Idle Help

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RebelYankee

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Hi all,

I have a 2015 LR4 with the 3.0SC and 94k miles. When I come to a stop, about 15-30 seconds later the idle drops to about 620 and the truck shakes a little. Happens with and without aircon, but only in gear. I cleaned the MAF's, cleaned the throttle body, changed the plugs, checked air filters. There are no codes and no hesitation when I hit the gas.

Any ideas?

Appreciate any help.

Jamie
 

f1racer328

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Maybe some BG 44K for the injectors could help.
 

f1racer328

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I would read through these threads if you haven't already. Could also be a vacuum leak.
 

RebelYankee

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Thanks for those. I did read through a bunch of posts on different forums, but nothing that was exactly like I am experiencing.

But I think the vacuum leak is good thought. Thanks.
 

RebelYankee

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More info, and hopefully good news.

So I have a cheap Bluetooth reader that I used on my D2 with no issues. Have had it for years. When I used to use it on my wife's 2007 Mazda CX-9, and it would always make the car throw a code. So I never really used it in her car. So while trying to troubleshoot this low idle issue, I pulled it out and hooked it up to the LR4 while I took a cruise on the highway doing a BG44 cleaning. Everything was great until I put it in sport and started to use the paddle shifters. At first I got a message that the blind spot mirrors malfunctioned. Then it was the parking brake. Pretty much total chaos. Was still running fine so I got off the highway to fill it up. Got back in the car and it didn't recognize the fob. Had wife bring me the other fob and nothing. Didn't work holding either fob under the steering wheel either. Wife also brought me a 10mm wrench (which I now keep in the car at all times). I unhooked the positive from the battery for a few minutes and the fob worked again. So lesson learned do not run all the time with a cheap reader in the car.

I used the gap tool to check for codes, and it was full of communication errors. Cleared and all good.

Today I noticed that the rpm's will drop when there is an electrical load. Hvac, seat heater, steering wheel heater... with everything turned off it runs fine. I don't know how old the battery is and it's pretty much covered on all sides so I can't see the sticker. Alternator is strong at 14.7v and never wavers even with the lower idle. So could this just be a battery that's going bad?

Thanks,
Jamie
 

powershift

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I would destroy that OBD2 reader. Take it out behind the barn and shoot it before it breaks something.
 

f1racer328

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When you have multiple codes that seem unrelated, and happen somewhat suddenly, it usually indicates a bad battery. This ones weird though with your code reader. Are you still having the low idle shudder?

If the vehicle is new to you, and you're not sure how old the battery is it might not be a bad idea to replace it. You can fit an H8 sized battery in by the way. I buy mine from Costco. Interstate H8 AGM. There's a few threads on that here, along with how to set the new battery type with your GAP tool.

If you're dropping RPM from electrical load that screams battery to me.
 

RebelYankee

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Yes, I am still getting the low idle and shudder. Goes away when I turn off the hvac and electronics. I noticed it was electrical when I was at a stoplight and turned on the seat heater and the rpms dropped. I'm thinking battery too. The one in there now is a Diehard AGM. No idea how old it is.

Do I need to reset the bcm when I replace the battery?

Edit: the codes were 100% from the cheap Bluetooth reader. From what I found, the reader was competing with data throughput from all the computer modules.
 

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