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View Full Version : CR's popping out the exhaust....let's get it on !


UNBROKEN
08-06-2010, 04:35 PM
I'm gonna stand by my and many others theory that it's from draining the rail.
I've seen one driving by me popping so bad the exhaust pipe looked like it was shooting out morse code signals.
Others contend it's a timing issue.
I've never heard timing "pop". Rattle, yes...
If pulling out some timing is stopping the "pop" in some trucks I contend that it's just due to making the motor just happy enough to live with low RP

We've all heard the popping noise.
WHAT IS IT?


For the record...I expect this one to get heated...so try to stay civil but put on your big girl panties just in case.
Now...let's figure this out....

DIESEL_POWER
08-06-2010, 04:54 PM
Could be draining the rail like you suggest, or it could be a timeing pop.


Drainin the rail and popping would be from not enough fuel.
timing popping would be from too much pre ignition before TDC.

And then there are head gasket failures that allow water or psi from other cylinders in the wrong bore that cause popping too.

Then theres the whole programmer finger pointer theory....

bbbxcursion
08-06-2010, 05:03 PM
Mine popped like crazy when I had a bad crank sensor. I thought I was draining the rail but it even did it on 1/2 power Smarty. Scoped the sensor and found out it was going crazy in the upper RPM band.

jeff115
08-06-2010, 05:08 PM
when my rail pressure got low it would blow grey smoke and pop really bad and it only did it when the pressure droped really low.

Forrest Nearing
08-06-2010, 05:34 PM
whenever I lost rail pressure, the truck just nosed over and lost power and rolled a crapton of smoke out the exhaust

LReiff
08-06-2010, 06:17 PM
Here is how I've experience popping and what I've tried, take it for what it's worth...back when Revo/TNT was first released.

Truck: '03 2500 auto 250 hp engine, stock injectors. Data logging while driving through a forced "pop" condition.

RP was any range

Fuel pressure from the LP never went below 15 psi.

Tried all RP settings, no change

Tried all the Torque settings and anything other than stock made it worse...hence my theory that torque adds timing

New fuel filter, no change

Swapped on a new CP3, no changes whatsoever, swapped back to original CP3

Capped rail, no change

New RP sensor, no change

Thought it was caused by low RP from slow reaction of the FCA when accelerating hard from a stop but I disproved that theory by accelerating easy until RP was at or above 10k before hitting it hard and it still popped.

By this time the customer was ready to call Bob and my hair was starting to go grey LOL

This whole time I had been back and forth between timing 1, 2 and stock...switched to timing 3 and it went away if torque was kept lower than 2, tried timing 4 and it disappeared altogether.


I've since tuned numerous other 03-04s with Revo/TNT and have set power between 5&7, Torque 1-3, Timing on 3 or 4, RP wherever and have never had popping problems.

More recent
On my '04.5 TNT/Race tune, I had popping with the large (200+hp) injectors until I set Timing to 4.

MissouriHooker
08-06-2010, 08:37 PM
You think it could be diffreant programmers? The triple dog I had did the popping thing real bad!, Switched to smarty and no more pop! Plus the tnt-r is way more aggressive then the crazy larry tune. Just a thought!

rams-n-hogs
08-06-2010, 08:52 PM
We've all heard the popping noise.
WHAT IS IT?





If we knew what it was, the problem would be solved.:D


All kidding aside, I've heard popping on 2 different trucks, but it was different on both of them. One was a blown head gasket, which kind of sounded like a miss. The other was caused by a pressure box, and it sounded almost like a machine gun popping out of the exhaust. Once the pressure box was removed, the popping went away. That led us to believe it was a pressure issue. I don't know if timing would pop out of the exhaust. I would think you would here it as more of a rattle.

jeff115
08-06-2010, 08:54 PM
for got this in my first post but, If I turned the pressure up it helped alot with the popping

Forrest Nearing
08-06-2010, 09:41 PM
You think it could be diffreant programmers? The triple dog I had did the popping thing real bad!, Switched to smarty and no more pop! Plus the tnt-r is way more aggressive then the crazy larry tune. Just a thought!

Bully Dog has **** for tunes on the 03-04 trucks :o

Sandaholic
08-06-2010, 10:19 PM
I don't know that I've ever even heard "rail pop". Timing rattle I have for sure. Any video's on youtube or anything that I can hear rail pop? I have heard plenty of rattle from my truck running different tunes and programmers. The timing rattle never seemed to be associated with rail pressure. So I guess I don't have a theory. I just want to know what this rail pop sounds like.

And why is it more of an 03-04 thing. Does it have something to do with the 3rd injection event in some way?

Forrest Nearing
08-06-2010, 10:36 PM
it has something to do with the tuning... it sounds like the truck is popping and banging out. it's not timing rattle, WAY different

jeff115
08-06-2010, 10:41 PM
sounds kinda like a ricer right before they launch when they start poping real loud

JasonCzerak
08-06-2010, 11:54 PM
sounds kinda like a ricer right before they launch when they start poping real loud

Import.


Ricer is a term used to describe "idiots", doesn't matter the vehicle they drive.

jeff115
08-07-2010, 12:02 AM
ok yes. import.

Dodgentwo
08-07-2010, 12:26 AM
sounds kinda like a ricer right before they launch when they start poping real loud

Its called a 2-step.

And I agree, it sounds like a automatic gun going off kinda.

7inchstack
08-07-2010, 01:10 AM
had it happen on my truck a few times, its only when i have the smarty on a tune that dosnt add timing. SW 2 and 6 have been the worst by far. if i put it back to SW7 its fine. also when its poping ive still got good rail pressure, so i dont think its draining the rail. im almost leaning more towards its a timing issue.

'strokeThis_'07
08-07-2010, 01:23 AM
Mine pops and surges with the Dr. P hooked up. Doesn't need to be turned up any, just plugged in it pops.

jordanjames81
08-07-2010, 03:16 AM
going to be watching this one.

rams-n-hogs
08-07-2010, 05:52 AM
Mine pops and surges with the Dr. P hooked up. Doesn't need to be turned up any, just plugged in it pops.

It was a Dr. P box that caused it on the truck I heard it on, and it is an 06, IIRC.

XLR8R
08-07-2010, 09:23 AM
One man's pop is another man's timing rattle...

there's conflicting anecdotal reports of the culprit being either pressure or timing because of their effect on each other.
Also, one wouldn't expect 555 & 600 series motors to deal with the issue identically - makes sense that re-entrant & non re-entrant combustion exhibits different characteristics as a result of insufficient rail pressure (consider how poor atomization interacts with the different angles).

When rail pressure drops below 10Kpsi, gray smoke & a certain amount of popping - along with power reduction - is sure to follow.
While max RP at idle will knock like a 12V with 3 dead holes, 30Kpsi+ drives OK under load (testing with a known bad FCA makes for some good data, and a certain amount of anticipation during tear-down!LOL)

Timing rattle - whether commanded by the ECM tune, roached FCA or other "failure", is distinctly different.

Popping from low rail pressure - whatever the cause - is mitigated by calling for more PSI (i.e. turn up the pressure box) if higher RP is able to be generated.

LReiff
08-07-2010, 09:49 AM
The POP that this thread is about is so noticeable that I've felt the truck shake from it, the power is not even when the POP is happening. A blind and deaf man could tell you that there is something going wrong.

Jack-Diesel
08-07-2010, 11:06 AM
We had a CR injector tip that was split ,it free revs and idles good no smoke or miss . Put a load on it pop's like hell. single pump never over 26000psi on the rail . It split two tips in 3 or 4 mo the first was like a broke injector does. Smokey missing ...... Just a smarty

R.C.inc.
08-07-2010, 11:26 AM
From my experience its timing

Big Swole
08-07-2010, 12:47 PM
Check the rotory cap or points!










lol

Delinquent
08-07-2010, 12:55 PM
is this the pop that is made up in the higher rpm's? or is this pop made at other times

jlibert
08-07-2010, 01:07 PM
he times i've heard rail pop, it sounds like a shotgun blast.

the popping that I've heard smarty cause isn't as loud, and is usually multiple pops.

badbowtie
08-07-2010, 01:16 PM
I hooked up a rp gauge in cab this morning. My truck with arson3 and stock injectors will hold 24k rp and pop like a shotgun at high rpms with timing set on 4 on TNT SW7 set timing to 3 and no more pop still holds 24k on ISSPRO RP gauge. Lost RP sensor last november so had new cummins RP sensor installed then. LP pressure never drops below 18psi.

Forrest Nearing
08-07-2010, 01:33 PM
One man's pop is another man's timing rattle...


one man's pop is an ignorant man's timing rattle...

they are two very different things

Dodgentwo
08-07-2010, 07:27 PM
Would a pressure relief valve that has "popped" have any connection to the popping problems? I just took the banjo off mine and there is diesel sitting in it and if I turn it over, it sprays out, obviously. I believe i read on the rail cap threads that this means my PRV is bad, or had "popped" and needs replaced or capped?

Also there is a FP gauge on the filter housing. It would usually read around 20 at idle when i first got the truck. it now reads closer to 15 at idle. I would assume this would be caused by the PRV blowing?

Another thought. When I first put my smarty on with TNT it would pop. I changed to REVO, didnt like it and went back to TNT. Put the timing up some and it cleared the popping up on SW7. Decided to try SW9 and the pop returned. After that it will pop on SW5-9 even and odd, no matter what timing?

Any thoughts

Dodgentwo
08-07-2010, 08:49 PM
No one?

Dodgentwo
08-07-2010, 09:58 PM
Man I figured this thread would take off a lot more.

rage_blue
08-08-2010, 12:10 AM
just throwing this out there, I have heard some really odd poping that we found to be cuased by a loose valve seat, it would come and go as the valve seat came loose.

JoshH
08-08-2010, 12:45 AM
It is possible the popping is caused by both low rail pressure and low timing or a combination of the two. Please understand I will have to make some assumptions since I have never seen the programming in a Cummins ECM (as I'm sure is the case with most).

When a common rail engine is attempting to inject a certain quantity of fuel, it has a table it references to determine how long to open the injector for a given fuel quantity at a given fuel pressure. As the pressure drops and/or the fuel quantity goes up, the amount of time the injector fires goes up. If the pressure were to drop low enough, the injectors could still be firing when the exhaust valve is opening (this would be much more likely to happen at higher RPM as the amount of time the injector fires does not change as the RPM goes up, but the amount of time you have from TDC to BDC does drop as RPM increases). Advancing the timing would advance the end of the injection event up by the same amount, possibly enough so the fuel is no longer being injected when the exhaust valve is opening.

Timing alone could also cause the same thing even without a significant drop in rail pressure. In order to increase power output in a common rail engine, the most effective way to do this is to increase the amount of time the injector opens (increase pulse width). If the pulse width is increased too much without increasing timing along with it, you could end up with the same scenario as above.

Of course, there are several possibilities for what is causing the pop, but I see those as two very possible tuning related causes.

Joesixpack
08-08-2010, 12:57 AM
It is possible the popping is caused by both low rail pressure and low timing or a combination of the two. Please understand I will have to make some assumptions since I have never seen the programming in a Cummins ECM (as I'm sure is the case with most).

When a common rail engine is attempting to inject a certain quantity of fuel, it has a table it references to determine how long to open the injector for a given fuel quantity at a given fuel pressure. As the pressure drops and/or the fuel quantity goes up, the amount of time the injector fires goes up. If the pressure were to drop low enough, the injectors could still be firing when the exhaust valve is opening (this would be much more likely to happen at higher RPM as the amount of time the injector fires does not change as the RPM goes up, but the amount of time you have from TDC to BDC does drop as RPM increases). Advancing the timing would advance the end of the injection event up by the same amount, possibly enough so the fuel is no longer being injected when the exhaust valve is opening.

Timing alone could also cause the same thing even without a significant drop in rail pressure. In order to increase power output in a common rail engine, the most effective way to do this is to increase the amount of time the injector opens (increase pulse width). If the pulse width is increased too much without increasing timing along with it, you could end up with the same scenario as above.

Of course, there are several possibilities for what is causing the pop, but I see those as two very possible tuning related causes.



There's no way the injectors are fueling until the exaust valves are opening, if it were the case you would have a chit ton of white smoke, or unburned fuel and a incredible amount of duration!

Don't have much input on the subject though, never have come across the phenomenon and for that matter have experimented with all kinds of duration, timing, rail pressure, you name it with the stand alone and never get any kind of pop.

But one question, will stock software ever do it?

Sandaholic
08-08-2010, 12:24 PM
There's no way the injectors are fueling until the exaust valves are opening, if it were the case you would have a chit ton of white smoke, or unburned fuel and a incredible amount of duration!

Don't have much input on the subject though, never have come across the phenomenon and for that matter have experimented with all kinds of duration, timing, rail pressure, you name it with the stand alone and never get any kind of pop.

But one question, will stock software ever do it?

Good question :pop:

apocalypse1812
08-08-2010, 12:37 PM
I'm gonna stand by my and many others theory that it's from draining the rail.


I will Agree with this theory, I have heard it before on a 04 CR that was running HUGE injectors, and a Power Puck, stacked with a smarty.

He did a dyno run, started popping, blew a Head Gasket, and put down 183hp...

oh yeah, and his truck was on 38's with no regear...

rajkalkat
08-08-2010, 07:52 PM
mine was popping but once i replaced the tone ring the problem was gone

Amish Elegance
08-09-2010, 08:49 AM
There's no way the injectors are fueling until the exaust valves are opening, if it were the case you would have a chit ton of white smoke, or unburned fuel and a incredible amount of duration!

Don't have much input on the subject though, never have come across the phenomenon and for that matter have experimented with all kinds of duration, timing, rail pressure, you name it with the stand alone and never get any kind of pop.

But one question, will stock software ever do it?

We need you to O scope one that does it. :hehe: I have access to one, but only use it and have knowledge of measuring limited AC functions. Part of my knowledge base on the schedule for future improvement.

Since I cannot seem to see a consensus on how or where this pop comes from, the one's I've seen pop from the tail pipe. The problem I have with attributing it to timing is exactly the scenario you describe above; especially when a reduction in timing eliminates the symptom.

Delaying the injection event by reducing timing places the end of the injection pulse closer to the opening of the exhaust valve. I can't see how that would improve things?