Tupe up tips needed: 1996 Mercury Marquis 4.6l

H

Hoytman

New member
Joined
Jun 17, 2011
Messages
2,711
Reaction score
0
I did some internet searching and wasn't satisfied with the information I was seeing, so I thought I'd ask some of the motorheads here at Autogeek for assistance.

A 'parts replacer' would be better fitting name for me than a mechanic. That said, my dad quit tinkering with cars when I was a little boy. Since then everything I've ever learned (not much) about working on cars was learned by rolling up my sleeves and diving in. Let's just say I've learned to know what I can and shouldn't try to do. Here's my dilema...

1996 Mercury Marquis with 122,xxx miles and 4.6l v-8 is running horribly. Car looks stunning and has been garage kept all it's life. However, it recently starting missing while driving down the road, it then began idling a little rough, and has quit a few times when putting it into reverse. I assume it's all related to either bad plugs and/or plug wires. I've never worked on a 4.6l before.

Took it up to autozone, they scanned it and 4, 5, and 7 are misfiring. So, again I'm thinking bad plugs and or wires. I bought both, Duralast wires, Bosch platinum plugs. Not sure if I should upgrade the wires or not. Also, not sure if I need to upgrade to Bosch Double Platinums as some internet searches have suggested. Some of those same sights suggested staying with OEM wires which are Motorcraft...at least I think they are.

Some searches said that the plugs will be gapped correctly from plug manufacturer (1996) for this year 4.6l. What I can't locate (I don't have a manual, but may get one.) is what the factory gap should be...if I even need to change the gap on the new plugs.

That said, does anyone have any other suggestions on tuning this 4.6l up? Fuel filter change, pcv valve, etc.? Car has always ran stellar and was baby'd it's entire life.

Are the plugs down inside the heads on this car like some of other models from 2000 on?

Someone told me some of the plugs were in the back and that I'd need to remove a bunch of stuff along the firewall just to get to them. I've changed plugs on much older v-8's of yesteryear ('89 and further back), but something this new is new to me.
 
Look for the Vehicle Emissions decal...
usually located somewhere near the front of the engine compartment.

Type and gap of sparkplug should be found there.

Note:
Aren't Bosch's plug-gaps already preset?

Good Luck Bill!!


Bob
 
The original equipment brand for mercury( and any ford brand car) is motorcraft with that said a tune up may help though it may be a bad coil pack as for the spark plugs it will be located on both sides of the engine you may have to follow the wires and remove some things but its well worth it lastly the gap is 0.54
 
I just had one of those moments just now. One of those...DUHHHH...moments.

I knew there was coil packs on these engines, but...

Being that I was stupidly thinking Chevy 350's, thinking that it'll be an easy plug and wire replacement, I am now thinking that this job may get more involved than I thought and may take me longer than my health will allow me to tackle at this time. I may be better served taking it to my mechanic.
 
I have never worked on one of these but with that many miles I would swap out the plugs. I beleive Ford uses a coil set up instead of plug wires. You may want to double check that. I would not buy into Bosch's claims. I took a quick look on autozone and I would recommend iridium plugs from Autolite (XP104) or NGK (7164). I would stick with the OEM gap. The plugs should already come pre-gapped but I would double check to be sure. I would also recommend you use some anti-seize on them as well when you install the new ones. A fuel filter, air filter, oil change and pcv valve change would be good. Even cleaning the throttle body as well. You may want to look into flushing the coolant system and possibly changing out the transmission fluid and filter.

I would recommend you find some youtube videos or write up on how to do some of these things. It's a good way to learn and get your hands dirty. Plus it saves you a lot of money if you can do basic maintenance.
 
Learn something every day...and if you don't...well, then you aren't trying hard enough.

That said...

1996 has plug wires, and newer models have coil packs...and there are no wires if it has coil packs...at least from what I'm currently being told.

Just spoke with my dad and he said his 2006 F150 doesn't have wires, but does have coil packs. I certainly did NOT know.

My engine does have wires, so I'm still hoping this will be an easy job. If I'm going to the trouble to change anything, it'll be both wires and plugs.

Bosch and other plugs may come factory set, but they aren't going in unless I check them.

Guz...if this turns out to be easy...Lord knows I need to save money...then I'll do all of what you mentioned myself.

Now the tranny flush...well that's another issue because I'm getting a little shimmy from the tranny which tells me there's something else going on there that'll require a masters hand. That said, I have been, and will be checking out more videos and write-ups.
 
Hoytman said:
I just had one of those moments just now. One of those...DUHHHH...moments.

I knew there was coil packs on these engines, but...

Being that I was stupidly thinking Chevy 350's, thinking that it'll be an easy plug and wire replacement, I am now thinking that this job may get more involved than I thought and may take me longer than my health will allow me to tackle at this time. I may be better served taking it to my mechanic.
Click to expand...
Here you go Bill...

1996 Mercury Grand Marquis Manual:
MERCURY 1996 GRAND MARQUIS MANUAL Pdf Download.

Table of Contents:
Table Of Contents - Mercury 1996 Grand Marquis Manual [Page 3]

Sparkplug information:
pg. 294

Coil location:
Mercury 1996 Grand Marquis Manual (Page 201 of 329)
Mercury 1996 Grand Marquis Manual (Page 240 of 329)

Bob
 
If I recall correctly, and I may not, none of the 4.6l engines came with distributors. I actually was working for Ford and went to school for this engine at the time. If you have the set up I recall, you will have spark plug wires and coil packs - but the coil packs are in 2 banks of 4 mounted on each cylinder bank - not over the individual cylinders like is common today.

My guess would be one of those coil packs is bad, although changing the plugs and wires may also be a good idea depending when it was done last. I would find try to find out if all the misfiring cylinders are fed by the same coil pack.

The coil packs look like this:

meqeqany.jpg


But, before you spend a nickel, I'd check the wire harness and connections, especially around the coil packs, for broken/cracked wires or damaged connectors. That is free to do. Also, check for corrosion or burning where the spark plug wires connect to the coil pack.

Another easy/free thing you may be able to do is swap the coil packs side to side and see if the misfires go to opposite cylinders. But, you'd have to check if the coil packs are the same part numbers first.

Keep us posted.
 
With platinum plugs, you can't regap them, it will pop the platinum Coating. I would double check, but don't get to tapping or prying them.

It seems you have a coil pack issue.

Sent from my SAMSUNG-SGH-I777 using AG Online
 
swanicyouth said:
If I recall correctly, and I may not, none of the 4.6l engines came with distributors. I actually was working for Ford and went to school for this engine at the time. If you have the set up I recall, you will have spark plug wires and coil packs - but the coil packs are in 2 banks of 4 mounted on each cylinder bank - not over the individual cylinders like is common today.

My guess would be one of those coil packs is bad, although changing the plugs and wires may also be a good idea depending when it was done last. I would find try to find out if all the misfiring cylinders are fed by the same coil pack.

The coil packs look like this:

meqeqany.jpg


But, before you spend a nickel, I'd check the wire harness and connections, especially around the coil packs, for broken/cracked wires or damaged connectors. That is free to do. Also, check for corrosion or burning where the spark plug wires connect to the coil pack.

Another easy/free thing you may be able to do is swap the coil packs side to side and see if the misfires go to opposite cylinders. But, you'd have to check if the coil packs are the same part numbers first.

Keep us posted.
Click to expand...

Haven't been home yet to look, but if they're located where they are in that photo, then this should be relatively easy.

I already bought wires and plugs, but I'm goint to do some of those tests first. Swapping the packs to see if the cylinders switch would require me to drive to the autoparts store. In that case I might ought to see how much the coil packs cost and just replace them also.
 
I think the plugs are in the center of the head - BMW style. When you look at the head in the car, your not actually looking at the valve cover, but a plastic cover on the valve cover. IIR, that comes off and the plugs are fairly easy to get to then.

As for the tranny, you can try a lot of things... But, if it's torque converter shudder (when the converter locks up), I'd change the fluid to the recommended Ford fluid. Likely, that will not fix it.

However, I can tell you the transmission additives by Lubeguard usually will fix a torque converter shudder during lock up. They make 3 different products, this is one of them:

betahyma.jpg


That stuff looks like a 50¢ piece of junk, but it actually contains friction modifiers that can eliminate most torque converter shudder during lockup. Ford used to call it "chuggle and bump". Dunno where they got that from. The Lubeguard additives really do work well to fix this issue.
 
Okay...that was pretty easy even though the plugs were down inside the engine. Just used electricians tape to tape my plug socket to my extensions...which was a must for this job.

This particular 4.6l has the coil packs up front...2 banks of 4 as swanicyouth showed in the photo.

Decided that since I already had plugs and wires that changing the plugs, the least expensive of the two, would be my best and easiest route.

After plugs were in place I started it up and drove it 16 miles without a glitch. Not a single misfire...when before the code said 4, 5, and 7 were misfiring.

I will note the second plug from the firewall (drivers side...not sure which cylinder) was covered in oil...the entire plug and even the lower part of the boot. Considering how oily things were along the covers I'm assuming that's where the oil came from and leaked down from the top of the plug cover. Plugs were all worn about the same.

It'll be interesting to see if it fowls another plug. I did not try to gap the Bosch plugs. The gap was close to .054 on them anyway.

I still need to further investigate this tranny shimmy and that additive might work. However, while I'm investigating the tranny shimmy and before I have any work done on it I want to clean the engine bay up. With your guys help, maybe I can figure out how to get this fixed too.

Anyone have any suggestions on how to clean all the oil and dirty grime and sandy grit away from those spark plug boots and in the crevice of the valve cover covers?

Thanks to all you guys for your help and suggestions.
 
I'm going to take flack for this, but nothing cleans oil grime off leaking engines like Brake Clean. It's probably not good for you or the environment, but using it one time probably won't melt the polar ice caps or give you cancer. I routinely bathed in this stuff daily for like 7+ years - and I'm still alive. Get 3 or 4 cans. The stuff just works. No scrubbing required. Quite honestly, when I was working as a mechanic we would use tons of this stuff (along with Ardex Solvent) to clean up leaky engines and getting surfaces oil free for new gaskets.

It's flammable though. One day I'll have to tell you about the Jeep I lit on fire.

Occasionally, a valve cover gasket will leak around where the spark plug is located (especially if the plugs are in the center - like the 4.6l) and oil will puddle in the spark plug hole, leaking into the cylinder - and oil fouling the plug. It usually happens on the cylinder(s) closest to the firewall.

Does the trans "shudder" in all gears? Or, just high gear(s)? Is it slipping? Is the fluid burnt? Milky? Correct level?
 
swanicyouth said:
I'm going to take flack for this, but nothing cleans oil grime off leaking engines like Brake Clean. It's probably not good for you or the environment, but using it one time probably won't melt the polar ice caps or give you cancer. I routinely bathed in this stuff daily for like 7+ years - and I'm still alive. Get 3 or 4 cans. The stuff just works. No scrubbing required. Quite honestly, when I was working as a mechanic we would use tons of this stuff (along with Ardex Solvent) to clean up leaky engines and getting surfaces oil free for new gaskets.

It's flammable though. One day I'll have to tell you about the Jeep I lit on fire.
Click to expand...
I already have several of the red cans of Brake Clean. You're correct, it works great for removing oils and grease from brake parts. Never thought of using it on a grimy engine around plug wires and such for fear of drying them out.


swanicyouth said:
Occasionally, a valve cover gasket will leak around where the spark plug is located (especially if the plugs are in the center - like the 4.6l) and oil will puddle in the spark plug hole, leaking into the cylinder - and oil fouling the plug. It usually happens on the cylinder(s) closest to the firewall.
Click to expand...
I'll bet that's what happened too. This car has always ran flawlessly...aside from the tranny shimmy.



swanicyouth said:
Does the trans "shudder" in all gears? Or, just high gear(s)? Is it slipping? Is the fluid burnt? Milky? Correct level?
Click to expand...
Actually, a shudder or vibration as described here http://www.stangnet.com/images/stories/docs/sn95_TSBs/98-08-07.pdf seems to be the best description. It seems to occur a slow acceleration and speeds from around 30-45 ... or when it's lugging in over drive. Doesn't seem to slip any though. I got on it real hard after replacing the plugs and it shifted fine. If it was going to slip it should have done it at that time I would have thought.

As far as smelling burnt fluid, being milky, and correct level...I haven't checked any of that yet. Had a small mishap today with some onion seedlings I'm nurturing along...as in the wind knocked over the pot. Ever tried to replant 1000 teeny tiny onion seedlings by hand? Lets just say I was a bit flustered before working on the car and by the time I replanted things, and changed the plugs in the car I was ready for a break. My health hasn't been the greatest lately, so with all that my nerves were on their last leg. This was 'have to' mechanic work and it's not something I enjoy. Now tinkering around with a hot rod is right up my alley. I'll be glad when I can get to the relaxing part of detailing this car and making it shine.
 
Dad also informed me that this car was ordered with a special road handling package which included, dual exhaust, trans oil cooler, and what ever else that was included with that package...which would be nice to find out.

Apparently the tranny has had this problem before and a mechanic drained it and changed the filter and put in an additive that contained whale sperm as stated by the tranny mechanic. Could have been and might have been snake oil as far as I know.
 
I had a '96 Grand Marquis about 8 years ago. I had a miss and what I thought was a slipping trans. There were two things I did which in turn resolved both issues.

1. Do a tune up. It's just plugs and wires on that year, no distributor. If memory serves me correctly, there are only two coil packs, one per bank, but you shouldn't need to touch them unless the plugs and wires don't take care of any miss or rough idle you have.

2. The 4.6L engine has a TERRIBLE EGR (emission gas recirculation) system. The passages that lead into the egr (under the throttle body) will become caked with carbon. It can be easily cleaned once you pull off the housing.

Once I took care of the above, that engine purred like a kitten.
 
You must log in or register to reply here.
Back
Top