Cylinder Misfire after lower chain tensioner change

[Beer+Oversteer]

The car is an m52 swapped 318i. The car is converted to obd1 and will not register any codes. The car was running fine until I borrowed the lower chain tensioner for another car for a few days. I put a spare in with a new spring and started it up, car started with misfire. This could just be coincidence. The car has been sitting for a while before this.

I played the coil pack unplug game and found no change when I unplugged coil pack for cylinder 2. The rest of the coils made it run worse when unplugged. Cyl 2 was dead, not firing at all.
First things I tried:
Swapping coil packs, no change
New spark plug
ANOTHER plug with different prongs
Entire ignition harness from a working car
Replaced plugs for all cylinders

The last thing I tried was swapping the injector for 1 and 2, cyl 2 still wasn't firing.

Any suggestions? I don't have a compression tester. Does this sound like a timing issue? It starts and runs just like before without hesitation, it just is down a cylinder. It doesn't stall or anything.

[Eric93se]

Shouldn't have anything to do with the chain tensioner.

So you've eliminated a lot of possibilities, last would likely be the DME. You would have to open it up all the way and inspect for damage and white oxide (also bad solder joints as found in another thread). If you find any oxide, get a can of Deoxit 5% and hose it down, scrub the whole boards with an old toothbrush. Let it completely dry, 24hrs in warm/dry place before assembling.

Actually one other possibility would be the connector on the injector, you would have to expose the wiring in the rail and use needle nose pliers to gently push the connector in, it's happened before.

[Beer+Oversteer]

Shouldn't have anything to do with the chain tensioner.

So you've eliminated a lot of possibilities, last would likely be the DME. You would have to open it up all the way and inspect for damage and white oxide (also bad solder joints as found in another thread). If you find any oxide, get a can of Deoxit 5% and hose it down, scrub the whole boards with an old toothbrush. Let it completely dry, 24hrs in warm/dry place before assembling.

Actually one other possibility would be the connector on the injector, you would have to expose the wiring in the rail and use needle nose pliers to gently push the connector in, it's happened before.

Here's an additional fuck up. I installed the ground for cyl 1 on TOP of the coil pack by accident. I had only ran the car for about 20 seconds before I noticed and fixed it. Could that have shorted the DME?

[bluptgm3]

I would do a compression check, then go from there. If you have good compression then investigate injector wiring and spark plug wiring and go from there to DME.


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[eliseogonzalez]

Doubt this has anything to do with it, top or bottom of coil pack is ground regardless, mine are all grounded on top of coil packs, however my car runs like crap right now so maybe that's part of my problem.

[Eric93se]

Yeah your ok with the grounding mistake.

Can't recall the specifics but when cylinder 1 goes down I think there is something to do with oil pressure and the top chain tensioner leaking, but you would have to read up on it.

[Beer+Oversteer]

Alright, I took out the DME to check for any damage or signs of water, and it was 100% dry and no signs of corrosion or shortage on any pins both on the connector and ecu. I don't have a spare ECU that will work with this car to check. How should I go about checking for injector wiring or plug being faulty for Cyl 2?

[spyderg0d]

Check for the same things as anyone else. Cam and crank sensors, coils, fuel pressure. Might just need a hard reset to wipe the maps from when it had the "bad" tensioner.

[Eric93se]

For the injector wiring there is the rail that holds all the wires, the top can be removed but carefully the plastic clips can break.

[66 6]

If you replaced the cam chain tensioner you must have unplugged/removed the crank sensor? so have you checked it as well as the teeth on the harmonic dampner?

[Beer+Oversteer]

If you replaced the cam chain tensioner you must have unplugged/removed the crank sensor? so have you checked it as well as the teeth on the harmonic dampner?

I replaced the lower chain tensioner, which is just bolted into the head with a 32mm tensioner. Nothing needs to be unplugged.