Tune Up With Msd Wires

[BlackDenali99]

Well I did a tune up on our 2001 Yukon Denali that has 96,000 miles. I pulled the original wires and AC Delco/NGK plugs and they were "worn" to say the least however the truck never ran rough and still had a fairly good idle, over all the factory stuff seemed to hold up fairly well.

 

On our trip from South Dakota to Ohio (roughly 1200 miles) with the stock parts still on I saw 13.8-16.3 mpg average was 15.3 mpg overall. The 13.8 was in South Dakota when we were driving into a pretty stout headwind, shortly after getting out of the wind our MPG improve significantly. The averages were taken from the trip computer and then verified by the old miles/gallons method. The trip computer proved to be pretty accurate for estimating MPG averages.

 

Once in Ohio I went to Jeg's and purchased the MSD wires for 2000-2005 GM Trucks. I also replaced the plugs with NGK TR55GP platinum plugs @ $2.99 at Napa. The overall tune up was not hard at all although the rear passenger side plug was a bit of a pain. Had I had better tools though it would have been alot easier but I was using my father in laws tools and they were limited.

 

On the trip from Ohio to South Dakota with the newly installed parts and going the same route I averaged between 14.8-17.5 MPG. average was 16.7 overall. So in all the tune up game me about a 1.4 mpg increase. I can't say for sure what gave me the gain however it did go up over all even when I was tooling around in town. I should also note that we had about 70-100 MORE lbs of cargo on the way home than on the way out. So it may be possible to get an even bigger increase but overall I was pretty happy.

 

The truck does seem to run better and much smoother than before, and it may even have a bit more power as noticed by the butt-dyno. Overall I would say it is worth the time, money and effort.

[C & A s Dad]

That right rear plug is a little intimidating. However, I found that a 3/8 drive flex head ratchet and 1" extension will allow direct access to it without using a universal joint swivel.

 

Did you put it back up with antiseize on the threads and electronic grease on the boots?

 

Hey, don't bother posting any pictures of that dyno test. Some things are better left read than seen.

[cmoore74]

Do you feel the MPG gain was mostly due to the original plugs being worn, due to the better wires and plugs, or a combination of the two (i.e. did you get better mileage ealier on in the life of the plugs and the tune-up just restored the MPG's you used to get or was this a definite improvement over the stock plugs and wires)?

 

I'm getting close to buying a tune and I've heard a plug change is in order with the tune and while I'm changing the plugs I might as well upgrade the wires (thinking Taylor wires but I may also look at the MSD wires).

[BlackDenali99]

I would say that the plugs/wires added to the overall MPG I have been getting. I would usually see about 14-14.5 mpg city and now it is closer to 15. Also the best mileage I have ever gotten on the truck on a road trip was high 16's, never once had it crossed into 17mpg territory until this tune up. I bought the truck with almost 75,000 on it so it is hard to say what it was getting before I owned it. I should also say that speeds on the trip were 70-75 the whole way and on the way back a bit faster at times, nearly 85. However when I hit traffic and was slowed down I would see better mpg. I am sure if I went say 60-65 the whole way and unloaded the nearly 300-350lbs of luggage and cargo I was loaded with I could have seen over 18 mpg.

[snogoer]

That's about maxing out that motor. It won't get much better unless you get a good tailwind.

 

While you can wait to 100k to change out the plugs it is hard on the wires and coils doing this because of the increased gap.

 

Once you get 55 to 60k on her, you should change out the plugs. It is much cheaper than replacing the coils and wires which become abused at that mileage.