Injector issue?

[Turbowski]

Good evening all,

I have a 2006 Dodge 2500 4x4 with the automatic transmission. What I am noticing is every once and a awhile the truck hesitates to start. what I mean by that is it takes about 4-5 seconds to start instead of starting right up. It happens in warm weather and cold, maybe once every 15 starts or so. Also, there is a pretty good ticking under the hood while i am at cruise speed. once i get on it a little bit to get on the highway the ticking goes away. Also, when i rev the engine up it stutters on its way back down to idle. usually i only rev to 2500 or so. I did the self diagnosis by turning the key on and off a couple times to see if there was any codes in which there was none. I took the truck to a local shop and the mechanic started the truck and put the throttle to the floor and it took about five seconds to start coming back down. The mechanic told me that it was a tell that the injectors are hanging up and that I shouldnt drive the truck because it may run away on me when I am getting on the interstate. The truck doesnt have a tuner on it and has 98k miles.

I also talked with a buddy of mine that works on these trucks and he informed me that the hesitation on coming down is normal for these trucks with the automatic transmission since there isnt a waste gate on the turbo. Sorry if this is a noob question. I am just paranoid and dont want to do to much damage.

The truck doesnt have any blow by and there isnt any gray smoke when I start it.

 

[Prairie Dog]

Wow, lots of bad info there!
The truck isn't going to run away on an on ramp or anyplace else. An injector could stick and burn a hole in a piston but it isn't going to result in a run away throttle condition.
And yes, you do have a wastegate - it is electronically actuated.

Some lag is normal, are you sure it was 5 full seconds?

 

[Ozymandias]

Mine does the same when revved up ant then let the throttle go to Zero.
Needs a couple seconds till it settles at idle. First Gen common rails have that "feature".

 

[Turbowski]

Wow, lots of bad info there!
The truck isn't going to run away on an on ramp or anyplace else. An injector could stick and burn a hole in a piston but it isn't going to result in a run away throttle condition.
And yes, you do have a wastegate - it is electronically actuated.

Some lag is normal, are you sure it was 5 full seconds?

I say it was 5 seconds but to be honest probably 3-4 seconds.

 

[Turbowski]

Mine does the same when revved up ant then let the throttle go to Zero.
Needs a couple seconds till it settles at idle. First Gen common rails have that "feature".

Ozy, does yours stutter on the way back down?

 

[Ozymandias]

Ozy, does yours stutter on the way back down?

I don't know the term stutter, but it goes down in steps, maybe 4-5 steps from 2500 to 800.

 

[Prairie Dog]

Steps are normal.

 

[Jihn]

First Gen common rails

Okay whats a first generation common rail ??? It's like calling a 5.9 and 6.7 a third generation, but they are not the same from whats being posted on here.

Jihn

 

[Ozymandias]

Okay whats a first generation common rail ??? It's like calling a 5.9 and 6.7 a third generation, but they are not the same from whats being posted on here.

Jihn

The once that came out 1998 from FIAT and Mercedes, they all had it.

In Europe we speak about Generations from the Commonrail according to the then needed Emission Label. Euro 3 to 6 now.
Every new Label needed new and better Technology, for example more Rail pressure, more Injection events and so on.

Our Gen3 5.9 is a first Gen with a slightly higher max. Rail pressure but otherwise basic, not a lot of electronic, just a couple needed sensors, a (compared to today) weak and slow ECM.
And one of this is the going down in steps if revved up to keep the rail pressure within a safe level.

..the Gen3 6.7 would be a second generation according to this.

 

[Turbowski]

I don't know the term stutter, but it goes down in steps, maybe 4-5 steps from 2500 to 800.

Thanks Ozy, Steps would be another way to describe it. I appreciate the input.

 

[cerberusiam]

Step down in rpms is not normal with a caveat. You cannot just rev and lift or you will get hanging and weird behavior as the fuel system tries to adjust and not blow itself up. If you hold the rpm steady for 10-20 seconds then lift you get a relatively smooth decel curve, might be some small hang sin there but relatively smooth. What need sot worried about is multiple hands in the 2 count range, that indicates the ECM is struggling to adjust fueling ramp down for some reason, usually because the injector mechanical's are not being predictable.

Try a good dosing with a lube and injector cleaner to see if that changes any behavior. A heavy tow with EGT temps at or exceeding 1000 degrees will also sometimes clean up rough running and\or decel issues. The fuel quality and in-cylinder carboning all play into how the engine revs and de-revs plus smoothness.

A problem would be haze or white smoke at an idle, at speed on the road a grey haze indicates injector issues and needs immediate investigation.

An injector can go from working perfectly to hanging open and melting pistons in minutes and for no apparent reason. At speed it is hard to notice that unless it is a major hang, at idle and acceleration a knock is the usual result of injectors hanging.

 

[Turbowski]

Step down in rpms is not normal with a caveat. You cannot just rev and lift or you will get hanging and weird behavior as the fuel system tries to adjust and not blow itself up. If you hold the rpm steady for 10-20 seconds then lift you get a relatively smooth decel curve, might be some small hang sin there but relatively smooth. What need sot worried about is multiple hands in the 2 count range, that indicates the ECM is struggling to adjust fueling ramp down for some reason, usually because the injector mechanical's are not being predictable.

Try a good dosing with a lube and injector cleaner to see if that changes any behavior. A heavy tow with EGT temps at or exceeding 1000 degrees will also sometimes clean up rough running and\or decel issues. The fuel quality and in-cylinder carboning all play into how the engine revs and de-revs plus smoothness.

A problem would be haze or white smoke at an idle, at speed on the road a grey haze indicates injector issues and needs immediate investigation.

An injector can go from working perfectly to hanging open and melting pistons in minutes and for no apparent reason. At speed it is hard to notice that unless it is a major hang, at idle and acceleration a knock is the usual result of injectors hanging.

Thank you Cerb, so what I understand is, don't worry about the step down since it's normal for these trucks mostly. And, I just need to run a good tank of injector lubes and cleaner through, then hook up to my travel trailer and take it for a trip.

 

[cerberusiam]

Yep, do that and re-test with what I described. You have to let the fuel system stabilize at any rpm before lifting or it will hang and step down. Most people make the mistake of doing a snap rev and that just means the self-protection is working.

I have a set of essentially 100 HP injectors that will smoothly de-rev if you stabilize the fuel pressure before lifting off the throttle. Try to snap rev it an it overshoots, smokes, hangs, and steps down in several big lunges until the ECM gets it under control.