Anyone getbad mpg from these plugs? ever since i changed them my avg. dropped from 18-19 to 13-15. I think i may switch back to the factory plug.

 

I've been getting same to slightly better mileage since I switched, are you sure you gapped them properly?

 

Nope, I get about the same or just a few tenths better than before. The engine idles slightly smoother but I have noticed that the acceleration is much smoother with not bogs or hesitations as before. I gaped mine at 0.38 since the factory plugs where gaped at 0.36 to 0.38 but NOT 0.40. As you can see in my message above they printed the wrong information on the factory hood sticker about the plugs for the HO engine and sent me a revised hood sticker. So far, I like the 3923s.

 

Sounds like you are getting about right now, if you were getting 18-19 before, are you sure you were driving a 3rd gen Dakota??? [&:]

 

I'm Back!!!!! I hope everyone had a wonderful holiday..

Another question AGAIN about plugs....LOL

For those that have the 4.7L HO engine. I do not think running 3923's is a good idea....
from the factory the plugs are Champions - RC7PYCB4 correct???? the Autolite replacement plug should be a 3922.. Yes, isn't
this plugcolder than the 3923'S

http://www.autolite.com/pdf/SparkPlu...ringSystem.pdf

Autolite plug numbers ending in a 4 indicate that the plugs are the normal heat range. As this last digit decreases, the heat range becomes correspondingly one range colder.

So, is the 3923 a hotter plug???? and I do not think you want to use a 3923 in a 4.7LHO engine..[:@]

Using a 3923 plug in a non 4.7L HO engine is fine, one stage colder than a 5224 or 3924

some one correct me if I'm wrong !!!!!

 

the 3922 plugs should be used with nitrous or boosted applications. these plugs are two steps cooler than the factory champions. the normal 3923 plugs will work fine in the ho 4.7. have been running the 3923 plugs with my cam and pcm upgrades without any problem

 

OK... not going to argue about it , I guess the Autolite web site is wrong.....[:@]

but here is the link fom Autolite... This is for the 4.7L HO engine using a Champion RC7PYCB4


http://www.power-21.com/honeywellpow...b4&em=True

 

look at each plug next to each other, they are the same the heat range for both are d-11 the only difference is the pop code for the 3922 it is d which states fair moving parts and the 3923 states code a which is fastest moving parts. so i think the web site has some misinformed stuff

 

so I just came in from changing my plugs on an 05 3.7L QC, after 18K miles. The original plugs were NGK-R ZFR6F gapped at .046". up until now my mileage has been a dismal 13-15 mpg. From what I'm reading, these were the wrong type plugs to have?? Anywho, hopefully my mileage will be better along with a smoother run, we'll see

 

Idono what’s going on but this miss gap thing and wrong plugs is crazy. I say we take over the Warren Ave engine plant because they lost it four years ago and isn’t getting any better.