Setting TDC in the M42 (Edit: Now a crank/no start issue)

[TobyB]

Check for spark by pulling a plug.

Check for fuel by squirting some starter fluid in there.

Everything else is just... details.

t

[bmwman91]

It is hard to say. Some people have had bad luck with the Bosch one, some have been OK. The funny thing is that Bosch also makes the "genuine" one, but it has a different plug on the end an costs like 3x as much lol. Anyway, if you are getting fuel and/or spark, the CPS is probably fine.

[sedrat]

Ahh maybe I should try an OEM crank sensor. I got the one from bosch and I'm now reading that I don't want to be using that one

[sedrat]

OK, yeah if they are all spraying fuel when cranking then they are not the issue. That also means that your crank position sensor is working since the ECU has to know the engine position before it will fire the injectors.

Are the ignition coils connected to the correct cylinders? See if you can verify that you are getting sparks at all.

For the most part, the engine should at least sputter with any of the other sensors unplugged (AFM, TPS, CLT, ICV, etc). The only one that will totally prevent it if not connected or working is the crank position sensor, which it sounds like works if the ECU was able to fire the injectors.

Could the crank damper or hub be misaligned? If the woodruff key was missing, or the little dowel in the hub, then the timing could end up waaaaay off.

The coils are definitely connected to the correct cylinders. I need to find my spark tester, but that's a good point.

The crank sensor is fresh, so I trust that it's working.

I definitely remember aligning the crank damper to a woodruff key, but I don't recall seeing a dowel. I don't think I ever separated the hub from the crank damper though, but I'll have to check that again when I get back to my car next weekend.

Maybe it's a continuity issue somewhere? The parts themselves might test fine, but maybe the wiring in between is an issue.

[bmwman91]

OK, yeah if they are all spraying fuel when cranking then they are not the issue. That also means that your crank position sensor is working since the ECU has to know the engine position before it will fire the injectors.

Are the ignition coils connected to the correct cylinders? See if you can verify that you are getting sparks at all.

For the most part, the engine should at least sputter with any of the other sensors unplugged (AFM, TPS, CLT, ICV, etc). The only one that will totally prevent it if not connected or working is the crank position sensor, which it sounds like works if the ECU was able to fire the injectors.

Could the crank damper or hub be misaligned? If the woodruff key was missing, or the little dowel in the hub, then the timing could end up waaaaay off.

[sedrat]

Finally found some time to take a look at the injectors. Turns out I have Mustang injectors. All 4 were nearly spotless though and based on the amount of fuel that came out, I definitely have fuel pressure. Resistance was a bit high, but all were consistently only 1 ohm high, so I think they're fine.

I guess my next theory is an intake leak or a bad sensor. Thanks again for the help so far

[bmwman91]

Assuming the fuel pump was left untouched and you did not throw the fuel rail at a brick wall FPR-first, the injectors are really the only area I would be looking next. It does not hurt to replace the fuel filter while you are at it since it's a maintenance item, but it is not likely to be a problem here either.

[sedrat]

A bent valve is super unlikely. The M42 can actually take a pretty good amount of piston-valve interference before permanently damaging anything. If anything, the large increase in wet compression pressure indicates worn rings in #3, but not enough to prevent it from starting.

I thought that was the case, but the uneven compression values scared me a bit. Now that I think about it, I don't think I cleaned the carbon build up on the block, pistons, and the valves evenly. That might be at least part of what I'm seeing.

If you are sure you are getting spark, check for fuel delivery. I had a no-start issue that was due to all 4 injectors being stuck closed. If they were sitting out of the car and dry for a prolonged period, they could have stuck shut (or if they were cleaned and then sat, they can also stick closed).

I haven't checked my injectors yet, thanks for the tip. Besides the fuel pump, is there anything else I should focus on checking?

When you set cylinder #1 to TDC, were the cam lobes for #1 pointing up-and-inward?

Yes, they were.

[bmwman91]

A bent valve is super unlikely. The M42 can actually take a pretty good amount of piston-valve interference before permanently damaging anything. If anything, the large increase in wet compression pressure indicates worn rings in #3, but not enough to prevent it from starting.

If you are sure you are getting spark, check for fuel delivery. I had a no-start issue that was due to all 4 injectors being stuck closed. If they were sitting out of the car and dry for a prolonged period, they could have stuck shut (or if they were cleaned and then sat, they can also stick closed).

When you set cylinder #1 to TDC, were the cam lobes for #1 pointing up-and-inward?

[sedrat]

The other weekend, I finally got to a point where I could attempt to start the car. It cranked, but did not start. Everything in the ignition system is either fresh or within spec, so I don't think that's the issue. It may be an intake leak or the fuel pump, but I haven't had a chance to check those yet.

I did do a compression test and the compression on cylinder 3 is a bit low compared to the others, so maybe this is my problem. Does this imply that I may have bent a valve on the install?

Dry Compression Test (psi):
1) 230
2) 210
3) 150
4) 235

Wet Compression Test (psi):
1) 250
2) 250
3) 210
4) 260

Could this have been caused by the timing being slightly off? I would think not because I would expect them to be consistently off, but I'm no expert.

[sedrat]

Thanks for the dowel trick. Tried it a few times and the stroke was within .5 mm from just using the mark on the oil filter housing (with the cams locked) each time so I'm going to call it good.

[bmwman91]

Sorry if I was not clear, as rogue said, I meant to make your own mark on the timing case with a red sharpie or something like that. The arrow on the oil filter housing is sort of far away, especially if you are trying to line up the notch while the engine is in the car (looking down at a sharp angle makes it a major hassle).

[roguetoaster]

Pretty sure he means that you should set crank TDC via the hash/filter arrow, and then make an auxiliary mark with something like a red paint pen elsewhere so it's easier to see if the crank moved.

[sedrat]

You do not necessarily need the flywheel lock to set the crank to TDC. The last few times, I did it through the spark plug bore using a wooden dowel and pen...if you know the stroke (IIRC 81mm), you can set it pretty accurately. The ideal would be to have 12in / 300mm calipers so that you could just use the depth gauge. Anyway, it is not perfect and you'd at least get within a couple of degrees that way, and the engines ran fine. It just took a few passes of checking and re-checking since the piston movement is really small at the extremes.

The M44 timing case should not affect anything.

Just make sure to make a clear mark between the crank damper and timing covers or something so that you can easily get it back to TDC when setting the cams. You will want to get it all aligned, then turn the engine a few times by hand (CW crank rotation ONLY, never CCW) and then re-check that the cams are still at TDC with the crank. The tensioner piston should also be fully released and pushing on the guide rail. If you want to be REALLY sure, you can check the cams' alignment again after a short drive if it starts and runs well.

Thanks again for being super helpful man. I'm not quite sure what you mean here ("clear mark between the crank damper and timing covers or something") though, would that just be the nick on the trigger wheel and the arrow on the oil filter housing?

I ended up buying the cam lock tool, so I was thinking I'd line up the cams at TDC. Then, I'd measure the stroke between cylinders 1 and 2, rotating cw if necessary to align the crank at tdc. Then, I'd torque down the cam gear bolts and double check the stroke again. Hopefully everything should be aligned after that.

[bmwman91]

You do not necessarily need the flywheel lock to set the crank to TDC. The last few times, I did it through the spark plug bore using a wooden dowel and pen...if you know the stroke (IIRC 81mm), you can set it pretty accurately. The ideal would be to have 12in / 300mm calipers so that you could just use the depth gauge. Anyway, it is not perfect and you'd at least get within a couple of degrees that way, and the engines ran fine. It just took a few passes of checking and re-checking since the piston movement is really small at the extremes.

The M44 timing case should not affect anything.

Just make sure to make a clear mark between the crank damper and timing covers or something so that you can easily get it back to TDC when setting the cams. You will want to get it all aligned, then turn the engine a few times by hand (CW crank rotation ONLY, never CCW) and then re-check that the cams are still at TDC with the crank. The tensioner piston should also be fully released and pushing on the guide rail. If you want to be REALLY sure, you can check the cams' alignment again after a short drive if it starts and runs well.