Idle issues.

[Eric_Cumminsguy6.7]

Hey all long time viewer here.
Been scratching my head over this one for the last few days.
I've got a 2013 ram 2500 outdoorsman, south bend dual disk clutch, i believe a dsp 5 position tune switch, deleted, and a fleece cheeta turbo. I think right now im sitting at just under 110k on the clock. The truck has been running great for quite some time now and of course somethings gotta happen in the cold months of the year. I'm having a weird idle almost like someone threw a lope tune in the truck. It's not super consistant either sometimes it's constant and then it'll clean up. I threw my scan tool on it and recorded a bunch of info if it'd help any of you's help me figure this out. I figured I'd change fuel filters (stock) thinking they were gummed up and needed to be done anyways and that didn't solve it. Started poking around with the scan tool and noticed the High pressure command and actual seem to be kinda different. I notice sitting at idle the commanded seems to be pretty smooth 4998psi while the actual jumps around between lows of 4600psi to highs of 5000psi sometimes 5100psi. I've seen several forums saying it could be the FCA from people with similar issues. I'm wondering if I'm going down the right path? Pressures driving seem to even out and match, although there have been a few occasions where I'm steady on the throttle and it'll really surge, like pretty badly. I can figure out how to post these graphs if anyone wants to see them, I have all the recorded information of idles and drives, and a bit when it seems to clear up. I should also mention there are no codes stored or set either. Thanks!!!!

 

[AH64ID]

That rail pressure is normal, there is always a slight difference in demanded vs actual pressure as the ECM adjusts.

How rapid is the lope? Are you hearing it or seeing it on the tach, or both?

Any chance the lope is the grid heater post-heat cycles?

 

[Eric_Cumminsguy6.7]

yeah i can see it on the tach. let me take some photos of this graph and show you. I can say it has gotten a lot worse though. It sounded fine when I was warming it up early this morning a little bit of the lope, I'd have to say it's kinda rapid at times I can see it visibly shaking the truck at times and the tach will also bounce around too, I am not sure what you mean about the grid heater post-heat cycles. It will do this whenever the truck is cold or warm. Anyways back to the new development, after driving the truck for a bit it's now starting to lose power and feel like it's coming to a stall every now and then. It'll clean up and run fine for a few minutes and then it'll start messing up like that. I'm like 80% confident it was losing the high pressures when it'd come to a stall almost. Unfortunately I didn't have the scan tool hooked up and recording when this was going on...... Here are three of those graphs, the first one is during a drive, the second one where things are more erratic is before I put some fuel treat in ( saw a post where someone said to try this to kinda free up FCA ), Then the last one was after that when it cleaned up a bit. The graph that is a bit more erratic might be a bit tricky to read sometimes it won't overlap the lines. But you can kinda get the gist of it maybe? I have all of the other I/M monitors saved so if there is another one or combinations anyone would like to see I can provide that too.

 

[lpennock]

Does look like a sticking FCA.

 

[Eric_Cumminsguy6.7]

I figured I'd try to get one of the current state of it now in the shop. The truck is at temp 190* so I wouldn't think the grid heater would come into play in this case maybe it does I'm not too sure on this part. I tried to gradually bring it up to 1k rpm and hold it there to see if it exacerbated this issue. When doing this it just jumped as you can see in the graph. Trying to hold 1k rpm it was still kinda erratic so I tried taking it up to 1200 rpm to see what that did and it seemed about the same there. I was pretty gentle trying to bring it up to 1k so I don't think it was me fat footing the throttle that got that nasty jump in it. Is there a way to post a video I can get whatever angles and information to make it easier!

 

[Eric_Cumminsguy6.7]

I'm taking a shot in the dark here but I'm assuming the commanded and actual can deviate a bit? And the actual should stay kinda steady instead of all over the place? I'll tell you what, I had a second gen a while ago and after the 2nd vp pump decided it was going to go out I decided it was time to make the jump to something newer. Injection Pumps and I have a love hate relationship. They love my wallet, and I hate them for It. LOL

 

[AH64ID]

Given a constant load and rpm the demanded rail pressure will be constant but actual rail pressure can fluctuate a couple hundred psi from the demanded and be normal. The rail pressure varies so much I turned the refresh rate down on my MM3 and now CTS3 because it's impossible to read at the default refresh rate.

So all that is to say that I'm not seeing anything really crazy with those graphs.

Post heat is great heater activation after the engine is started, it will put a big draw on the alternator and can sometimes be heard as a lope especially with different turbos/exhaust.

 

[Eric_Cumminsguy6.7]

Given a constant load and rpm the demanded rail pressure will be constant but actual rail pressure can fluctuate a couple hundred psi from the demanded and be normal. The rail pressure varies so much I turned the refresh rate down on my MM3 and now CTS3 because it's impossible to read at the default refresh rate.

So all that is to say that I'm not seeing anything really crazy with those graphs.

Post heat is great heater activation after the engine is started, it will put a big draw on the alternator and can sometimes be heard as a lope especially with different turbos/exhaust.

I think I kinda understand what your saying here. I've heard that before, I can also kinda tell when it kicks on it'll load up the engine a bit and the lights will dim a little for a second or two and then it'll kick off. Yes no? I'm not noticing that here so much. I'll try to upload a video then, and I just got a new FCA so I will try throwing that on and see if anything changes. Ill update in a bit

 

[Eric_Cumminsguy6.7]

Given a constant load and rpm the demanded rail pressure will be constant but actual rail pressure can fluctuate a couple hundred psi from the demanded and be normal. The rail pressure varies so much I turned the refresh rate down on my MM3 and now CTS3 because it's impossible to read at the default refresh rate.

So all that is to say that I'm not seeing anything really crazy with those graphs.

Post heat is great heater activation after the engine is started, it will put a big draw on the alternator and can sometimes be heard as a lope especially with different turbos/exhaust.

With that also being said how could the one graph that is all over the place ( being the truck running rough/loping ) and then the other where the lines are not so peaky not mean anything? The one I see pressure moving and RPM following, whereas the other seems more stable. ( I'd expect values to fluctuate some but not near that much, I know they wont be "perfectly" flat. Flatter is better no? Now I am open to the possibility of the angry pixies having something to do with this. Is it possible that I could be intermittently missing/losing voltage to that actuator causing it to spike randomly? My only hangup to that idea is that supposedly when you disconnect the harness to that actuator it will allow the pump to climb to 26k PSI so why would I still lose power at 50% throttle instead of gaining it when it happened today?

 

[sag2]

It's been a while since I have seen one with a loping idle, but it can be caused by a bad FCA. It is normal for the commanded and actual to be a couple hundred PSI off, usually they are +-200 to 300. Try disconnecting the FCA and see if RPM is then high but steady before you change it.
It is interesting that the commanded is jumping like it is, especially if you are not touching the throttle. Have you looked at the APP in relation to rail pressure to make sure the APP voltage is not jumping around?
For about $150 the FCA is still not a bad guess.

 

[Eric_Cumminsguy6.7]

It's been a while since I have seen one with a loping idle, but it can be caused by a bad FCA. It is normal for the commanded and actual to be a couple hundred PSI off, usually they are +-200 to 300. Try disconnecting the FCA and see if RPM is then high but steady before you change it.
It is interesting that the commanded is jumping like it is, especially if you are not touching the throttle. Have you looked at the APP in relation to rail pressure to make sure the APP voltage is not jumping around?
For about $150 the FCA is still not a bad guess.

Well now I'm stumped..... I just threw the new FCA on and there was no change. I was fairly certain that was the culprit. As for the APP voltage, I'm not exactly a motor rocket scientist, could you break that down for me? I've got new graphs and pulled info from the PCM as well as the overall module information ( what I've been posting earlier) I did just go through and throw some more stuff together. I believe this is what your looking for?

 

[Eric_Cumminsguy6.7]

As far as that pedal goes, those little spikes from .12 to .25 I'm not sure about, does that do a pulse every so often as a check or something like that? I imagine the pedal is a pwm signal or something of that sort?

 

[Ozymandias]

Disconnect the FCA and see if it does it anyway.

 

[sag2]

You need to graph the APP voltage with the commanded rail pressure. APP at idle should be steady. I recall it might spike occasionally (but more like a couple volts, not a tenth or two) as a circuit test, but if the commanded rail pressure jumps at the same time as the APP spike you might be onto it.

 

[sag2]

You could also disconnect the APP once truck is running and see if it calms down.

 

[Grumpy8811]

As far as that pedal goes, those little spikes from .12 to .25 I'm not sure about, does that do a pulse every so often as a check or something like that? I imagine the pedal is a pwm signal or something of that sort?

TPS signal basically is read as anywhere between between 0 and 100%.. or voltage in your case.
it should be a more or less smooth signal that tracks linearly with pedal position..
those little blips at idle looks like it has a transient signal which is either coming from the pedal assembly itself or is some type of electrical noise coming from the chassis.

one thing to note is throttle response is never as quick as electrical blips.. but if any electrical blip occurs often enough and in a hi enough range it can cause driveability issues.. and those little electrical blips , if they are in the range of what is reasonable will not set a code..aka signals generally range between .5v and 4.5v so anything inside of that range is viewed as acceptable to a ECM... even if there are hundreds of signals per second, as long as they stay inside that acceptable range, no codes get set.

someone else mentioned disconnecting the TPS and seeing if the problem goes away... that would be my first attempt at identification.

 

[Eric_Cumminsguy6.7]

Well got an update for y'all, after that FCA didn't solve what I was certain was the issue I got irritated. With all the electronics and sensors this truck has I was hoping something would set a code, I sometimes hate chasing gremlins especially when it's clearly an issue and the equipment is needed. Top it off lack of sleep and food was making for a bad combination. Decided it was time for a second set of eyes on it. Driving it over to my local shop and it was perfectly fine OFC! He asks to keep it for a hour or so after he hooks into it and was looking. He hooked up some gages and looked at the lift pump pressures. At idle it could produce 10PSI to the filter and every so often it'd dip below when it'd idle rough he said at one point he saw 4PSI, he said sometimes the sock gets clogged or the pump is on it's way out. Seems to add up on my end and would account for weird pressures coming out of the CP3, weird idle, loss of power randomly among other things.
Regardless at least it's the cheaper of the 3 possibilities I was thinking. ( CP3, Injectors, Lift Pump)
Now I'm in the market for a new lift pump. I installed a Fass titanium signature series on the second gen I had and really liked it, especially since both filters were right there under the bed on the outside of the frame rail. Since those older trucks just had the lift pumps on the side of the blocks I could just plumb that right into the sending unit no problemo. Now that they are inside the tanks on these new trucks as part of the sending unit, I'd have to drain the tank and plumb in a sump and either cap off or unwire the pump inside the tank, and remove the old filters ( brand new they have 11 gallons through them....) Am I better off going with a new sending unit and pump from Fleece, or the FASS? I've been really happy with fleece's turbo as it's just a touch bigger than stock and sounds great. To add to it the fleece is just a drop in for $30 more than the FASS system. (Fleece $829, FASS $799).

 

[Ozymandias]

Replace with a factory pump, it's the best you can have for these trucks.

But I don't think this is your problem, sorry, as long as there is flow to the CP3 everything is fine. The pressure of it is very secondary. 4psi is what we see at WOT right from the factory.

Again, try to idle it with the FCA disconnected and see if it fluctuate also or not. In the past we have seen problems with the wiring going to the FCA, broken.

 

[Eric_Cumminsguy6.7]

Replace with a factory pump, it's the best you can have for these trucks.

But I don't think this is your problem, sorry, as long as there is flow to the CP3 everything is fine. The pressure of it is very secondary. 4psi is what we see at WOT right from the factory.

Again, try to idle it with the FCA disconnected and see if it fluctuate also or not. In the past we have seen problems with the wiring going to the FCA, broken.

How long can I let it idle like that? I know disconnecting it allows it to climb to max pressure 26k if I'm remembering right. Before I start damaging other components. I'm not sure if I'd know right away or not since it isn't consistently happening/ am able to replicate it for it to happen. If I also chart this am I looking for the commanded to say 5000PSI and the actual to be somewhere in the realm of 26K? Is it better for me to wait for it to start happening and then unplug while its running or unplug first and then start it? I don't mind testing things or trying them I don't want to mess something else up and make an even bigger more expensive mess.
If that 4psi is what we see at WOT from factory then why would it be seen at idle occasionally? I'm not trying to argue or anything I'm just trying to understand why it'd get that low just at idle and not wide open in the first place

 

[Ozymandias]

I don't think it will harm anything, it just sounds horrible like a 2nd Gen 24V all the time. Pressure isn't out of spec for the Motor, just for the load.
If this would harm it I'm very sure they would have programmed it that way to shut down in this case (high rail pressure for given rpm).