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22RE EGR valve not getting vacuum

DouglasVB

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Today I went to get my truck smogged here in California and it passed with flying colors EXCEPT the EGR valve isn't getting vacuum. My emissions were actually really good (HC: idle = 12ppm, 2500 rpm = 16 ppm. CO: idle = 0.00%, 2500 RPM = 0.01%) enough so that the guys at the shop were talking about how clean-burning my engine is.

The smog shop said that the EGR valve specifically was not getting vacuum. I believe they were testing the vacuum line from the BSVS valve at the EGR end of the line.

The truck is a 1986 model year and I have a 1988 model year Toyota field service manual but I believe the EGR system is basically the same between those years on a 22re.

It looks like it could be:
1. A plugged or degraded or leaking vacuum line (lines were replaced about 3 or 4 years ago)
2. A bad BSVS valve
3. A bad EGR vacuum modulator

When I visually inspected the components just now, the cap for the BSVS is missing. Dunno if that matters for its functionality at all or not. Otherwise everything else looks fine.

Does anyone have words of wisdom on the best way to go through and diagnose and fix this?
 

DaveInDenver

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The circuit is pretty simple really. Yeah, first thing is to check hoses are good, no leaks or anything. You don't mention NOx but those numbers would indicate EGR function and modulation. IOW, how NOx reads at idle, WOT and in between tells you if the EGR is receiving no vacuum at all (BVSV) or incorrect modulation (e.g. not following the throttle position).

The BVSV should be letting a vacuum pull with the engine warm and not when it's cold. The BVSV can be tested on the bench using cold and hot water but it's pretty simple. With a cold engine EGR being on port 'J' (bottom) is getting air vented in from the top (e.g. no vacuum). With a hot engine EGR on port 'J' gets the vacuum being pulled on the top port 'K'.

If the cap on top is missing perhaps debris or goo is fouling the BVSV.

If the BVSV seems to be working then put a vacuum directly on the EGR and see if it actuates and releases. If both of those things happen then it's got to the modulator.

First check that the modulator is hooked up right. The 'Q' port to the BVSV 'J' port, 'P' to throttle body 'E' (behind the butterfly valve) and 'R' to throttle body 'R' (ahead of it). If it looks right then check that the filter is clean or maybe shotgun the modulator with a new one. In my experience the modulator is the most likely thing not to be working right but that's a sample engine of one.
 
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DouglasVB

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I guess Cali doesn't do NOx. There's CO2, O2, HC, and CO on the smog report but that's it. No NOx. Huh I wonder why.

The smog shop hooked up a vacuum gauge to the EGR valve vacuum port and said that they weren't getting any vacuum in any throttle position. They drove it up and down the street with the vacuum gauge in it to make sure that the engine was under enough load, etc. Still no luck.

I've got a vacuum gauge I can T into different parts of the vacuum circuits and do some testing. I guess I'll start there.
 

DaveInDenver

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If the hoses are good and the routing is all correct then I'd probably suspect the BVSV at this point. The only condition where the modulator would allow no vacuum is idle. With anything else it will either be fully open or modulating between open and closed.

That's not to say it's not clogged or inoperable, but perhaps I'd say less suspect. OTOH the modulator is first in line so if there's no manifold vacuum (e.g. a leaky hose) or it's dead then the BVSV wouldn't even factor in.

Just put the vacuum gage between the modulator and BVSV and see what happens to give you some clue where to start.
 

DouglasVB

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If it ends up being the BVSV, how much coolant am I going to lose when I pull it out? It seems that every time I need to do something on the engine, I've gotta drain the coolant 😅

It's looking like I've got some time this afternoon in my work schedule to pull the truck up to the garage and start poking around.
 

DouglasVB

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Hmm... Not really sure what to make of what I saw just now going through the diagnostic procedure in the Toyota FSM.

I checked and cleaned the filter on the EGR vacuum modulator. All good.

I checked the truck idles okay with the EGR vacuum disconnected. All good.

I checked the BVSV with a cold engine. No vacuum. All good.

I checked the BVSV with a hot engine by connecting a vacuum gauge with a T at the EGR vacuum port and got low vacuum (like 1-2 inHg) at high RPM. All good (I think this is the test it failed at the shop).

I checked the EGR vacuum modulator by disconnecting Port R and connecting a hose straight to high vacuum. Engine ran really rough. All good.

I checked the EGR valve by hooking it straight to high vacuum. Engine ran rough and died. All good.

I checked the BVSV by blowing air into the J port and it let air out the top when cold. All good.

I checked the BVSV by blowing air into the J pipe and it let air out the K port. All good.

I checked the EGR vacuum modulator by blowing into the Q port with the R and P ports plugged. Air came out through the filter. All good.

I called up the shop to double check how they did the measurement and the guy on the phone wasn't particularly helpful. He just said to bring it in again tomorrow and I could talk to the tech.

So either my monkeying around with stuff got it working again or I tested something wrong or my vacuum gauge isn't very accurate or their vacuum gauge isn't very accurate so one or the other was reading wrong. Or maybe they paid attention to the busted RPM gauge in the A pillar gauge pod which has no bearing on what the engine actually does 😂

I'll go and re-run the tests a bit later when it's cooler and the engine is cold again in case I missed something.
 

DouglasVB

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Trying to round up some part numbers in case I need them...

EGR Valve Control Solenoid (also called vacuum modulator): Toyota P/N: 2587035040
EGR Valve: Toyota P/N: 2562035130
BVSV: Toyota P/N: 9092505086
 

DouglasVB

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Okay I went through and re-tested. Now I am getting somewhat convinced that it is the EGR vacuum modulator valve.

Checked the vacuum modulator filter -- good
Checked the seating of the EGR valve -- good
Checked the BVSV with a cold engine (0 inHg) -- good
Checked the BVSV and EGR vacuum modulator with a hot engine at 3500 RPM connected to the vacuum hose to the EGR valve (0.5 inHg only some of the time) -- BAD
Checked the BVSV and EGR vacuum modulator with a hot engine at 3000 RPM connected in the same location but now connecting Port R straight to manifold vacuum (0 inHg reading) -- BAD
Checked the EGR valve by applying manifold vacuum directly to it (engine stalled) -- GOOD
Checked the BVSV when hot for air flow between port J and port K (was able to blow air through it without too much resistance) -- GOOD
Checked the lines between the BVSV and the EGR Valve and EGR Vacuum modulator (air flowed through) -- GOOD

So that leads me to believe the EGR vacuum modulator valve is bad.

I called up the local parts shops and none of them could even find the part in their databases. The local Toyota parts counter can have it by Thursday though so I think I'll go with that. About $128 before tax.

So that's where I'm at.
 
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