Hi guys,

i've got a problem with misfiring in my 98 f150. its the 4.6 and has 115xxx miles or so. The spark plugs, wires, and COP's were are replaced this summer with the troyer performance ignition upgrade. it came with accel wires, cops, and denso iridium plugs. The truck had a very low misfire for some of the summer, nothing that i really thought much of. as winter came, or whenver it rained hard - misfiring became more frequent and much much more noticiable. My buddy sprayed the wires and determined they were arching(sp?) and with heavy moisture, they were causing the misfire. Just this monday we replaced the wires with ford motorcraft wires. The truck still misfires the same as before.
now - interesting part. it only misfires at 1500rpms or less. at idle when at red light, misfiring, in no particular order. when accelerating up to an 1500 rpms, the truck misfires/hesitates until its above 1500 and then accelerates smoothly. also, when under driving on the expressway, when the truck is in 4th gear and i go to accelerate - the truck is either misfiring or has a very pronouced hesitation/shudder as you accelerate the truck up to 1500rmps. then past that, we're smooth sailing, or the truck has already downshifted to 3rd and is at a higher rpm. The truck also misfires horribly when i put in in reverse. (but again i'm usually below 1500rpms when in reverse)

What the heck could be causing this??!?!? my mechanic buddy dosent understand how theres not a pattern to the misfire - its not happening on any one particular cylinder. Also, he dosent understand why it would never happen all the time when driving. I know i should have the codes read- well i've got the xcal II and it picks up no codes. there isnt an engine light either.
mods - xcal II tuned by VMP, Troyer underdrive pullies, AF1 intake, magnaflow exhaust, and the troyer ignition.

I am going to have the fuel filter replaced - but i cant imagine thats the cause for this irregular but very specific RPM regular problem...sorry for the length of this post - but thanks for all help!!!

John

 

Pull the plugs and coil packs and replace them with OEM Motorcraft. Make sure you use dielectric grease. I would also contact VMP and see if your tune may be having some issues. Clean the MAF sensor.

 

Don't buy any parts yet.... If the truck has a missfire, then it will set a code. You just have to help it do it. Here's how.

Step 1: Get the truck up to 65 mph on a smooth straight road. Let off the gas, and coast all the way down to 30 mph without touching the brakes or the gas.

Step 2: Drive the truck in such a way as to make the missfire happen the worst. If driving up a long hill at low rpm does it, then do it until the check engine light starts blinking. The truck's computer will then determine which cylinder is causing the problem, and you can go from there.

 

Sounds like a classic, yet highly annoying low grade misfire. You may or may not be able to get it to throw a code; I was never able to when I had a similar problem. Mine ended up being a plug, even though they were all replaced with Motorcrafts a month earlier. There are a few possibilities... have the COP's/engine gotten wet? If you didn't use dielectric great when you installed the COP's it's very easy to get moisture in the plug wells which can cause this problem. A COP could have gone bad; you could buy a new one and rotate it thru to see if you can find the bad one. I'm not sure what brand of COP's you have. I would also pull all the plugs and check them. It is possible you have a bad or fouled plug.

 

AZ, it's not a COP engine, it's a 98 4.6. As stated, it has the Troyer ignition upgrade kit with Denso Iridium plugs and Accel wires/coil packs. The OP called the coil packs "cops" by mistake. From what I hear, Accel makes a lot of junk these days, hence my recommendation to put stock parts back in.

 

Step 1: is 60/40 chester and it has do be accomplished twice successfully within the same drive cycle. - Right , No Brakes.

Maybe your over compensating on the decel. That will work, but it has to be done twice/ same cycle or you can get a blinking CEL without setting DTC in the KAM.

Step 2: Correct, but man it can be a PITA to get this to actually happen with a COP ignition, let alone a Coil Pack version..
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If the fuel system checks out and your compression is good, I would thro a couple parts at it. ~ Two new packs. Accel has the worst record as far as failure. MSD's or OEM would be choice. -

http://www.jegs.com/i/MSD-Ignition/121/8241/10002/-1

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BTW- Reverting to the stock tune first is always best when problems come up. I'm assuming you've tried that..? Just in case, try that first.

 

Thanks guys!!!

Well the very first problem was really the stupid fuel filter. When it was taken out it was FULL of dirt. my buddy said it was the worst he's ever seen and it was replaced, but it must have just been a crap filter. (and i admit i should have replaced it sooner) so the misfire dosent happen nearly as bad right now but its still there and under heavey acceleration the truck still has a miss. Next step will be putting injector cleaner in and running the truck hard to see if it clears things up. The plugs are likely to be fouled up unfortantely but we're gonna try the easy steps first haha. I will try that test to throw a code though too! And i really wish i didnt have these accell coil packs. When i had my first f150 troyer sent me MSD coils packs and wires, for this truck i have now the kit came with all this stupid accel stuff. I hate to throw it away b/c it was so expensive but if the misfire continues that will be what i have to do. Thanks a ton for the suggestions everyone!!!

John

 

update
just took the truck for a long drive with a full tank gas and the fuel injector cleaning solution. The truck is back to stubmbling at low rpm's and also when i tried to open it up on the expressway - it would stumble going into higher rpm's, shake pretty bad and then when i'm up at lik 70mph, it seems like the engine is half shut down and i cant get the thing to go above 80 mph no matter how hard i tried. Is straining as if half of the engine were working. but if you go back down to lower speeds it drives ok. this is getting frustrating for sure

 

problem fixed!
i ended up throwing the stock 12yr old coill pack back on the truck just to see what would happen. the truck runs amazing! those accel coil packs really do suck! Im not gonna put the accel spark plug wires back on, i dont think they were helping out too much either. I guess my word of warning would be for anybody considering the troyer ignition upgrade - make sure he sends you MSD parts, not accel. I pretty much bought the kit and paid for the plugs...nothing against that this was a learning process for me. Thanks for all your help though guys!

 

Told yuh lol. Yea Accels have had a bad record for quite awhile with these modulars. Mike shouldn't even offer those, surprised he still does.

Glad you got it figured out, -that's always a relief lol.

 

yet another ACCEL failure thread

 

seriously, im very relieved. And Jbrew i agree, I cant believe troyer sells them either. but honestly when I ordered the kit it still said MSD on his website(i'm pretty sure) so i tought id be getting those which i know run great. oh well its running great so im not gonna complain any more. just ended up being an expensive lesson....Thanks again guys!

and yea another accel fail thread! lol

 

I'd send that crap back and ask Troyer for a partial refund. The only decent parts in that kit are the Denso plugs.