Maven , I went out this morning , pulled cold vehicle in my garage unplugged the purge solenoid electrical connector and Evap tube side hose off of the purge solenoid and put my finger over the evap side port of the purge solenoid and could feel vacuum where it shouldn't have it when solenoid is not energized.
Also did a KOEO check with a noid light plugged into connector, and is not lit , so it is not getting a non pcm uncommanded ground anyplace , so the purge solenoid is NFG and must intermittently hang open and leak at lower temperature , because it held vacuum fine yesterday with my hand vacuum pump , however the vacuum was applied to the evap side port instead of the engine side of the the solenoid like it normally should. I will check and make sure the hose connections are not reversed because I did intake gaskets not very long ago but never make mistakes, lol
Now I'm trying to see if I can get up my Counselor 2 to display a AC wheel sensor output , set it on AC scale , 2V range, tried different time MS settings , working off the white and black alligator clips on Counselor 2 but can't get a display
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Old 06-20-2014, 10:02 AM
Crusty Crusty is offline
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SnapOn scanners graph really well.
USE this capability....
See if you can get the wheel speed sensors on screen in GRAPH.
KEEP THE SPEED SLOW, as in under ten miles per hour.
Drive the vehicle and see if one sensor is a little flakey at three or four or five miles an hour.
If you keep the vehicle speed slow you csn save screenshots and movies and catch the glitch that sometimes is only there for a few revolutions.

Heck....even a rumbling wheel bearing can set off codes.
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Old 06-20-2014, 11:14 AM
Witsend Witsend is offline
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Cool

I cleared C1228 code for right rear wheel sensor, and should let it go as a no problem found .I couldn't feel any false ABS activations , the harness looks fine, the hub is smooth and quiet ,the ABS light is not on at this time but a code 1228 for the right rear wheel speed sensor was in memory. I have an old Snap On MT 2500 non graphing and a DS708 that I didn't catch any drop out of wheel speed graphing all 4 wheels.
Just thought I would try the Lab scope function on the Counselor 2 to see if it is capable of displaying a low voltage AC sine wave on 2 volt scale turning the hub slowly by hand and compare the humps to an opposite wheel.
Can't the counselor 2 display a low speed , low voltage , AC sine wave wheel speed sensor trace? Cars have had ABS since the late 20th century when the Counselor 2 was still having it's glory days . I think it's capable, it's got to be me not doing something correctly.

Last edited by Witsend; 06-20-2014 at 11:56 AM..
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Old 06-20-2014, 11:35 AM
Crusty Crusty is offline
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AFAIC the money you spent on the counselor-II would have been better directed to a Solus-PRO or a Vantage-PRO......
What you are experiencing with it doesn't surprise me...it MIGHT have worked 25 years ago but.....lol
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Old 06-20-2014, 11:53 AM
Witsend Witsend is offline
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Talking there truly is more than one way to skin a cat

Well I figured out that I'm able to view a wheel speed sensor pattern after having a beer and selecting alternator waveform.
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File Type: jpg counselor 2 001.JPG (907.5 KB, 33 views)
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Old 06-20-2014, 12:27 PM
Crusty Crusty is offline
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Well thete you go.....LOL.....
Licking the batteries again.....LOL
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Old 06-20-2014, 12:56 PM
Witsend Witsend is offline
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Talking

Ok not sure if it's conclusive but I got a printout of the frozen Counselor 2 trace of the suspect right rear wheel speed sensor and one of the LR wheel speed while turning the hubs counting one one thousand , two one thousand , three one thousand . I think the printer hicupped and the trace proceeded after being frozen , but it looks good enough to justify replacing the right rear hub, though.
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File Type: jpg printouts 001.JPG (902.8 KB, 29 views)
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