Changed out new plugs and mpg went up?

Status
Not open for further replies.
C

Chris142

Joined
Jun 5, 2003
Messages
30,619
Location
Apple Valley, California
I've been chasing a bad mpg problem with my Jeep for a few weeks now.

Original thread---->
http://www.bobistheoilguy.com/forums/ubb...rue#Post2317313

We found a vacuum leak at the throttle body. I replaced the throttle body with a good used one and my mpg was still in the toilet. I then replaced the 02 sensors with new OEM ones.

Still got 11-13mpg.

About 4 months ago I replaced the spark plugs with new ones. The exact ones that the Jeep calls for and the same number that it came with when I bought it new.
Champion RsomethingEE.

Anyway. Fed up with terrible milage. Changed out the 140 gear oils for 80w90, drained the 15w40 from the engine and put in 10w30 etc.

I pulled the Champions out, checked the gaps(were ok) and they looked good. Still drinking gas!

Bought some Autolite APP985's to try since it liked the last set I used before I put the new Champions in.

Did some off roading today. Slow stuff that wont get very good mpg anyway.

Filled up and checked my mpg. I got 15.8 mpg!

While not great this is where it should be. I actully got better mpg crawling around in the desert with new Autolite plugs than I got with the new Champions on the hwy!

We reciently had a thread where Champions were bashed and I defended them since I had never had a problem with them until now.

The Champoins look fine, no codes etc. How could they effect my MPG that much?
 
I worked at a Dodge dealer and we actually had bad Champion plugs right out of the box. We did a tune-up for a customer and after it was all done the vehicle would not start. The tech felt pretty stupid after doing all that and the vehicle won't start. Well they checked everything and in the end figured why not try to swap the plugs out again? That was it! Just because they are new does not mean they are good. I do not personally feel it is any particular brand. I think the quality of most stuff at this point is really going downhill be it automotive or not.
 
Originally Posted By: powayroger
You also put in a thinner oil which could increase the mpgs.
3 weeks ago and 3 tanks of gas ago. Changing to the thinner oil made no difference
 
Run a Fuel System Cleaner....like RedLine Sl-1....Should give a little extra MPG...as well as clean out your fuel system. Best to put in fuel tank (last fill-up) just prior to your OCI.

Also....a dose of MMO (3 oz. per 10 gal. fill-up) could help your MPG....and provide additional power....but you must do it every time you fill.
_____________________________________________
03' Ford Focus (2.3L Duratec PZEV) / 99K
PP 5w20 / Purolator PureOne / OCI: 8K +/-
 
Originally Posted By: 71Chevyguy
Just because they are new does not mean they are good. I do not personally feel it is any particular brand. I think the quality of most stuff at this point is really going downhill be it automotive or not.


Just like home air conditioning systems. I was told by an AC repair company owner(my brother) when I have to replace my AC the new one won't last as long as this one that ran ALL DAY TODAY again! It's 23 years old.

How's the air filter? I have a funny way of checking them. On a clear day hold it up to the sky and look at it. New ones pass a lot of light. STP are made in USA.
 
Last edited:
I like Autolite plugs, I have them in all 3 cars listed in my signature.

If it is working then don't mess with it now.
 
I found changing the fuel filter in my mustang -very low mileage but it was an 2001 - REALLY helped MPGs.

It also stopped it from a random (very random) stall out. It would stall withing the first 30 sec. of starting (hot or cold motor made no difference) It would happen once or twice a week and it would never take more than one turn after that.
 
Jeep doesn't use a replacable fuel filter. It's a lifetime filter in the pump and the pump is pretty new. I've ran tons of injector cleaner through it in the last 2 months.
 
Originally Posted By: Chris142
Jeep doesn't use a replacable fuel filter. It's a lifetime filter in the pump and the pump is pretty new. I've ran tons of injector cleaner through it in the last 2 months.

What 'injector' cleaners did you use. Most of them are pretty useless.

The following three are the best: Techron, Gumount Regane and RedLine Sl-1....the Sl-1 is my favorite.
____________________________________________
03' Ford Focus (2.3L Duratec PZEV) / 99k
PP 5w20 / Purolator PureOne / OCI: 8k +/-
 
A jump /increase of MPG that is that massive would have meant the old plugs were misfiring so badly you could feel it, and no doubt would have set a code.
Keep an eye on your future readings.
 
Just one tank at the "higher" mpg after the change or multiple tanks? I'd wonder after one tank, and see a trend after a couple before I get too excited...
 
Fixing the vacuum leak was probably the MPG KILLER. The other things you done were minute when it comes to increasing the MPG.
 
I'm on my 2nd tank. Before I changed the plugs, @ 100 miles into the tank I would be down near 1/4 tank. I'm still above the 1/2 mark. I was getting a consistant 160 miles to 15 gallons of gas.

I'll know more when I fill it and divide the miles driven by gallons used.

Warstud:I replaced the leaking throttle body a couple weeks back and it made no change. Ran about 4 tanks of gas thgrough it since I replaced that.
 
I had a friend recently have a vacuum leak that was forcing it to run rich/open loop all of the time. It was flagging a 02 sensor code CEL too, but one after another inspection visually, we found one of the hoses had a hole in it. Replaced it and MPG up back to normal.
 
Status
Not open for further replies.

Similar threads

ctechbob
2018 Jeep Compass 100k+ Mile Plugs
Replies
3
Views
219
shortyb
U
2002 Sebring O/C and tune up
Replies
3
Views
262
harbor
C
Changing drain plug gaskets
2
Replies
21
Views
659
slybunda
C
More problems with Bosch spark plugs
2 3 4
Replies
60
Views
2K
si1491
S
Spark Plug coating on electrodes, from pics?
Replies
10
Views
350
Sequoiasoon
Back
Top Bottom