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California Emissions EGR VSV discontinued, 95 Camry 2.2

1235 Views 31 Replies 8 Participants Last post by  Splieslife
Hello,
I’m an intermediately skilled mechanic. I have a California emissions 95 Camry 2.2 that has an erratic idle when warm. After going through IAC valve and other first checks including replacing aging vacuum lines, all signs point to the EGR and EGR Vacuum Switching Valve being the likely culprits.
I wanted to buy a Toyota EGR VSV so I could move it to the firewall. However, Toyota tells me that the California emissions EGR VSV (Toyota #25860-74160) is discontinued and a brief search on the internet indicates this part is hard to find.
World Schematic Map Font Line

Above is a diagram that I obtained from the dealership. The top is federal, the bottom is California. You’ll notice that the two parts look different, the California part looks like two of the federal parts stacked on top of each other. Conversation and limited research has indicated that the California EGR VSV may have a third vacuum line going somewhere. It’s been hard to find information or a video that is specific to California emissions.
I’m just looking for insight and suggestions on locating this part. Some sites will indicate that their part will work for a 25860-74160 such as this;

https://www.sixityauto.com/aisin-vs...0-3092000871.html?find=1995-toyota-camry-3753

Font Rectangle Material property Screenshot Parallel


I’ll probably scoop this part and give the firewall move a try. If anyone has any info on differences between California and federal EGR VSV and related vacuum hose routing, it would be very helpful. As you all know, the EGR VSV is in a difficult location; my goal had been to just unplug the electrical connection and plug back into my new part on the firewall with the two lines going to the EGR and EGR Vacuum Delay Valve as is standard with federal emissions.
Worst case, I can always try to move my current part, but this just seems like a pain. I also would be hard pressed to know exactly where any third vacuum line was going to, should it exist (the working area is very difficult to access).

I appreciate your time for the long read, thank you.
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1998 Rav4, manual transmission, 2WD, JDM engine installed in 2013
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Short Answer
I think the lower drawing actually shows two VSVs having different functions: The VSV for fuel pressure control (required on California emissions) and the EGR VSV.

To replace the EGR VSV, I would buy the Aisin VST-026.

Long Answer
The service manual (EG section) has drawings of the EGR VSV and Fuel Pressure Control VSV, mounted right next to each other. In my next post, I linked a site that has the service manual sections.

For the EGR VSV, I see on toyodiy.com the following for a 1995 2.2L Camry (drawing 17-08):

25860 VALVE ASSY, VACUUM SWITCHING, NO.1
25860-74050 NO.1 1 $89.75
25860-74160 CALIFORNIA SPEC 1 $197.57

I googled on the two part numbers and the parts look alike except for color. The Aisin equivalent part numbers are:
Federal, Aisin VST-006 (advertised for both 25860-74050 and 25860-74160)
California, Aisin VST-026 (advertised for only 25860-74160)

As you may know, Aisin is the OEM manufacturer for many Toyota parts.

For 2580-74160, Rockauto's search engine also spewed out both VST-006 and VST-026.

The only difference between the Aisin VST-026 and Aisin VST-006 might be the filter built into the one end? I am not sure.

I will post the EGR VSV vacuum hose routing separately.

Other causes of a rough idle when warm include an iffy ECT sensor; air in the coolant; and a failing front oxygen sensor.
 

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Underneath the hood might be a vacuum hose diagram. Here is what I know:

EGR VSV Port E is the port closest to the VSV filter. VSV Port E connects to the port on the top of the EGR valve.

EGR VSV Port G is the port furthest from the VSV filter. VSV Port G connects to the port labeled "Q" on the EGR vacuum modulator.

Any doubts, go to https://cardiagn.com/toyota-5s-fe-engine-repair-manual/ and download the following sections:

Engine Mechanical
MFI/SFI System
and possibly the Emission system.

Keyword search these sections for "VSV" and similar.
 

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Discussion Starter · #4 ·
Hey,

I spent half an hour writing a detailed response only to have it get deleted after being prompted to sign in.

Thus, I'll be brief.

Thank you for your help. I'll try the Aisin part I linked. I'll likewise clean the EGR and follow up.

I'll trouble shoot some of the other systems you mentioned.

Cheers
 

· just a nobody
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I'm guessing ease of access - that VSV is mounted underneath the Intake manifold from the factory: it's a PITA to get to. Moving it up onto the firewall makes access / diagnostics much easier. (BTDT here.)
Can understand if the VSV needs to be connected and disconnected often, or if the old one is bad; however, base on the descriptions, it is not the case.
If OP wants to check if the EGR system is causing the idling issue, can simply disconnect the vacuum hose to the EGR valve itself.
 

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Discussion Starter · #8 ·
Hello,

Still have yet to dive back in on this one but I'll briefly provide clarification for my attention to the EGR system;

The car has been in my family since 1995. My parents owned it and for the last 10 years its been sitting mostly idle in their driveway. My parents ran it every couple months and kept up with maintenance, but it was barely used. A few years back it developed this wandering idle when warm and was only ever periodically warmed up afterwards (they didn't want to drive it far). My dad and a friend who's a veteran Toyota mechanic have chipped away at the issue on and off for years(it was low priority as my parents have other vehicles). They've replaced and gone through many of the obvious culprits for idle trouble; IAC valve, ECT sensor. The only system that they had not addressed was the EGR and vacuum lines.

A few weeks back, my current vehicle began to show signs of going soon, so I bought the Camry knowing its history. I replaced all the vacuum lines that are easy to access, cleaned the throttle body and generally gave everything a liberal hit of carb cleaner, short of opening up the EGR. I also hit all connections with contact cleaner and then dielectric grease. The EGR and EGR VSV are some the only untouched systems left.

I know the car was running great in years past (currently only has 160k miles) and in my experience valves like the EGR can easily become stuck through long periods of disuse. The EGR VSV is difficult to address in it's current location (I can't properly inspect the state of those vacuum lines) so I plan to move it in conjunction with a cleaning of the EGR.

If this is fruitless I'll look into the O2 sensors and possible air in the coolant as my friend above stated.

I'm confident it's the EGR as the car is incredibly smooth for the first 15 minutes of driving before the wandering idle begins. After, cutting the throttle causes the RPM to rove between 500 and 1000rpm. The steering wheel also shakes mildly when I cut throttle. Applying throttle smoothes everything out. When I come to a stop, the car can die if the idle is allowed to dip too low. If this happens multiple times in quick succession, then the car is difficult to start like the engine has flooded. My theory is that the EGR is stuck open or closed, causing the computer to dump more fuel when the O2 sensor is indicating an incorrect fuel mixture.

To summarize, I'm in a unique situation where I have a ton of information regarding the cars history and what has already been addressed.
 

· just a nobody
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How long do you have to drive the vehicle before this condition happens?
In general, EGR related issue only happens when the car had been driven on the highway for extended period of time; meaning the EGR valve had stayed opened for long periods of time.
If you want to eliminate the EGR system as a possible cause, just disconnect the vacuum hose to the valve, and drive the vehicle; if it is related, the idling issuse won't happen.
There are other casues that could affect idling, sticking injectors for one, especially with a vehicle that had been sitting often!
 

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Discussion Starter · #10 ·
Hey,

So I've only taken it for a spin once since I've acquired it. This was after I had replaced all the vacuum lines as described above (battery had also been disconnected during all of this).

I drove 6 blocks to the gas station, then a mile to a station that has a free air pump, then half a quarter mile to the freeway. I then drove three or four miles on the freeway to where I exited to turn around. Thats when the idle issue kicked in.

I only suspect the EGR as the car is very smooth prior to warming up. I would imagine that an issue with the injectors would be constant, but I could certainly be incorrect.

Which vacuum hoses do you specifically recommend disconnecting on the EGR and do you leave them open or seal them with a clamp?

Cheers.
 

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Discussion Starter · #13 ·
Hello all,

Great news, I plugged the vacuum line that goes from the EGR VSV to the EGR and the idling problem went away. My new EGR VSV is coming tomorrow which I will be relocating and rerouting.
The only other issue to report is that the intermittent wheel shaking is still an issue. It comes and it goes.
 

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Discussion Starter · #14 ·
Alright, so further updates;

I installed the new EGR VSV and relocated it onto the plenum. When I fired up the car the problem came back unfortunately, though it felt slightly less severe. I’m going to clean my EGR and investigate the booster.

I’m hoping it’s not an electrical issue somewhere making the EGR act up. When I unplugged the vacuum going to the EGR, the car ran perfectly.
 

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Some random guess. Maybe you didn't clean iacv well? Maybe coolant temperature sensor is bad? Look at fuel trim, too much gas or air?

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· just a nobody
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Alright, so further updates;
I installed the new EGR VSV and relocated it onto the plenum. When I fired up the car the problem came back unfortunately, though it felt slightly less severe. I’m going to clean my EGR and investigate the booster.
I’m hoping it’s not an electrical issue somewhere making the EGR act up. When I unplugged the vacuum going to the EGR, the car ran perfectly.
Does your car have a EGR modulator valve? Make sure that is working properly, and the hoses are connected correctly!

 

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Some random guess. Maybe you didn't clean iacv well? Maybe coolant temperature sensor is bad? Look at fuel trim, too much gas or air?
The OP affected the idle symptom issue by only removing a vacuum hose connected to the EGR valve (eliminated the idle problem when warmed up). I would think the OP would be best served by digging into that element first, not the IAC or coolant temperature sensor.

OP, if the engine runs normally when cold, but doesn't when warmed up, and with a warm engine with the engine idling (no foot on the gas pedal), I really don't think your EGR VSV is the problem at all.

I'm attaching a picture of a sticker that has the vacuum routing diagram for a 1995 Camry 5S-FE (2.2L) with California emissions, just for reference. I am also attaching a service manual section from my 1993 Celica service manual - it looks to me like the EGR system on a 1995 Camry 5S-FE is essentially identical to that on my 1993 Celica 5S-FE. If you look first on page EC-38, that page will help you a lot. There is a table at the bottom that ties the diagram boxes labeled (1), (2), and (3) above it. Look at that very closely and spend some time understanding it. I think it will help you understand next steps needed to verify what is wrong.

Note in the table, when the engine coolant temperature is below 131 deg F, the ECU will not supply power to the EGR VSV. That means the EGR valve should be closed when the engine is running, no matter if you are on the highway or have it idling. Next note that when the engine coolant temperature is 140 deg F or above, the ECU may or may not energize the EGR VSV. The engine coolant temperature is that which the engine coolant sensor for ECU is telling the ECU. The ECU will also not energize the EGR VSV if the engine RPM is above 4000. The ECU will also not energize the EGR VSV is the throttle plate is not beyond port E on the inside of the throttle body. The ECU gets that information from the throttle position sensor on the throttle body. The ECU will only energize the EGR VSV when the throttle plate is moved beyond port E on the throttle body.

With all that said, you stated the engine runs & idles smoothly when cold/cool. This tells me your engine coolant temperature sensor for ECU is functioning properly, and the ECU is responding properly by not allowing the EGR VSV to be energized. However, once the coolant temperature is above 140 deg F, the ECU properly removes that restriction on not energizing the EGR VSV, which is also correct. But, the ECU should be not activating the EGR VSV if the throttle plate is not beyond port E (which if it was, the engine should be at a very high idle speed). This tells me you may have a problem with your throttle position sensor, or at least the signal getting back to the ECU. Has your throttle position sensor ever been removed? If it was, it needs to be calibrated when reinstalled to ensure it has the output of a closed throttle plate when the throttle plate is closed. If not calibrated properly, or not working properly, your ECU may be getting a signal that the throttle plate is opened further than it really is. There may be other root causes that produce this symptom, but the fact that your EGR VSV is energized when the engine is in a slow idle (throttle plate closed) tells me the problem is in the throttle position sensor and/or the wiring going to the ECU. The ECU could also be defective in that it can no longer read the position location coming from the throttle position sensor.

If it was my car, that is where I would be focused on right now.
 

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Discussion Starter · #20 ·
Hello and thank you for your detailed response. I’ll address 93Celicaconv;

I’ve viewed several vacuum routing diagrams and have replaced all hoses except those than run from the EGR booster underneath to the two ports on what I believe is the exhaust. As mentioned before, I moved the EGR VSV to the top of the plenum.

My next planned move was to remove and clean my EGR valve. I’ve already vacuum tested the diaphragm (it’s holding vacuum fine). Unfortunately the 24mm crows foot that I ordered was stolen off of my front step by a package thief and I’m waiting for a new one to come.

I’ll briefly address some other systems that I’ve serviced;
-all new spark plugs
-coolant flush and change to HOAT coolant w/ new radiator hoses
-air filter replacement
-oil change
-PCV change
-added fuel injector cleaner to fuel
-throttle body removal and clean
-IAC was replaced with oem unit by my family
-they may have possibly replaced the throttle position sensor, not sure if they would’ve recalibrated it, I’ll need to look into this.
-they replaced the coolant sensor, I think it may not have been OEM, I’ll also need to follow up on that

As mentioned before, deactivating the EGR by removing the vacuum hose to the diaphragm fixes the problem. I’ve had to commute with it deactivated this way all last week for my freelance job (100 mile round trip). I’ve noticed poor mileage; close to 23mpg with mostly freeway driving, I’m not driving aggressively or heavy on the throttle. Also there’s a rush of air either in or out of the gas tank when I remove it to refuel. I understand this could be a symptom of the deactivated EGR not allowing the EVAP system to function(or it could be a clue worth looking into).

As you say, EGR is likely not the source of the problem. I still plan to remove and clean it so that I can rule it out as a possible issue.

I’ll look into the throttle position sensor (calibration as well) and the coolant temperature sensor. Is there any simple way to diagnose an ECU as being potentially faulty? My imagination would be that these are expensive and difficult to change; I’ll do some research.

Aside from not being able to pass emissions, is there any negative effect to continuing to drive with the deactivated EGR? Am I going to ruin my Catalytic converter by sending unburnt fuel into it?
 
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