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Possible issue - maybe idle

-Rich-

-Rich-

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Location
Rickmansworth
Car
2.4 Tourer Auto
For the last week I've noticed a slight issue with the car, it sometimes feels abit hesitant (only slightly) and not as smooth as it has been. The idle also seems abit erratic, sometimes dropping to just over 500rpm if I back off the throttle either slightly or completely. If I back off to slow the car the idle might drop right down to around 500rpm and then back up again.

I'm going to try cleaning the MAF and ICV first. I've found this guide, is it for the 2.4, it doesn't say or are they all the same?

http://typeaccord.co.uk/forum/topic/1517-maf-map-sensor-cleaning-imrc-valve-cleaning/

Is there a guide for the ICV or can someone tell me where to find it, a photo would be good :)

The car was serviced last year before I bought it and has done 5,500 miles since. It's due an oil change, which I'll do soon but is there anything else that can cause this?

Air filter isn't due for ages but I might replace that as well, what is a good aftermarket brand to get, K&N ok? I know some MAFs don't like the oils on these so a dry filter might be better?

Thanks
 
How old are the spark plugs? And when were the valve clearances last adjusted?
 
I had a look at the history last night and the plugs were changed at 76k miles (2009) (for the 75k service) and the valve clearance was adjusted then.

The 100k mile service was done at 94k miles (July 2012) and the car has just under 100k miles, so they are due. The plugs used when they were last changed are the Denso SKJ20DR-M11, so I will replace them with those - http://www.gsparkplug.com/shop/denso-skj20drm11.html

I have never done valve clearance on any car before, is it necessary to check it every 25k miles and is it something I could do? I'm fairly confident with most jobs. Can I change the plugs and get a garage to check the valve clearance or do they need to be out to do this?

When warm the car seems to idle at 600-650 rpm, is this right, I'm sure it used to be higher? When I brake or back off the throttle sometimes (it's not everytime) the revs drop down to idle speed and then jumps back up again to 1k-1.2k rpm.
 
The handbook says that spark plugs need changing at 25k miles so I ordered the new ones, which should be here soon. But reading the Honda service checklist last night they say for iridium plugs it's 75k miles, so really these should be fine.

The idle isn't hunting when the car is stationary, it only seems to be when I'm driving. What should the normal idle be for the car as well?
 
Just cleaned the throttle body, it was a bit gunky. I noticed the butterfly isn't closing fully and there's a slight gap. Is the idle electronically controlled cos I can't see a cable, how can I adjust it?

Also where is the MAF, is it the round sensor on the intake hose near the throttle body end?
 
Yes the idle has what is called a IACV or idle air control valve. The butterfly should close fully so do look into that. There is small channel that runs between the butterfly and that is regulated by the IACV to keep idle smooth.

I actually stripped down my friends 2.0i vtec and we took off the throttle and cleaned the IACV and scrubbed the main butterfly. Be sure not to take the butterfly apart as its difficult to align it back up. The IACV can be removed for a clean. I even reused the old gaskets as i was careful when taking it apart.

The IACV has a feed of coolant going through it and this is how it works out how much air is needed. Be sure to make sure the gaskets are sealed and that not water leaks into the intake.
 
If I press the butterfly I can move it a little more to fully close it. I drove the car this morning but didn't reset the ECU after cleaning the butterfly, it seemed better but the idle may need to adjust some more.

Is the 2.0i the same as the 2.4i cos I've been watching this video and it looks different on mine.

http://www.youtube.com/watch?v=1u3XGC0sZe0

The black sensor on the left hand side of the throttle body I don't have on mine and it seems to be a drive-by-wire system so there is no throttle cable just a black box/sensor. I've since found out where the cable is so I'll clean that over the weekend. I'm not so sure this engine has an IACV and it's adjusted electronically? I still can't find the MAF sensor, which is usually just before the airbox on previous cars.

This is the throttle body on my car and from the photo is looks like the butterfly is slightly open, the same as mine.

http://www.ebay.co.uk/itm/HONDA-ACCORD-03-07-K24A3-2-4-PETROL-140-KW-THROTTLE-BODY-7-CL-CM-Drosselklappe-/171207887960?pt=UK_CarsParts_Vehicles_CarParts_SM&fits=Car+Make%3AHonda%7CModel%3AAccord%7CCars+Type%3A2.4&hash=item27dcc90c58
 
Well going by the lack of replies I'm guessing this isn't a common problem?

Looking into it some more I've come across this thread for the TSX - http://www.tsxclub.com/forums/1st-gen-problems-fixes/57705-weird-idle-problem-help.html I think this is an extreme example, mine seems mild in comparison and mainly seems to do it between 20-30mph. When I've stopped the idle is fine although it's higher in N than it is in D. Driving the other day on the M25 at 50mph+ was fine the revs didn't fluctuate so it seems to be under a certain rpm that it's doing it, I would say under 2k.

***uming the TSX engine is the same as our Accords the IACV is built into the throttle body, which is why I can't find it.

I did the reset procedure for the drive by wire system after cleaning the TB, which has raised the idle but the problem is still there, although at least the car doesn't feel like it's going to stall when it was dropping as low as it was.

I've found one throttle body on ebay if I wanted to swap mine over to try it or someone on that thread has also mentioned the throttle position sensor can cause idle problems.

What do you guys think the next step should be - get a replacement TB?
 
Have you tried a bottle of injector cleaner in the fuel tank?
I used to add a bottle to the tank on my old Prelude with each service and it always idled much higher after that had got through the system.
Cheap enough to try before you go for more expensive things.
 
I thought about doing this the other day so when I'm next at the shops I'll get a bottle of redex.
 
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