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I want to know more about EGR valve CEL

Zap

Zap

Elite Member
So, my Mazdaspeed 6 has often gotten CELs and it also has this inconsistent stutter at WOT in the mid RPM range. The CEL is usually gone by the time it gets near a shop, but today they pulled a "saved code" that said something like:

P041 EGR valve insufficient flow

What does that mean? 😕
 
Sounds like an EGR problem, without being familiar with that specific engine it's tough to say exactly how to fix it but I'd start by removing the EGR and make sure it doesn't have a build up of carbon around the area where the valve seals closed and make sure the valve moves freely, you might be able to clean the valve with some carb cleaner but it's probably not terribly expensive to just replace the valve. Sometimes it helps to start the engine with the valve removed to blow out any carbon that may be in the EGR passage ways, if the passages need a real cleaning though just blowing some exhaust through the system may not really help much. I've seen photos of carbon balls the size of a marble come out of an EGR passage so it's worth trying, as long as you've got the valve off but I wouldn't necessarily expect a miracle. Some carb cleaner and a set of small brushes might be a better way to clean the EGR passages.
 
I did some searching real quick and it looks like the Mazda 6 may have a known issue with the EGR system, the trouble code you posted is missing a digit though so I had a hard time drilling down to find what might specifically help you.
 
Sounds like the differential pressure sensor. Only a open EGR would cause wot issues if its EGR related. If its not seeing a flow, even though there is flow, it will keep opening it more, creating too much flow and causing stumbling under load. The sensor never shows correct flow, so eventually it gives up and report insufficient flow even though there is excessive flow.

Although what the sensor says is irrelevant at wot as it should be unconditionally commanded closed. If it isn't, then the problem could be with the vacuum modulator, the part the ecu actually controls.
 
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Alright, it's happened again and I now have more information. This time the CEL was still on by the time I got to the dealer. I asked for a printout so this time I have the proper code and not just my botched memory of it.

P0401-FF-PCM
P0203-FF-PCM

They said the first one may have caused the second one.

Description - P0401

EGR system insufficient flow detected
Click to expand...

Besides the CEL coming on now and again (and going away by itself) when the weather is cold (and especially cold & wet) I often get a stutter/hesitation in the mid-RPM range (3000-ish) during near WOT conditions. Now that the weather is warm, don't get these problems.

Any ideas?
 
Lots of problems we've seen on the mazdaspeed forums with the EGR valves. Shit just gets clogged. You can get an EGR block off plate, problem solved, valves no longer getting gummed up, etc... and a tune to fix the CELs and different air coming out the back

DSCF0803.jpg
 
I have seen some pretty bad pictures of the intake valves on direct injection engines where the carbon is basically growing on the intake valves. I have considered this mod myself for that reason. I haven't scoped my speed6 to look in there yet though. Basically the going theory is there isn't any fuel to clean the intake valves so the EGR / and to a lesser extent the recirculation valve just let it crust up. So on that note... beyond pulling valves to wire wheel them how would you deal with this? Pull the intake manifold and do what you can with a small wire brush?
 
With our Duramax diesels we use a blocker plate and whats called a "finger stick" which is a little electronic device that you connect into the EGR harness wires and it fools the ECM so no matter what the EGR valve does it just doesnt matter... On my truck I have even gone so far as to remove the EGR cooler and have blocked the up pipe with a custom made plate with a mount that I built myself... I also blocked the intake side with a custom made plate but plan on making a whole new intake pipe so there is even less restriction (stupid EGR valve)... The problem is the EGR valve is part of the intake pipe and serves as the mount for it as well (reason to make a whole new pipe)...

Gassers are bit different but the idea is the same... Do a search for "finger stick" and it might be what you could use after you block it... If you just block it and dont either tune it as suggested or use something like the fingerstick it will most likely re-code...

Read a few of these post it gives some insite to how it works...:thumbsup:

http://www.dieselplace.com/forum/showthread.php?t=425263&highlight=finger+stick
 
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The issue with the speed6 is the ECU tests EGR function through programming, IE "If I open the EGR valve, I should read a rich condition, so lean out the mix (using less fuel)" If that doesn't seem to match, you get the code above. It requires an ECM program to remove it. On the brightside you can still pass inspection with it disabled in Cali...
 
I'm at the dealer right now (they have free WiFi and coffee bar). They are going to do the EGR valve replacement for half the quoted price (which I'm taking their word for), in the $300 range. Figure I'll try this first, and see how it goes.
 
I'm having this problem on my 2001 Accord V6. First tried cleaning the valve, which didnt really look all that bad to begin with. Light came back on a few days later, at which point I replaced the valve, which was $75 and 5 minutes of work. It threw the code again a few weeks later, so now I'm going to have to pull the intake manifold and scrape the gunk from the EGR port. It's a common problem on this engine.

If they want $300 simply to replace the valve, if it's anything like replacing mine, you are getting reamed.
 
Mxylplyx said:
If they want $300 simply to replace the valve, if it's anything like replacing mine, you are getting reamed.
Click to expand...

some are actually difficult to replace due to location. not sure where his is tho, could be worth the 300. i know the older avenger i was looking at was going to cost me about 300 to replace at a shop. i could have done it for a LOT cheaper, but the time involved was considerable just to get parts out of the way.
 
4 MONTH UPDATE: The new EGR valve has fixed probably 90% of the problem. It no longer throws CELs all the time and almost all the 3000-3500RPM hitching is gone. Only time it does that now is under wet conditions, such as right after a car wash, after driving fast through a big puddle or when raining. I'm thinking it may be the CAI inhaling some water.

Thanks for the link. Doesn't look too complex, though I'm not the type to do car wrenching myself other than rotating tires and changing wiper blades. 😳

If it becomes a problem again, I'm liking the idea of an Accessport and an EGR delete/block-off. Get rid of a problem + maybe add 10 more HP. 😛
 
6 MONTH UPDATE: So far so good. Running really well, without throwing any CELs, no hitching in acceleration (except maybe from CAI snorkeling in water). I think it was $300 well spent (speaking as someone who doesn't wrench on his own cars).

Here's a pic of the car on 2/18/12 on the way home from AWOL LAN 19. Just had the car washed the previous morning, but it snowed on the way up. We had all our computers in the trunk, and probably 800+ pounds worth of dudes in the car (well, less because I was taking pic). Rear end was sagging a bit. The wheels are -1" (17") cheap alloys with Blizzaks.
lowriderms6.jpg


Here's a pic from a week ago after an oil/filter service at the Mazda dealer (Rosen Mazda, in Waukegan, IL). If it isn't freezing, they wash your car for you. Combined with $15 off coupons and their "buy 4 get 1 free" offer, ends up being around $20 each time for oil/filter/carwash. Took the pic to remind me what a clean car looks like.
cleanms6.jpg
 
Spoke too soon. Got a CEL today. Well, kind of to be expected because it was pouring rain today. Was doing fine, but then I went WOT and the CAI probably inhaled some water.
 
I spent ~$850 on my EGR valve replacement at the stealership last spring on my 07 speed3 so I think you are getting a pretty good price. One morning CEL came on and it was running like sh*& so I brought it in. Stealership diagnosed EGR so I did some research cause I about fell over when they quoted me ~$850. I know I got a bad price but wasn't sure what else to do.

I don't wrench at all so when I found some threads that said cleaning it was easy I took a look....... Step one remove top mount inter cooler. That's when I said I'm better off just paying for it.

I've been running fine mostly since replacing it but do get an odd reaction if I accelerate too fast when down shifting possibly a gear low or completely at WOT. Not sure if it's the LSD trying to stop my tires from burning up or the governor kicking in. It seems to bog me down if that makes any sense. Not sure how else to describe it.
 
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I'm like Bartman39, on my 08 dodge cummins I did the EGR delete and removed the cooler. IMO the whole EGR thing is one of the worst inventions of all time. An engine's exhaust should never enter the air intake.

At 8k miles(when I removed the EGR) my intake was coated in so much soot it made me want to vomit.

I say get an EGR blocking kit, and when you need to go in for a emissions check then remove the block and let it run stock for a few days.
 
mc866 said:
I spent ~$850 on my EGR valve replacement at the stealership last spring on my 07 speed3 so I think you are getting a pretty good price.
Click to expand...

It is because while it was still under warranty I was complaining about the CEL coming on all the time. Often it would no longer be lit up by the time I got it in. Thus, it can be said that my $300 was a ripoff because it should have been fixed under warranty. :hmm:

mc866 said:
I've been running fine mostly since replacing it but do get an odd reaction if I accelerate too fast when down shifting possibly a gear low or completely at WOT. Not sure if it's the LSD trying to stop my tires from burning up or the governor kicking in. It seems to bog me down if that makes any sense. Not sure how else to describe it.
Click to expand...

Don't know about the more recent ones, but the older Mazdaspeed 3 like your 2007 have power intentionally cut in 1st and 2nd gears.
 
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