Well fellas, here's my last-ditch effort before I drive my current project to the closest walmart parking lot and leave the keys in the ignition with the windows down.

I just recently installed new AP 160/0 injectors rebuilt and balanced by bitterroot diesel along with a new motorcraft engine harness, ICP and IPR. I had some issues with the initial tunes I was using after the install. These issues were a hanging idle and a choppy return to idle. These issues also, only revealed themselves as the oil temps increased. The hotter it got, the worse it got. After a few revisions with the tuning, the hang idle was cured....kinda. The choppy return to idle persisted though. I reached out to a different tuner just for grins to see how their tunes ran. I explained my problems and their first test tune completely eliminated the hang idle. The choppy return to idle persisted though. I did some data logging at the second tuners request and I am waiting to hear back. I figured I would see if the FTE collective had any thoughts on the matter.

Truck is a ZF6. Here's what I mean by "choppy return to idle" I rev the engine in neutral and as the RPM'S decrease the engine starts loping and bucking. Imagine a harley or a cammed camaro. It takes about 5-7 seconds for the idle to return to normal. Even after the idle returns to normal I can still feel and hear the faintest fluctuation in the idle. I swapped the new ICP with the old and that made zero change. I even unplugged the ICP while it was running and that made no change. That almost made it worse. I have logged some data through forscan. I'll be honest, I don't really know how to interpret that data. Everything seems very healthy with my limited knowledge. I could be wrong though, happens a lot.


Here's the data I have. Maybe there's something in here.

IDLE------------------------- ------WOT

EOT 181* --------------------EOT 197*

IPR 10.9-11.33%----------- IPR 37.89%

ICP 498-550psi --------------ICP 2826.6psi

MFDES 1.4-2.7mg----------- MFDES 68.875mg

EBP 16.4psi --------------------EBP 18.4psi

FUELPW 1.46-1.50ms -------FUELPW 4.86ms

MAP 14.2psi ----------------------MAP 27.1psi

Something else to note, is the MFDES is ALL over the place as I drive. It also seems to go nuts when the choppiness occurs.

Thanks for anything yall can provide.

 

Which tuners have you used? Not to point finger at all, but I have been through all this a million times, and with over 500 tunes/revision between my two trucks, I feel I may be able to hopefully help with some ideas

 

Can you post the CSV files of the drives where these issues happen? Need to see the data over time.

EBP seems low if MAP got to 27psi - something's not right there.

Interested to see what Eric spots.

 

I agree with Jeff about the EBP raising an eyebrow and if you can post the .csv files. There is a 5MB file size limit on the FTE.

If you need help with resizing them or anything, I can help with that.

MFDES should not be erratic or chaotic in the way it displays on the PID gauge. FORScan samples at near 12ms though, so this is another angle the ..csv may provide.

 

My gremlin wasn't as severe as yours but was similar in that it included a rough idle recovery and was worse as the temps got higher. It turned out to be the IPR. It might be worth a try to swap your old one in if the truck ran well previous to replacing it.

 

Another thought I just had...

What happens if you remove the Hydra chip altogether and use factory/OEM tuning? I know the throttle will become an ON/OFF switch with the 160/0 injectors, but does the RPM still hang and is there still a stumble when returning to idle?

 

Hopefully this works

Here's some data from my choppy idle

 

That above file is only 10-15 seconds. Sitting in the driveway.

I do have the original IPR I can swap if needed. Pulling the chip is a good idea as well. Hopefully we can figure something out from the data.

 

Try calibration 00.

 

I see your rough return to idle PW and MFDES jumpiness. Commanded IPR% does not return smoothly to idle, but has a step in it. Assuming you let off on the pedal quickly after punching it, that's a little odd.

I compared your data to my stock injector rev/idle for a baseline (sorta), just to see what a normal shape would be for the PW and MFDES curves, though the actual values will be different for your 160/0.



You need to pick the EBP_A(psi) PID instead of EBP(psi), and that green trace will straighten out. I think you're probably fine on that parameter.

If we did not blame the tune, I'd want to clean the IPR, especially since unplugging the ICP makes no difference. But with a relatively new IPR, I'm not sure that will do much. Your idle smooths out after a few seconds, right? That tends to say the IPR is doing it's job. I think it would stay rough if it was dirty/sticking. Once it clears up, you have a normal commanded IPR% of 12, on a not quite warmed up engine (125*F).

Interested to see how it behaves with the tuner removed, or on 00.

 

With mine, I believe the IPR was not responding quickly enough. The idle would drop and chop for about a second and then come back up and smooth out (most of the time). It acted up more when the engine was heat soaked so I'm thinking the coil was going bad, even though it ohm'd out OK on the bench.

 

Ok, so there's two possibilities for you, cowboy. Maybe a stock calibration or removal of the tuner will help guide you to the solution.

 

Thank you @BWST for charting that data. I’m going to remove the hydra completely see what happens.

 

I know it is a pain to remove the PCM in a manual transmission truck, but in order to figure out if the issue is hardware or software related, I feel this is the best course of action.

 

You do know you don't have to do that (remove it for testing).

With key on, engine running or off, put the chip in "00". Wait two seconds (for the confirmation flash) and then turn the key off. The next time the ignition switch is turned on, it will behave as if the chip isn't there. Seriously, THIS IS AN INTENTIONAL DESIGN FEATURE.