Bringing this m20 back to life

[HerbE30]

Have you check your distributor and rotor button? Pop it off and check for any corrosion. It was the cause of my issues, took a while to trace it down.

[YosemiteSam]

Precicely. If you hold the plug ~1/2" from the block and it still jumps that then you are probably good. Just be careful, if you are touching the body of the car or the engine block you are liable to get shocked. It's not dangerous, but it will make you jump. I was once doing something similar and the only part of my body I dodn't notice was too close to the car was my junk, that one hurt a lot.

[mbonanni]

Bringing this m20 back to life *misfire*

I'm interested, but regardless if there is enough resistance or not there was spark from plugs 1-6 using my method, so I know Im getting spark. Would it change anything if I said I held them close to the engine hook/body/valve cover so I could get a larger gap? Essentially more resistance, yes?

Just to clear it up are you're saying when the plugs are installed and the car is running there is potentially more resistance in the wires (Or plug?) which can result in no spark? So this lil guy simulates the car being under load which is why it would give me more accurate results for the spark? Essentially if I got no spark while using this tester It would mean either bad dist cap, rotor, or ignition coil. Is this correct?

[YosemiteSam]

Disconnected fuel pump, removed each plug individually and watched to see if there was spark while I cranked it over. I believe 2/6 plugs were black. Cant remember which ones but will check and get back.

This is not a good way to check for spark. Get yourself one of these: https://www.amazon.com/OTC-6589-Elec...s=spark+tester (you can unscrew the thing on top so they work with E30 wires) and check spark that way. If you just have the spark plug on the end of the wire you don't have nearly enough resistance to see if it will spark while cranking/running. Added bonus to these tools is that they make a nice crisp snap when it sparks so you can see as well as hear the spark.

[mbonanni]

Interesting. In that case, how did you check for spark?

Disconnected fuel pump, removed each plug individually and watched to see if there was spark while I cranked it over. I believe 2/6 plugs were black. Cant remember which ones but will check and get back.

[YosemiteSam]

I removed the rail from the head, put paper undr each injector then cranked over several times. each piece of paper was wet with fuel when I checked them.

Interesting. In that case, how did you check for spark?

[MrBurgundy]

I doubt its the timing because the other three cylinders are firing. If the timing was off, it would effect all the cylinders.

And yes, if the timing was off, it would show on all the cylinders in a compression test.

Also, check the distributor cap and rotor.

[mbonanni]

I have not got the chance to do a compression test, but if I happened to mess the timing up when doing the timing belt recently then those cylinders wouldn't read correctly if I checked for compression, correct?

I may just tear into the timing later today when it isn't so damn hot and check again to see if my marks line up. If I was off a tooth would it cause a miss in three cylinders? Perhaps stuck valves or something of the sort?? The motor has been sitting for 10 years.

[MrBurgundy]

That's a dead miss. I didn't know you pulled the wires in the vid. I just watched the whole thing.

Have you done a compression test?


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[mbonanni]

How sure are you that you are getting fuel from all the injectors? 2,4, and 6 all share a single injector drive. If the PCM were not sending out the signal for that bank, or the wire were cut/broken/corroded/etc those three injectors would not fire.

I removed the rail from the head, put paper undr each injector then cranked over several times. each piece of paper was wet with fuel when I checked them.

I'd start off by fixing the vac leaks.

Is it a dead miss or does the engine react to each ignition wire being removed?

I will get to that soon, however right before this video I broke it and it ran identical, which is why I decided to still post it. I'll run to the parts store later and pickup some tubing.

Also, not exactly sure what a dead imiss is vs what youre describing is, but I showed in the video that removing plug wire 1 the engine runs rough, removing 2 it doesn't run rough, and so on for the respective cylinders.

[MrBurgundy]

I'd start off by fixing the vac leaks.

Is it a dead miss or does the engine react to each ignition wire being removed?

[YosemiteSam]

How sure are you that you are getting fuel from all the injectors? 2,4, and 6 all share a single injector drive. If the PCM were not sending out the signal for that bank, or the wire were cut/broken/corroded/etc those three injectors would not fire.

[mbonanni]

I recently picked up a 1991 325i that had been sitting for 10 years. Things I have done or have checked to get her to this current point.

New Spark Plugs (good bosch ones)
New fuel (most of the old stuff had been emptied before storing)
New used fuel pump
Getting spark in all 6 cylinders
Getting fuel from injectors in all 6 cylinders
Timing belt
Waterpump
Tensioner
Oil change
New Chassis ground cable
New Battery

I checked for spark and fuel in each cylinder and they all checked out individually. I believe I am getting the misfire in cylinders 2, 4, and 6. I tried swapping plugs from cylinder 1 & 2 thinking it was the plugs had fouled (visually one looks black and fouled), but it still missed in 2. I also switched the wires from cylinders 1 and 2 and they neither fired, not sure if that means anything given the different timing.

I did just do the timing belt, could this possibly be a culprit? Maybe I was off by a tooth? Excuse the lil vacuum sound in the video, while I was removing the valve cover earlier I broke the line /: Could this be the culprit? It was running rough before I broke it...

Here is a clicky link while I try to figure out how to embed correctly

https://www.youtube.com/watch?v=djGmwr1fU6A