2005 Mercury Gran Marquise

[B.G. Smith]

I know most of you are not into old cars but thought I would ask. This is the 4.6 V8 with drive by wire throttle control, coil on top of each cylinder, has 161,000 miles on it. Firs time started each day it stumbles some for maybe 1/4 to 1/2 mile then clears up, good for rest of day. The stumble is kinda hard, like a down shift on standard transmission. There is no braking by the transmission unless the overdrive is off and then it is light so I don't think it is the transmission unless is is momentarily going into reverse and I don't know if that is possible?? Any help appreciated. This is daily driver.

 

[AEdelheit]

I have a 4.6l in my 99 Mustang, the upper intake manifold was prone to cracking causing a vacuum leak though I believe that was updated by 05, I found corrosion on the coils packs causing a miss so replaced them and it took care of the problem for me.

 

[B.G. Smith]

I thought at first it might be a fuel problem but doubt it would go away after first use. I will pull the coils as son as I am able, little handicapped right now. That makes sense since it might be a little damp on first startup then dry out. Thanks for the reply. bg

 

[TFucili]

I had an Exedition with 5.4, and had lots of trouble with the coil packs.

 

[Timd32]

My vote is coil packs, you can check them with a meter, its not a horrible job I did all 8 on my uncles '07 last year, this year starting running rough already lost one of the 8 from last year.

He did not opt for OEM, was box store parts.

Also I forgot if they include the whole rubber boot, I think they do, but would do them at the same time and we threw plugs at it as well.

On the 07 you can get the codes via the radio or dash, forget exactly but it has some decent diagnostic to them that might help troubleshoot.

 

[JR]

I agree with the coil assessment. If you ever need to replace one Rock Auto sells OE coils for a fair price. I never had much luck with aftermarket.

Also I'm sure you know the spark plugs can be problematic on those if left in for the recommended service intervals. Even at around 60k - 70k miles the plugs in my 08 were "fun". I cut the mileage intervals in half after that, used a good antisieze and never had a problem again.

 

[Timd32]

I know I had to loosen the Brake Booster to get something out of the way on the '07, was not hard just have to get under the dash. I forget exactly what we were doing exactly. But if it looks in the way it was for me.

Its possible I did a valve cover gasket at the same time, so dont just take that loose.

 

[SnoKing]

Start it up at night with the hood open and see if you see sparks jumping around!

 

[Wayne M.]

If anything like this is going on, the MIL will be on with codes, including a transmission problem. Aside from the good cold start, my bet is a fuel pump issue or clogged filter.

 

[AEdelheit]

Start it up at night with the hood open and see if you see sparks jumping around!

Coil on plug so dont think this would work though have used it before with traditional distributor and wire setups.

 

[BigPapa]

We have a lot of Fords in our White Fleet. We use a lot of DG508 Coils and SP493 Spark Plugs.

 

[B.G. Smith]

Thanks for all the replies. Wayne M., I tried the switch on, off twice then into start position but it didn't respond, do you know the sequence to make it display code? I still have not been able to do any checking as am still physically challenged. bg