2.3L ('83-'97) Spark knock after ICM change, No CEL , runs much better except for knock when lugging.

[Dredwolf]

I have not posted in a long time, life does that, but I am hoping to narrow this down, parts are expensive these days.
1993 Ranger XL, 2.3 with dual plugs, and well over 300K miles, and right now, my daily driver when it was supposed to be my little farm truck.
CEL for a long time, other things took focus. Started running really bad last week, finally got a quiet day to diagnose.
Got the exhaust side coil pack error from the CEL, did some more tests, ordered a ICM I could afford with decent reviews.
Took time to clean mounting plate, used thermal pad material for heat transfer from ICM to base plate, and think I have a solid ground, but I can run a separate ground wire.

After installing the new ICM, CEL cleared immediately, and the little truck has noticeably more power, to the point of not needing to down shift during an aggressive test drive. It ran well during a 10 mile interstate and back roads test loop, to the point it was grin-inducing.

Drove it today to take garbage, get animal feed, etc., and while it still runs a lot better, normal "I'm in my truck running an errand driving" is producing a slight spark knock with any slight lugging. I realized after looking at my notebook in the garage its been WAY too long since plugs and wires.
I did swap the coil packs around while trying to sort out the initial CEL., but I'm trying to avoid getting into a parts swap loop, I just can't afford it right now. Again, no CEL at all at this time.

Plugs and wires is an easy task. I had a slight knock last month, before the ICM change, but a cheap can of octane boost cleared the knock and I thought it might have been poor/cheap fuel.

Thoughts, opinions and snarky comments welcomed.

 

[scotts90ranger]

The dumbest thing I would check (I like doing dumb things first, or at least looking at them, never know... I know I don't do anything wrong but there's gremlins mixing stuff up behind my back, I swear...) is to be sure the plug wires are on correctly on both coil packs... I don't have which side is what memorized but you can mix up 1&4 or 2&3 but don't mix up the other combos... being batch fire the outers are combined and the middles are combined.

Other than that the only things that would cause it to have spark knock would be running lean which could be from a dirty MAF (electronic parts cleaner or MAF cleaner is all I'd use to clean them) or a bad O2 sensor that's just exceeded it's life span but that usually causes low voltage so would make it run rich so I would start with cleaning the MAF...

 

[19Walt93]

I assume by "ICM" you mean the TFI module on the side of the distributor. I'd check the timing before getting too involved in replacing parts.

 

[scotts90ranger]

I assume by "ICM" you mean the TFI module on the side of the distributor. I'd check the timing before getting too involved in replacing parts.

No, he means the DIS module on the side of the intake, no distributor on a '93, crank reluctor wheel locked to the crankshaft so no timing adjustments at all...

 

[Dredwolf]

The dumbest thing I would check (I like doing dumb things first, or at least looking at them, never know... I know I don't do anything wrong but there's gremlins mixing stuff up behind my back, I swear...) is to be sure the plug wires are on correctly on both coil packs... I don't have which side is what memorized but you can mix up 1&4 or 2&3 but don't mix up the other combos... being batch fire the outers are combined and the middles are combined.

Other than that the only things that would cause it to have spark knock would be running lean which could be from a dirty MAF (electronic parts cleaner or MAF cleaner is all I'd use to clean them) or a bad O2 sensor that's just exceeded it's life span but that usually causes low voltage so would make it run rich so I would start with cleaning the MAF...

So, I finally made time to work on the '93 tonight, outside, in the dark, because of....reasons. Anyway, prepping for the Great Sleet Storm of 2026 (not be to confused with the actual snow a week later), I decided to check the passenger side plugs while checking the antifreeze in the radiator....and had every plug wire on that passenger side come apart in my hands on the spark plug end. So.....fast forward to tonight, where I had a set of new wires, and Autolite Double Platinum plugs, and decided to fix the obvious failure. Dug around in the garage and found my Chilton and Hayes manuals, and per the diagrams, I had the plug wires correct coming off each coil for the driver side and passenger side. I went ahead tonight and did the passenger side, new plug wires and new plugs with the gap checked. I need to change the air filter, so I'll clean the MAF then. I don't think the O2 has ever been done, so that is worth a check too. Still no CEL, and quick run to the gas station seemed to run smoother, but the driver side plugs and wires still need to be done.