Yes, Injectors #8 and #3 were swapped and the miss fire and high balance rate stayed with #8....
LBZ: Help! No one can figure out the issue.
- Thread starter stibuilder
- Start date
The intermittent command of 2.2 mm3 pilot fuel is very odd. I'd recommend looking through the tune to see what all can cause pilot fuel to increase. One of those attributes is jumping around. You might have some crosstalk between an injector wire and the ECT sensor, for example, causing a temporary spike in pilot fuel. I'd look, but I am at work.
My tune is locked from Kory, and not sure if they are willing to unlock it or offer any help. Based off my first emails and phone calls it was pretty limited. I thought about ordering a tune from Rob and seeing if it was any different.
Can you load the stock tune back up temporarily? Being only 30% over injectors it shouldn't cause any issues at idle. Not worse than what you're seeing lol.
We have tried the stock tune and a different ECM and get similar operation.
I have been able to figure out at least in part the cycling of the pilot seems to be due the fact the truck was not up to operating temperature when the data logging was done. My truck does the same thing when cold but my injector pulse width is smoother and almost flat. What I can not figure out is why the high injector flow and duration. The data logging shows the duration is technically less than stock when not a spike, which I assume is to compensate for the larger injectors. But when on a spike the flow is sky high. 21.2mm3 @ 822us vs 11.6mm3 @ 643us. The truck is way over fueling causing a loop?
1st screen shot issue truck
2nd screen shot my truck
I have been able to figure out at least in part the cycling of the pilot seems to be due the fact the truck was not up to operating temperature when the data logging was done. My truck does the same thing when cold but my injector pulse width is smoother and almost flat. What I can not figure out is why the high injector flow and duration. The data logging shows the duration is technically less than stock when not a spike, which I assume is to compensate for the larger injectors. But when on a spike the flow is sky high. 21.2mm3 @ 822us vs 11.6mm3 @ 643us. The truck is way over fueling causing a loop?
1st screen shot issue truck
2nd screen shot my truck
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I never could get anyone to return my emails or phone calls over there when I had a question. I'd find a tuner that will give you some customer support especially if it turns out to be an issue with your tune.
Latest email from the shop:
Hi Kendrick,
I have attached an estimate to this email for what we have done, plus checking valve lash, compression testing and sublet injector testing. I like your way of thinking in regards to the injectors in the firing order, but I’m not sure I can get on-board with it yet
I did speak to ATP Trucks again regarding the tuning being correct and they were able to confirm this time it is correct for the truck.
One thing Chuck and I are thinking is a good idea is sending the injectors out to get flow rate numbers for them and programming them. I know most injector builders say this is not needed because they build the sets balanced, but what if they didn’t this time? Chuck brought up a truck he remembers from the past that ran very poorly with the aftermarket injectors it had and programming them fixed it. I asked ATP if this would be an issue with the tuning and they confirmed it will not be.
Let me know what you think.
Hi Kendrick,
I have attached an estimate to this email for what we have done, plus checking valve lash, compression testing and sublet injector testing. I like your way of thinking in regards to the injectors in the firing order, but I’m not sure I can get on-board with it yet
I did speak to ATP Trucks again regarding the tuning being correct and they were able to confirm this time it is correct for the truck.
One thing Chuck and I are thinking is a good idea is sending the injectors out to get flow rate numbers for them and programming them. I know most injector builders say this is not needed because they build the sets balanced, but what if they didn’t this time? Chuck brought up a truck he remembers from the past that ran very poorly with the aftermarket injectors it had and programming them fixed it. I asked ATP if this would be an issue with the tuning and they confirmed it will not be.
Let me know what you think.
Lots of great ideas in this thread, im going to call them to see if they can do a little more diag before we start spending big money.
What are the balance rates doing when cold and when warm? I’ve noticed when I shut an injector off it always affects the balance of another cyclinder. I wouldn’t concentrate so much on just 8. Maybe check one in the firing order before and after #8
We moved 3 and 8 in the very beginning so I find it hard to believe its an injector issue again. Maybe move ones in front of 8 to see if that changes anything, the one thing they have found is noise or voltage spikes on 8, i wonder if there is something else in the harness thats causing noise in the wire.
I would be doing all the diagnostics on a stock tune, just to eliminate variables.
I still think you have a sensor issue. Something is causing the ECU to cyclically increase fueling.
The other possibility is unusual engine load. Have you tried taking off the serpentine belt to see if it runs smoother? And it is possible (but unlikely) the torque converter is loading the engine cyclically.
You can use EFILive's DVT to temporarily alter the idle RPM. Try bringing it down to 600 RPM and see what it does, then try bringing it up to 1000 and see.
If you rotate the engine over by hand, does it feel pretty consistent every time?
This is a weird one, that's for sure.
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I still think you have a sensor issue. Something is causing the ECU to cyclically increase fueling.
The other possibility is unusual engine load. Have you tried taking off the serpentine belt to see if it runs smoother? And it is possible (but unlikely) the torque converter is loading the engine cyclically.
You can use EFILive's DVT to temporarily alter the idle RPM. Try bringing it down to 600 RPM and see what it does, then try bringing it up to 1000 and see.
If you rotate the engine over by hand, does it feel pretty consistent every time?
This is a weird one, that's for sure.
Sent from my Cat S60 using Tapatalk
Thanks to everyone for all the feedback.
I went back and took a look at engine torque and it's flat. I assume that mean the engine is rotating smoothly. But I do not know if that is a real number or calculated.
The data I have posted so far have been very short duration. Here is a one minute duration at idle. It really shows how bad the cycling is.
I went back and took a look at engine torque and it's flat. I assume that mean the engine is rotating smoothly. But I do not know if that is a real number or calculated.
The data I have posted so far have been very short duration. Here is a one minute duration at idle. It really shows how bad the cycling is.
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Dumb question, but do you have problems starting? Have you tried alternative fuel supply (like not from the tank) to see if you have a pickup issue? Air in the fuel might be causing your headaches.
That's quite interesting, i could have them put new filters on the FASS possibly.
Feed the pickup and return lines on the FASS to a bucket so they know that the pickup is not the problem. If problem still persist, then bypass FASS and try again. Air will not get in on the pressure side of the FASS, thus if it is air it will be on the vacuum side.
Also have them try plumbing a good fuel supply line to the top of the filter or back of the CP3 to ensure there is not a collapsed line causing issues.
Also have them try plumbing a good fuel supply line to the top of the filter or back of the CP3 to ensure there is not a collapsed line causing issues.
The shop called today and said the issue was resolved about 95% by reprogramming the injector codes. They took one code stored in the ecu and used that for all 8 injectors. Im waiting on a call back from LDS on if they can go back and provide me with the flow numbers for the 30% overs. I recorded the injector codes off all 8 before i put them this summer.
This is interesting because so many people told us we didn't need to program anything they would just work.
:coolspot:
Really happy the truck is getting close. I had just picked out a new 3500 to replace it.
This is interesting because so many people told us we didn't need to program anything they would just work.
:coolspot:
Really happy the truck is getting close. I had just picked out a new 3500 to replace it.
Also how much fuel pressure should the FASS be pushing? Mine is around 11/12 and down to 9/10 under load. The shop feels like that is a little high.