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Engine/Transmission/Powertrain/Exhaust / EGR and how it works
« Last Post by SteveAWD on August 23, 2023, 10:08:08 am »After all the problems I've had, and still having, I thought I'd have a try on here for any "expert" advice that may be lurking on here. This may be a long one!
My CX5 is a 2013 AWD auto sport-nav and we have only had it since last March. Since then it went back to the dealer for a new turbo which they paid for and for a short while it was ok. Then there's been this sort of misfire on tick-over when cold and in "D" which goes away once the engine has warmed up. Its fine when in P. No codes showing.
Eventually I booked it in with a local mechanic who did a de-carbon of the EGR, cooler and inlet manifold which the dealer paid £500 towards. He found a blanking plate in front of the EGR which he removed and gave to me when I collected the car.
Then, shortly after that I did a "sniff" test which proved that the head gasket was leaking. It wasn't very bad but was using a small amount of coolant over a week and was slowly filling the over-flow tank.
After spending £750 on a de-carbon I thought I may as well have a go myself and change the head gasket. Not an easy job but I did it. I totally re-conned the head, including all the valves/seals and had the head re-surfaced, plus a new exhaust camshaft/followers.
I still had the problem, and also have a fair bit of smoke and smell from the exhaust so I got a friendly MOT station to test the emissions and perform a compression test and the outcome from that was that the compressions were good but it would not pass an MOT. Still no codes showing.
After all this the engine has performed well but the "missing" on tick-over when cold is still there so I thought I'd experiment a bit by making up some EGR blanking plates myself to see what would happen. After fitting them the "missing" went away. So did the smoke.
Then after a bit of thought I decided to change both EGRs but that didn't cure it. Then I replaced the blanking plate to the COOLER EGR and the problem went away. So did the smoke.
Now I'm finding this a bit confusing, especially after finding an online document from Mazda on the way these EGRs work.
Have a look and see what you think. I've changed quite a few sensors so far but it would seam I still have a lot to change before I get a positive result!
https://www.mazdabg.com/ftp-uploads/Mazda/6/GJ%202.2%20D/EGR%20CONTROL%20%5BSKYACTIV-D%202.2%5D.pdf
My CX5 is a 2013 AWD auto sport-nav and we have only had it since last March. Since then it went back to the dealer for a new turbo which they paid for and for a short while it was ok. Then there's been this sort of misfire on tick-over when cold and in "D" which goes away once the engine has warmed up. Its fine when in P. No codes showing.
Eventually I booked it in with a local mechanic who did a de-carbon of the EGR, cooler and inlet manifold which the dealer paid £500 towards. He found a blanking plate in front of the EGR which he removed and gave to me when I collected the car.
Then, shortly after that I did a "sniff" test which proved that the head gasket was leaking. It wasn't very bad but was using a small amount of coolant over a week and was slowly filling the over-flow tank.
After spending £750 on a de-carbon I thought I may as well have a go myself and change the head gasket. Not an easy job but I did it. I totally re-conned the head, including all the valves/seals and had the head re-surfaced, plus a new exhaust camshaft/followers.
I still had the problem, and also have a fair bit of smoke and smell from the exhaust so I got a friendly MOT station to test the emissions and perform a compression test and the outcome from that was that the compressions were good but it would not pass an MOT. Still no codes showing.
After all this the engine has performed well but the "missing" on tick-over when cold is still there so I thought I'd experiment a bit by making up some EGR blanking plates myself to see what would happen. After fitting them the "missing" went away. So did the smoke.
Then after a bit of thought I decided to change both EGRs but that didn't cure it. Then I replaced the blanking plate to the COOLER EGR and the problem went away. So did the smoke.
Now I'm finding this a bit confusing, especially after finding an online document from Mazda on the way these EGRs work.
Have a look and see what you think. I've changed quite a few sensors so far but it would seam I still have a lot to change before I get a positive result!
https://www.mazdabg.com/ftp-uploads/Mazda/6/GJ%202.2%20D/EGR%20CONTROL%20%5BSKYACTIV-D%202.2%5D.pdf