Re coils

Hi guys the diagnostic thing says intermittent misfire I have changed the plugs still the same looking for some decent after market coils as the originals are very pricey what do you think  cheers Rackster

My other car developed a misfire last year and I went down the route of checking everything, eventually changed spark plugs, coil packs, O2 sensors, MAF sensor, cleaned the throttle body, flushed the fuel, pretty much everything.

It turned out to be a low battery. When the battery was fairly flat the car would start and run OK, but get a misfire after deceleration to low revs and then feeding in the power.

If I kept the battery charged, it never misfired.

Have you tried cleaning the coil packs with switch cleaner and inspecting for cracks? If the misfire is random, it probably isn't the coil packs and likely to be something else, CAM position sensor, poor earth fuel, etc.

Robin

Thanks for that Robin when you say low battery how low?mine was 12.5 volts the other morning before start up I will put it on charge tonight and see what happens
Cheers Rackster

My other car is not a Jimny, so comparisons might be difficult, but battery voltage was around 12v before start up. Indicated voltage when the misfire occurred was 14v, but at low revs, 1,500 rpm in top gear. Although voltage was good at low revs the alternator probably couldn’t supply the pulse currents for the injectors/ignition these would need to be supplied by the battery and if it was weak it probably struggled leading to a weak spark or incorrect firing of an injector.

When does your misfire occur, low revs, high, any pattern to it?

Robin

Hi Robin it occurs at low revs I'm a keeper and have to stop and open gates you can hear the exhaust popping intermittently then drive off ok

Since the advent of smart alternators and such clever stuff a problem with the battery can manifest in many ways,missfire included.
However on the early generation Jimny (not G4) so long as your alternator is working a battery problem is unlikely to cause a missfire unless it's serious enough to pull the alternator voltage down.
12.5 volts at rest is ok, but more importantly it should be 14v with the engine running. If it stays around 12.5 - 13 volts something wrong with the battery or charging circuit. 

If you are uncertain Halfords can check your battery and charging circuit for free. Go to a store without an auto center as the ones with will try to book it in as a garage service, at the stores without they can't so it's free. 

Coil failure can be intermittent, and mostly related to heat.
Most often it is the rear pack that fails, because there is a bit more heat build up there. Same on my Swift (also m13). I have changed the coils around so i am not quite sure longer but I think I got one ebay 30£ coil, one '99 Baleno coil on my Jimny and one jimny coil on my Swift. You can buy a used coil from any G or M-series engine suzuki from 99 (98) or newer as long as it looks like yours it would work fine.

Hi guys changed the coils the HT leads plugs checked power to the injectors did a compression test all ok. No engine management light on nothing on the diagnostics .Still got the intermittent misfire  where do I go next? Camshaft or crank sensor? Cheers Rackster 

Do you get an engine management light on when you get a misfire? If not the ECU didn't think it was bad enough, you have to have 2 or 3 in a row on the same cylinder or more a certain amount spread across cylinders.

Does the misfire only occur at tick over and as soon as you open the throttle it is fine? Could it be described as uneven tick over rather than a misfire? If it is it might be a dirty throttle body, dirty/fault IAC valve.

It might also be the MAF sensor or as you say the crank sensor.