engine missfire! help!

[ripp]

yesterday I went out with the car after 4 day of resting (the car that is..) and noticed that the engine (while still cold) had the tendency to cut of fuel under acceleration, not too bad but you could feel it
Then I stopped to hear it idle for a while and it was obvious I had a problem, the idle was excessively lumpy. went for another 5 miles hoping it's just something to do with fuel and the problem went away as I got home.
Today went out again... only this time the car wouldn't start! until the 3rd time that is and then the problem I had the day before got worse: juddering under light acceleration, exhaust fumes smelled like unburned gas so one of the cylinders not working, right?
Tomorrow I'll check the leads and the plugs (which are new by the way) and hope it'll be a quick fix...
other suggestions welcomed!
thanks!

 

[TimR26]

If spark plugs are new it's likely to be the coilpack or ht leads.

 

[oVerboost.]

Check compression, mine had same symptons and its down on cyl.3

 

[ripp]

but what could cause the sudden loss of compression? the car was perfect until yesterday.. I really hope I can manage it by myself tomorrow though

 

[172Ben]

A sudden problem could cause a sudden loss of compression.

Just because it was fine yesterday, doesnt mean there cant be anything wrong.

Check plugs and leads like you said, then i would maybe do a compression test just to be sure.

Also maybe CTS aswell? Coil pack?

 

[ripp]

what is CTS ? I'm not familiar with some abbreviations

 

[Nayparkin]

Mine had been doin the same until i finally got the problem sorted. I started with the plugs (still missfired) then to the coilpack (slight improvement stopping the missfire on idle but still present under load) then to the leads which were changed yesyerday and they have sorted the problem.

Try disconnecting the MAP sensor and see whether that changes anything as i've read a lot of posts saying this was a problem, if not then a compression test.

Lambda sensor is a possibility also.

Hope this helps

 

[172Ben]

what is CTS ? I'm not familiar with some abbreviations

Sorry

Coolant temp sensor

 

[ripp]

I removed the leads and the plugs away from the car, they looked ok. now I'll have to figure out how to check out the leads, maybe put them on another car I don't know
while the plenum is unbolted I thought I giveit a good clean but how on earth is this plug coming out? (the one that enters the plenum from behind, having beneath the letters "RT" from spoer - I have no idea what is that)
see pic:

 

[ripp]

well I've installed it all back together and first the idle went somewhere between 1200-1500 rpm quite longer than I've expected but when the car got to optimal temperature the idle went back to normal. took a drive with the car and it's ok. for now..