My search of this issue didn't turn up anything that helps. Maybe I'm using the wrong search terms.

The Problem: My idle hangs up when decelerating. At 1,000 rpm it hangs for a bit, then works its way down to 950, 850, 800-ish.

The manual says that normal idle is 750 (+/- 50), and 850 (+/- 50) with electrical load.

I'm not too worried about this issue, but I'm certain that it wasn't doing this before.

Note: I did a valve adjustment two days ago. All went well. I got a check engine light, but then I remembered that I forgot to tighten the belt clamp that fastens the air intake to the throttle body. No check engine since then. Engine runs well, very nice in VTEC. Could be a little smoother at idle, but I just don't know how much more fiddling a person has to do with the valves to work out the roughness. Just before my next oil change, I'm going to run some Techron and clean the injectors.


Am I worrying needlessly?

Thanks!

 

unhook the battery cable. When you got the CEL it sent the car computer into safety mode and is being very slow to correct back to normal.


leave it unhooked for 10-20 minutes. You just need a 10mm wrench

 

You mean that I should let the ecu relearn the idle setting...?

That could help.

Thanks.

 

Driving it will set the idle learn. What you are doing when you disconnect the battery is re-setting the whole ECM. But I think you are just listening ore closely than normal. Rapid closing of the throttle plates causes more emissions so it is compensated for that by the ECM.

 

^^Didn't disconnect the battery yet, but had to put 100-ish miles on the car today.

Started the day with the hanging idle, but it seemed to be less so as the day went on.

Will keep you posted.

 

Take 15 minutes and do the Idle Learn Procedure. (actually, you ARE supposed to disconnect the battery first, to give the ECU a proper "lobotomy")


Both our Fit and our CR-V suffered from fast, slow-to-return idle after throttle bodies were cleaned and valves adjusted.

 

Like I said the idle learn that you guys are talking about is really resetting the WHOLE ECM NOT just the idle. Anytime you disconnect the battery the WHOLE ECM is reset do you think the ECM knows well crap this guy just wants to reset JUST the idle?

And do you also realize that the idle is set EVERYTIME you start and drive the car automatically?

You guys are confusing just one step in the pre-delivery check list to look at the idle speed before delivery to see if it is correct it is not a procedure for diagnosing or correcting problems. IF there is a problem with the idle speed and you disconnect the battery you are resetting the whole ECM not JUST the idle.

 

@loudbang:

1) If the idle resets itself every time you start the car, then this is not an idle reset problem (?).

2) Why would a valve adjustment be the cause of a hanging idle? Should I be looking for other problems?

3) Is there any reason why one should not reset the ECU? It happens every time someone removes the battery anyway, so it's not a big deal, right?

 

It's not a problem to reset the ECU, unless you need to go to inspection in an emissions-conscious state the next day. Some OBDII emissions checks need several drive cycles to reset their Readiness Codes.

I'd have to look it up again, (maybe LB knows for sure) but at least, when the throttle body is cleaned or otherwise serviced, the ILP is a necessary step and is specified in the shop manual.

I'm kinda anal about TB cleanliness, having had dirt affect my idle in several cars over the years (not just Hondas). If I can see the throttle butterfly, I clean it. And on my Hondas, I do the ILP.

 

1 correct the idle speed is checked by the ECM constantly

2 It usually the simplest thing you know occums razor. If it was ok before the valve setting then it means something you did during that job is what is causing your problem.

But again are you sure there is a problem like how long does this hang last for a second or less or a longer time?

I would go back and look at what you did during your valve adjustment as far a disconnecting things and make sure they are back in the proper position and all connectors hooked up.

3 for sure no problems resetting frequently do it as often as you want but it gets to be a pain in the butt re-setting the radio, windows and clock

In reality EVENTUALLY the ECM will "Reset" itself just during normal driving as it is constantly checking what is going on and making corrections.

Manually resetting it by disconnecting the battery just speeds up the process that the ECM would eventually get around to doing on it's own.

Usually there is no good reason to reset the ECM settings unless you want to clear codes, installed some new mods and can't wait, or have a problem of some kind. Other than those things the ECM will "reset" itself without any outside interference after all that is it's job..

 

What I am experiencing is not a crisis. In fact, it may be within the normal specs. It may further be that I worry about things too much.


Thanks for the hand-holding nonetheless.

 

Hey that what we are here for to help people get through their crisis.

 

You're a regular Oprah, my friend. Let's talk about our feelings some more. Maybe over a glass of white wine.
















j/k