Everybody,
Attached are my emissions test from the last few years. My NOX results have increased. When it failed the 2011 test, I had the catalytic converter replaced. It then passed. In 2013 it failed again & I replaced the vacuum control/modulator for the EGR valve. I'm due again in December of this year.
Sometime in early '14, the Check Engine Light started coming on. I finally checked the code on it & it was a 71, which is the EGR system.
My question is: how do I know if it is the EGR valve or the EGR valve solenoid? When it failed in '13, I pulled one of the vacuum hoses off and sucked on it & the idle dropped. I figured this meant that it was working correctly. That's just a guess tho. It was just a chance that I replaced the vacuum modulator. I did it just because it was cheap.
If it is the EGR valve, any tips/tricks to remove it, particularly the large tube at the bottom of the valve.
This is on a '95 Camry, 4 cylinder, manual transmission, ac, & 360K miles. No emission work ever done except the converter & vacuum modulator.
Thanks,
Chris

 

The EGR system is not getting enough exhaust gas to the intake based on exhaust gas temp.

Issues can be:
EGR temp sensor is not working.
VSV circuit that turns the EGR on is not working.
EGR valve is stuck closed.
Problems with EGR vacuum hoses.
Clogged EGR gas valve or passage.

Temp sensor can be tested but seldom fails.

Use the same method you used before to check EGR valve operation. The valve is closed at engine idle. You applied vacuum to open the EGR valve at engine idle. This allows exhaust gas into the engine causing the engine to stumble or stall.

The VSV turns the EGR system on. When the valve is powered, vacuum is allowed to pass and operate the system. When off, the EGR vacuum system is vented to atmosphere. It is a 12V DC valve you can remove and test.

Check EGR hoses for leaks and damage.

As to removing the EGR valve. Go under the car and disconnect the lower tube at the other end (not where bolted to the EGR at the bottom). Then remove both tube and valve as a unit.

 

I assume that my EGR valve then works correctly because the idle does change when I apply vacuum to it. The vacuum hoses appear to be ok. So I will check the vacuum solenoid next. This has 2 leads on it. If I apply 12volts from the battery to it, should the idle drop as if I was applying vacuum directly to the valve? Which lead needs the 12volts?......

 

If you don't know, check your car to determine to which standard the emissions systems was built, California or Federal. The cars use different EGR equipment. The Fed car is the one using a single valve, the California has a bracket with two valves.

Apply 12v to the leads. The valve has a electrical solenoid which is not polarity biased (apply +/- to either terminal). On the car, the Black/Orange wire is +12v. The engine computer grounds the other terminal to turn the switch on.

If you apply 12v to the switch, the vacuum should flow the same as when you do this manually.

Take note of the hose locations to the valve. One comes from the engine (vacuum), the other goes to the EGR system. The valve also has a filtered vent to atmosphere (the small barrel can attached).

When the valve is off, the hose from the EGR system hose is vented to atmosphere by the filtered vent. The hose from the engine is turned off.

When the valve is on, the hose from the engine is ported to the EGR hose and vent cut off.

You can remove and test the valve by applying manual vacuum to determine if it works as it should.

VSV is a common failure but test it first before replacing.

 

I applied power to one lead tat a time with the car running. No change in idle. I checked the egg valve again with vacuum applied. The idle did drop. I was trying to provide a pic from my phone, but can't for some reason. The valve is on top...near the back attached to the intake. Not hard to get to at all. Other description s I seen online describe it being difficult to get to and the passenger tire needs to be removed for access.

 

The Black/Orange lead is powered when the ign switch is on. The computer grounds the other lead to turn the valve on.

You need to ground the other lead or remove the electrical plug and apply 12V +/- to the leads.

The tube is bolted to the valve at the bottom. If you can't unbolt the tube flange due to access issues, undo the tube at the other end. This requires going under the car.

 

I applied 12v and ground to the leads. No change in idle. The problem is that the valve I have looks different than the pics I have seen of it online at O'Reilly's, NAPA, & RockAuto. I may need to go to the dealer. Another issue is the emission sticker I have shows two VSV valves & I only have one. Another sticker I have shows it meets California standards, but again only one valve. Any input to this? Am I looking at the correct valve. The VSV I have has a vacuum line coming from the intake & another vacuum line that goes into a vacuum harness. Here are some pics.

 

more pics

 

If you look at the schematic there are 2 VSV's for the CAL car.

See link below:
https://www.rockauto.com/catalog/mor...429&cc=1273463

 

I did look at schematics & the other sticker stating it has California emissions. I was hoping they were incorrect & the valve I was looking at and testing was the VSV. Apparently it's not that easy. I looked at some YouTube videos & the VSVs are located underneath the intake & are not visible from the top of the engine bay. I will put the car up on ramps sometime in the next couple of weeks and take a look. As far as testing the valves, is it the same procedure? Do both valves need to be checked or?? Thanks for the help so far.