Strange issue

[Charger]

Hi guys ,been ghosting here for a while and learning about these HEMI's . Well I bought a 2004 1500 RAM with the 5.7. Long story short, I've had it for a bit over a month and in the process of changing all the fluids. I pulled a plug just to check and the electrode was worn down to the ceramic. A gap of .085 !! The ODB scanner was NOT throwing any codes. The engine just lacked power.
Well I changed them out with NGK 5306 and gapped then to .045 with dielectric grease and aluminum anit-seize. Well after that the mileage went form 15.5 to 12.4 MPG !!!!! I can just about watch the fuel gauge move. Do I need to remove battery cable and reset the ECU ??

Abit about me, I've twisted wenches all my life , rebuilt a few engines , tinker with outboards and resell them. I do all my own PM on every vehicle I've ever had, so this aint my first rodeo.

Any thoughts or advice is welcome, thanks.

 

[Casper]

Prior to adoption of the 100K interval RAM 1500 Hemi spark plug change interval was 30K miles through at least 2012 maybe even into 2014, for copper plugs. So no surprise that your gap was huge if the plugs had been neglected.

Conventional wisdom is the stock plug is the best option for the HEMI, unless you are heavily modified, and the NGK 5306 is the OE replacement for a 2004.

I'm curious why you gapped at .045 since all the documentation I've seen is .044 (minor difference I realize).

You did replace all 16 plugs, right? Because if you replaced just 8 and the others are as bad as the ones you replaced, the PCM may be pulling timing to prevent pre-detonation.

Otherwise I don't think the gap is going to make much difference. What kind of shape are your wires and coils in?

 

[Charger]

They're gapped at 45 simply cause I forgot the exact spec. Also my wire S.P. gauge had 45. so........

I changed all 16 plugs, Wires and coil pacs looked ok. All the old plugs were tan to light brown.
After talking with a few buds of mine , I'm starting to think maybe because the gap was so large and producing a weak spark that the ECU ran a lean mixture? Producing less power but better fuel economy. How does that sound??

 

[Casper]

If you disconnected the battery while changing plugs the computer should have gone into relearn mode upon start up.

So your theory isn't without merit.

If you did not disconnect battery, you should do so now to force the relearn anyway.

 

[Charger]

I disconnected the neg cable after reading this , Drove it a bit and its reading 10 mpg on the O/H console ................going to drive it a few days and report back. Starting to have a problem starting it up ,thinking the IAC needs a cleaning. It did this before disco the battery. By the way truck is bone stock w/ 35 psi in tires which are street tread.

 

[Charger]

Well no change.......... going the clean the TB and replace or clean the air inlet / charge temp sensor , I MAY have fudged it up pulling it apart......... lol

 

[Charger]

Replaced the air inlet / charge temp sensor and the PCV . Glad cause the PCV was clogged, I had been noticing condensation on the oil filler cap. Well now its reading 12 mpg. I know the O/H read out for mileage isn't that accurate just using it to go by. I'm ready to put the old plugs back in. Found out it does not have an IAC.

 

[Charger]

This is how worn the plugs were, some were worse








Throttle body was a mes........... Cleaned it up looks like new now




Intake is still a mess, I can only imagine what the backside of the valves look like ......
But its running much better and MPG's are back up.

 

[Casper]

Seafoam the intake?

 

[Charger]

Thinking about it ,but right now I'm fighting a "hard to start " problem thats not throwing any codes. I know that the PO replaced the fuel pump ,I can hear it running. From what I have read its probably a leaking injector. Cold starts are fine, warm starts it just turns over and its hard to catch. Also at times I smell raw fuel. If anyone remembers carburetors, it acts like a flooded engine. Running seafoam through the tank to try to clean them up.

Need to get a fuel pressure gauge...........more toys for the tool box