'98 Jeep Wrangler JTEC Throttle Follower Decay Settings

[SkylinesSuck]

1998 Jeep Wrangler TJ (manual transmission) with a 4.0 based stroker. I've had it tuned by someone else who was using SCT tuners. They never finished so I bought HP Tuners to finish it and I'm making progress. One issue I'm chasing is my hanging idle when in motion. Idle will stay at 1200rpm+ until I come to a complete stop. I have been researching on here and it looks like the setting I need used to be called "dashpot steps" or something similar and has since been relabeled "throttle follower decay." That setting isn't available to me in either the stable or beta versions of VCM editor. I have downloaded other JTEC tunes to look at and it's there for them. Any tips? Thanks!

[duster360]

99% of the time, a hanging idle that magically fixes itself once stopped, is caused by a vacuum leak adding excess airflow to the throttle follower airflow.

I'd seal off all the vacuum ports on the intake and retest to verify.

[SkylinesSuck]

I have smoke checked the intake for leaks recently and there are none that I can find. I can hear the IAC valve actuating and raising the idle when it happens. Also, I can even stop pointing nose down on a hill with the idle normal, then start rolling with my foot on the clutch and the idle will kick up to 1200 rpm.

[Dwg86]

I hope you can figure it out. My Jeep with a 5.9 transplant is doing the opposite. As soon as my computer sees wheel speed it cuts my idle.

[SkylinesSuck]

Weird. Did you play with the throttle follower settings? HP tuners support said they are going to add that parameter to the software for me in the very near future.

[Dwg86]

Weird. Did you play with the throttle follower settings? HP tuners support said they are going to add that parameter to the software for me in the very near future.

I dont see "throttle follower settings" in my tune. I had Injected Engineering in Ga dyno tune it. They couldn't figure out why it's doing this, so I had them send me the tune file, but I have no idea what I'm looking at. This is all new to me. But mine is doing exactly the opposite from you. If I'm sitting on a hill in neutral and just start rolling, my engine will lose rpms and sometimes die.

[jbee]

I dont see "throttle follower settings" in my tune. I had Injected Engineering in Ga dyno tune it. They couldn't figure out why it's doing this, so I had them send me the tune file, but I have no idea what I'm looking at. This is all new to me. But mine is doing exactly the opposite from you. If I'm sitting on a hill in neutral and just start rolling, my engine will lose rpms and sometimes die.

My 04 does the same thing... following for info

[Omunoz]

this issue can be a combination of problems, i had this happen to a few jeeps, it can be related to the iac sensor not resetting to the proper steps ,if you change the values of the map it may take some driving time for ecm to adjust. one of the things i do is to reset the ecm every time i make changes to the tune.

[SkylinesSuck]

@Dwg86 I'm going to check again later this weekend but I think I opened up a tune file you posted up in another thread and saw the setting in there. Maybe it was from somewhere else? It was labeled grey something or other. And just curious, did you ever change your IAC to see if it had any affect?

[SkylinesSuck]

002_Gray was the file and it's in there. Not sure how to embed a pic on here.

[Dwg86]

Yeah, I started a thread about the problem. I’ve installed a new Mopar IAC. I haven’t tried to adjust anything yet with HP. I just bought another ECU on eBay to try. There’s a Service bulletin from dodge that talks about “lost idle steps” and the computer will need to be reflashed with new software. My computer doesn’t have the update. I’ve had a couple other intermittent problems so I decided to try another computer. The one I purchased has the sticker on the computer that says the factory update has been done. I’ll just need to download my tune into the computer and hope I don’t download any problems from my old computer into the new one.

[SkylinesSuck]

Gotcha and I hope it fixes out for you. Are you on jeepstrokers btw? Anyways, that parameter is there for you to play with. I can email you the pic I took if you care to see. It's labeled "Throttle Follower" and the button says "Decay RPM" under the idle tab.

[Dwg86]

Yeah, it’s been a while since I’ve been on jeepstrokers. I’ve seen you on there. This 5.9 is a transplant into my 97 TJ. That would be great if you could email me. This is all new to me, and I’m learning.
Sorry, I didn’t mean to hijack this thread.

[SkylinesSuck]

Not a hijack at all. What's your email addy?

[Dwg86]

Sent you a PM

[drumnbasslvr]

I'm afraid your Hp Tuners isn't up to the task with Idle steps. For Jtec PCMS I use Snap on scanner. It shows it just fine. Set your steps from 60 to 0 at idle while maintaining your desired and tune prescribed idle. Adjust your throttle body screw to close or open throttle body to achieve proper steps. But, after an adjustment, you need to cycle key and restart in order for steps to learn properly. Jtec will think the throttle is open or closed depending situation. On key on, it learns 0 throttle voltage. All of you will be remedied with this. I'm sure.

[SkylinesSuck]

I have a Snap On scanner as well. I'm not understanding what you are saying though. I think you are saying use the idle stop to adjust things and use the scanner to see where it's getting adjusted?