havoc UK

Well, had a call from the garage...they've checked the valve clearances and they were all fine.

They also checked the compression and it came back 'within tolerances' (apparently the mechanic didn't make a note of the results! )

But it's still idling rough!

They are now suggesting that the head might need to come off to check the valves and valve seats, despite the compression results. 5.9 hours of labour, at my risk if it's not needed, as the Hondacare Warranty doesn't cover investigative work!!!

And of course the dealership will suggest it needs doing but they won't take the risk that they are wrong!!!

(To be fair, they've done this without argument, and without payment though...)



Right then.
- The EMS light hasn't come back on again in 200 miles. Not to say it won't, but it's been off for a while now. Previous symptoms were random misfires causing the EMS light to come on, plus a rough idle.
- I've changed the plugs.
- I've put some Forte Gas Treatment in this last tank.
- This dealer has checked the valves.
- Not sure what the original dealer it was recovered to checked. They seemed adamant it was valve clearances...

New symptom (yesterday, in traffic, in the heat) was 'hunting' at low revs in 1st gear. Hadn't just changed gear, hadn't been rough with throttle, it just started hunting and felt like it was going to stall...
...which a quick search suggests COULD be MAP Sensor, although the dealer suggested MAP sensor issues would give me different symptoms...but didn't say what.


So...HELP!!!

Si2k

A leak down test will check the sealing of the valves/ valve seats. NO need to take the head off.

I remember previous posts on the subject, but did you get the injectors checked /cleaned? Might be worth a try if the leak down test is ok

mikey k

redo the compression tests and note the values
leakdown test
try a map swap for a know good one
Worth checking the injectors as well
What state is the throttle body in

fluffyninja

I'm with my learned coleagues above. Try a few of their suggestions above.

Few other posibilities
If it's hunting then it'll be getting either bad commands from the ECU or the parts aren't receiving the correct commands.

What I mean mean by that is a sensor at fault somewhere, a wire harness problem or a problem with the component at the far end.

MAP sensor is a good starter for 10. Might also be worth getting a wet rag and wrapping it around some of the hoses when it's rough idling. Would give you an indication of a hose split somewhere.

If it were one of the oil control valves for the valve timing/lift then chances are you'd get a different error but might be worth just checking nothings stuck in them.

If you were having a valve problem (i.e. worn or recessed seat) then as others have said I'd expect the compression to be going wrong and MIL light to be coming back on immediately after you cleared it (which doesn't appear to be happening)

When you pulled the plugs what did they look like? Was one plug darker than the others (very badly carboned up)? Might indicate oil getting into the chamber and burning but that would probably have your oil consumption going doo-lally. Might burn unexpectedly which could cause a misfire.


Shall have a think and see if I can come up with anything else

havoc UK

Thanks Si, Mikey, FN!!!

Plugs...all were similar, all looked just fine.
Compression...on a not-quite-cold engine, 214/211/214/215 (already did it last weekend just-in-case) - no idea if that's good, bad, or indifferent, but they're all close enough...
Oil consumption...negligible - well within what I expect from a VTEC


So there we are...I have to confess when he started talking valve-seats and 'take the head off' my bullsh't detector was starting to ping rapidly at signs of an impending fleecing...

I'm still thinking electrical something, but that covers a whole multitude of sins...will try a few things as and when I've the time...and keep an eye on that MIL light!

Red S2000

Wild guess, is your air filter clean?

C&S Evo7

IACV can be the cause of hunting

Leakdown test by a competent garage should show any signs of worn, leaking valves , damaged seats , etc. a compression test will not show this unless the valve is really badly damaged.

this is unlikely unless you constantly use 95 ron fuel

Bogsye

I'd be tempted to invest in a diagnostic tool like Autoenginuity's Scantool.
It seems to offer the ability to view live data off the various sensors and also do some datalogging. I recall they were about

m1bjr

My guess would be an injector fault.
Either injector itself, or its connection.

Interesting one this, let us know what you get it down to?

havoc UK

Right, just to pull everything together:-

Original thread:-
https://www.s2ki.com/forums/index.ph...c=513405&st=25


Symptoms:-
- Rough idle
- very occasional MIL light - cause stated as 'misfire #1 / 3 / 4 cyl'. 3x over 150 miles and a week-and-a-half, been off now for 2 weeks and 250 miles.
- hunting/kangarooing when warm in stop-start traffic on M42 on a hot-day. One and only incidence so far.


Work done so far:-
- Spark plugs changed
- Forte gas treatment added
- Valve clearances checked (and messed up! ) by Honda dealership


Possible causes:-
- Injectors
- Coil(s)
- Valves / seats (but compression OK)
- MAP sensor
- IACV (? How to check ?)
- Leak in one of the hoses
- Cat converter problem
- Faulty sensor (e.g. lambda sensor...any others?)
- ECU gremlin


So...
- have I missed anything?
- what of the above can I check myself? And any guidance how. Not an exceptional mechanic but I can do simple stuff...managed plugs just fine.
- what SHOULD I get a garage to look at?
- and what should I leave alone for the moment?


Thanks very much (again),

Martin