Engine Idling

[Noel]

Hi all,

Since changing my spark plugs the engine is not ticking over smoothly anymore, the idling speed is much the same but there is definitly a bit of an intermittant shake in the car, slight audible variation too...

They car is actually driving better, but this isn't normal.....Is it?

Should i be concerned......put the old plugs back in maybe?

I reset the ECU but has made no difference, checked the connections, all seems ok

The only difference is the plugs that were in were a lower heat range then what i put in, Denso IK20 ...now IK22, would this make a difference......

The Plug gaps are different....much larger on the ones that came out....

What to do...?

Concerned!

[MacRS200]

The reason that the plug gap is bigger on the old plugs is that they have erroded, the new plugs are the correct gap. Also the grade "colder" on the plug should not make a major difference when idling, try taking out a plug and checking the colour of the electrodes.

On the ECU reset how did you do that, Battery or fuses? I now follow advice I found on the altezza.au forum for an ECU reset and remove the 20A ECU fuse as well as the ETCS and EFI fuses. When I only removed that ETCS and EFI I used to get some wild "hunting" on idle revs sometimes and uneven idle for a while after till it settled down. Never had that on the IS.

[Noel]

No didn't go near the fuses, just disconnected the Battery for 5 mins....

I'll have another go, fuses this time

[ColinBarber]

did you check the gaps on the new plugs? Maybe one or more of them didn't have the correct gap. Why did you go for a colder plug? Do you have mods?

[Noel]

did you check the gaps on the new plugs? Maybe one or more of them didn't have the correct gap. Why did you go for a colder plug? Do you have mods?

The plugs are supposed to be pre gapped and did all look the same, biggest difference i noticed was how much smaller this gap was.......

No mods ........ went on recommendations from users on this forum..... I do drive "lively" though......

what should i do?

put back the old ones?

What gap size should they be....?

[Mr Singh]

try the old ones, see if it feels the same.