Hey all.
My 2004 mazda 3 2.3 liter was burning oil and missing on the #4 cylinder which also had next to no compression. I tore it down and discovered I had a broken exhaust valve on cylender 4. I ordered a remanufactured head with cams. Upon reciving the head I decided to check the piston rings before putting it back togeter and discovered all 4 oil rings were stuck. So I re-rung all 4 pistons and reassembled the motor with the new head and all the timimg tools. When all assembled the engine would not start. It only sparks once when the key is first turned then no spark.

After not starting I checked and double checked the engine timing with the camshaft and crankshaft timing tools in place and checed all the wiring harrness connections and still no start. After alot of head scratching and checking I realized the new cam had a different camshaft position sensor gear. I was completly realived at this point.

I tore every thing back down and switched the intake cam to the original from my engine and put every thing back together expecting it to fire right up...but it didn't. Same problem as before.

The only thing left I could think of that I had not checked was the camshaft positon sensor as I had replaced the crankshaft position sensor upon rebuild of motor. Replaced cam sensor and still no start.

The engine will spark once when turning over and then nothing. The engine does try to run when it gets that one spark.

At this point I am completly defeted and frustrated and need to get this car runnung. Any help would be great!!

 

I wish I could help. I am stumped as well.

I still think it has to do with the timing. Are you sure you got every little step right?

It reminds me of a friend who had a Jaguar engine rebuilt and did the final assembly in his garage. We put the engine in and started it. It misfired horribly and it wouldn't run. In the end it turned out that the shop turned the drive shaft for the distributor by 180 degrees. therefore the rotor pointed to the opposite lead. Rerouting the ignition wires fixed it.
Recheck your steps one more time. I.E. you must turn the engine in the running direction to find TDC, don't correct by turning the crankshaft back. Make sure #1 is on the compression stroke etc.
Hopefully someone else has a better idea.

 

U got the wrong head. There are two different setups for Cali and federal emissions cars. The dealer got u the wrong one. The difference is the camshafts. If u have the old head then check the tone rings and compare to the new head.

 

What are the tone rings? I have my original intake cam in the head and the new exhaust cam but could put original in. I also still have old head but don't know what tone rings are.

 

It is the ring with the notches that the sensor uses to signal the position. The one in this picture happens to be a crankshaft tone ring:


I am glad that racer662009 is active!

 

I have my original camshaft with the original "tone ring" or camshaft position sensor gear so I don't think that or the head are my problem. Upon further investigation I have noticed that every time we taker the valve cover off the intake cam timing is retarded a degree or two. Now starting to think the problem is in the variable valve timing phaser gear?

 

Now noticing that with a wrench on the hex portion of the intake cam we can advance or retard valve timing a degree or two without the vvt sprocket moving at all.?

 

Times like this, and I have been there several times in my life, sit back, and review what you've done. I'm sure you've done this, but stop, regroup, and recheck it again. Check valve timming first. Set numbre one cylinder to TDC compression, route wires in proper firing order to the cylinders. Pull both CPS sensors. With an ohmeter these should read around 1k ohm, with that hold the end next to something metal, these sensors have a permenate magnet that needs to be sure they are still magnetic. Reinstall if good, then if no start you will at least have verified the prior.

What was refernced to the refluctor ring/gear/tone ring is this. Those are specific to what the pcm looks at. I.E. if you have a 22 gear ring on a setup that looks at a 24 gear ring, the actual speed of the cam/crank will show faster to the pcm than it actually is. I know you posted you put the original back on.