I have been working on this for months, so please forgive me if I have to add to this post later.

I had coil packs start going out so I decided to have the remaining packs replaced. I had just before this replaced plugs, and 2 bad packs. When the heater core went, I just had them do it all. So, after the parts exchange, the engine developed a slight shake at idle and while cruising (maintaining speed on highway) to the point it feels like a misfire.

We first checked for vacume leaks by a smoke test, found 2 small hoses behind battery that were leaking, fixed. Shake still there.

Thought we were getting oil or antifreeze into cylinder causing misfire, replaced value cover gasket and intake manifold gasket due to a leak that developed in the meantime on back of intake.
Replaced whole intake when leak was found.

We have also replaced iac due to idle fluctuations. After all that, still there.

We have monitored everything possible on the scanner, everything performing normally.

I did get one code for coil 3 circuitry, that went away, attributes it to leak in intake and it has not returned.

Now the shake: this is random so to speak at idle in park. It does have the feel that it has a cylinder involved, due to the fact it feels as though it occurs with every revolution of motor. But then when shifted into drive, the shake becomes steady, no breaks in between or randomness.

Any ideas would be appreciated as I am already bald from this problem.

 

It's entirely possible that you have more failing COPs, or plugs, it could be also other things as well.
bad crankshaft position sensor?
sticky injector?

How does it run if you hard accelerate?
Did you clean the throttle body when changing the intake? there are couple of ports inside for the EGR that tend to get carboned up and give issues.

of course you could take it back to who ever did the work too....just a option

 

We have monitored the coil pack voltage and firing and the are performing correctly, also, all ports were open and clean.

If accelerating it runs smooth, only when idling or cruising.

If it were a cop, the pattern of the shake would not change when put in drive, right?

Either way, all have been tested and showed proper resistance and voltage.

The shake is noticeable through the seat and steering wheel primarily. It is not as pronounced on the front of truck. Just the firewall back, that is the weird thing to me.

Today, my mechanic put the truck on the rack while running in park, and said the exhaust on the backside of the cats was shaking quite a bit, but not in the same pattern as the shake in the cab.

Also, plus only have 5-600 miles on them and look good as we have pulled them to check.

It is with the mechanic who did the work and he is as stumped as I am. I am trying to avoid the ford dealership like the plague as ours does not have a good reputation on solving problems.

I did have an erg code but changed the mad sensor and no more code, so I am not sure if that would be the issue or not.

 

Understand that dealership plague

from my meager understanding....the COPs can have a weak output on a idle or cruising level. once more is asked for the...the tables that make up the parameters that the ECM works from...give more fuel and spark. so then things clear up as one accelerates.

Many place this weak spark output on aftermarket plugs and or COP's...so did you replace everything with Motorcraft? many times aftermarket COP's can be bad out of the box. Was dielectric compound used to help seal plugs and boots. might want to check the connections to the COPs...sometimes the wires have poor connections

Going to presume that there is no codes at this time to help indicate what might be the gremlin/s? Was the battery unhooked for any of this repair?....to clear the codes and reset the ECM?

Might be something unrelated to the engine/ignition...like a flywheel or torque converter...or motor /tranny mount? Concidering that the vibration is worse towards the rear.

how is the fuel pressure? How is the Alternator output?

Still could be a vacuum leak too...but you had a smoke test done...was it runn again to see if any other leaks still persist? The elbow on the PCV line on the rear of the Throttle body is known area

 

Fuel pressure is good. Alternator is perfect just rebuilt. Pcv line has been checked and rechecked. Motor mounts/trans mount were checked yesterday.

I am going into shop to talk this morn. Will update tonight.

 

took a look at it this morning with the mechanic. there is a strong vibration down the drivers side exhaust pipe from header to where it turns to go to the passenger side. I was thinking stopped or restricted cat. But that wouldn't cause a vibration, would it?

 

suppose its possible??...if the exhuast is restricted on one bank...I could see how that might affect it....but usually one gets all kinds of "right or left bank" codes.

does the cat rattle if struck with a solid blow...aka 2x4...don't swing for the fence ...just a solid rap.

 

it does not rattle at all

 

could take it down to a reputable exhaust shop and have them look at it..flow rate and back pressure test

Have had a compression test done on the engine?

 

i forgot to mention before, but a back pressure test was done and was showing no back pressure.

Compression is good.

 

If that is all good....well it boils down to electrical...weak COP, or poor connection somewhere...etc.

Have you had the ECM "reflashed"?

Just curious...How full is the crank case???...over filling the crankcase will do this too

 

i have not had the ecm flashed. Crankcase level is good as well. I found a ford tech that does work at home. The dealership made them buy their own computers with the diagnostic software, so I am going to see him Tuesday.

 

took truck to another shop to have better scan done

 

ok, i am still battling this. ford tech could find no abnormalities. i am still lost. still a slight miss. i do have a evap code that keeps popping. i replaced a torn vent hose on the gas tank. i thought that would fix it. i has not. i dont know if that has something to do with the slight miss i am getting.

 

by the way, the ford tech hooked his computer to it and could not find anything electrical.