EGR blockage?

[hpmaxim]

I don't know why my car hates me. Since I got the car, I found: a leaking fuel tank, which after I replaced, seems to starve the fuel pump for fuel when it gets below 3 gallons in the tank when turning right, then I had non-functioning evap emissions valve. Then (and admittedly I may have hastened this one), I had the car go suicidal after misfiring and blow up the pre-cat, then the downpipe flange rusted off, and now... I'm getting P0401, which is supposed to be low EGR flow. I have not noticed any driveability issues and I haven't noticed any pinging.

I presume that if I'm getting the DTC code its probably real, and I need to clean or replace the EGR valve? Is cleaning usually effective? What is this "Canadian" EGR valve I hear about?

 

[jeffwalbridge40]

The Canadian egr has an inlet for coolant. As for cleaning the current egr, it is usually effective. Though on one of my Protege's, (I've had 5), the egr was completely seized up. It should only take a moment after pulling it to be able to make the call if cleaning is the right path.

Sent from my VS986 using Tapatalk

 

[jeffwalbridge40]

I should also add that with all of these emissions systems failing, it seems to me you should be looking for the root of the problem before taking any other steps to alleviate the symptoms.

Sent from my VS986 using Tapatalk

 

[hpmaxim]

I think the EVAP thing just froze from sitting for an extended period of time. I have no idea why the tank was leaking, but it was and I doubt its related to anything. I'm sure the fuel starvation is related to the design of the new tank, can't imagine what else it could possibly be. The misfiring WAS caused by a batch of bad gas, and the downpipe flange was just rust. It's possible that the clogged EGR is a side effect of running rich which was a side effect of the misfire... I have no idea, but I do not think there is a "root problem" here.

Is the Canadian EGR valve available in the US? If it is, should I use it? Is there a way to test the EGR valve once I take it off and attempt to clean it? I've seen mention of an "EGR control solenoid" what does that do and could it be causing the P0401?

 

[jeffwalbridge40]

Well a the leaking tank aside, all of your problems seem to be fuel related, and I do not know the order or timeframe of the issues. You can get the Canadian EGR online, but I honestly do not see any real benefits from using that as opposed to the stock model. The EGR control solenoid is the actual "valve" portion that the computer tells to open or close.

Sent from my VS986 using Tapatalk

 

[jeffwalbridge40]

Once you remove the EGR valve, there are 4 screws on the top to remove. Be careful​, they seem to be made of very soft metal. I've​ had to notch several of them... Anyway once you get those removed there is a piston to push on, if that moves pretty much at all, go ahead and clean it. If not go to the local junk yard, pull one off any 2.0 Mazda, take it home and spray the s*** out of it with carb cleaner, and use pipe cleaners to scrub the carbon off. Should cost less than $40 including a few cans of carb cleaner.

Sent from my VS986 using Tapatalk

 

[hpmaxim]

I had got the car from my father, discovered the leaking fuel tank and replaced it with a new aftermarket unit. The car sat for 2 years. Shortly after I started driving it, I got an EVAP code and diagnosed it as a stuck solenoid (can't remember which one, it was near the back of the car). I was able to get it working again by cleaning it. I had no more emissions related trouble until I put 5 gallons of bad gas into the car. The car started misfiring, and then I was told that the ECU enriched the mixture to compensate for the misfire (no idea why it would do that, but I was told by multiple people that's what it did). The enriched mixture along with the misfires damaged the pre-cat. The flange on my downpipe then rusted off. I replaced the downpipe and cat, and its been somewhere between 500 and 1000 miles since I replaced the cat/downpipe and now the P0401 gets thrown. Like I said, it might be related to the bad gas/rich running... but I'm 100% sure that was related to bad gas which is now out of the system.

The fuel starvation is very obvious when it happens, and it only happens when you are turning right with little fuel in it. It's hard for me to imagine its not related to the internal design of the fuel tank.

Not sure what you mean by the the actual valve portion that tells the computer to open or close. A solenoid would open or close something, not provide a signal to the computer to open or close something, its not a sensor. It seems like its a vacuum switching valve, which would be perfectly normal -- but I don't see a vacuum control on the picture of a new EGR valve at Rock Auto, and what does that 6 pin connector do? I was assuming the the connector was actuating a solenoid on the valve which pushes on the piston, because I don't see a vacuum control on the valve. Of course, I also don't see the exhaust pipe leading into the valve (which I've been told sometimes gets clogged causing the problem).

 

[jeffwalbridge40]

The EGR valve is mounted on the intake, just below the throttle body. There is a pipe coming from the exhaust to the intake which feeds directly to the EGR valve. The two holes you see are inlet and outlet, as the point of the EGR is to control the recirculation of exhaust gas into the intake. The 6 pin is connected to the actuator which activates the EGR control solenoid, which opens the EGR valve. Sorry for the confusion on the control solenoid part, my phone likes to randomly delete s*** as I type it, or add random sentences as I'm trying to delete.

Sent from my VS986 using Tapatalk

 

[pcb]

The EGR is a step motor with three or four degrees of open to adjust the amount of exhaust gas flow.



The EGR's on our car became a problem shortly after the vehicle hit the market.
The problem was worse in Canada due to the overall cooler climate so the redesigned EGR was first introduced here, hence the name "Canadian".
People from the US were phoning Canadian dealerships hoping to buy one and have it shipped.

The Canadian EGR (the one with coolant lines) isn't listed for the P5 at Rock Auto... It's under the regular 2.0 l protg listings. It's a bit of work to install due to the coolant and vent lines.

If this is the first time your EGR has caused you problems then a simple cleaning should be adequate and last a good long while. Some guys have to clean theirs every year and turns into a PITA.
I figure if your car is burning oil as so many of our engines do, the exhaust is dirtier and more inclined to foul your EGR.

 

[hpmaxim]

Well, I was in for a pleasant surprise, followed by an unpleasant surprise followed by a... huh?!

Pleasant surprise: it was WAY easier to remove than I expected. Literally, I just disconnected the battery, removed the bar, removed the battery, loosened the hose clamps on the intake tube, pulled out the little hose and the metal bracket out of the tube, pulled the tube out, and then just got in there with a 1/4" socket wrench with 12mm, and was able to get it off pretty darn quick. Got the gasket too without much effort.

Unpleasant surprise: None of the four screws wanted to come out with a screwdriver. I was able to grab them with a visegrip, and twist them. Two of them came out, two of them snapped. Once I got the motor off the valve (which required more effort than I expected), I was unable to remove the two that snapped. One snapped with some thread left, the other snapped flush to the tube. The one that had stuff sticking out I tried grabbing with the visegrip again, and it snapped inside the tube. I drilled that one out.

Huh: The inside was dirty, but I expected it to be dirtier than it was. I was able to clean it some, but the valve seemed to open and close pretty easily, both before and after. It's hard for me to imagine that was the problem.

I also tried sticking a screwdriver into the ports on the manifold to try to see if I hit anything, but they felt relatively unobstructed.

I measured the four resistances (as described in the page above) and all rang out at between 22.5 and 23.5 ohms, so they are all good. I do wonder if that's more of a solenoid-ish thing than a motor. Could I simply put 12V from C to E (or A) or from D to F (or B) to test it off the car? Or should I just get new screws and re-install and see if it goes away.

If this isn't the problem, what's the next thing to check? I assume some sort of blockage in the tube from the exhaust manifold or clean the intake manifold with seafoam or something?

 

[pcb]

... I do wonder if that's more of a solenoid-ish thing than a motor. Could I simply put 12V from C to E (or A) or from D to F (or B) to test it off the car?

Yes... Test it...

It's a solenoid thing that moves in a straight line, but instead of being "open" or "closed",.. It's got a few stages of openedness...

You should be able to see how far it opens...

(That's my guess anyway... Mine's working fine... I'm not taking mine apart till I have to...)

 

[mattzerstoren]

I'm also interested in cleaning my EGR valve, have a bit of a rough idle at low RPMs. When researching other threads about this, I read it's also a good idea to clean the IAC valve as well?

 

[pcb]

As soon as my idle starts to stumble, I put 1/3-1/2 can up the brake booster and it settles right down...

I haven't needed to do that for quite some time now because I put it in my gas at every fill...

 

[pcb]

You can clean your EGR and IAC with seafoam... Or brake cleaner... Or acetone..

 

[hpmaxim]

Well, I put 12V on C and D, and grounded the other pins (one at a time), in different orders, and sometimes tried reversing polarity. It pulled .5A (which is about right), and you'd get a spark when hooking up to the terminal. I'd hear an occasional "thunk", but I didn't see the piece actually move. It makes me wonder if that piece is what's stuck. If so, the only two things I can think to try are to grab and pull it with pliers, or to crank up the voltage on the solenoid and try to free it that way. I'm pretty sure I can go up 70V (although I'm scared of dealing with anything above 36V or so). Or... replace it.

Okay, never mind... I grabbed it with a pliers and pulled it out. I then repeated what I did before and found that it'd thunk and give me a little bit of movement and then not do anything after that, until I switched to powering a different coil. So, I'd say it actually is basically behaving like a stepper motor.

 

[pcb]

Okay, never mind... I grabbed it with a pliers and pulled it out. I then repeated what I did before and found that it'd thunk and give me a little bit of movement and then not do anything after that, until I switched to powering a different coil. So, I'd say it actually is basically behaving like a stepper motor.

Make sure it will pull itself closed and will go to various points of openedness... You don't want it getting stuck in any position...

 

[hpmaxim]

Easier said than done. I'm still not sure exactly how it works. I presume you need to operate the windings in a particular sequence to close it or open it. Each movement is a nearly imperceptible amount, you'd probably have to go through the sequence 100 times to fully close or fully open it. Which also means, there is far more than 4 settings. I think its unlikely to get stuck in a particular spot though, I believe the motor is working correctly and the piece slid in and out fairly consistently. It took more force than I was expecting, but it moved smoothly.

 

[pcb]

Easier said than done. I'm still not sure exactly how it works...

Yea me either... I'm just going by this...




I guess if it appears functional you could just reinstall it...

If it throws another code you can use the SST to fix it...

 

[hpmaxim]

Yes, I think the diagram is correct, but basically the way it works is C and D are always powered: A, B, E, and F are grounded to actuate. But you are going through a sequence, so its like: B, A, F, E, B, A, F, E, B, A F, E etc, to go one direction and then it would be E F A B E F A B E F A B to go the other, but there are 24 possible sequences and I don't know which is right.

Oddly, I've found a couple really good deals on the Canadian EGR valve (new), so I'm just going to buy one. I presume you can just plug the hoses and not worry about them, or hook it up as shown.

I do like your SST.

 

[pcb]

Oddly, I've found a couple really good deals on the Canadian EGR valve (new), so I'm just going to buy one. I presume you can just plug the hoses and not worry about them, or hook it up as shown...

I don't think that's a good idea... It's the coolant running through it that makes it reliable.
If they're not hooked up it may be more inclined to fail ??

You're probably better off with a normal EGR than a "Canadian" one not hooked up.
Normal ones are cheaper too.