Car Misfires/Runs Rough/Spits Fuel... Any ideas?
Discussion
Also totally failed at emissions out of nowhere, HC -Hydrocarbon was at like 740 (should be under 200, CO &Lambda all good,only the HC which I guess indicates Unburnt fuel?)
Also, It appears it perhaps spits out fuel sometimes out of the exhaust? (I'm fairly sure it's not water & there is no black or white smoke coming out..)
See this video & listen to how rough/choppy the exhaust sounds.
https://www.youtube.com/watch?v=Ia-NNCg7vDw
It's a 2003 Honda Jazz 1.2 Petrol (170k miles), Have had the car for 10years, started running a bit rougher perhaps a year ago, now has gotten gradually worse,until the failed test on emissions...
It does feels/sounds like the car is misfiring very slightly,especially at Idle , can't really tell that it's running worse when driving it...
Fuel consumption is a bit higher but not drastically.
No Lights/errors on Dash, local service couldn't see anything reported wrong when plugged to computer as well.
What I did:
-New Spark Plugs (the old ones looked in very good condition)
-Fresh oil /all filters
-dumped in a bottle of redex & gave it an Italian tuneup.
-Cleaned EGR,internal pin was sticking from carbon buildup,however no change afterwards after loosening the pin/cleaning.
-Tested Ignition coils by unplugging each while running to see if all work, they all work,not 100% sure how effective as there were some very light internal signs of corrosion as I took a couple apart to inspect.
-Could not see any obvious sources of vacuum leaks
Not really sure where else to look and what to try?
Someone suggested a Failing Cat ,however wouldn't all Emission data be out of order if cat was faulty?
Testing O2 sensors is on my to-do list once I get a good multimeter and learn how to test them.
I guess something is failing on that car as it's getting worse,however it's not completely dead yet as it doesn't throw up any errors.
Also, It appears it perhaps spits out fuel sometimes out of the exhaust? (I'm fairly sure it's not water & there is no black or white smoke coming out..)
See this video & listen to how rough/choppy the exhaust sounds.
https://www.youtube.com/watch?v=Ia-NNCg7vDw
It's a 2003 Honda Jazz 1.2 Petrol (170k miles), Have had the car for 10years, started running a bit rougher perhaps a year ago, now has gotten gradually worse,until the failed test on emissions...
It does feels/sounds like the car is misfiring very slightly,especially at Idle , can't really tell that it's running worse when driving it...
Fuel consumption is a bit higher but not drastically.
No Lights/errors on Dash, local service couldn't see anything reported wrong when plugged to computer as well.
What I did:
-New Spark Plugs (the old ones looked in very good condition)
-Fresh oil /all filters
-dumped in a bottle of redex & gave it an Italian tuneup.
-Cleaned EGR,internal pin was sticking from carbon buildup,however no change afterwards after loosening the pin/cleaning.
-Tested Ignition coils by unplugging each while running to see if all work, they all work,not 100% sure how effective as there were some very light internal signs of corrosion as I took a couple apart to inspect.
-Could not see any obvious sources of vacuum leaks
Not really sure where else to look and what to try?
Someone suggested a Failing Cat ,however wouldn't all Emission data be out of order if cat was faulty?
Testing O2 sensors is on my to-do list once I get a good multimeter and learn how to test them.
I guess something is failing on that car as it's getting worse,however it's not completely dead yet as it doesn't throw up any errors.
I've had a couple of cars (Yaris/Jeep) fail on emissions (high hydrocarbons) and both were 'fixed' by moving away from using supermarket fuels to Shell/Esso. This was a few years ago mind.
I know there's a huge debate on the validity of this, but that was my experience at the time - if you are using supermarket fuel it might be worth a try.
Failing that, start with the basics like a compression test, new plugs, etc.
I know there's a huge debate on the validity of this, but that was my experience at the time - if you are using supermarket fuel it might be worth a try.
Failing that, start with the basics like a compression test, new plugs, etc.
I'd try an O2 sensor, but the bit that makes me question that slightly is you said there's a misfire at idle. Normally O2 sensors aren't used to adjust idle fuel trim too much on cars of that age. Are the injectors OK?
At 170k miles it could just be starting to get shagged - try a compression check to see if there's low compression through a valve or piston ring somwhere.
At 170k miles it could just be starting to get shagged - try a compression check to see if there's low compression through a valve or piston ring somwhere.
bagusbagus said:
Testing O2 sensors is on my to-do list once I get a good multimeter and learn how to test them.
It's remarkably easy for a narrowband lambda sensor and can quickly show you how well the ego feedback system is working.I suggest you get yourself an infrared thermometer too. This can often show where one or more cylinders are misfiring leading to a cooler exhaust header.
ked 
bagusbagus said:
Also totally failed at emissions out of nowhere, HC -Hydrocarbon was at like 740 (should be under 200, CO &Lambda all good,only the HC which I guess indicates Unburnt fuel?)
Post up the actual numbers from your MOT failure. As stevieturbo says it's impossible for a misfire to only cause an increase in HC.Gassing Station | Engines & Drivetrain | Top of Page | What's New | My Stuff