4AGE running problem - Got many stumped ?????? (AE82) Electrical

[maxhag]

Ok, so, I have this 4age AE82 which I am trying to get running right. Sounds easy enough, but it's got many of us stumped.... Doing my head in......

I will do my best to explain this well, so please read carefully.......

So, the car is a clean 100% unmolested factory AE82 4AGE bigport. I bought the car for my brothers first car 6 years ago. He drove it for a few years until it started fucking up on him to the point where he couldn't run it.... He was young, and NOT mechanically minded at all. He bought another car and it has sat for almost 3 years in our mothers backyard in Melbourne.......

I finally got a chance to drive to melbourne a month ago to pick it up......

Now, what my brother had described to me when it died, sounded like a vacuum/map/tps type issue.... Sure enough, alot of the vacuum lines were broken/cracked/perished. I replaced these.....
Second, the engine would crank very slowly, and would drain the battery or jumper pack pretty much straight away.... Even when jumper cables from another car, the cables were getting very hot. Anyway, after a few tests, I found I had continuity between the + and - battery terminals..... I traced this back to a short in the DOME circuit. I've pulled the fuse (drivers kick panel) from that circuit and it fixed that.

Car cranks freely and runs........

BUT.... (now, here is where this gets complicated)


It runs, but very strangely....

* It only runs properly on 2cyls.... Cyl #1 and #3.

* if I have all 4 ignition leads on the motor, it runs worse, compared to if I have 3 leads on. IE; runs better on 3 leads (or even just 2 leads infact)....... Now, it doesn't matter if I disconnect cyl # 2 or #4 leads, both have the same effect. For a motor running on 2-3 cyls, it seems quite good, but connect a 4th lead (lead # 2 or #4), and it still runs, but worse.......

* If I pull the lead off cyl # 1 or 3, it will stall and die (so these 2 appear normal)..

* So, you would prob now be thinking I have problems with cyls # 2 and 4. NOT THE CASE..... Why? If I earth either of the 2 or 4 leads out on the body etc, it has the exact same effect as if I was to be connecting it to the spark plugs, therefore making the actual motor cyls irrelevant etc....... So it's an electrical issue.... Also, the results of a compression test was 180,177, 177, 178, so compression is fine.....

* I have changed spark plugs, then swapped between cyls etc, and no change...

* I have tried 3 differant sets of ign leads

* I have swapped the coil and ignitor from another working AE82 and made no differance...... I have 12-14v at the coil..........

* Alternator is working and charging, 14v when running

* I have tried another ECU

* I have cleaned tested the dizzy cap with a multimeter, and appears to be fine. Inside dizzy "looks " fine and clean.

* now, when checking the spark from the coil, the spark in orange and weak, not blue at all
* when checking when spark from the dizzy, they are all orange, but leads #1 and #3 are clearly much stronger. Leads # 2 and #4 are weak as piss......


I hope this is making sense, I was dreading on how to explain all this.....

Here is a video to try to give you an idea of what I am trying to say..... Watch and listen carefully......







The last thing I haven't changed is the dizzy itself. I have tracked one down and pick it up tomorrow. I don't quite know how/why a dizzy would cause weak spark from the coil, or even why it would not work properly on 2 cyls only, but I am running out of ideas


So, if brief,
Why would earthing out #2 and #4 leads on body drastically effect running motor? (and why would #1 and #3 leads/cyls be fine)
Why do I have such a weak and orange spark?

[phoenix]

I had a similar issue when doing a 4age conversion. Turned out we didn't have the a resistor connected. On the AE82 I think the resistor is on the inner guard, looks like a silver finned heat sink. Perhaps this is flogged out on your car

[Matt]

That resister you are talking about is for the injectors, the spark on these is batch fired and the injectors are too. Does the same thing happen if u take off 1/3 and leave 2-4 on?

[maxhag]

^^ nah, there is a clear differance in what is happening with 1 & 3 compared to 2 & 4...
It wont even fire up on just 2 & 4 leads..

[Javal]

You mentioned you did a bit of testing on the B+ Wiring but just as a quick extra check i would make sure that the head has a good earth, i.e the earth on the block is clean and tight and the cable doesn't have excessive voltage drop.

[maxhag]

Ok, I just picked up another dizzy and hey presto!

All fixed......

I have never seen a dizzy fuck out like this before, but i guess anything is possible with electrics...

Thanks....

[Matt]

Only half logical explanation would be that when the spark was being emitted from the cylinders in question that it was momentarily blocking the crank angle sensor within the dizzy.

Bit of a stretch of an explanation, but it would be nice to understand exactly what was going on there.

Gotta admire your patience with this, as it would do most peoples head in.