Have a question about how often spark plugs need changed. I feel it`s a stupid question.. I`ve never owned a vehicle with just plugs and coil packs. I`m getting horrible gas mileage. I`m not getting any message alarms on bad sensors and I have fairly new tires air is up.

99 Jeep Grand Cherokee Laredo 4.0 straight 6

 

Have you had the Jeep long? A full tune up never hurts a vehicle. Check plugs, Filters, oil. The standard stuff. If you want to spend a bit more you can also change the O2 sensors. The more basic stuff you replace, the more you can eliminate from potential causes of bad mileage. Then again, these jeeps are not known for being stingy with the fuel.

 

I`ve had it for almost a year I`ve been keeping up on oil changes and filters etc. but I hate to say I haven`t had the plugs done. I`m not at all familiar with this type of electrical system..first time I`ve had one with out plug wires..lol I`ve worked on almost all vehicles I`ve owned, I`ve done a little on this one but haven`t gotten too deep with it. How often is the requirement on changing the coil packs? Yes they`re not at all stingy with the fuel..lol I`m avg 16 mpg on the highway, seems like it should be a little better..

 

My owners manual recommends new plugs every 30k miles, but since you have coil on plug, the service life of the plugs is a little longer. I couldn't hurt to replace them now, you have no real idea of how long those plugs have been in there.

 

Ok thank you, do I go with Baush Platnum plus? I know it isn`t the best but not the worst.

 

Champion plugs seen to work best, from a guy that was in the engine design dept, he said that the jeep engines are designed to work best with that plug.. I've tried others but always come back to OEM ones and get best preformace and durabality. Just my 2cents.

 

Great thanks! I appreciate you`re and everyone`s help..

 

CAT, I have a 2000 GC 4.0. that I bought from the original owner who never had the plugs changed. I changed the original plugs at 121,000 and there was hardly any center electrodes left on them. I checked the gap just for fun and they were over .080, new they are supposed to be gapped at .035. I put in Champion 4412 truck plugs now discontinued, but some parts stores still have boxes of them on their shelves. The coil packs are held on by 3 large bolts. Easy enough to remove then just lift them up and off the plugs as a single unit. Putting it back on just be carefull that all 6 boots sit squarely over the plugs then bolt it all down and your done.

 

Thanks! That was my next question, I was curious as to how difficult it would be to get the coil packs off..lol