06 Cummins rail and backfire issue.

We had one that had a random "backfire" and we ended up having a bend tone ring for the crank position sensor. Was just off enough it would randomly lose a tooth.
 
RDPsmoker said:
We had one that had a random "backfire" and we ended up having a bend tone ring for the crank position sensor. Was just off enough it would randomly lose a tooth.
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Now that is an interesting thought. How did you figure that out? Could you see it deflecting or something?
 
You could see a bobble in rpms on the moduis. And after a sensor swap we somehow came up with just changing the tone ring out. Through us off for a long time because it only did it at idle and was an issue only after the rebuild.
 
I have a backfire in my race truck too. Mine happens when my flexalite fans kick on. I cost me a couple races before I figured it out it was doing it going down the track . The truck would run consistent numbers and then all of the sudden I would be off. Come to find out the fans would kick on and cause the motor to stumble and miss. Someone at the Scheid race came to me and said he heard the truck missing going down the track. I haven't been able to figure out why it does it but it must throw a spike or low voltage to the ecm.
 
Toolman said:
I have a backfire in my race truck too. Mine happens when my flexalite fans kick on. I cost me a couple races before I figured it out it was doing it going down the track . The truck would run consistent numbers and then all of the sudden I would be off. Come to find out the fans would kick on and cause the motor to stumble and miss. Someone at the Scheid race came to me and said he heard the truck missing going down the track. I haven't been able to figure out why it does it but it must throw a spike or low voltage to the ecm.
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Do you run standard batteries or a marine deep cycle battery? The reason I ask is a deep cycle cant handle a sudden spike very well and it will eventually kill the battery. I had issues in my puller where I was killing deep cycle batteries every season. A battery store told me to switch my starter over to a normal battery and leave all my other stuff like pumps on the deep cycle. Seemed to work. I wonder if like you said the fans are hitting and the battery cant recover fast enough from the initial hit
 
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Thanks Jeremy I am running a standard battery and it was an old one. I have since replaced it but it still does it. The weird thing is I have ran these fans for several years now and it never did it. I clanged my motor last spring and after that it started. I have checked all the connections and ground but can't seem to find it. Now I just make sure that before each run the fans are turned off.
 
Ok guys. using scanmaster on my laptop, the live data meter. The rail pressure at idle is 5100 psi. The fuel level input was only 28%.

Does this make any sense?

On a side note, never use glowshift gauges.
 
look under fast track data scan and it should tell you what the percentage should be at idle
 
Its been a while since I looked at one and I can't remember for sure but I would think as throttle is given and load increases it should. 28% to me seems high for idle but I've not got one here to scan
 
I know what part of the problem is now. As soon as the grid heater cycles, it pops out the tailpipe. It's causing an intermittent ECM code.

No idea how to fix it, besides deleting the grid heater.
 
Something back feeding power?
Could a fca cause spikes like that?
Also have you tried disconnecting the rp guage from the sensor?
 
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I think it has more to do with voltage variances to the ECM then anything. It is probably just a bad ground somewhere . I am going to go back though mine this winter and see if I can find it because it didn't do it last year, then after I changed the motor it did it.
 
Toolman said:
I think it has more to do with voltage variances to the ECM then anything. It is probably just a bad ground somewhere . I am going to go back though mine this winter and see if I can find it because it didn't do it last year, then after I changed the motor it did it.
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I found many threads about stock trucks doing this. The ECM is programed to cut the alt. from charging while the grid heater turns on and pulls it's 90 amps. I've read this is why you'll see the voltage drop even after a heater delete.

None the less, i need the heater and will be going through all my grounds again. From what i've learned, if i ever do a cummins swap again, I'll use a cummins ECM and programing, not dodges.
 
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