charliekay

Hi guys,

Was out driving this afternoon, cruising, not driving hard, CEL came on. No warning, nothing felt funny. Drove back home and plugged in my Bluetooth OBDII scanner, a few codes came up. Car was driving fine but down on power and idling rough.

P0300 - Multiple Cylinder Misfire Detected
P0301 - Cylinder 1 Misfire
P0302 - Cylinder 2 Misfire
P0303 - Cylinder 3 Misfire
P0304 - Cylinder 4 Misfire
P0305 - Cylinder 5 Misfire

Car has Weistec M156 Brisk Spark Plugs.

First thought is the plugs.

Won't have a chance to look at it til tomorrow so any other thoughts are appreciated.

Thanks.

Charlie

mthis

Did you install the plugs when you installed the blower ?
How many miles /km on them and did you gap then when u installed them ?

charliekay

Installed with the blower. 10-12k kms ago. The shop did them so I presume they did it right.

average joe

Just run the car again and see if the codes come back.

Could just be dirty fuel?

charliekay

I just got back home so I'll try it again in the morning. Bad fuel was my first thought as well considering it was multiple cylinders misfiring at the same time.

Hopefully I'll get a chance to go over it tomorrow.

Merc63

You have lots of km if I remember correctly.

Are you on your stock O2 sensors? Pull the plugs, if they are fouled up and blackish, you probably need new plugs and primary O2 sensors.

charliekay

75,000kms on the car, ~12,000km on the blower.

Stock O2 sensors.

I will check them when I get a minute to go over the car.

My thinking is either.

1. Spark plugs - doubt it, chance of 6 plugs going at once it highly unlikely
2. MAF sensors
3. O2 sensors
4. Bad fuel - The CEL came on ~20kms after filling up the tank.

Who knows but I will let you guys know when I find the problem, fingers crossed it's something simple.

mr747

good luck i think it could be plugs not all 6 just one or 2

Merc63

Pull plugs first. These cars run closed loop 24/7 so if you O2 sensors are cooked fueling will be messed up and foul the plugs.

charliekay

Thanks mate.

Will do.

Going to pull the plugs, check the O2 sensor and drain the fuel tank and put try different fuel.

99% sure it is one of those 3.

Merc63

Have fun draining the tank.

mthis

From my experience with 02 sensors if one goes u will get cel for misfire on cyl 1.3.5.7 or 2.4.6.8 one side of the engine if both go you should misfire all 8cyl.

What are the chances of 1thru5 plugs going same time ?

Why not mix the gas with race gas before trying to drain it .

charliekay

Didn't get a chance to look at it, so got it dropped of at my workshop for them to do it, they have looked at it and think it is the o2 sensor.

Looking good at the moment, will let you guys know definitely once we have it fixed.

Charlie

mthis

hopefully that's what it is and it's good to go.

jrcart

How old are the plugs? I had a similar misfire code on my Wesitec C BS this past spring and ended up being a cracked spark plug. Not sure how or why it cracked but I replaced all the plugs and everything has been fine since.

charliekay

Just an update, it was the o2 sensors. Plugs were checked they were ok, cleaned anyways.

o2 sensors replaced and car is back to normal.

Hopefully that was it and there is no deeper issue that caused the misfire which caused the o2 sensors to go, only time will tell.

Rate

That's great news Charlie... and hopefully that's all there is to it.

AMG893

Out of interest, how would you have drained the tank?

Merc63

You can't unless you have the tool to remove pump cover. You can put a hose on the pump output and hit it with 12volts.

charliekay

What Merc said, was planning on siphoning it out.

charliekay

Thanks guys, took it for a spirited drive yesterday and it ran perfectly, no hiccups.

AMG893

Ahh ok. I think i get it.

Glad its all fixed