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Hi all, I hope everyone is doing well and could possibly aid me in my project.
I have a 2006 MazdaSpeed6 that I purchased about 2 years ago. The car had no compression in 2 of the cylinders, some ugly rust on the fender wells, and looked like it lived a long life with un-frequent maintenance.
Upon disassembly I discovered that multiple exhaust valves were burnt, which in turn pretty much destroyed the piston heads.
So i rebuilt the engine from the ground up. Bored the block out, got all new valves put in the head, and balanced the crank, at the local machine shop and had everything decked. Installed Manley H-Beam rods, Manley Platinum Pistons, APR main and head studs, balance shaft delete, Cometic head gasket, Garrett GTX2867r turbo, rebuilt front diff with SP63 caps, Southbend Stage 2 Daily clutch, PERM PCV plate, Corksport catted downpipe,JBR EGR delete, and some other things I'm probably forgetting.
Now that the freshly rebuilt engine is back in the car and in theory ready to go, it cranks but will not start. Initially it would crank but no spark or fuel, I found a bad ground connection which fixed the spark. But it still will not start. I've back probed the CMP sensor (camshaft position) and the CKP sensor (crankshaft position) with my Snap-On Verus scanner and they look to be getting the proper pulse on the oscilloscope. And intermittently when i try to start the car, it will kind of cough like its trying to start but then nothing after that, just dead cranking. I bought a physical copy of both the Mazda wiring schematic book, and the Mazda workshop manual, ran through all the continuity tests and other trouble shooting guides in the workshop manual, but to no avail.

I have noticed that it doesn't always do the 'cough' when cranking. Sometimes it will just crank and crank with no signs of life, other times it sounds like it wants to go. And the times it doesn't try to start I've noticed that the RPM signal on my scanner will stay at 0 while cranking and randomly jump to 115RPM for a moment, and the times it does try to start the RPM signal goes right to 115RPM while cranking, I don't think I've ever seen a different value on that PID either, its either 0 or 115 (should there be a little bit of variance in that value?). Also on the times it does try to start, in the scanner you can see the INJ PW jump up to 7-15ms but stays there even when i stop cranking.

I should mention, the car WILL try to start with a shot of ether..

I've pulled the plugs out (they were brand new, but when i took them out they were pretty black from the car trying to start) cleaned them up, double checked the gap, and reinstalled them.
I've also double checked the position of the CKP sensor per instruction of the workshop manual.

Any advice is greatly appreciated..
Thanks, Brad Z

584 Posts
It seems your thread have been "buried". I hope someone can give any advice on what to check next.

I am assuming that you have fuel and fuel pump is running good without any blockage all throughout the line to the filter and up to the engine.
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