Hi guys. This is my first post after being an occasional reader for about 8 years now. To this point, every problem I have experienced had at least one other person have the same problem and I was able to fix it using the advice on this site so here is a big cheers for being awesome!!! However I now have one that I haven't been able to find any assistance on, both here at Fordmods or on the greater internet, that I'm hoping someone can point me in the right direction.

My trusty EL was running fine, then dropped one cylinder one day. Thinking dizzy cap, i replaced it and the rotor. Didn't improve, and then proceeded to drop 2 more cylinders very soon after. Despite this, it still manages to start and run (not drivable though). The cylinders out of action are 2,3 and 5. The all have spark, and many times have the leads been checked to confirm they are hooked up right. Had a quick look at the ECU, but found no obvious problems. Plugs are new, as are the leads. Yet to be tested is injector drive, but the exhaust smells really rich and smokes like a b**ch, so my guess is that they are ok.

I was leaning more towards the problem being with the dizzy, as cylinders 2,3 and 5 are all sequential in the firing order, but I wouldn't have any spark of that was the case.

Now I'm totally stumped (not something that often happens). Has anyone had something similar happen, or can offer some insight?

Hello,

I would start by replacing the leads.

Sounds like you've dropped injector pulse to the odd no cylinders - 1/3/5 as opposed to 2/4/6. They are a bank fire setup after all. It is easy to get #1 and #2 plugs the wrong way.

Put a test light across the injector plugs and see what are/are not pulsing on cranking.

You state that 2,3 & 5 are not are not firing. How did you come to this conclusion?

Did you pull the leads off when running?

Have you pulled the plugs to see if they are "wet"?

Have you done a compression test on all cylinders?

Leads were pulled while running, I found there was no change in idle speed when removed on the bad cylinders but it would immediately die when a good one was pulled. The all showed strong spark when the leads were tested with another plug against the block. Plugs haven't been removed and checked to see if they are wet.

I compression tested it not long before this problem and they were all in spec, and it hasn't left the driveway since that test.

Suggest you pull the offending plugs.

If they are wet, then it is lack of spark, if they are dry, I would suggest that it is injectors.

+1 for SWC's diagnostic test

As the firing order is 1-5-3-6-2-4, the affected cylinders are not sequential on the distributor, so it is less likely to be a distributor issue. But I would still check the distributor shaft for play, to eliminate that as a possible cause.

If a cylinder is getting spark but not firing, either:
- there is (way) too much or too little fuel
- the spark is too weak, or
- the spark is happening at the wrong time (eg, if leads have swapped around, some cylinders will fire and others will not)

When you check your plugs, look for colour (should be white/tan/grey) and check the gap (anything from 0.8-1.1mm should fire).

The smoky, fuel-rich exhaust suggests another possibility: the ECU can fail, causing the injection to be seriously over-rich. The MAP sensor can do the same thing.

You mention that you have tested for spark with another plug against the block ... and that you pulled the plugs from the dead cylinders ... but did you check those plugs for spark?

Checking for spark with another plug doesn't rule out faulty plugs in the dead cylinders.