182 Miss Fire

[richie87]

Hi, Looking for a wee bit of advice, I've got a 182 which has a very slight miss fire on idle, car drives fine but comes up with p0301 cylinder 1 miss fire.

Ive tried new leads, coil and swapped the plugs around, miss doesn't change cylinder when doing this. I've done a compression test and number 1 is around half a bar (7psi) lower than the rest, this was done with inlet plenum removed and all plugs removed. Iirc the compression in number one was 12.5 bar (181psi) and the rest were 13 bar (188psi). If I remove no1 plug lead the miss gets worse and if I remove no1 injector plug it also gets worse.

Can anyone advise on common faults or what to check next?

Thanks
Richie

 

[bloke]

without stating the obvious...injector

 

[STEVE.M]

Don`t forget,as it`s French,No 1 cylinder is the gearbox end!

 

[bb55am]

mine developed a misfire a couple of days ago after going through a deep puddle, the misfire was happening between 3-4k, and sounded like a machine gun, if i really put my foot down through the gears it sometimes wouldnt misfire, i checked all plugs, leads, electrical connections for water etc, cleaned throttle body, waited a few days for any water to dry out...but still misfiring, i thought maybe injectors?? so took it to garage and the guy said 90% sure it would be the coil pack going due to cold weather, so he swapped it over but ..still misfiring..so he connected to laptop and it come up with,
destructive misfire
downstream oxy sensor...(lambda on manifold)

So i went home swapped over my 2 lambda sensors and boom problem solved, turned out to be faulty pre cat lambda.
Im going to need a new lambda for the decat, as the emissions light will come on but this will not give me a misfire as im fairly certain this lambda doesnt effect running of the car.

If your trying to diagnose a problem like this definately try swapping the lambdas around (if you can get them off) before buying any coilpacks, new plugs etc
Hope it helps.

 

[richie87]

Thanks guys. I knew the French numbered them that way but it had went totally out my mind so thanks for that Steve! Anyway the same still applies as I've swapped plugs round all cylinders and disconnected all the injectors, individually of course.

O2 sensor was my next port of call but that will be for tomorrow.

Cheers again guys, I'll let you know how I get on.

 

[bloke]

it's an injector, o2 wouldn't flag up specific cylinder misfire.

 

[STEVE.M]

Thanks guys. I knew the French numbered them that way but it had went totally out my mind so thanks for that Steve! Anyway the same still applies as I've swapped plugs round all cylinders and disconnected all the injectors, individually of course.

O2 sensor was my next port of call but that will be for tomorrow.

Cheers again guys, I'll let you know how I get on.

O2 lambda should throw up it`s own fault code?Try swapping No1 injector around,and check the O ring is in good nick.
I don`t think the compressions are an issue,but out of interest,wet test to see if there is any improvement.
When you say you pulled HT lead and injector wiring on No1,I assume you mean next to gear box?
Finally,do not discount the possibility of that old favourite,corrosion in the wiring.

 

[richie87]

I've seen a couple of folk saying O2 sensors so might as well try it but yeah if expect a specific code for that.

I tried all disconnecting all 4 ht leads and injector plugs individually because the ones at the timing end made the car run rougher so didn't seem to be the issue. Removing each plug resulted in more misfiring.

What's the best way of getting to the injectors to remove them? Can you get them by removing the grille or do you need to remove the manifold?

Yeah I don't think compression is an issue either.

 

[bloke]

I've seen a couple of folk saying O2 sensors so might as well try it but yeah if expect a specific code for that.

so why bother pulling the codes if you're going to ignore them and waste your time?

it's an injector, plain and simple.

 

[KevF182]

No need to remove grill or manifold for injectors. But you need to get the alloy cover off - 2 nuts hidden in the recesses, can be quite hard to access, need to find the right extensions+socket combo. Once this is off you see the fuel rail and the bolts you need to undo to be able to remove the rail holding the injectors.

 

[raviedavie]

I had exactly the same happen to me. I got new injector few weeks back for £30 on eBay. Changed it and hey presto !

 

[richie87]

so why bother pulling the codes if you're going to ignore them and waste your time?

it's an injector, plain and simple.

Who said anything about ignoring the codes? I've unplugged each injector which each time has caused the car to misfire far worse that it did before leaving me with the impression at the time of the injector working.

The reason I said I'd check the O2 sensors is because when googling I've come across people saying that has caused the issue on more than one occasion and b55am has also had the same problem. I will try swapping injectors around first though.

Thank you for your help guys, I appreciate it.

 

[bloke]

don't bother swapping them, measure resistance, looking for around 15ohms.

 

[richie87]

Ok thanks, I'll try that in the morning.

 

[richie87]

Injectors all mesure 14ohms on my meter. Obviously this is less than the 15 that it should be but its a £30 meter and all injectors measure the same across the board which I'd say is the important part.

 

[Dan_R*]

Just because your injector is spraying (and electronically ok) doesn't mean its spraying properly Try swapping them or buy one that you know works then you'll be able to tell if they are sound.