Misfire On Cylinders 1 And 2

[paolo137]

Hi everybody,
I've been having a minor issue with code error P0301 and P0302 coming up once in a month for a while now.
That should be "misfire on cyl. 1 and 2". Car drives smoothly.
Mech says to change the coils of the sparkplugs (of course, all of them ,not only 1 and 2...)
I'm a little puzzled: coils can fail, of course, but why do I always get misfire on the same two cylinders, and always at the same time?
My question is: is there anything that could cause both cyl. 1 and 2 to misfire simultaneously? Don't know: wiring, fuel line, whatever.
Any input will be much appreciated as usual. :)

[katabrontes]

I had the same problem with my 350 in France last year. It was fine when the car (and outside temperature) was cool but on hot days as the engine warmed up the misfires started. I could definitely feel the misfire as I pushed down on the throttle. If the engine is running smoothly I can't see how there could have been a misfire on any cylinder. In the end they replaced only the faulty coil but it was quite expensive (abut €200). As they had to order the part specially I guess its not a very common failure. I should think if the problem is consistently on only 1 & 2 the other coils should be fine. The other problem they found was a slightly loose connection on a small vacuum hose between the inlet manifold and a sensor which they fixed by clamping it with a cable tie. Might be worth trying this first.

[paolo137]

Will do! (thanks a lot!)

BTW, last week they had original Denso Coils on the American Bay at 35$ each...

[katabrontes]

It should not hard to fit the coils on the front cylinders. I understand the back ones are tricky as there is quite a lot of stuff to take off before you can access the plugs.

[paolo137]

Absolutely. That's why the man insists on changing them all. Business as usual...

And the american denso coils at 35$ are gone; now starting from 55$ each. Guess I'll just put to use the obd reader and wipe out the alarms for a while: we're talking about 1 or 2 misfires out of hundreds per minute, once in a month. I think me and my Lexy can live with that.

[ColinBarber]

multiple cylinder errors normally indicates something other than a coil pack such as an issue with a fuelling, normally an injector or vacuum leak etc.

[paolo137]

Thanks, Colin. If the warning keeps on coming up, I'll have the the hoses ckecked (injector would be a major pain in the lower back. Let's hope it's something else)