Need some help, Sputter/knock.

[rugrat2553]

I was on my way home last night when I got into the throttle a good bit (not WOT). The truck made it close to 1/4 mile if even that before there was a pop. I coasted a few hundred feet into an empty parking lot where I got out of the truck and looked for any signs of oil/water. There was nothing. The fresh oil (changed Thursday) is still close to the color it was when I put it in. The oil pressure gauge show normal range, temp is good. The only changes to the truck that I did was I just installed a new MBRP 4" exhaust.



I went back to the truck this morning to check the oil and water. They both looked normal. I started the truck to see if I could hear anything and the truck sounded fine. Revved it up to 1500, still fine. I go to drive the truck home (4 miles) and when there is a load on the engine it sounds like it starts to sputter/knock. It sounds like only 1 cylinder making the noise. The only way I can think of to describe the sound is to say it sounds like the cars on TV commercials that either have bad gas or ran out of gas.





2003 HO. Auto 4x4. nearly 180,000 miles. New 4" MBRP exhaust

 

[HBarlow]

I was on my way home last night when I got into the throttle a good bit (not WOT). The truck made it close to 1/4 mile if even that before there was a pop. I coasted a few hundred feet into an empty parking lot where I got out of the truck and looked for any signs of oil/water. There was nothing. The fresh oil (changed Thursday) is still close to the color it was when I put it in. The oil pressure gauge show normal range, temp is good. The only changes to the truck that I did was I just installed a new MBRP 4" exhaust.

I went back to the truck this morning to check the oil and water. They both looked normal. I started the truck to see if I could hear anything and the truck sounded fine. Revved it up to 1500, still fine. I go to drive the truck home (4 miles) and when there is a load on the engine it sounds like it starts to sputter/knock. It sounds like only 1 cylinder making the noise. The only way I can think of to describe the sound is to say it sounds like the cars on TV commercials that either have bad gas or ran out of gas.


2003 HO. Auto 4x4. nearly 180,000 miles. New 4" MBRP exhaust

A good dealership with a trained and skilled Cummins tech can hook up their computer and run a cylinder contribution test which will test injectors and overall condition. It will cost you about one and one half hours of shop labor, Their equipment will produce a computer print of the results.

 

[rugrat2553]

A good dealership with a trained and skilled Cummins tech can hook up their computer and run a cylinder contribution test which will test injectors and overall condition. It will cost you about one and one half hours of shop labor, Their equipment will produce a computer print of the results.

Thanks for the suggestion. Hopefully I will be getting it to Southern Diesel Performance this week.

 

[cerberusiam]

You are in the mileage range for injector issues, and, possible fuel lift pump issues. The description could be an injector problem or it is just running out of fuel due to a failed LP. If you dan't have the tools and gauges a shop is probably your best choice.

 

[rugrat2553]

Just an annoying update: I bought an AutoEnginuity bundle to run the contribution test on the 03. The cylinder contribution test would not run. Just kept returning "No Data" as a result. It did monitor the rail pressure and at idle it was around 5300psi. Around 1500rpm it jumped to just over 6000psi. Are these numbers about right? The Lift pump has been replaced I think as there are 2 wires that go down the frame rails and stop somewhere around the tank. Since the AE wasn't able to run the contribution test I am going to end up pulling the injectors and either take them to Southern Diesel or Garmons Diesel.

 

[cerberusiam]

Idle pressure is about right for an 03. You probably should run or have run an injector return flow test to see what it says. Nothing like testing on the vehicle as much as possible.

 

[Dodge-Tech]

Did you check all of your intercooler piping rubber boots and clamps?

 

[rugrat2553]

Ummm... Yeah, Im an idiot.

I figured I would give everybody a laugh and tell ya what was wrong.

I did the injector return flow test twice to verify the results and both times the injectors returned 90-100ml of diesel. BUT, the test did show me what the problem was.


Wait for it...

Wait for it...

It was out of fuel. The fuel light did not come on and the gauge was showing between 1/4 and 1/8 tank. The reason the return flow test showed me that it was out of fuel was because I bought 5 gallons of RED Offroad fuel because I didn't want to spend the extra $2. 00 on highway diesel and knew the tank was low. After getting the truck up to temp and following the instructions for the return flow test, the CP3 and the injectors returned pure RED diesel.

So my only guess is that when I was accelerating hard that night, the pump picked up a bubble of air and was pressurizing it and overboosting that cylinder and detonating causing the knock? It sounds good to me. I have driven the truck enough to fill up the tank 3 times and it isn't making a sound. Boost gauge is showing 22psi max and the lie-o-meter overhead is showing 18+mpg.

Enjoy the laughs.

 

[jhenderson]

I love an honest man.