upgraded coil pack

[malohnes]

I mostly lurk and let the experts do the talking. I have found lots of help and info witht he handy search function here.However I have a problem that never goes away and it is bugging me.

Been working on my 91 trying to quiet down the classic knocking. Tune up helped: plugs, wires, cleaned MAS, throttle cable mod, seafoam, homemade CAI...but I'm still having troubles with the knocking. This was done about 2k miles ago. I have 130k miles on the clock and 1 head was replaced 3 years ago.

For clarification, the knocking occurs on load, warm engine, gears 3-5 but mostly on 4 & 5 on hills. It comes and goes, worse on warm summer days, better on cool winter days. Sometimes even a fresh tank of gas affects it. Right now using premium, third straight tank revealed a mostly quiet engine, but it is starting to knock again. Lucas fuel injector cleaner has been used and fresh oil change using Amsoil oil and filter was recently done. I pulled plugs and found 5 out of 6 with hard whiteish deposits that broke of nicely so the plugs were cleaned and reused. The 6th plug was tan with slight buildup.

So okay, I did a search and found a few threads refering to coil packs getting weak when replacing/freshening the above mentioned items in a tune up. I have not found any aftermarket coilpacks. Any recommendations?

 

[joecrna]

Check out Aldive, he uses a Demon I believe. Its for a Mustang and you have to switch the plug wires around.

 

[cybergasm]

there are several aftermarket coil packs available

Accel Screamin Demon and even Jeg's Has there own private label coil packs for Fords

if you interested in the Accel packs try Summitracing.com
may have to do a search to see who selling the Screamin demon packs
and Jegs.com for the there coil packs

hope this helps ya

 

[malohnes]

Thanks. Never occured to me that Jegs or Summit would have Explorer parts!

 

[malohnes]

Thanks for the link to Aldives threads. I'm looking into the Screamin Demon. Performance Distributors has a direct fit coil pack for 4.0 OHV.

Once again Explorerforums helps out.

 

[Anime]

If your "knock" is a loud clattering sound then it could be the famous valve clatter of worn rockers/pushrods. Once they're worn the only fix is new rockers and rods.

If it's actual knocking with hesitation, my personal experience is that once you've taken care of the wires and air filter (and cleaned the MAF) it's only fuel related. Using only top tier gas and staying away from cheap gas and fuel additives cleared up the hesitation for me. But the valve clatter persists no matter what.

 

[mrboyle]

I seriously doubt the coil pack is getting "weak". I personaly have owned 2 Explorers with 220k+ on them and both were still running the factory coil pack (heck my '96 still has the stock plug wires on it). The "knock" you are describing is due to pre-ignition and is more than likely fuel related, not spark. Does the fuel you are running have any additives (oxignated, methonal, etc...)? The "ashy" deposits are typically due to either oil consumption or fuel additives. A properly fireing plug should have a very slight to light tan color to the electrode and ground.

 

[malohnes]

The knock sound is the marbles in the can sound.
The previous owners were very easy on the truck and it was hardly used beyond daily commuting. Hardy any highway miles even. I've had it 18 months and it has always had the knock, but since cleaning up it has progressively been better. I have a very steep grade right out of town that is 12 miles long and 3300 in elevation gain that I drive weekly. That is my test. Half throttle usually is fine in 4th, I go deeper that death rattle kicks in. Sometimes, shifting to 3rd and picking up revs helps, but the engine noise masks the knocking.

I thought of fuel, since other threads have indicated that premium provides no advantage beyond a tank or two, something my tests have shown me. I only have one gas station in town...small Alaskan rural town...so gas is spotty. Once in a while when we go north to canada I fuel up there and have had what I consider good gas. Good in that the knock goes away. However it had never been consistent. When it has been really bad, I'll reset the cpu and that works for a time. As for additives, other than fuel injector cleaner now and again, non that I am aware of.

I have new fuel lines ordered since I discovered one has a frayed braided cover. I'm also waiting for a new filter. I'm also using iridium NGK plugs which work very well for me. I picked up noticeable smoothness and seat of pants improvement and 2mpg over that Autolites that were in it. The coil pack idea came form the search. Since I would like increased fuel economy it made sense that a hotter spark would increase performance to my mind.

Thanks for the info regarding the plug deposits. I do seem to have a small oil consumption issue, 1 quart every thousand miles. No blue smoke at all. I checked the intake bolts, I found two loose, but not by much. I am considering replacing the gaskets soon.

I'll keep the thread alive and post changes as I explore and absorb the recommendations from you all.

 

[Kona]

Lol here is a possible explanation from Ford Truck Enthusiasts forum
http://www.ford-trucks.com/forums/100739-engine-knock-4-0l-engine.html

 

[malohnes]

Good thread there. I saved it and will search more info there as well.

However, I already de-carboned my engine in the summer time. Made a great deal of difference for me. I did not change the plugs afterwards, so I wonder how much of the build up I had was due to that and not from additives? Also, the knocking comes and goes with a supposed good tank so I am suspecting something else. Then again maybe not.....

Sooner or later I am going to upgrade the heads to 95tm's and when that happens the motor is coming out for a rebuild. 410 cam and hardened pushrods will go in for sure.

Until then, it sounds like this is just the nature of this engine.

 

[Anime]

Since you mention the rattle sound in higher gears on steep inclines it just sounds like valve clatter to me.

If you're planning on a rebuild, get new rocker shaft assemblies from Ford (only $100 each, get one for each side) to go with your hardened pushrods. This is what I'm doing soon, and looking forward to the quiet and the return of power/torque from valves fully opening.

 

[malohnes]

If it was just clatter as you mention, why does it come and go? I would think it should be present at all times, though under more demanding conditions it should be louder, but this is not the case.

Sometimes different fuel makes a difference, sometimes outside temp, or simply reseting the cpu...drives me batty sometimes.