Stuck Idle problem

[2000Cumminsyessir]

Hi guys, first post! I have a 2000 Ram 2500 5 speed. Runs great for the first 5 minutes in the mornings then she's having what I would say a miss at idle and rpm Fluctuating between 800 to 1000rpm. Once I hit the throttle the rpms stay at about 1100 and will not come down until it's in gear. Also when I drive it, and coming to a stop, the idle is high and makes it harder to stop. I had a map sensor code and got that cleared. I changed injectors (oem) thinking that was the issue but nope still there and does the same thing. 

 

I did replace crank & cam sensors. (I was playing the guessing game) I did notice when unplugging the cam sensor that no check engine light comes on and it runs the same with it plugged or unplugged and I believe all sensors should have 5 volts, which they all do. I had alternator tested for diode issues and it was fine. I replaced batteries about 2 weeks ago. 

 

I checked Apps sensor this morning and its reading 0.31v. There is no sticker on it to know what the voltage should be at. Would app sensor be the issue here or what? 

 

Thanks for all your help!

[Mopar1973Man]

That is my thought is the APPS sensor is not setting the proper IVS (idle validation switch). Being that if idle was grounded it would ditch the APPS signal and use the 800 RPM idle software. Then when throttling is grounded then idle software is ditched and APPS value is used gence you higher than normal idle speed because it not setting the idle ground for IVS.

[JAG1]

Wouldn't the aftermarket Timbo APPS be the ticket to fix this one Mike? 

[Mopar1973Man]

Yes it's an option but it would be nice to verify error codes one more time and see what the author gets for TPS value. At a true idle it should show 0% TPS. Again if the current APPS is electronic IVS then it voltage required to set IVS state. Now a Timbos APPS is angle set IVS. As long as the wiper inside can reach the Idle Position contact the idle position and the idle software will be set.

[2000Cumminsyessir]

I did check the live data for tps at idle it was 0%. I actually already ordered an apps sensor. I'll see if she likes it or not lol. I appreciate all your help! I'll let you know once I get it. 

[JAG1]

You should cancel the order if not a Timbo. They are superior and half the cost.

[Mopar1973Man]

 

8 hours ago, JAG1 said:

You should cancel the order if not a Timbo. They are superior and half the cost.

Very true...

[2000Cumminsyessir]

Well new apps sensor didn't solve the issue. It seems to drive great but the idle won't stay down and runs rough at idle. I did do the blue chip diesel test and with the vp44 hotwired it still ran rough at idle. I'm wondering if it's the vp44. I replaced the injectors with OEM and it still has the problem. So I'm thinking it may be the pump 

[2000Cumminsyessir]

 I wanted to show what its doing. i can still rev past 2k but listen to what it sounds like

[JAG1]

Doesn't sound good, has a definate miss. Did you get the Timbo APPS?

 

Also you could use an I R  thermometer and check if one cylinder may having excessive or significant higher temps than the other 5. I check mine in the same spot on the exhaust manifold to see.

 

 

Edited December 29, 2021 by JAG1

[Mopar1973Man]

APPS sensor isn't going to make a miss for sure. 

 

That miss I would start with injectors first either replace them or have your current ones pop tested. 

 

Can you check for error codes please? @2000Cumminsyessir

[2000Cumminsyessir]

6 minutes ago, Mopar1973Man said:

APPS sensor isn't going to make a miss for sure. 

 

That miss I would start with injectors first either replace them or have your current ones pop tested. 

 

Can you check for error codes please? @2000Cumminsyessir

I checked the codes and nothing comes up on my code reader. No codes with the key trick either. What's weird is I already replaced the injectors with oem that's what I thought that initial issue was. But it does the exact same thing with the old injectors and new injectors. 

22 minutes ago, JAG1 said:

Doesn't sound good, has a definate miss. Did you get the Timbo APPS?

 

Also you could use an I R  thermometer and check if one cylinder may having excessive or significant higher temps than the other 5. I check mine in the same spot on the exhaust manifold to see.

 

 

I went with a oreillys one. I had it ordered before I thought about ordering the Timbo. I will get one soon though. 

[Mopar1973Man]

Well the only other fuel related item is VP44 but that getting pricey for gambling. 

[2000Cumminsyessir]

2 minutes ago, Mopar1973Man said:

Well the only other fuel related item is VP44 but that getting pricey for gambling. 

Lol yeah I know it. I just can't seem to think of anything else it could be besides the vp44. It drives great though. It's just the idle issue and when coming to a stop the idle is too high. It seems it's not getting the correct amount of fuel at idle or when coming to a stop. That's my theory. 

[Mopar1973Man]

11 hours ago, 2000Cumminsyessir said:

It's just the idle issue and when coming to a stop the idle is too high.

 

Normal. Even "Beast" runs as high as 1,100 RPM's as you clutched in and rolling to a stop and then closer to a stop it drops down on the idle software to 800 RPM. This is a manual set up I'm talking about but since you don't have any info in your signature on the truck its a guess. 

 

11 hours ago, 2000Cumminsyessir said:

It seems it's not getting the correct amount of fuel at idle or when coming to a stop.

When the APPS sensor is in the IDLE MODE (Idle Validation Switch) then the ECM is in full control of the idle speeds as it rolling. Now if the APPS sensor is having issues and stuck in THROTTLING MODE then the idle could be inherently high because the ECM can't reach the idle mode. Have you adjusted voltage on the APPS sensor? (Hopefully not... )

 

 This explains much much more about the APPS sensor.

 

 

 

[2000Cumminsyessir]

16 minutes ago, Mopar1973Man said:

 

Normal. Even "Beast" runs as high as 1,100 RPM's as you clutched in and rolling to a stop and then closer to a stop it drops down on the idle software to 800 RPM. This is a manual set up I'm talking about but since you don't have any info in your signature on the truck its a guess. 

 

When the APPS sensor is in the IDLE MODE (Idle Validation Switch) then the ECM is in full control of the idle speeds as it rolling. Now if the APPS sensor is having issues and stuck in THROTTLING MODE then the idle could be inherently high because the ECM can't reach the idle mode. Have you adjusted voltage on the APPS sensor? (Hopefully not... )

 

 This explains much much more about the APPS sensor.

 

 

 

I replaced apps sensor yesterday.  Instructions said to set it to 0.55. I adjusted it a bit lower than 0.55 Same issue occurs as old apps sensor. 

 

When I hit the throttle while in idle the idle rpms will rev up to 1100 and not come down until it's in gear and it will drop to about 900rpm and it has a noise associated with it. I heard something about valve lash could need adjusting. When I changed the injectors, I didn't even mess with the valve lash. (I'm new to the diesel world).  2000 5.9 Cummins 5 speed. Thanks man for all your help!

[Mopar1973Man]

Ok... 

21 minutes ago, 2000Cumminsyessir said:

I replaced apps sensor yesterday.  Instructions said to set it to 0.55. I adjusted it a bit lower than 0.55 Same issue occurs as old apps sensor. 

 

So the APPS is replaced and now lets move on to other topics. So I guess you have factory stock injectors yet? How many miles on the injectors? Another way to look at this problem is hook up a live data tool with the truck warmed up complete and monitor the engine load if its 3% or lower to ZERO then your injectors are wore out and the ECM is attempting to cut fuel as deep as it can but since the injectors are popping too early and there is no longer any more control the ECM can try to pull the RPM's down. Second way to test this is to remove all six injectors and have the injectors pop tested typically about $15 a injector about $90 to test all six injectors.

 

Solution to this is replacing all six injectors. Like I said you can verify with a live data tool and check the engine load at idle warmed up.

 

 

Pop pressures in Bar (PSI)

280 (4,061) and lower - Typically the idle is rising and the Engine load is zero.

293 (4,249) - Bottom end of allowed by Dodge FSM

300 (4,351) - Some performance injectors are popped this low to aid to flow.

305 (4,423) - Fairly common pop pressure used by performance injectors.

310 (4,500) - Stock Injector pressure

320 (4,641) - Personally what I run on my truck to aid in fine mist spray and MPG.

327 (4,742) - High end of Dodge FSM allowed pop pressure

330 (4,786) and higher - Possible hard starting in the winter time. 

Edited December 29, 2021 by Mopar1973Man

[2000Cumminsyessir]

19 minutes ago, Mopar1973Man said:

Ok... 

 

So the APPS is replaced and now lets move on to other topics. So I guess you have factory stock injectors yet? How many miles on the injectors? Another way to look at this problem is hook up a live data tool with the truck warmed up complete and monitor the engine load if its 3% or lower to ZERO then your injectors are wore out and the ECM is attempting to cut fuel as deep as it can but since the injectors are popping too early and there is no longer any more control the ECM can try to pull the RPM's down. Second way to test this is to remove all six injectors and have the injectors pop tested typically about $15 a injector about $90 to test all six injectors.

 

Solution to this is replacing all six injectors. Like I said you can verify with a live data tool and check the engine load at idle warmed up.

 

 

Pop pressures in Bar (PSI)

280 (4,061) and lower - Typically the idle is rising and the Engine load is zero.

293 (4,249) - Bottom end of allowed by Dodge FSM

300 (4,351) - Some performance injectors are popped this low to aid to flow.

305 (4,423) - Fairly common pop pressure used by performance injectors.

310 (4,500) - Stock Injector pressure

320 (4,641) - Personally what I run on my truck to aid in fine mist spray and MPG.

327 (4,742) - High end of Dodge FSM allowed pop pressure

330 (4,786) and higher - Possible hard starting in the winter time. 

I replaced the injectors with Bosch 0432193635 RV275 28 days ago lol. But with engine at operating temperature the engine load says 0%. I replaced the injectors because I thought that was the initial issue with the miss and idle sound. but it seems to do the same thing. unless I got a bad batch of new injectors.

[JAG1]

If its still doing the same thing it's not the injectors. Seems to me its more a steady miss than a random miss like a valve but that's shooting in the dark. I am leaning toward an air leak in one of your High pressure and/ or low pressure fuel lines. Also possible bad overflow valve which is easy fix.

 

Check to see when you remove the fuel tank cap right after a run if there is a suction hiss when slowly turning the fuel cap off. If suction then the tank vent is clogged. If blowing out then you have a bad pressure copper ring on an injector or someone left one in there and there is two stacked up in there but, that be something I would do 

 

Did you follow protocal when changing injectors and snug up the high pressure cross over lines to the injector first before tightening down the injector? Previous owner could have left an extra washer in there too but, please check the easy things first.

[2000Cumminsyessir]

11 minutes ago, JAG1 said:

If its still doing the same thing it's not the injectors. Seems to me its more a steady miss than a random miss like a valve but that's shooting in the dark. I am leaning toward an air leak in one of your High pressure and/ or low pressure fuel lines. Also possible bad overflow valve which is easy fix.

 

Check to see when you remove the fuel tank cap right after a run if there is a suction hiss when slowly turning the fuel cap off. If suction then the tank vent is clogged. If blowing out then you have a bad pressure copper ring on an injector or someone left one in there and there is two stacked up in there but, that be something I would do 

 

Did you follow protocal when changing injectors and snug up the high pressure cross over lines to the injector first before tightening down the injector? Previous owner could have left an extra washer in there too but, please check the easy things first.

Thanks so much! I did follow the protocol when changing injectors and I made sure all the old washers were out before installing the new injectors. I will go for a run and listen for a suction or not.