[CSRcummins]

I saw that another fella post about rough lopey idle and I didn't want to thread jack.

Symptoms: When I push in the clutch ( coming to a stop) the rpms drop as normal but don't stop at the ~750 range. They drop way past then come up again until it steadys out around 750 ( 500-1000-600-800-normal). Also when I start the truck after its been ran, the idle is lower that normal, it will go to ~750 eventually. Sometimes shakes the truck like crazy. It started after I pushed the truck pretty good goofing off with another truck.

I have a fp of 18 at idle and 16 wot. Injectors have about 3000 miles. Vp was replaced < 3 months ago. Fuel filter replace around November no more that 6000 miles. Valves adjusted when I put studs in about 2 months ago. No codes. Checked three different ways four times in the last three days. Checked exhaust manifold with a heat gun- 4 where around 270 and 2 where around 210

Any advise would help I'm stumped. I would thing maybe APPS but I thought since it electronic it would code, could be wrong.

Thanks in advance!

 

[93oilburner]

I am having almost a exact same problem. I am checking my Airdog tomorrow. Going to pull the filters and look at the check valve. I have even tried 2 different VP's, adjusted valves...Mine is at the point now when I push in the clutch it will sometimes surge and then die, little scary when I am in traffic and brake pressure goes to hell. Please let me know if you find a solution. Someone else on here suggested the APPS sensor.

 

[CSRcummins]

I forgot to mention that im also getting some excess smoke - more than usual. I hope someone can chime in with a answer
Keep me posted on what you find out with the airdog

 

[tom mil77]

Hey guys, you can find out whether your problem is electrical (apps, cam sensor, etc.) or mechanical (pump, injectors, air in fuel) by performing a hot wire test. This eleminates all sensors. It would best to go to blue chip diesel site for better instructions. Also while there check out the test for air in fuel. I had a problem similar to you guys and chased my tail for over a year, replacing parts I did not need. Someone else suggested the aformentioned test, and this led me to the conclusion my pump was/is bad. I never really suspected the pump because it had very low mileage, but the tail chasing cost me to go out of warranty. Good luck hope this helps; maybe someone far smarter than me will be able to help you more.

 

[lilal]

Ok I have the same problem with my truck new injectors and a new airdog 2. seams to have a loppy idle almost a echoy miss sound threw the exhaust Help needed

 

[93oilburner]

I hope someone is having better luck than me at figuring this out. I just went and changed my fuel filters, cleaned the water seperator, pulled the check ball out and made sure it was ok. The only question I have is, my fuel pressure at idle was about 13psi, I took a pair of visegrips and pinched off the return line out of the Airdog and I had no pressure change. Shouldn't the pressure out of the pump have jumped way up?

 

[CSRcummins]

I have done the same thing you have done with no help. ( filters and return spring / ball) I plan on going more in depth this weekend. Check the valves, volts to apps and anything else I can think of.
When you clamp your return line I would think that the pressure would go up but im not positive, it would make sense tho.

 

[lilal]

I unplugged my tuner yesterday then it threw a code or the check engine light came on so i put the scanner on it says map sensor low voltage got a new sensor ill get it put in tonight and see what happens. My fuel milage has also been bad like 13.5 mpg so i think this might be part of the problem. My check engine light will not come on with the tuner pugged in.

 

[93oilburner]

I ordered a Timbo APPS last night. After playing with it some more it now has a dead spot just off idle were you can hear the timing back off to the point it barely rattles, no power, push through that spot and it runs as normal. Hope it fixes it till I can get garage space to swap in a p pump

 

[CSRcummins]

Keep use posted on the apps and map sensor. Hopefully its a fix

 

[93oilburner]

Well I have not recieved my TPS yet but I have deeper issues now. I hope it is related to the TPS. Got in the truck this morning and as I left the parking lot and started to push the gas pedal the truck got quiet, as in no timing rattle just a deep exhaust note, it was not a dead pedal. Push through the flat spot and it would rattle as normal. Any thoughts?

 

[JDiesel93]

I saw that another fella post about rough lopey idle and I didn't want to thread jack.

Symptoms: When I push in the clutch ( coming to a stop) the rpms drop as normal but don't stop at the ~750 range. They drop way past then come up again until it steadys out around 750 ( 500-1000-600-800-normal). Also when I start the truck after its been ran, the idle is lower that normal, it will go to ~750 eventually. Sometimes shakes the truck like crazy. It started after I pushed the truck pretty good goofing off with another truck.

I have a fp of 18 at idle and 16 wot. Injectors have about 3000 miles. Vp was replaced < 3 months ago. Fuel filter replace around November no more that 6000 miles. Valves adjusted when I put studs in about 2 months ago. No codes. Checked three different ways four times in the last three days. Checked exhaust manifold with a heat gun- 4 where around 270 and 2 where around 210

Any advise would help I'm stumped. I would thing maybe APPS but I thought since it electronic it would code, could be wrong.

Thanks in advance!

I have the EXACT same problem as you and 93oilburner, and I think it might be a dirty MAP sensor. I have heard of a dirty MAP sensor as a possible explanation and that would explain excess smoke.

 

[CSRcummins]

Oilburner, did it code ?

Jdiesel, that's what I'm started to lean to, and/or tps. I picked a map sensor up from my cummins dealer about 3 months ago but never installed it cause the plug is different.

 

[93oilburner]

I just took the truck out to get a few things and it did the no timing rattle thing, I throttled into it and it ran real rough from 2000 on up then threw a CEL. Pulled the codes and I have 2 for the Cam sensor. P0251 and P0252 so I am going to pick up a sensor in the morning. It is surging like crazy at idle and usually dies after the 3rd surge. If I hold it off idle it is fine.

 

[93oilburner]

After doing a search everyone on here seems to be saying IP failure with those codes but I think in my case it may be the cam sensor since I have tried 2 VP's with the same symptoms. My code reader said something about the P0251 Injection pump/cam sensor malfunction and P0252 Injection pump/cam sensor circuit. I will try the cheaper of the 2 first. (cam sensor $80)

 

[CSRcummins]

I would go with the cheaper fix first too. But those symptoms are way worst than mine, I hope I can get it figured out before they get worst.

 

[93oilburner]

Mine started out like yours. Slight miss at idle then about a 50 rpm fluctuation now a truck that won't idle.

 

[RAMmins12]

hey guys, dont mean to jack your thread but I'm having a similar issue also. I just finished up the 47re to nv4500 swap and took it out for a test drive. idled great when it was cold but when i came up to a stop light after driving it for about 10 mins, i noticed a rough idle sort of like a miss right around 1000 rpms. you could watch the needle bounce around on the rpm gauge too, but you could really notice it outside the truck, like a popping sound through the exhaust. anyway, you could def tell that its missing/idling rough but only after its warm. shut it off and let it cool down, start it back up and idles great. it didnt do this before the swap either. im getting normal fp readings with my AD150 (15-17psi) and the power still seems to be there. doesnt miss or accelerate rough either, just at an idle. let me know what you guys come up with, i'm just trying to figure out where to start looking to solve this problem cause its driving me nuts

 

[JDiesel93]

I have only experienced this problem in Park or Neutral. It seems like I could idle all day in Drive without a problem, so its probably something electrical.

 

[93oilburner]

Mine is almost identical to yours RAMmins. Runs good when it is cold, after a few minutes it starts going down hill. Just gets worse as it warms up. I will be changing my cam sensor here in a few minutes. Mine keeps throwing a code for the cam sensor. When it is warmed up and I rev it passed 2000 it starts to miss and blow white smoke. CEL comes on. I will keep everyone updated if it fixes it.