M50 Motor Swap Running Rough.

[RedStar240]

I have been driving my M50 swap for about two months and it appears that one cylinder is not firing. I have done Plugs fixed the small vacuum leak. I tested the coils and there are no problems with the coils how ever plug 4 doesn't work. I was hoping someone has experienced this problem and maybe help me with the trouble shooting. Is it possible the fuel injectors? causing the single at plug four to cut off?

[justin_l_]

Do a compression test? Maybe a dead cylinder...

[jrdeamicis]

Does it have spark on #4?

[e30s50dan]

Harbor frieght sells a spark plug tester that cost 5 buck and is a life saver plug your coil in and to the plug. In line light will help determine if you have a bad coil. I had two. Fine at idle but as soon as you r3v the engine the light went out. Great tool. And get your self a infared temp gun and point it at each exhaust Also at HF for around 30$. Good luck

[RedStar240]

Does it have spark on #4?

Nope.

[RedStar240]

Harbor frieght sells a spark plug tester that cost 5 buck and is a life saver plug your coil in and to the plug. In line light will help determine if you have a bad coil. I had two. Fine at idle but as soon as you r3v the engine the light went out. Great tool. And get your self a infared temp gun and point it at each exhaust Also at HF for around 30$. Good luck

Well the reason i have determined that coil four was not bad is that i swapped coils around and they all work just plug for cylinder # four doest seem to work i haven't had time or good weather to look at the wiring but thats my next step i was just seeing if anyone had problems similar?

Another thing i was considering was an injector possibly? Idk if an injector isn't working maybe the cylinder doesn't fire??

[atldohc]

how does plug 4 compare to the others when you pull them? if cyl 4 still has a problem after swapping coils then you need to start checking other things. possibilities include wiring from coil plug to dme, low compression on cyl 4 as justin said, an injector or injector wiring problem, or bad dme. is plug 4 wet with fuel when you pull it? if so its likely the injector is working. but its still possible the injector is just leaking, partially clogged etc. if i was you i would swap injectors next and see if the problem follows that injector, along with a compression test

*edit- i just saw you said there was no spark, so also check continuity from the coil plug pins to dme

[Adrian_Visser]

If you have verified that you have no spark and it isn't the coils then you need to check the wiring to the dme.

[RedStar240]

what is the dme stand for? I have a feeling it is the injector. Because i dont recall much gas on the plug last time i took it out.

[jrdeamicis]

Have you tried swapping plugs around? And or replacing all of them?

Just because all the coils work does not mean that the #4 spark plug is good.

You should be able to quickly pin-out the harness.

[Adrian_Visser]

I have been driving my M50 swap for about two months and it appears that one cylinder is not firing. I have done Plugs fixed the small vacuum leak. I tested the coils and there are no problems with the coils how ever plug 4 doesn't work. I was hoping someone has experienced this problem and maybe help me with the trouble shooting. Is it possible the fuel injectors? causing the single at plug four to cut off?

Does it have spark on #4?

Nope.

what is the dme stand for? I have a feeling it is the injector. Because i dont recall much gas on the plug last time i took it out.

Do you have any idea how troubleshooting works? You have said 3 times that you have no spark why would you think it was an injector? The injector delivers fuel if it wasn't working you would still have spark which you do not.

The DME is the engine computer. On other cars you may call it the ECU.

As stated above make sure the plug for that cylinder works.

If that doesn't work check the wiring.

The coil has power in the run position from the green wire (pin 3) on the coil connector.

The Brown wire (pin 2) is ground for the secondary winding.

The Black/Blue wire (pin 1) is the trigger wire to the DME it grounds the primary winding. it goes to pin 23 on the DME connector. With the engine running it should be switching ground every time the plug should be firing.

Check those things and update accordingly.

[RedStar240]

Because i was talking with a mechanic friend of mine and he says that a lot of the cars wont fire the coil is the injector isn't working.

Do you have any idea how troubleshooting works? You have said 3 times that you have no spark why would you think it was an injector? The injector delivers fuel if it wasn't working you would still have spark which you do not.

The DME is the engine computer. On other cars you may call it the ECU.

As stated above make sure the plug for that cylinder works.

If that doesn't work check the wiring.

The coil has power in the run position from the green wire (pin 3) on the coil connector.

The Brown wire (pin 2) is ground for the secondary winding.

The Black/Blue wire (pin 1) is the trigger wire to the DME it grounds the primary winding. it goes to pin 23 on the DME connector. With the engine running it should be switching ground every time the plug should be firing.

Check those things and update accordingly.

[RedStar240]

Alright so i'm fairly sure it is the injector however i have not done a ECU test yet i should be doing that this weekend. But i pulled plugs and one smelt like oil the other oil + gas guess which cylinder works?

[e30s50dan]

Trust me dude listen to these guys. The coils are notorious for going bad. The injectors not so much. As stated above I had two coils that were kicking my ass but atfer troubleshooting and advise from r3ver trouble fixed. Just my 2 cents!!!

[M-technik-3]

Who did the swap? Kinda sounds as thou you payed to have it done and don't understand troubleshooting.

If someone else did bring it top them have them fix it and watch and listen to them.