Valkyrie

Car just threw up a CEL within days of its MOT due date while stinking of unburnt fuel at idle standstill. So badly so that I've had to open the windows in traffic.

Opened the diagnostics on my phone via REV and this was the result -




Now, does this simply mean I'm gonna have to replace the cat, or does it carry over into possible new lambda/O2 sensors? Or could it even be an exhaust leak? P0420 is the code which I've now cleared via the phone app but I'll need to figure out which parts and sundries I need before I remove it.

BenRNBP

My gut is saying there's something else causing the over fuelling and the P0420 code is a side effect of that - sticky injector maybe ?

another thought, do these engines suffer from icing in the intake tract ? I doubt it with how hot they run but it's worth asking.

Valkyrie

That's interesting actually, I've wondered if the injectors were on the loud side too. Any way to investigate injector function?

BenRNBP

Are you able to monitor the ECU with Rev ? I'd have a look at the Long term and Short term fuel trims if you can ( I know Torque for android can do this) if you've got anything below -10% or above +10% then the ECU is trying to compensate for something - not sure how I'd test injector function without taking them out and sending them away for flow testing.

Also have a look at what the engine coolant temp sensor is doing as it might be telling the ECU the car's not warmed up yet and so over fuelling. Of course there's the normal faulty MAP that might cause something like this too.

Valkyrie

Cheers Ben, I'll have a look into this and the perameters REV allows when I next get back from work in a couple of days. Not sure if REV/iOS stuff is as comprehensive as the Android stuff but we shall see.

not4s4l3

Hi Valkyrie,

In my opinion you shouldn't clear the code until you fix it. Then clear to see if it will persist.

I recently had a CEL thrown (other code than yours, something about Lamda sensor) and eventually I had to replace both stock CAT and sensor.

First question will be, do you hear any clunking noise underneath the car when getting off the gas pedal?
(friendly advice if you DO hear a sound, look at this the soonest as you might end up decapitating your o2
sensor - pretty much like me! )
https://www.s2ki.com/s2000/gallery/i...89-o2-sensors/

If yes, could be a broken cat but you won't be sure until you get it up the ramp or on jack stands and punch it gently listening for things 'moving' inside. If it rumbles then it tumbles.

Next culprit for me will be the O2 sensor not measuring flow properly. I'll check that next. Remove it and see what CEL error you get.
Did it change than the one before?

Just to let you know that stock Cat was ridiculously priced 8 times more than Berk 70mm HFC (£225) which I finally purchased from America. Same with the o2 sensor. OEM was £170, I got it for £50.

Anything that I can help with please do let me know!

Best of luck man and keep us posted!
I know the evil amber engine light is really annoying but on the bright side you could have had a lot worse
CELs thrown at ya!

Valkyrie

Thanks buddy, much appreciated. Stuck away on the Isle of Man right now adds to the issue but hopefully I can borrow a ramp this weekend.

I've listened for clanging from the cat and haven't noticed any yet so it doesn't give the indication that it's coming apart. My last car did that and I just replaced it with a ceramic Aussie down pipe, however I ended up melting ringlands on two consecutive engines so I'm glad this is only a CEL so far!

I'll try the O2 sensor removal at the same time, too. Just looked on eBay for replacement stock Cats and they vary madly in price between genuine honda items and standard OE cat replacements. I'll try my local honda in Nottingham but I doubt they're competitive.

not4s4l3

Absolutely no probs! Glad, IF I can be of any help!
By the sounds of it, your cat should be healthy.

Don't get me wrong, I'm pretty much the OEM sort of guy, if OEM breaks replace it with OEM; but Honda is now asking for everything under the sun! OEM cat is ceramic and Berk HFC is stainless steel and significantly lighter.

You will be lucky if it is the o2 sensor. I can point you out on this NOT so good looking site, but it did the job for me! (£50 delivered o2 sensor, I've just checked now and it has dropped to £42.70).
(I've got a 2008 model)
http://www.rockauto.co.uk/catalog/x,...,parttype,5132

Valkyrie

Just had the chance to drive it home today from work and I've had REV running too after 30 mins low speed drive, it doesn't have all the perameters but this is what it threw -



Set up fuel trim monitoring via SB1 & LB1 (whatever that means) on the left there. SB1 jumped from +4 to -20 max diff' but usuall stabilised at +/-3 whereas LB1 stayed är a constant -7.

If anyone knows what that means in practical terms that'd be great. Wreaks of fuel still!

BenRNBP

Is it misfiring at all ? Could be something like a dodgy plug / coil pack that's just not igniting the charge ? Not quite as bad as I expected but the ECU is trying to compensate for a rich condition by pulling fuel. (I'm guessing SB1 is short term and LB1 is long term trim)

Have a read here http://www.easterncatalytic.com/educ...agnostic-tool/ especially the bit that says:

"Running too rich – High negative fuel trim corrections can be caused by MAF sensor problems, high fuel pressure, leaking fuel pressure regulator diaphragm, faulty evaporative emissions components, leaking injectors, defective O2 sensors, exhaust leaks/pinholes before the O2 sensor, coolant temp sensor problems, and base engine issues such as low compression and incorrect camshaft timing. "


Should give you something to go on at least ! Good luck in getting to the root cause.