Jim Henderson
Dedicated LVC Member
Finally did the plugs on my 2004 LS V8 last weekend. I have NO CLUE if any of my comments apply to the V6.
let me say of the 20 or so cars I have owned/worked on, the LS is probably the biggest PITA to change plugs on. Only car that came close in the past was my 79 TA which required working thru the wheel well for a couple plugs. Got the wrist motor oil tatoos to prove it from slicing my wrists working on the TA.
Anyway, it took me about 3 hours not rushing this week end to change all the plugs. I am a reasonably capable shadetree mechanic, i.e. I rarely stab myself with a the screw driver. If you can change plugs on ANY other car, you can change the plugs on the LS, with some time, patience and a bunch of ratchet extensions etc.
Tools you will need are a 7mm socket and perhaps an open or boxend wrench preferably with an offset. You will need the 7mm to remove the coil screws(1 per plug) and the 6(8??) per side screws for the coil valve cover plates. The reason I say an offeset wrench is handy is that one or two screws are almost impossible to get a ratchet onto and since the screws sit down in a shallow detent, a flat wrench may not work. Ideally an offset ratcheting box wrench would be great, if it fit down into the detent. I mostly used my 1/4 inch ratchet set for the screws and my 3/8 for the plugs. I did use an air ratchet for fun on some screws escpecially since the screws take so long to do manually. But clearance is a problem on most screws.
Only other tools you will need are various assortments of extenders, universal joints, wobbly extenders etc to get at the screws and or plugs. Some require you you reach way down past stuff and some you will wish you had a very low profile ratchet since there are a couple screws where there is almost no room to get in there.
Each coil has a small flat " lever" at the end of the connector. This needs to be squeezed or pushed down GENTLY to unlock the connector. I also discovered it helps if you can kind of pull it up as you reconnect the connector since many of them did not "Snap" as they locked. Do not break that lever, I have read that then you have to jury rig some way to lock the connectors in place.
All the plugs are down a tube and will require a sparkplug socket, forget the size but it is common and used on the smaller sized plugs. It should fit down into the plug tube, Mine was a close but easy fit. You will need at least one 3 inch extender since the plug is down deep. More and different sizes may be a must.
The most difficult plugs to remove are the ones on the passenger side. The rear most is difficult to get at since you need an extension that is JUST Right to fit into the plug tube AND not hit the firewall and some wiring/tubing in that area. Also getting at the lower cover screw will need a short socket. A universal joint or a flexible shaft may be required.
The second rearmost plug is a beach to get at due to a couple connectors and wire bundles that get in the way. It may be just easier to disconnect and move the connectors, but the crackly sounds all the plastic POS make on our cars worried me. The right combination of extenders will work.
The front passenger plugs are easy although the second low screw on the cover might need a short socket.
The driver side plugs are easy to get at once the cover is off. The back one might be easiest with a universal joint.
A LONG extender will help a lot on I think the 3rd plug back since it has to get past some tubing/wiring? in front of the master cylinder. The extension should just fit down thru the snake nest.
The back lower cover screw is the pita that requires either a very low profile socket or an offset wrench. I had to turn it maybe 1/4 turn at a time, pita.
My car has about 116000 miles on it and I think the dealer replaced the originals under warranty back at around 30K?? Factory was NGK. The plugs the dealer used were Motorcraft AGSP32FSM and were the textbook picture of a normal worn plug. The Motorcrafts have that tiny needle like electrode.
The replacements were Champion 3071 Platinums with a "normal" looking electrode.
Before changing I had some intermittant stumbling under moderate to hard acceleration, especially at freeway speed. Also the car would stumble sitting at a light and maybe every other day or so the Check engine light would flash and or stay on.
It is amazing how much BETTER my car runs with new plugs. At idle you almost don't know it is running. My gas mileage didn't seem to suffer much though. It is still too early to be sure if it went up any after the change.
Hope this info helps other V8 owners. Sometimes a stumble or check engine light is not always bad coils. My coils were replaced under warranty along with plugs way back. The coils and spark plug tubes were clean, so the new valve cover gaskets must be doing their job.
Jim Henderson
let me say of the 20 or so cars I have owned/worked on, the LS is probably the biggest PITA to change plugs on. Only car that came close in the past was my 79 TA which required working thru the wheel well for a couple plugs. Got the wrist motor oil tatoos to prove it from slicing my wrists working on the TA.
Anyway, it took me about 3 hours not rushing this week end to change all the plugs. I am a reasonably capable shadetree mechanic, i.e. I rarely stab myself with a the screw driver. If you can change plugs on ANY other car, you can change the plugs on the LS, with some time, patience and a bunch of ratchet extensions etc.
Tools you will need are a 7mm socket and perhaps an open or boxend wrench preferably with an offset. You will need the 7mm to remove the coil screws(1 per plug) and the 6(8??) per side screws for the coil valve cover plates. The reason I say an offeset wrench is handy is that one or two screws are almost impossible to get a ratchet onto and since the screws sit down in a shallow detent, a flat wrench may not work. Ideally an offset ratcheting box wrench would be great, if it fit down into the detent. I mostly used my 1/4 inch ratchet set for the screws and my 3/8 for the plugs. I did use an air ratchet for fun on some screws escpecially since the screws take so long to do manually. But clearance is a problem on most screws.
Only other tools you will need are various assortments of extenders, universal joints, wobbly extenders etc to get at the screws and or plugs. Some require you you reach way down past stuff and some you will wish you had a very low profile ratchet since there are a couple screws where there is almost no room to get in there.
Each coil has a small flat " lever" at the end of the connector. This needs to be squeezed or pushed down GENTLY to unlock the connector. I also discovered it helps if you can kind of pull it up as you reconnect the connector since many of them did not "Snap" as they locked. Do not break that lever, I have read that then you have to jury rig some way to lock the connectors in place.
All the plugs are down a tube and will require a sparkplug socket, forget the size but it is common and used on the smaller sized plugs. It should fit down into the plug tube, Mine was a close but easy fit. You will need at least one 3 inch extender since the plug is down deep. More and different sizes may be a must.
The most difficult plugs to remove are the ones on the passenger side. The rear most is difficult to get at since you need an extension that is JUST Right to fit into the plug tube AND not hit the firewall and some wiring/tubing in that area. Also getting at the lower cover screw will need a short socket. A universal joint or a flexible shaft may be required.
The second rearmost plug is a beach to get at due to a couple connectors and wire bundles that get in the way. It may be just easier to disconnect and move the connectors, but the crackly sounds all the plastic POS make on our cars worried me. The right combination of extenders will work.
The front passenger plugs are easy although the second low screw on the cover might need a short socket.
The driver side plugs are easy to get at once the cover is off. The back one might be easiest with a universal joint.
A LONG extender will help a lot on I think the 3rd plug back since it has to get past some tubing/wiring? in front of the master cylinder. The extension should just fit down thru the snake nest.
The back lower cover screw is the pita that requires either a very low profile socket or an offset wrench. I had to turn it maybe 1/4 turn at a time, pita.
My car has about 116000 miles on it and I think the dealer replaced the originals under warranty back at around 30K?? Factory was NGK. The plugs the dealer used were Motorcraft AGSP32FSM and were the textbook picture of a normal worn plug. The Motorcrafts have that tiny needle like electrode.
The replacements were Champion 3071 Platinums with a "normal" looking electrode.
Before changing I had some intermittant stumbling under moderate to hard acceleration, especially at freeway speed. Also the car would stumble sitting at a light and maybe every other day or so the Check engine light would flash and or stay on.
It is amazing how much BETTER my car runs with new plugs. At idle you almost don't know it is running. My gas mileage didn't seem to suffer much though. It is still too early to be sure if it went up any after the change.
Hope this info helps other V8 owners. Sometimes a stumble or check engine light is not always bad coils. My coils were replaced under warranty along with plugs way back. The coils and spark plug tubes were clean, so the new valve cover gaskets must be doing their job.
Jim Henderson
. Much of that was spent cleaning various parts, looking for that damned pcv valve, and wondering why my passenger vcg did not fit. It was also my first time to do the job and that amount of engine work was new to me. All the v6 tech articles on this site are written for the gen1. They did help and I took photos to remember where all those intake bolts went, it helped. There are some obvious and some subtle differences in the engine from gen1 to gen2.