Hello All,

I have a 1999 Expy with 104K on the dial. I recently noticed when idling (and only when idling) the truck sort of shudders ever so slightly - but enough for me to notice. I took the truck in for a tune up. That seemed to fix the problem. A couple of weeks later the shudder was back. But this time it was accompanied with the Service Engine Soon light. I took the truck back to the same garage. They informed me that the truck was reporting a misfiring 3rd cylinder. So they replace the spark plug wire and turned off the check engine light (there may have been more work completed on the truck at that time unfortunately that is all i remember the attendent telling me). Again a week or so went by with no shudder. A few days ago the shudder returned with the check engine light. So again i went back to the same garage and they told me (before the check the read on the truck) that if the truck was reporting the same cylinder then it meant that i probably had serious motor problems. True enough - it reported the number 3 cylinder misfiring again. They also told me that I should now take the truck to Ford. I'm planning on taking the truck to Ford this week.

Here's my question: What lays ahead for me and my truck? Has anyone encountered this? Will this require the engine to be rebuilt? Or should I even consider rebuilding it? Any information that you can provide is greatly appreciated. I would also like to mention that this is my main mode of transportation. I would hate to see this truck die on me. I was hoping to get the dial up to at least 180K

Thanks in advance for your time and wisdom.

 

If you have spark plug wires then you have a 4.6L with coil packs. A misfire on the #3 cylinder probably means that the coilpack has crapped its pants and you will probably need to replace it. It takes about 10 minutes and shouldn't cost you more than $85 for the part.

 

thanks for the info jbabbler... also good catch on the engine size - i forgot to mention that in my original post. Now as far as replacing the coil packs, is that a job for the novice mechanic?? Give me a processor and a motherboard and i can build you a computer... but when it comes to working under the hood of a car, I'm lost.

 

Replacing the coil packs will be right up your alley. Just trace the plug wires back to the little box they plug into. Buy that box, replace that box with the new one and plug the plug wires to it in the EXACT SAME PLACE they were on the old one. Seriously, its very easy and you get the satisfaction of doing it yourself. Look at this old post of mine from a few years ago....

http://=https://www.ford-trucks.com/...rewed at Aamco

 

After replacing the coil pack the truck is still shuddering while idling. I guess its worth mentioning that I only replace the coil pack for the 3rd cylinder which reported the misfire (passenger side). Is there a need to replace the other pack as well? If this should have resolved the shudder while idling, is there any other options for me? Or do i bite the bullet and take it to Ford? Any advice would be greatly appreciated!

 

Wait a sec, if you have plug wires you will only have 1 coil pack for each bank. If you changed only the cop for the #3 cylinder then you shouldn't even have plug wires. Do you have individual coils on each plug or do you have a small box that the plug wires plug in to?

As for the shuttering while idling, that sounds like the EGR is stuck open or the IAC needs to be cleaned. Ae you familiar with those? They are easy to fix as well.

 

My explanation wasn't clear enough... my apologies.

I changed the cop for the #3 cylinder which included the other three as well (I don't recall the other three cylinder numbers that are apart of this pack that i changed). So the entire cop was changed for the passenger side bank. That still leaves the other bank (driver side) which i have yet to change. I wasn't sure if that would have an effect on the shuddering or not. Should that one be changed as well?

As far as the EGR and IAC is concerned I'm clueless.

I also have noticed a sputtering sound coming from the exhuast when the truck is at idle. I wish I knew more about cars.....

 

Well, the EGR valve is the Exaust Gas Recirculation valve. It takes exaust and allows it to be sucked back into the intake in order to cool head temperatures. It opens and closes based on the results of readings from the DPFE sensor. The DPFE reads the flow on either side of an orifice and compares the values. The EGR should be completely closed at idle bu if it sticks open then it actls like a Giant vaccuum leak. It is located on the side of the Throttle body )driver's side) and is held on by two bolts. I bought mine from rockatuto.com for $41 and installed it in 15mins. To see if this is your problem, tap on it while idling and see if it closes. Other causes of rough idle are the TOS which is the sensor that tells the computer where the throttle is and the IAC hich is the small valve on the Throttle body that allows air to pass while the car is idling.

 

Would any of those cause the computer to report that the 3rd cylinder is misfiring? I am going to try this afternoon. Nonetheless, it sounds like a trip to the dealership is in order.

 

If it says Cylinder #3 it is either the plug, plug wire, coilpack. Thats all it can be.

 

this may be a long shot, but may be worth mentioning.....

I had an intimidate misfire (would misfire for 10 minutes under load and then be fine for weeks, repeat..)

The problem was that the spark plug has a metal tip that screws into the top part was loose, and under vibration and bumps would become loose and loose contact...misfire......

removed the plug, tightened it up and runs fine......

 

As my original post mentioned I finally took the truck to the dealer. I explained the long story to the service tech. 3 hours later I get a phone call and they tell me that I am receiving misfire codes because I have Bosch sparkplugs. The tech goes on to say that Ford engines respond very funny to Bosch spark plugs. I'm not sure if they don't get hot enough or what (I guess I should have asked). But after changing all of the spark plugs the truck is doing fine. The subtle rough idle is gone. The service engine soon light is off and has remained off. And I'm on my way back to the original garage to see if I can get some of my money back. I, in effect, got another tune up so the first should be free.The first shop I took my truck to for that tune-up in November install those plugs and i'm guessing they should know not to install plugs that may not function properly. And to think, the guy at the first garage told me that I prolly had major engine trouble... tisk tisk.

Has anyone else heard of Bosch plugs not being able to handle the load????

BTW thanks to everyone who offered assistance!!!

 

Click SEARCH enter "Bosch spark plugs" and be certain to include the F150 forums....

Very commonly noted problem. A few report satisfactory results, many have reported problems similar to yours.

Steve

 

hi ive hade the same thing but it was the engine bulk harness on the passenger sind the one with the bolt on top. all i did was zip strip it in place at the point it wouldnt move till i get a new harness i know u have fixed it by now but if not anythoughts to what u check i would be gratefull because i look at the book and could fallow the flow chart thank jj98

 

It's hard to argue with succes, but Bosch makes very good spark plugs. If you believe everything a service writer tells you I have a bridge for sale that you might be interested in buying. Most service writers don't know squat. A few are knowledgeable, but they're the exception. If all your spark plugs were Bosch and Bosch are faulty why did you only get a DTC on cy#3? Doesn't make sense. By the way you can't have coil packs and COP on the same engine. Are you sure your original mechanic replaced all the plugs with Bosch plugs. Did they return the old plugs to you for inspection when you picked up the vehicle? I always return parts to the customer.