Injector not firing...

[steved]

What would it act like and would you notice if a single injector wasn't firing??

 

[JLandry]

I've played around with selectively killing injectors in my truck using a Chrysler DRBIII scan tool. You most definitely notice it at lower engine rpms. At idle it causes a distinct rhythmic galloping effect in the engine.



Best regards,



John L.

 

[GaryOwen]

Had a skip at lower rpms that would clear up at about 1400 to 1600 rpms. Had mechanic check injectors by kill test. It was idling rough initially, and when a good injector was killed, it would run even rougher. When the bad injector was killed, there was no change. Not sure what type of tester he was using to kill injectors.



Gary

 

[Bob4x4]

Had a skip at lower rpms that would clear up at about 1400 to 1600 rpms. Had mechanic check injectors by kill test. It was idling rough initially, and when a good injector was killed, it would run even rougher. When the bad injector was killed, there was no change. Not sure what type of tester he was using to kill injectors.



Gary

Ob the 2nd gens you can loosen a fuel line,on the 3rd gens you must use the appropriate scan tool

 

[steved]

Idle is one thing... how would it drive??



Would acceleration or cruise be affected??

 

[MMeier]

Idle is one thing... how would it drive??



Would acceleration or cruise be affected??

Steve, when I had 2 act up a while back, it shook the whole truck at idle, once past ... say ~ 1800-2000- or so RPM it could still be felt, but not as bad, drove home a stack of trailers (1150 miles) at 75 MPH, did not affect cruise speed, mileage hurt a bit though.

 

[steved]

I had a little "thump" in the exhaust tone at idle and there was a little roughness (not smooth, but not choppy). The acceleration and cruise were smooth, and mileage never wavered.

I'm trying to determine if a single injector not firing (all the time) would cause a poor running condition... I'm wondering if it could be a intermittent thing and would only not fire at idle (most times) and fire fine at cruise/acceleration??

 

[MMeier]

Hard to say with these damn things... know what I mean? When those 2 quit on me, taking off was a PITA, had to slip the clutch and get the R's up, other wise it would die on me, then had to rev out to about 3k or it would fall on its face also. Once up to speed, not too much slowed it down, but could still feel the miss.

 

[steved]

I'm wondering if the ECM varies the voltage depending on load/RPM? And a weak solenoid would only show at lower voltage...

I am fairly confident I had a miss at idle, but everything seemed fine at cruise and acceleration...

 

[mberry]

Mine had an injector messing with me last summer. Usually, once I got on it getting on the freeway, it cleared up. It really only happened when the engine was not up to temp but it would fire if the RPM's went up, even if cold. Sounds like we have sister or brother trucks that had/have the same symptoms. It hasn't done it once in several months now though.

 

[Bob4x4]

I'm wondering if the ECM varies the voltage depending on load/RPM? And a weak solenoid would only show at lower voltage... ...

Nope,,,,,,,,,just duration and timing are changed

 

[steved]

Ok, well the duration of the voltage applied to the solenoid would make a weak solenoid actuate at longer duration... right?

 

[Bob4x4]

Not longer. but if it was slow to react it would throw the timing of that cyl off.

Have you tried a new fca yet?

 

[steved]

The problem resolved itself... but yes, I did install a new FCA with no change.

Check this out:

https://www.turbodieselregister.com...-2003-2007/203461-i-m-done-3.html#post2010480

The injectors seem to have been the issue... just trying to understand it...

 

[ktb]

my truck had a miss fire at idle and under low engine load most noticable when the engine was warmed up turned out to be a lose nut on the injector i was impressed with the tech. found that before he started changing parts

 

[steved]

I checked the injectors while I had the cover off to ensure this wasn't the case... I wish it would have been that simple.



Besides, they had acted up, been removed, reinstalled, and still had the issue... I'm sure a loose nut would have been caught at some point.