Changing Spark Plugs

Hi guys. Does anyone have a step by step guide on how to change the spark plugs on a 1999 3.5 Intrigue. I'm pretty confident I can do this myself but need a step by step of what to do since I have never done it.

Also any recommendations for what plugs to use?

Thanks in advance.

Get the AC Delco brand NGK plugs for this car. Those are stock. On this forum and from owning 2 Intrigues, cheap plugs mean you will be re-doing them again shortly or immediately. Get a plug gapper and some plug grease. You will need a set of socket wrenches with a spark plug removal socket and the length adaptor for the socket. First you have to take off the engine cover 2 bolts 15mm socket I believe. Second you have to unplug both coil packs the one in front and the one in the back. The one in front is right behind the radiator fan just next to the oil pour cap. The one in the rear is straight back from that close to the fire wall. Some people even unplug the battery for this job I dont but, if you want to play it safe it's a good idea. Third there are several black bolts on the coil packs there are a total of 14-16 very easy to remove bolts. Then pull the coil packs up you may have to maneuver the rear one out but it isnt too bad. Inspect the rubber boots on the coil those wrap the plugs those should stay attached to the coil pack if they fall out make sure you put the thick end of the boot towards the pack there are a total of 6. You want to look for cracks or tears. Next get your socket wrench with your plug remover socket and the extension. Loosen all of the plugs so you want to turn them counter clockwise. I find with my sockets they dont pull the plug out. I have to use a set of curved needle nose pliers to remove them from the housing. You could try a normal needle nose. I imagine it would still work. Next you are going to want to gap the new plugs (the space at the tip of the plug where the spark happens) to .060 no more no less. To make the gap smaller I usually tap it with a hammer or whatever tool is closest to me. To make it bigger slide the gap tool until its at .060. Put the spark plug grease around the threaded part of the plugs. Insert plugs into plug housing and tighten clockwise. Make sure they go in straight!!! I usually tighten them just a little bit past the point that they stop. You deffinately do not want to overtighten or under tighten them that is a very costly repair. I am sure there are torque specifications if you are not confident in doing them this way. I have done it this way forever and never had a problem. Then you put the boots back on thick end towards the coil and insert the coils. You will have to maneuver the rear coil around a bit until it seats itself. Put the black bolts back on the coil pack tighten them and plug in the coils and the battery. Your done. Usually I get a could of white smoke on the first fire up with new plugs so dont be alarmed. I also have to wipe out the plug housings because I have bad cam seals on my 99 Intrigue So oil gets in there. Your going to want to make sure you didnt have any leaking in there as well. If it starts misfirng after completion let the engine cool and take apart again to make sure the plug gap is set at .060.

Next you are going to want to gap the new plugs (the space at the tip of the plug where the spark happens) to .060 no more no less. To make the gap smaller I usually tap it with a hammer or whatever tool is closest to me. To make it bigger slide the gap tool until its at .060.For the 3.5L, i've read it's .050 in the manual and .060 in Chilton's. Also from what i understand the .060 number is supposed to be for the 3.8l engine.

The oem plugs for the 3.5l have a gap of .050 which i think might be another hint.

Anyone have any definitive answers on that?

HINT!!!!: I learned years ago ----> keep an old spark plug wire, hold the spark plug end, then cut the wire, leaving 6-12 inches. Use THAT for your spark plug remover!!! As far as gap, 3.5L is .05

Get the AC Delco brand NGK plugs for this car. Those are stock. On this forum and from owning 2 Intrigues, cheap plugs mean you will be re-doing them again shortly or immediately. Get a plug gapper and some plug grease. You will need a set of socket wrenches with a spark plug removal socket and the length adaptor for the socket. First you have to take off the engine cover 2 bolts 15mm socket I believe. Second you have to unplug both coil packs the one in front and the one in the back. The one in front is right behind the radiator fan just next to the oil pour cap. The one in the rear is straight back from that close to the fire wall. Some people even unplug the battery for this job I dont but, if you want to play it safe it's a good idea. Third there are several black bolts on the coil packs there are a total of 14-16 very easy to remove bolts. Then pull the coil packs up you may have to maneuver the rear one out but it isnt too bad. Inspect the rubber boots on the coil those wrap the plugs those should stay attached to the coil pack if they fall out make sure you put the thick end of the boot towards the pack there are a total of 6. You want to look for cracks or tears. Next get your socket wrench with your plug remover socket and the extension. Loosen all of the plugs so you want to turn them counter clockwise. I find with my sockets they dont pull the plug out. I have to use a set of curved needle nose pliers to remove them from the housing. You could try a normal needle nose. I imagine it would still work. Next you are going to want to gap the new plugs (the space at the tip of the plug where the spark happens) to .060 no more no less. To make the gap smaller I usually tap it with a hammer or whatever tool is closest to me. To make it bigger slide the gap tool until its at .060. Put the spark plug grease around the threaded part of the plugs. Insert plugs into plug housing and tighten clockwise. Make sure they go in straight!!! I usually tighten them just a little bit past the point that they stop. You deffinately do not want to overtighten or under tighten them that is a very costly repair. I am sure there are torque specifications if you are not confident in doing them this way. I have done it this way forever and never had a problem. Then you put the boots back on thick end towards the coil and insert the coils. You will have to maneuver the rear coil around a bit until it seats itself. Put the black bolts back on the coil pack tighten them and plug in the coils and the battery. Your done. Usually I get a could of white smoke on the first fire up with new plugs so dont be alarmed. I also have to wipe out the plug housings because I have bad cam seals on my 99 Intrigue So oil gets in there. Your going to want to make sure you didnt have any leaking in there as well. If it starts misfirng after completion let the engine cool and take apart again to make sure the plug gap is set at .060.

Seriously? You think people even read this?

Hi guys. Does anyone have a step by step guide on how to change the spark plugs on a 1999 3.5 Intrigue. I'm pretty confident I can do this myself but need a step by step of what to do since I have never done it.

Also any recommendations for what plugs to use?

Thanks in advance.


Get Delco/ NGK plugs (I got mine at Autozone). They come gapped.

Get a thin walled, extended length 5/8" socket (also at Autozone).

Get some antiseize compound (also at, you guessed it).

Get some brake cleaner or carb spray.

Get a mirror.

Let engine get totally cold.

Remove connector to the coil pack and then these screws:
http://im1.shutterfly.com/media/47a0df33b3127ccef94c57a9abb700000030O08IZtXLZszag9 vPhI/cC/f%3D0/ps%3D50/r%3D0/rx%3D550/ry%3D400/


Carefully pry the coil pack away from the cylinder head cover:
http://im1.shutterfly.com/media/47a0df33b3127ccef94d1ed24a0c00000030O08IZtXLZszag9 vPhI/cC/f%3D0/ps%3D50/r%3D0/rx%3D550/ry%3D400/


Carefully remove any spark plug boots that stay on the plugs by lightly grasping with needle nose pliers and gently rotating while pulling. Make careful note of how they go back on the coil pack.

Use cleaner and either a MityVac or compressed air and a rag to clean the oil out of the spark plug holes that often builds up. A mirror helps see these, especially on the back side bank.

Replacing them is pretty straightforward, like any other car. Just don't forget to plug the coil packs back in.

That is odd. I'm still getting .060 plug gap. Even autozone said .060. Dunno. All I know is my plugs are at and have been at .060 for yrs and work great.

That is odd. I'm still getting .060 plug gap. Even autozone said .060. Dunno. All I know is my plugs are at and have been at .060 for yrs and work great.
i was actually assuming the .050 reference in another topic was in the service manual.

However, i've just now checked the actual regular Intrigue manual in the glovebox and it confirms it under Normal Maintenance Replacement Parts. (2000 intrigue manual)

Spark Plugs...... Type: PTR5C-13/12556183, Gap: 0.050 inches (.127 cm)

funnily enough it actually references the NGK part number and not the other AC delco part number of 41-980. (And of course inside the AC Delco box is an NGK plug)

would you guys suggest a tiny bit of dielectric grease anywhere or not bother because it's all protected by the coil pack?

would you guys suggest a tiny bit of dielectric grease anywhere or not bother because it's all protected by the coil pack?
OK, the OEM plug is GM part no. 12556183, a repackaged NGK PTR5C-13. Gap is .050. Torque is 15 ft-lbs. Anyone who tells you different is mistaken.

http://market.autopartsfair.com/images/products/engineparts/f100037153ngk.jpg

I used whatever the Zone sold me, some NGKs.

Factory mentions nothing about dielectric and I wouldn't use it.

Install boots onto coil pack then coil pack onto cylinder head cover.

That is odd. I'm still getting .060 plug gap. Even autozone said .060. Dunno. All I know is my plugs are at and have been at .060 for yrs and work great.

I am absolutely 100% certain that .060" is the correct gap for the 3800 (all - Series I, II, and III) and .050" is correct for the DOHC 3.5L.

Also FWIW the use of anti-seize with OEM plugs is not recommended on the 3.5L (but obviously won't cause a castastrophic failure either)

I am absolutely 100% certain that .060" is the correct gap for the 3800 (all - Series I, II, and III) and .050" is correct for the DOHC 3.5L.

Also FWIW the use of anti-seize with OEM plugs is not recommended on the 3.5L (but obviously won't cause a castastrophic failure either)

Yeah, thanks for making that clear. OP was talking about the 3.5.

I wish folks would read the OPs carefully instead of chiming in with irrelevant information and insisting they are right.

OEMs seldom recommended anti-seize on plugs for fear of ham-fisted shade tree DIYers slopping goop on electrodes. I think used properly, anti-seize helps offset the other hacks who take aluminum engines apart warm.

But I also think changing non-misfiring plugs is way over-rated.

Yeah, thanks for making that clear. OP was talking about the 3.5.

I wish folks would read the OPs carefully instead of chiming in with irrelevant information and insisting they are right. it is kind of relevant actually. He's just adding extra confirmation that the 3800 is partly the reason why there was confusion on the plug gap. in fact i brought i up earlier in this topic.

do a google search on intrigue plug gap and you'll see why it needs to be cleared up once and for all.

Thanks for all the replies. Haven't had a chance to do it yet.

I checked out the NGK's krivasauto mentioned and the gap is .052 instead of .05 will this make a difference?
http://www.kragen.com/ProductDetail.aspx?MfrCode=NGK&MfrPartNumber=7740&PartType=960&PTSet=A

Thanks for all the replies. Haven't had a chance to do it yet.

I checked out the NGK's krivasauto mentioned and the gap is .052 instead of .05 will this make a difference?
http://www.kragen.com/ProductDetail.aspx?MfrCode=NGK&MfrPartNumber=7740&PartType=960&PTSet=A

Are you getting some sort of special discount on those NGKs?.... as the same plug in the AC Delco box is $6.49 a plug at Advance, Oreilly, and a few other stores.

NGK boxed versions seem to run near $10 or more.

Thanks for all the replies. Haven't had a chance to do it yet.

I checked out the NGK's krivasauto mentioned and the gap is .052 instead of .05 will this make a difference?
http://www.kragen.com/ProductDetail.aspx?MfrCode=NGK&MfrPartNumber=7740&PartType=960&PTSet=A



A .002" difference is negligible. The NGK plugs come pre-gapped at .052", but GM specifies .050" (according to Mitchell On-Demand). I was going to point this out earlier, but I didn't want to confuse anyone anymore than they already were.