M42 Full Rebuild now won't start

[theTBLACK]

And a side question - would a bad crank position sensor or cam position sensor cause a no start? Mine were replaced, but I'm not sure if they are faulty - or how to test/what signs would be apparent if they were working.

[theTBLACK]

Yeah, you could have gotten the crank 180 degrees off. IIRC the stock flywheel has 2 holes for the alignment dowel, so it is possible to mix things up that way. Pull spark plugs 1 & 2 with the engine at TDC and make sure that piston 1 is above 2.

So should I just pull the plugs, and put a wooden dowel in 1 and 2 and make sure 2 is higher? (With tick marks and front lobes at TDC)

[bmwman91]

The cams are in the same position as the diagram you referred to - Cylinder 1 TDC, and the tick mark on both sprockets are pointing straight up, like the photo posted previously.

Is there a way that the cam lobes and ticks are in the right place, but the piston at BDC?

Yeah, you could have gotten the crank 180 degrees off. IIRC the stock flywheel has 2 holes for the alignment dowel, so it is possible to mix things up that way. Pull spark plugs 1 & 2 with the engine at TDC and make sure that piston 1 is above 2.

[theTBLACK]

Are the cams AND crank in the TDC position together? The cam lobes for cylinder #1 (front-most one) should be pointing up and in when piston #1 is at the top. I am guessing that maybe piston #1 is at BDC when the cams are at TDC.

Check out the diagram in my other thread (last image in the first post). It spells things out very clearly. You want everything positioned shown to the left of the image for Cylinder 1 TDC for Power Stroke.
http://www.r3vlimited.com/board/showthread.php?t=374858

The cams are in the same position as the diagram you referred to - Cylinder 1 TDC, and the tick mark on both sprockets are pointing straight up, like the photo posted previously.

Is there a way that the cam lobes and ticks are in the right place, but the piston at BDC?

[bmwman91]

Are the cams AND crank in the TDC position together? The cam lobes for cylinder #1 (front-most one) should be pointing up and in when piston #1 is at the top. I am guessing that maybe piston #1 is at BDC when the cams are at TDC.

Check out the diagram in my other thread (last image in the first post). It spells things out very clearly. You want everything positioned shown to the left of the image for Cylinder 1 TDC for Power Stroke.

http://www.r3vlimited.com/board/showthread.php?t=374858

[theTBLACK]

Yep. Verify that with the engine at TDC and the cams in their TDC position, the timing marks on the sprockets are in this pictured position and the trigger dowels are present, intact and at the ~7o'clock position.



If your fuel injectors are firing and your spark is strong, it's down to timing. Something isn't occurring when it should, we just have to find what and why.

Mine looks exactly like that first photo. Tick marks straight up and down.

[varg]

The sprockets as in the two wheels with the surrounding chain at the front of the motor? How would I go about doing so, and how will I know they are in the right position?

Yep. Verify that with the engine at TDC and the cams in their TDC position, the timing marks on the sprockets are in this pictured position and the trigger dowels are present, intact and at the ~7o'clock position.



If your fuel injectors are firing and your spark is strong, it's down to timing. Something isn't occurring when it should, we just have to find what and why. While you're at it, you may want to also verify the crank pulley's position with the old "long wooden dowel down the #1 spark plug hole" trick by checking that the timing mark on the pulley and timing case are aligned when the TDC position is indicated by the movement of the dowel. I'm not trying to imply that you don't know how to do this stuff, just putting out there what I've seen happen to others.

[theTBLACK]

Verify that not only is valve timing correct (I read you have done that part), but that the sprockets are oriented correctly with relation to the cams.

The sprockets as in the two wheels with the surrounding chain at the front of the motor? How would I go about doing so, and how will I know they are in the right position?

[varg]

Verify that not only is valve timing correct (I read you have done that part), but that the sprockets are oriented correctly with relation to the cams.

[theTBLACK]

Unplugged the afm harness and crank it. See if that makes any difference in cranking.

I tried this - didn't make a difference.

[theTBLACK]

Not always. If you are one tooth off it'll still run but then again if you are more than that you run the risk of hitting valves and pistons.

Check the easy stuff first and then report back. Im sure it is something stupid.

When you key on engine off before you crank is the CEL illuminated?

CEL is illuminated at this point.

[theTBLACK]

Here is what I did today.

1. I noticed the spark plugs were dry - so I double checked the fuel lines. They were on backwards this whole damn time, so I swapped them. Then they were wet. Fixed that issue

2. I checked for spark and I'm getting it.

3. Checked compression. Good on all cylinders.

4. Stomp test again - no codes.

5. Tried to different DME. No difference.

Any ideas where to look or diagnose next?

[varg]

Have you cranked with the fuel rail out (injectors attached) and verified that they are firing?

The injectors get +12V from the main relay via the red/white wire coming from Pin 87, leading to the harness box under the intake manifold. Verify +12V is present here when cranking. The ECU grounds the injectors in pairs (1&3, 2&4) to fire them. If you haven't, check continuity of the wires between the injectors and the ECU (pins 3 and 32)

[theTBLACK]

Back at it again - cranking and wants to fire with fluid but no dice. Also, the plugs are dry. Probably injector issue. What would cause that? I've tried different DME.

[Balleristic31]

Any chance you swapped the coolant temp sensor plugs around? Or the coolant temp sensor is bad?

I had an issue similar to your's on an m20 car that ended up being a coolant temp sensor being faulty causing a no start even with all the other proper conditions (fuel, spark, etc..)