Loping Idle

my truck is doin the same thing. sent my 90hp injectors to industrial and came back w/ 5 out of 6 were basically junk. Had em rebuilt and puttin back in tomorrow. Ill let you know if that fixes my problem
 
wag06cummins said:
have you gotten any further on whats causing this?
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Getting close. Todd has sent me the compression test fitting and it should be here Monday-Tuesday. I did however find something I should be kicking my own azz for! Anybody remember reading/hearing about the wire right below the oil filter that goes from the AC compressor to the line? This wire rubs on the frame and compressor and starts to ground itself out over time.
This whole ordeal started after I changed my oil and filter, and somehow it never crossed my mind to cover that wire even though I've read about that wire numerous times! So anyway I ran wire loom over it and zip tied it up.. What a difference it made at idle!! :nail:

It still has a "slight" lope at idle in gear while the engine is less than 170* (again, it is much better still), but above 170* it basically runs normal. Since I'll have the test fitting here I'm going to do a compression test anyway, but I'm very relieved it runs a whole lot better!
 
Dam PCI.......its great when working..its a PITA when NOT. (Programmable channel Interface).
 
Yes it is Todd. I can't believe I never thought of this since it is a common problem on the 3rd gens. I hope the compression test shows perfect results. Although, a cracked HG between cylinders makes sense as the engine gets warmer it could close the gap and run good. I'll see if I can post a new video of a cold vs warm idle but it is only a slight difference.
 
any update?
i just changed my fuel lines to my cp3s today and also changed my return line. i just drove it around the block and it seemed like it ran smoother. ill find out more tomorrow but may be something to think about. i just dont know what one of those 2 things made the difference or if it was a little of both.
 
blackdieselram said:
any update?
i just changed my fuel lines to my cp3s today and also changed my return line. i just drove it around the block and it seemed like it ran smoother. ill find out more tomorrow but may be something to think about. i just dont know what one of those 2 things made the difference or if it was a little of both.
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No update yet. Waiting on the compression testing tool and I havent had much time lately to try other stuff. Truck ran perfect (after it's warmed up) for a few days and now it's back in lope mode. I'm going to tie those wires by the AC clutch better and see if it goes away again. This weekend I hope to change around my fuel lines as well. I just need to figure out how to delete the stock hard return line off the rail PRV #1 so I can return it to the tank with PRV #2.
 
do you still have the factory supply line on the truck? thats what im going to use when i get mine. at the moment my factory return line is out of order so i need to get that fixed asap.
 
TXAustin said:
No update yet. Waiting on the compression testing tool and I havent had much time lately to try other stuff. Truck ran perfect (after it's warmed up) for a few days and now it's back in lope mode. I'm going to tie those wires by the AC clutch better and see if it goes away again. This weekend I hope to change around my fuel lines as well. I just need to figure out how to delete the stock hard return line off the rail PRV #1 so I can return it to the tank with PRV #2.
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Check again....


Your item was delivered at 1:44 pm on June 13, 2011 in NACOGDOCHES, TX 75965.





Enter Label/Receipt Number.

Enter Label / Receipt Number.
Detailed Results:

Delivered, June 13, 2011, 1:44 pm, NACOGDOCHES, TX 75965
Arrival at Post Office, June 13, 2011, 9:14 am, NACOGDOCHES, TX 75961
Processed through Sort Facility, June 12, 2011, 7:21 pm, TYLER, TX 75708
Electronic Shipping Info Received, June 10, 2011
Processed through Sort Facility, June 09, 2011, 9:06 pm, SAINT PAUL, MN 55121
Acceptance, June 09, 2011, 12:22 pm, MINNEAPOLIS, MN 55434
 
Yup it did come yesterday apparently... They put the package in the wrong mailbox. Hopefully I can start tearing into it in a few days.
 
Im curious what you come up with on the compression test. Thats my next step w/ almost the same prob w/ my truck. Like yours, mine runs great when warm. I just changed my head gasket and put in the new rebuilt injectors and still have rough idle....
 
if its a rough idle, starting to sound like an FCA/CP3 issue.
 
quadzzeeburnout said:
Im curious what you come up with on the compression test. Thats my next step w/ almost the same prob w/ my truck. Like yours, mine runs great when warm. I just changed my head gasket and put in the new rebuilt injectors and still have rough idle....
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That makes me happy to know a new HG didn't change yours. It doesn't white smoke at all. Just a good haze of black at idle, but that's expected with these 65lpm nozzles.

I'm going to call Todd soon but before I start pulling the injectors tomorrow night or Friday I'm thinking I should get some new connector tubes in. I just realized the injectors have been pulled 4 times now, but the tubes have never been replaced. Since the new injectors were installed months before this started I don't think it's related, but it is probably worth replacing since I'm pulling the injectors anyway. There was little change going down to the stock pump, so it has nothing to do with the Dmax pump. The FCA is fairly new.
 
is there an easy way to test the cp3? I have changed the relief valve in the rail w/ no improvement. When its runnin rough at idle and smoking I can just push the throttle a little bit and it smooths right out.
 
quadzzeeburnout said:
is there an easy way to test the cp3? I have changed the relief valve in the rail w/ no improvement. When its runnin rough at idle and smoking I can just push the throttle a little bit and it smooths right out.
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That's how mine is. Little stumble at take off but after that (1100rpm) it runs good. Another thing I just noticed today is my Edge monitor (I use as extra gauges) the boost isn't reading anymore. I noticed this a few months back but normally don't have it on the screen so I forgot until today. I'm wondering if the map sensor is bad and making the engine think it needs more fuel at idle than it does? Just another thing I'll check tomorrow. I'm awaiting Todds call back about the connector tubes before I pull the injectors and can't get the parts.
 
have you guys changed out your FCA to see if that helps? the map sensor is also a VERY good possibility. Also check your sensor at the intake also. pretty sure ive heard of an issue with that air intake sensor causing problems also!
 
TXAustin said:
... I'm wondering if the map sensor is bad and making the engine think it needs more fuel at idle than it does? ...
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I think that is the direction to pursue first. When tuning with EFI, I adjusted a MAP voltage table slightly at the low end and it caused a lopey idle when warm. Off idle the engine ran fine. I changed it back and it runs good again.
Maybe clean the sensor or swap with a known good one to test before buying.

Good luck
 
Drasko said:
have you guys changed out your FCA to see if that helps? the map sensor is also a VERY good possibility. Also check your sensor at the intake also. pretty sure ive heard of an issue with that air intake sensor causing problems also!
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The FCA is fairly new but I did pull both out and clean them. If the rattle test is somewhat accurate then they work. I still have the old FCA's I can swap out (they weren't bad, changed it for another problem but that wasn't it). I'm 99% sure it's not either FCA by now. I'll call around and see how much a MAP sensor is around here.
 
mq105 said:
I think that is the direction to pursue first. When tuning with EFI, I adjusted a MAP voltage table slightly at the low end and it caused a lopey idle when warm. Off idle the engine ran fine. I changed it back and it runs good again.
Maybe clean the sensor or swap with a known good one to test before buying.

Good luck
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Very good info thank you! Sounds like a good possibility that the MAP could be causing it.
 
Well I didn't have time to mess with the truck today, but I did run errands with it for once. I've come down that it is something electrical. Each time I've started it would either run basically normal, or start up and would lope like crazy at idle the whole time. No matter what there will be a slight stumble off the line (between 800-1000rpm), but it's not like I built this truck to be a daily driver. I'm thinking the large nozzles cause the slight choke, but I don't have another high HP Cummins around to compare it to. Of course with stacks you hear every little change in the exhaust tone as well..

Hopefully I can find time tomorrow to clean the MAP sensor and see if the boost shows back up on the Edge monitor. I'm going to try and call Todd again tomorrow to see what he thinks.
 
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