EGR problems, need help

Ryan Mechanic Middle Village, New York Posted   Latest   Edited  
Question
Driveability
2001 Toyota Solara SE 3.0L (1MZ-FE) 4-spd (A140E)

So today I have a lovely Toyota Solara with a disconnected EGR valve and a high flow low flow code. The client States that the previous shop disconnected the valve because the vehicle would run rough intermittently. I scoped the signals from the EGR position sensor and the VSV and noticed that at certain points during EGR command my my measurement doesn't change and other times it seems like there is no command and my voltage from the position sensor stays high. 

I took a couple of screenshots from my scope and was wondering if anybody had some insight into how to check if it is a mechanical issue with the VSV or a mechanical issue with the EGR. I actuated the EGR with the vacuum pump and it seemed to work fine and I can clearly hear the VSV click and it loses vacuum when it opens so I'm a little stuck here. The green trace is commanded and the yellow is the position sensor.

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Joel Diagnostician
Soquel, California
Joel
 

I do a lot of repair for emission under my smog license , I will check vsv computer command , and vacuum at same time two channels I prefer pressure transducer , you can use the vacuum gauge, and find out if there is vacuum when solenoid is commanded on or vise versa, those solenoids fail with hot temperature intermittently very common ,hard to catch it takes a lot of time in some cases ,

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Ryan Mechanic
Middle Village, New York
Ryan
 

After checkin more throughly , the Egr valve and position sensor are aftermarket. I feel between that and the mileage, it would be more effective to replace both to ensure proper operation. 

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Geoff Diagnostician
Lahaina, Hawaii
Geoff
 

Yes! That was SOP on that system anyway, By the age they normally failed, it wasn't worth the come-back risk to replace just half the system.

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Tomi Diagnostician
Chicago, Illinois
Tomi
 

I would double check your map sensor vacuum tube they tend to get a little clogged and throw off map readings. It happened to me once. Aftermarket vsv are junk so you may want to stress it a little by turning it in and off a few times in a row. Good luck!

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Michael Mobile Technician
Clinton, Utah
Michael
 

Hi Ryan,

I had one of these last year that the Catalyst was partially plugged. The extra backpressure made the EGR flow too much even though the duty cycle was correct.

+2 Ð Bounty Awarded