I thought I'd put a little guide to anyone who's thinking of, or needs to, blank off the EGR valve on their GH 2.2 diesel.
After several months of absolutely terrible running on my Mazda 6 (hesitation at light throttle and after overrun, surging, occasional poor starting, sound similar to detonation, dreadful acceleration in warm weather etc etc) I boiled the problem down to the EGR valve. I used OBD Fusion on my iPhone 7+ along with a Carista OBD2 bluetooth module and the extra Mazda pack from OBD Fusion (worth every penny). As the EGR valve opened the issues would begin, but as soon as it was closed running was smooth and powerful. Unfortunately the valve is open a lot as one drives, and that really interferes with the feel of the car.
Now, I couldn't find any guides online for the 2.2D, I couldn't find any images of where the valve is located, but I did manage to find a couple of EGRs for sale on eBay, including the handy item picture.
On the 2.2D it's right at the front of the engine, literally right in front of one's eyes as the bonnet/hood is opened. There's not even a need to remove the engine cover. At the top end of the pipe is the inlet manifold, at the lower end the EGR valve.
Top end at the inlet manifold...
Lower end at the EGR valve...
Now, nobody seems to sell blanks for the 2.2D at all, couldn't find a single occurrence of one anywhere. So I loosened the 12mm nuts and had a look between pipe and inlet manifold. The pipe diameter is around 30mm, so I ordered a pack of ten 40mm x 1.5mm aluminium discs from seller Cimlet on eBay. Within a day and a half I had them. I only needed two of course, but I have eight spare in case anyone needs them.
In actual fact there's no need to plug both ends, but I wanted to make sure the inlet side was thoroughly sealed to avoid any potential leaks (and the consequent heat soak). Here's what to do...
1. Loosen the 12mm nuts on the inlet manifold end of the pipe.
2. Pull the pipe toward you whilst sliding the 40mm disc in between the pipe side and the gasket (leaving the gasket on the inlet side).
3. Tighten up the nuts.
4. Loosen the 12mm nuts on the EGR valve end of the pipe.
5. Pull the pipe toward you whilst sliding the 40mm disc in between the pipe side and the gasket (leaving the gasket on the EGR side).
6. Tighten up the nuts.
That's it! Ideally if you have the necessary equipment it's worth clearing the codes, or more importantly the ECU adaptation which should clear with the codes. Start the engine, let it idle for a few minutes, then head out on the road.
Just something to finish up, if you're wondering just what crud comes through the EGR valve and into the inlet manifold. This was a temporary plate I put in whilst waiting for the discs to arrive, it was in the car for a couple of days (around 550 miles)...
That is literally a 1mm deep, burnt on pile of soot and crud and cr@p. That's what goes into your engine to be burned off. You have clean air in, clean fuel in, clean oil to lubricate - and then the car throws this much filth into the mix. Nice eh?
Anyway, hope that's helped someone.
