Engine Stutters @ Low Speed

[freddofrog]

thanks, Brian, what about the EGR valve as I remember the Jazz had issues with this?

I could be wrong, but I don't think the K24 engine has one. If it does, then I ought to think of changing the one on mine too

 

[uknowiama]

I suggested plugs as you can take then out and given their condition get an idea of whats going on with the engine.

http://motogymkhana.pl/katana/wp-content/uploads/2013/04/spark-plugs-guide.jpg

I suspect a failing coil pack, possibly.

 

[shab_the_man]

Coil pack could be the problem. Maybe check for unburnt fuel on the plugs

 

[Jon_G]

I'd be surprised if the K24 had an EGR valve... engines with a high degree of valve overlap control don't usually require one, as they can 'inhale' exhaust fumes directly from the exhaust manifold during induction.

 

[freddofrog]

I don't even know why any petrol engine should require an EGR valve, implies poor design from the beginning IMO

 

[Jon_G]

How else could combustion temperatures be lowered to minimise NOx production? Water injection?

 

[Accordaz]

another thought came to mind and I'm wondering if it's to do with the Cruise Control, as I use it a lot from 25mph, and having switched it off yesterday to see if it improved matters, and have found that it appears to run more smoothly at this speed without CC, so could it be to do with this!

 

[Stevearcade]

Is it a judder like when you have the car in too high a gear for the speed you're doing?

As it's an auto, my guess would be either gear box or spark plugs related. As you've had the gear box and engine oil changed, I think the next sensible thing to do is look at spark plugs.

What mileage is the car on? If it's nearing 75K, get the sparks done. If it's past 75K and it's not had the sparks done, get them done. If you don't know if the sparks are done, have a look and see then go from there. If you're unsure, take a photo of the plugs and post here. The lads can advise accordingly.

The tappets (valve clearance) might need doing also? They should get done every 50-75K I think...?

 

[freddofrog]

How else could combustion temperatures be lowered to minimise NOx production? Water injection?

I'd be surprised if the K24 had an EGR valve... engines with a high degree of valve overlap control don't usually require one, as they can 'inhale' exhaust fumes directly from the exhaust manifold during induction.

 

[Accordaz]

I'll put my new OBD on soon and see if it picks up a code, and report back!

 

[Accordaz]

well, managed to do an OBD scan today, and it found NO ECU fault codes, but for some reason I now have a tailgate fault whereby the tailgate won't open and it doesn't state this, strangely, so the next step will be to change the plugs...

 

[freddofrog]

so the next step will be to change the plugs...

or at least take them out and look to see their condition first, before splashing out on new ones

 

[Accordaz]

had a look at where the plugs are and it has a big loop of electrical trunk cabling etc, and it states having to take out the ignition coils; I'm off to Halford's to get a 16mm wrench to take them out tomorrow; hopefully it won't be too tricky a job!

 

[freddofrog]

the coils really do come out this easily

if you click on the picture, it is big :lol:

 

[Accordaz]

thanks, have downloaded it and printed it off

Whats best, NGK or Denso? I know both are Japanese, and have always had NGK plugs, but...

 

[toffee_pie]

you are meant to put iridium ones on the 2.4

such as the IZFR6K11 type from NKG

 

[Accordaz]

NGK plugs are the way to go from reading up on them, and I guess Stock No. 6994 are the ones to purchase? Saw them for £9.99 including delivery...anyone got them cheaper?

http://www.ebay.co.uk/itm/1-x-NEW-NGK-IZFR6K11-Iridium-SPARK-PLUG-Stock-No-6994-/271333676569?pt=UK_CarsParts_Vehicles_CarParts_SM&hash=item3f2cbf5619

 

[freddofrog]

you are meant to put iridium ones on the 2.4

such as the IZFR6K11 type from NKG

Both types are Iridium Eric, read my posts #26 and #29

thanks, have downloaded it and printed it off

Whats best, NGK or Denso? I know both are Japanese, and have always had NGK plugs, but...

I doubt if it makes much difference.

Best to get the plugs out before taking any other decisions.

 

[freddofrog]

btw, you'll probably do this anyway, but ...
when taking out the coil-packs, try to put them back in the same cylinder, not essential but if one of them is faulty and you put it back in a different cylinder, there could be a subtle difference in symptoms.
Same applies to the spark plugs.
And fgs don't drop any of them :lol:

 

[Accordaz]

well, after checking up on the price for the magnetic plug wrentch set (£25), it was too expensive for what could be a 'once off' usage, so have opted to have Honda do the 4 replacements for £97 inc, and we'll see if it cures the issue next Monday!

 

[freddofrog]

yikes ....what about non-magnetic and a bit of blu-tack on a chopstick, or if you're adept, the pair of chopsticks without blu-tack :lol:

 

[Accordaz]

btw, I will get them to retain the old plugs so I can see the state of each one, and post them for you to see; I'm also thinking it could be one of the coil packs at fault, because the issue only rears it's head when between 30 to 35 mph, and once out of this range it's fine!

 

[freddofrog]

have you tried it in difference gears in that speed range

2nd, 3rd, 4th, 5th

 

[Accordaz]

it's an auto! Something is breaking down at that point to cause it.

 

[freddofrog]

have you tried manual selection of the gears ?

edit: I've no idea how many gears the auto has, or if manual selection is possible, I'm presuming that the auto gear lever is conventional

 

[Accordaz]

yes, I do have tiptronic but it makes no difference.

 

[freddofrog]

so it's definitely related to car-speed not engine-rpm ??

 

[Accordaz]

correct, it certainly appears that way atm.

 

[freddofrog]

btw, I will get them to retain the old plugs so I can see the state of each one, and post them for you to see; I'm also thinking it could be one of the coil packs at fault, because the issue only rears it's head when between 30 to 35 mph, and once out of this range it's fine!

have you tried it in difference gears in that speed range

2nd, 3rd, 4th, 5th

it's an auto! Something is breaking down at that point to cause it.

have you tried manual selection of the gears ?

edit: I've no idea how many gears the auto has, or if manual selection is possible, I'm presuming that the auto gear lever is conventional

yes, I do have tiptronic but it makes no difference.

so it's definitely related to car-speed not engine-rpm ??

correct, it certainly appears that way atm.

if that is definitely the case, then it can't be related to spark (plugs or coil-packs) or fuel, and I can't think of anything else engine-wise (except maybe an issue in the ECU, as the ECU knows the car-speed).

otherwise it may be something related to the gearbox

 

[Accordaz]

OK, had a burn out on Saturday, and really made the car fly en-route to Tunbridge Wells, and took it out yesterday and all appeared fine at that speed, so have I cured it, only time will tell; anyway, got the plugs changed today as planned, and here's the state of the old ones for you to cast your eyes on:

you can click the pics to enlarge!