OBD-I s52, has spark and fuel, but won't start

[JGood]

What harmonic balancer are you using? Stock OBD1 Crank position sensor?


So you are using the 17.5 Injectors?
OBD1 Fuel Rail?

And the intake question of course?

The same parts that were on the car when it ran fine. Nothing was touched.

[atldohc]

Ok anybody reading should disregard my last post then. I did use the holding tools when I replaced my vanos seals and from what I remembered the ends were squared, and I also noticed a little play in the sides of the holding tool, but I may have been mistaken. Anyways I would suspect the harness/wiring if it's the only thing that changed. You may need to bust out some wiring diagrams. Also never tried this on the s52, but on many cars you can simply spray carb cleaner with injectors disconnected through a vac hose and the car will run fine. I've done this on A car before that had fuel pumping out the feed line yet wouldn't start, in the end needing a new fuel pump. I can't recall if you tested the pressure or volume yet.

[Good & Tight]

You guys are over thinking, the engine ran before and was untouched. My engine had the same exact symptoms, back firing and all and it was the main relay.
Not sure if it was mentioned, fuel feed line connected to the front of the rail right.

[jrdeamicis]

I am not saying that the O2 will prevent it from starting, but you need to know what helps and what doesn't.

You have 2 parts of a 3 part equation.

What harmonic balancer are you using? Stock OBD1 Crank position sensor?


So you are using the 17.5 Injectors?
OBD1 Fuel Rail?

And the intake question of course?

[JGood]

So your getting spark? And fuel? Well that just leaves ... Air!

Give it a solid O2 sensor and unplug the MAF. Reverse and repeat.

Already tried a different MAF, and tried leaving it unplugged altogether. No way an O2 will prevent it from starting. Hell, my car ran better without the O2.

[jrdeamicis]

So your getting spark? And fuel? Well that just leaves ... Air!

Give it a solid O2 sensor and unplug the MAF. Reverse and repeat.


So you converted it to run OBD1? using an OBD2 Intake or OBD1?

When you say back firing its backfiring into the intake?

[JGood]

Not saying this is the cause, bc it sounds unlikely to me as well, but check your valve timing. All you have to do is pull your valve cover and see if the two squares on the cams near the firewall are level after lining up the crank pulley mark to the one on the timing cover (tdc). You can find more info on how tos on this on the pelican, dr vanos, and beisan systems websites. Again probably not the cause, but it's good to eliminate possibilities

Since the motor hasn't been touched since it last ran, it would be impossible for it to change. It's not something that can "slip".

Also, if the squares on the cams are level, your engine is nowhere near timed right. The top side of those squares are not what is used for timing. They are not parallel when the engine is timed correctly, as the angles of the "squares" on the cams are not 90 degrees, they are more of a parallelogram. The side of the squares are used for timing (perpendicular to the head surface), and you need the cam block tools to check this.


Example:

[atldohc]

Not saying this is the cause, bc it sounds unlikely to me as well, but check your valve timing. All you have to do is pull your valve cover and see if the two squares on the cams near the firewall are level after lining up the crank pulley mark to the one on the timing cover (tdc). You can find more info on how tos on this on the pelican, dr vanos, and beisan systems websites. Again probably not the cause, but it's good to eliminate possibilities

[JGood]

Do you have the earth strap that is located underneath the engine cover?

http://www.realoem.com/bmw/showparts...08&hg=11&fg=15

There's 2 coil pack ground wires, the ground wire coming out of the front of the fuel injection harness, the main engine ground to the chassis, and several grounds near the DME. All have been triple checked.

[sushipower]

Do you have the earth strap that is located underneath the engine cover?

http://www.realoem.com/bmw/showparts...08&hg=11&fg=15

[JGood]

Are you still using the plugs that were wet?
What brand are they? If they are Bosch, toss them.
If you have not changed plugs, try heating the electrodes with a propane torch for around 15 seconds each.



I'm down to either plugs or the harness adapter and/or a timing problem.

m

They are NGK. Alright, I'll try new plugs, check the relay's, and try a new cam sensor (it's going to need one even if that's not why it won't start...)

[7pilot]

Are you still using the plugs that were wet?
What brand are they? If they are Bosch, toss them.
If you have not changed plugs, try heating the electrodes with a propane torch for around 15 seconds each.



I'm down to either plugs or the harness adapter and/or a timing problem.

m

[JGood]

I bet you don't have fuel. Unless you have actually seen fuel coming out of the injectors, you haven't got it. I've seen plugs come out looking wet with no fuel on them.

Is the ECU grounded properly? If it's not bracketed in, run a ground wire to the case.

They came out smelling like fuel, were very wet (you could touch them and get liquid on your finger that smelled just like gas), and there is just a general strong smell of fuel while cranking the engine over. Not to mention, backfiring is still firing, and you can't have fire without fuel, right? I'm not saying the injectors are letting fuel in the way it should be during the cylinder combustion cycle, but I'm 99.999% sure that fuel is going into the combustion chamber at some point while cranking.

We had it grounded. My m50e30 has the ecu laying in the glovebox, not touching anything metal, and runs great. We also tried that ECU, no luck.

[JGood]

Fuel is good. not verified, but I do have pressure at the rail and wet plugs
Ignition is there but inhibited by either valve timing/sealing or electronic issue. (backfire )
Air is available. check
Block is grounded. check
head is grounded. check
Ign coils are grounded in two spots on the Cam case. check

Try a 413 red label perhaps? check (post #1)


m

Maybe there is a small German man inside these engines, who is the brains behind the operation, and he is just napping in this particular engine? I'll give him a few more days of sleep and try to wake him up this weekend.

[JGood]

if your getting spark and fuel then the cps isnt reading when to fire right. could be the pins on the flywheel to tell it when to fire?

There are no pins on the flywheel, it reads off the front crank wheel teeth. Neither the CPS or crank wheel was touched while it was moved from the old car to the new car. The CPS read 540 ohms, so in theory should be functioning (although could possibly still be bad).