4.7 Dakota questions.

[BeepBeepRR]

Ok I picked up a Dakota 4.7 the truck runs but is missing badly. I have tested a few things but am kinda stumped. Here is what I have tested.

Coil packs.
1,3 2,4 coils unplugged no difference in the way it runs. 5,7 or 6,8 it runs worse. Took number 7 coil out and swapped with number one coil and same thing. Number one unplugged no difference but the coil moved to number 7 worked good.

Fuel pump rail pressure was 55 psi.

Pulled the number one plug wet with gas. Checked voltage at plug on center pin 13 volts. checked signal wire from pcm i have a pulse on every one. And voltage on every one.

So now im moving on to fuel injectors. Then my last assumption would be cams could be worn and not opening the valves. Am I on the right track? What would be the next logical place to check.

 

[aeon280]

Pull the front cover and check the timing tensioner guides. They are nylon and do wear out.

 

[BeepBeepRR]

Well I think I found the source of the misfire. Someone used RTV to put the back of the intake back on. And well resulted in a massive vacuum leak. Also there is a crossover pipe that goes from head to head and then to the air box. The hoses that connect to the head were cracked way bad. So another huge leak. Also the valley is full of nuts.

 

[aeon280]

Yeah, that will do it.

 

[Bobby Sixkiller]

Hopefully that’s your problem. Looks like pack rats been in there

 

[BeepBeepRR]

I picked up an intake from Ebay for 65 bucks shipped. Should be here soon. Just need to source the rubber hoses for the crossover pipe. They are basically ccv crank case vent tubes. And the other one is a PCV valve that is built into the side of the filler neck. That hose feeds into the rear of the intake. The intake had a crap ton of oil in the bottom of it. I think the crank case vents were not working so the crank case built up pressure and forced oil up the filler tube and was sucked into the intake.

This is what the CCV tubes look like. This is not the one that came off the truck, But very similar. I need the 2 valves and the 3 rubber portions of the setup.

 

[BeepBeepRR]

Well replaced the intake and tubing still runs like crap. The problem is 1,3,2,4 coils when unplugged make no difference how the truck runs. Im going to pull the valve covers today to see if it has a few broken valve springs. Then rig up my bore scope and check out all the pistons. I also need to buy a compression test kit.

 

[Bobby Sixkiller]

The problem with 4.7s is if it gets hot the valve seats literally fallout. Then they hold the valves open. Probably a head. My guess

 

[BeepBeepRR]

I was reading this post.. Thats why Im leaning towards something with the heads. This guy has the exact same issue. exception is his is a 5.7

https://www.dodgetalk.com/forums/showthread.php?t=474882

 

[BeeKool]

Interesting thread.
I really like my Dakota with a 4.7 but have heard they can have issues with timing. Im going to bookmark this one.
Ive been able to get 200k from my 3.9 & 5.2L Gen 2 Dakotas. Id like to think my 2011 could do the same.

The fact that it still ran with the massive vaccumn leaks is impressive.

 

[BeepBeepRR]

It also filled the valley of the intake with oil. That’s how I found the massive leak it got so full it puked oil out the bottom of the rear of the intake. That oil ran down the trans and all over the exhaust. Probably. Quart on the ground.

 

[BeepBeepRR]

Pulled the valve covers and spun the engine over all rockers are doing their jobs. No broken springs or anything. Intake valves are opening and closing. As are the exhaust valves. Stuck my scope in all 4 front cylinders and each one looked good but they all look like they have been gas washed. As in no firing of the coils. I have checked all wires 13 volts to the center wire and 5 volt pulse to the outboard wire. All seems to be good with the coils.
So I pulled the rails and injectors and checked each injector 12.5 ohms resistance on every one of them. Plugged every one of them back into the harness and into the rail wanted to do a test for spray. All injectors fired at their timed event. So it’s not an injector issue. I’m stumped now. 1,3,2,4 are the issue not sure where to go with the next stage of testing.

 

[Bobby Sixkiller]

Have you ran a compression test

 

[Bobby Sixkiller]

What happens sometimes when the aluminum head gets too hot the steel valve seats drop down and don’t reseat fully. It’s pretty common on these engines. The old 5.2 and 5.9 had iron heads and didn’t do this.

 

[Andew Sury]

Had an 05 in my shop today. Unplugged 1.3.2.4 coils and no change in running. Looked at timing on scanner. Two degrees. Lower timing chain shot. So I put a Smith 500 through the block. 269k. Needs an engine.

The Dodge 4.7. Not a great engine.

 

[BeepBeepRR]

Have you ran a compression test

just did not good lol

 

[BeepBeepRR]

Update... the 4.7 is dead and not coming back..
Checked compression on 1,3,2,4 and it was not pretty. The **** they made these pistons out of looked like it was flakes mashed into a piston shape. Weird looking material.
1. 60
3. 120
2. 0
4. 60

 

[Bobby Sixkiller]

Must have been way lean for a long time.

 

[BeepBeepRR]

I figured they drove it for a long time like this.

 

[Slap Stick]

That is detonation damage from all the oil in the cylinders. Oil doesn't burn like gas.
Same thing on the Magnum engines when the plenum gasket blows. Oil gets sucked into the cylinders and when you nail the gas you hear the rattling.