Changed Spark Plugs getting bad fuel milage

[ccm2001]

Seems like I'm getting 275-300km a tank
Changed all my plugs and ignition wires with all NGK properly Gapped and tourqed.
Old spark plugs were burnt.

Also changed my fuel filter ?

Thanks

 

[Tyleryac]

You experienced worse mileage after the plug change?

 

[ccm2001]

You experienced worse mileage after the plug change?

Correct

 

[Tyleryac]

When I changed my plugs, my gas mileage improved.

Here is somethings that may have gone wrong when you changed your plugs/wires...
1) You reconnected the plugs improperly (wrong firing order)
2) Your engine might not like the NGK plugs and wires
3) Perhaps a foreign substance got in the engine when changing plugs. Did you use compressed air to clean out where the plugs go?

That is what I can think of.

 

[lincolnshibuya]

stick with OEM, i.e. Motorcraft plugs.

 

[Tyleryac]

stick with oem, i.e. Motorcraft plugs.

+1

 

[Number4]

Have you run a tank of gas sense?

 

[rocket22]

Ugh, I agree

Is there ever a reason to switch from OEM plugs? Cost difference is minor if any. You end up trying to diagnose the issue you have introduced when the replacement is not exact. Don't waste any more time, get the OEM.

Again, I must be getting old, in my younger days I would have put in what ever was on special or thought would work better, prob one of those multi point plugs.

 

[ccm2001]

I'm gonna switch them over this weekend again... Lol was a pain for these 4.0l engines. Actually the NGK cost more then the Motocrafts.

Ordered from RockAuto

Thanks guys!

 

[ccm2001]

Have you run a tank of gas sense?

What do you mean? I've ran about 15 tanks of gas and noticed big decrease. Then again my gas gage is all over the place can never stay in one spot. Especially if I'm going over hills etc

 

[JoshMcMadMac]

I'm gonna switch them over this weekend again... Lol was a pain for these 4.0l engines. Actually the NGK cost more then the Motocrafts.

Ordered from RockAuto

Thanks guys!

Are they just "standard" single-point NGK spark plugs? I believe the stock Motorcraft plugs were made by NGK, so you probably have "factory equivalent" spark plugs installed. I do not think swapping another set in will resolve the issue. What did you gap them to, and how much different is your fuel economy?

 

[Number4]

What do you mean? I've ran about 15 tanks of gas and noticed big decrease. Then again my gas gage is all over the place can never stay in one spot. Especially if I'm going over hills etc

Wasn't sure if you'd gone thru an entire tank or if you were just gauging based on the message center. My first tank after doing the plugs on my V8 wasn't great, but it improved with subsequent fill ups.

When I did my 05 4.0, the MPG's went from 13 to 17 immediately.

Champion (Federal Mogul) and AC Delco have both manufactured plugs for NGK as OE, the plugs will still say NGK on them. I believe this was just for domestic vehicles.

Everyone needs to get off the OE bandwagon. I use OE for parts they don't make aftermarket.
Ford does not manufacture parts. They farm the job out to the lowest bidder like everyone else.
Premium aftermarket parts are almost always better engineerd. Then again, it depends on your parts store and what they brand as "premium."

 

[Tyleryac]

OEM parts are still some of the most expensive parts on the market.