Hi all, wondered if anyone could help with a puzzling problem with a 2003 Jazz L13A (no aircon), started suddenly around 40,000 miles.

Until the engine is fully warmed up, idle feels 'lumpy' and running feels a bit rough, with a vibration. Engine eventually settles to a smooth low idle. Problem disappears when the engine is hot but may never stop completely in winter.

To add to the puzzle, a voltage drop caused even by raising a window or operating wipers causes a slight engine 'shudder' on idle.

Charging system voltages and battery are fine. I recently fitted new spark plugs and metered all eight coilpacks, which all show consistent ~ 1950 ohm in and ~ 3.9M out. No improvement at all with the plugs.

Acceleration is good with no misfires and MPG is very good. Never been an engine warning light on. The problem isn't worsening and I have lived with it for a while but now it's bugging me... Any thoughts? I promise if I sort it I'll post the cure!

 

sounds like the regulator in the alternator?

when its running like crap, unplug the battery and see if it makes it worse or dies. i dont know much about these cars but ive had similar issues when my alternator started to crap out. i know its not much but its better than nothing

 

Thanks for the help. Problem is, I can measure 14.6V on high idle and 14.3V at low idle at the battery terminals and switching the headlights on doesn't lower these voltages significantly. Battery after overnight rest shows 12.9V and it's new anyway. Last winter it started fine at -17C.

The problem is subtle but annoying. It didn't come on gradually but like, overnight.

I know my testing of the coil packs wasn't conclusive but surely on running there would be a misfire occasionally if one were faulty. It never misses a beat, just this vibration.

I would even suspect an engine mounting if the problem didn't disappear when hot!

Still puzzled

 

Further question then. Has anyone ever noticed a slight engine shudder on idle when operating a window or wipers on their Jazz/Fit? Thanks.

 

^ yes. i always noticed it. i just assumed it was due ot the engine being so small that the slightest load effected it.

 

Ah now that is interesting. Over here most car engines are around this size, and ever since I noticed this effect I've looked for it in other cars and without exception every one was totally unaffected in this way by an electrical load.

I don't remember the effect from when I started running this car but I guess I could have missed it.

So is this a Fit thing? If so why? It seems a little remiss of Honda, who don't normally miss a trick. But then they do have a few surprises up their sleeves, like water ingress into the spare wheel well (I have a fix for this if anyone needs it).

I'm guessing Nighthawksi, that your Fit runs fine so I'll put this effect and the rough running down to coincidence.

If anyone still has any input I'd love to hear it.