Techstream EGR Valve Blockage Data

Thanks I'm just wondering why I get no values at all. I had just cleared DTCs before so perhaps no data?

 

That is weird.

I don't think most of the car's ECUs will talk in accessory mode.

Of the four available modes (off, accessory, on, ready), I generally do scantool stuff in 'on' mode.

 

I tried it on "on" mode and "ready" both gave no values but I had just cleared DTCs right before. Can someone confirm this will show zero data?

 

Ah, yes, clearing DTCs resets all emission monitors to 'incomplete'.

Each individual monitor will then become 'complete' again in its own time, once your driving has included the conditions that monitor needs to complete. For the EGR monitor, the conditions are that you've done a certain amount of driving around 30 MPH or so that involved decelerating for several seconds while the engine idled with fuel cut, because those are the times the EGR flow test gets snuck in.

As for showing 'incomplete' monitors as all zero but 'passed', instead of saying 'incomplete', that's probably the app you're using.

 

Not so weird. I meant I use "ON" mode. Sorry!

 

I got my first reading, assuming the next few are within this range would this mean my EGR system is ok? What's the happy medium here?
I haven't pulled the egr cooler or valve so I have no clue how clean or dirty they are, my intake ports were really nice though

 

Did you clean those small passages from intake manifold?
Can't see them because they're shiny in your pictures.

21-22 psi is what we see here after cleaning EGR cooler/pipe and intake manifold.
Mine is around 17 psi usually with some high in 19.xx and low in 12.xx.
No idea why jumping like that.
Cleaned only intake manifold and EGR pipe an year ago.

 

Ah, you've got the Car Scanner app that shows those numbers in kilopascals but labels them psi. We've seen that one before.

Maybe it would be worth dropping the Car Scanner folks a note about about that. If that pressure were really 17.4 psi it'd be around 120 kPa, yikes!

17.4 kPa sounds sort of reasonable. Squeaky clean is usually around 21 or 22. What's the mileage?

I cleaned mine when it was down around 10 something. But it's a personal call, what number you're comfortable with. The car will set a code at 0.95.

Aside from clogging, there is a thing that can happen in the EGR valve that also reduces flow, and isn't very hard to check for. It will show up in the flow result, so if you had a squeaky-clean 21 or 22, I probably wouldn't bother checking it.

At your 17.4, it's a little reduced, which might be some clogging, some valve mashing, or some of each. So maybe it would be worthwhile to peek at the valve rotor to see if any mashing is involved or can be ruled out.

Is that a bright light I see streaming through your manifold passages?

 

That's light shining g through the other end, did not clean them. That's the condition they were in when I removed IM. That range between 12 and 19 seems a bit extreme doesn't it?

Yes sir, it's the car scanner app, I've changed the units to kPa. It has 107,500 miles. That was a light I shined through to check for blockage.

 

You mean Car Scanner will let you change the display unit label, and the number being displayed doesn't change?

Re: the number bouncing around, the ECM doesn't have total control over the conditions when it sneaks the test in. You're always decelerating, with the warm engine spinning and the fuel cut off, but this is all at the mercy of whatever real driving conditions you're in. It seems to me the results generally cluster a little more tightly most of the time, but occasional outlying values show up. It's probably ok to look at where they cluster.

 

Correct on th units, number stays the same, got a second value, close to the 1st.

 

If only I could push the MPH - km/h button on the dash and have the numbers stay the same ... jaunts through Canada could take a lot less time.

 

I agree, there should be more oversight by the developer but it's a great service at an unbeatable value. Years ago you needed expensive machines to get these data points.

 

Here are my 1st 3 readings of the day. The first was in 12s and it got me thinking. Could a lower value be associated with a cold start in the morning time? Carbon build up should be more solidified and not allow the "juices to flow"? The next 2 happened when the car was nice and warm and seem closer to the range I've been getting. Was your 12 taken in the morning time when your car was cold?

 

The car doesn't perform the test except when the engine has warmed up, you've been driving for a bit, and you happen to decelerate for several seconds while the engine is running. If you get hold of the repair manual troubleshooting steps for the P0401 code, that's where it describes how the monitor test works and the conditions when it runs.

So if you're interested enough to keep frequently requesting the values and seeing how often you get an outlier like that, maybe there would be some kind of interesting pattern, but a relation to cold start probably won't be it, just because of the rules for when the monitor runs. It's also possible there won't be much of a recognizable pattern, just a weird outlier every now and then.

I'd note that the number you see when you pull up the monitor result is not a number from right then. It's a number from the last time the ECM found suitable conditions for running the test while you were driving, whenever that was, so it's probably not easy to remember what was going on then. The ECM is trying to sneak the test in during a few steady seconds of fuel-cut deceleration, but it doesn't control you or the road, so maybe the traffic changed in the middle of that test, or something.

 

Good info, I'll continue to track the first test of the day, although the data may or may not be from the morning time it would be interesting to see if it's consistently a lower number.

 

Spot on.
I have no idea when and why I have 12.xx or 19.xx.
Mostly I'm in 17.xx range so I guess I'm somehow okay with EGR cooler. Or at least I hope so.

 

Here's some EGR Monitor data that I posted in another thread:

My 2012 Prius v with 46K miles shows an EGR Monitor test result of 15.74 kPa (max: 655.35 kPa, min .64 kPa). The O2 Catalyst Bank 1 test result is not too far from yours at .265 (max 9.994, min 0.25), so not sure how much it will vary over time or mileage.

Other background data - bought the car in Aug '19 with 25K miles, average mileage is 43.5 mpg (70% city, 30% highway), OCI is about 4.5k miles, and oil catch can was installed at 32K miles. No EGR cleaning performed yet - will continue to collect more EGR test results through this winter and clean intake manifold, EGR tube and valve in this spring (around 50K miles). Plan to continue watching EGR monitor data and clean entire EGR/IM system (including cooler) around 80K miles.​

 

I’m not sure it’s even possible to extract the valve separately from the cooler. I’d do both at same time, when you get around to it. If you’re concerned about coolant spillage with cooler removal, there are strategies to avoid. See first couple of links in my signature.

 

I bet you can loosen the cooler enough to finagle the valve off. Not sure how much work it saves over taking the cooler completely off, but I haven't tried.