Cylinder #6 Misfire

[tummarabaap]

My CEL is on in my 98.5 M3. I ran it at my mechanics shop and he said that im coming up with a 243 code and that my 6th cylinder is misfiring.

Symptoms:
Just bought the car 2 days ago, previous owner told me it sat for two years while he was in Iraq. At first the car would turn on but you could definitely tell that it had a slight valve tick and it would feel like its about to bog down ( the idle would stay constant though). The car is cammed and it has an exhaust. In 3rd Gear from like 2200 to 3100 rpm's the car should shake until you gave it a lot of gas, after doing so the car would steady out.

I did some research on the forums and have done the following things
-Moved the coil packs around from plug to plug to see if its the coil packs
-Put a new M52 coil pack on the 6th spark plug, the car ran great for about 5 minutes then it started getting the same symptoms again
-Cleaned the MAF
-Cleaned the CCV
-Put in some new NGK Spark Plugs
-Sea foamed through the vac lines and put some in the gas as well.
-Did an oil change
-Did a compression test, came up about 120 in the 6th cylinder

After doing all of that the car is running 10x's better, but it still seems like the car is hesitating. I was thinking of checking the injectors next and also cleaning out the ICV. What else is their?

What do you guys think? The car sat for about 14 months and before it was put into storage it ran absolutely fine.

What next??

[AvusRacer]

Maybe old gas? If there was old fuel left in the tank, it will definitely run poorly/ lack of power.

[Balthazarr]

Maybe old gas? If there was old fuel left in the tank, it will definitely run poorly/ lack of power.

Without some stabilizer, it might cause trouble.
Get all the old gas out. Use some alcohol, if you have to to scavange any water in it.
Put in new gas; Chevron is my recommendation.

[tummarabaap]

What do you mean alcohol?

also, can I mix stabilizer with the seafoam thats already in the gas tank right now?

I put 3/4 of a can through the vac line off the master cylinder.
Then i put 1 1/4 can of it in the gas tank which is at about half full.

I think I'm just gonna go outside and turn it on and let it run through till the light comes on

Without some stabilizer, it might cause trouble.
Get all the old gas out. Use some alcohol, if you have to to scavange any water in it.
Put in new gas; Chevron is my recommendation.

[Balthazarr]

What do you mean alcohol?

also, can I mix stabilizer with the seafoam thats already in the gas tank right now?

I put 3/4 of a can through the vac line off the master cylinder.
Then i put 1 1/4 can of it in the gas tank which is at about half full.

I think I'm just gonna go outside and turn it on and let it run through till the light comes on

Why, Glenfiddich Whiskey of course.
Isopropyl alcohol to mix with the water and make it combustible.

[tummarabaap]

LOL

That is if there is water in the gas?

So I should let this gas run out fill it up with premium gas and add how much ispropyl alcohol?

Sorry for the ignorance.

Why, Glenfiddich Whiskey of course.
Isopropyl alcohol to mix with the water and make it combustible.

[Mad Dog 20/20]

Was the compression pretty even across all cyls?

I'd try swapping the cyl 6 injector w/ another cyl and see if the misfire moves w/ the injector.

[aht bmp]

Step one for any vehicle sitting...don't run old gas through the fuel system. Adding fuel additives is like taking a shower and putting your dirty underwear back on...fuel left sitting turns to a varnish-like chemical.

1. Use a simple cheap marine bulb pump and pump all the gas out of the tank.
2. Put all new gas in it.
3. Replace the fuel filter ... old gas sitting in the filter turns to gummy goo...can't get much power out of gummy goo.

If you still have hesitation under load/acceleration I'd check either fuel pressure/volume with a fuel pressure gauge or check the exhaust. Do a back pressure check to see if there's a restriction built up in the catalytic converters.

Also, the ICV wouldn't affect hesitation under load as it's working ... at idle (IDLE CONTROL VALVE).

Things that cause hesitation or poor power are mostly fuel starvation (not only pressure but also volume) and exhaust back pressure issues.

Regarding the misfire cylinder 6...fuel starvation and/or exhaust will also cause misfire codes of any number of combinations.

[Balthazarr]

Too late for stabilizer. Whiskey is for you.

Stabilizer goes in the tank before letting it sit.
Best strategy is to remove the old gas.

[tummarabaap]

all the other cylinders were at about 170 all across
im gonna try swapping them around a little later on today

Was the compression pretty even across all cyls?

I'd try swapping the cyl 6 injector w/ another cyl and see if the misfire moves w/ the injector.

Well my exhausts do smell like rotten eggs.

I just drove it right now and when i was giving it gas it was bogging like crazy but then it suddenly just went away.

Thanks for all the info I'm gonna try getting all the gas out of it and maybe replacing the fuel filter as well.

You think I should try getting new plugs?

Step one for any vehicle sitting...don't run old gas through the fuel system. Adding fuel additives is like taking a shower and putting your dirty underwear back on...fuel left sitting turns to a varnish-like chemical.

1. Use a simple cheap marine bulb pump and pump all the gas out of the tank.
2. Put all new gas in it.
3. Replace the fuel filter ... old gas sitting in the filter turns to gummy goo...can't get much power out of gummy goo.

If you still have hesitation under load/acceleration I'd check either fuel pressure/volume with a fuel pressure gauge or check the exhaust. Do a back pressure check to see if there's a restriction built up in the catalytic converters.

Also, the ICV wouldn't affect hesitation under load as it's working ... at idle (IDLE CONTROL VALVE).

Things that cause hesitation or poor power are mostly fuel starvation (not only pressure but also volume) and exhaust back pressure issues.

Regarding the misfire cylinder 6...fuel starvation and/or exhaust will also cause misfire codes of any number of combinations.

[aht bmp]

Don't sweat the plugs...not a very likely culprit. Do the plugs as maintenance rather than as a solution to the problem.

[tummarabaap]

hmmm

ok

what do you think i should do next?

get rid of the gas and then what?

[aht bmp]

1. Bye-bye old gas.
2. New fuel filter.
Do you have a fuel pressure gauge or back pressure gauge?

[Mad Dog 20/20]

all the other cylinders were at about 170 all across

Am I hearing you correctly - all other cyls were around 170 and cyl 6 was 120? If so, you have a blown hg (or some other serious malady).

[tummarabaap]

yes you are hearing me correctly, they are all low because the car has been sitting.

the cars drives perfectly fine. does not have any symptoms of a lown headgasket.

Am I hearing you correctly - all other cyls were around 170 and cyl 6 was 120? If so, you have a blown hg.

[aht bmp]

Mad dog is probably meaning that all cylinders should be equal ... plus or minus a few points. He's right about the head gasket potential.

Normally on a compression test if you have that reading...it's a headgasket. The problem I find is that some techs oops something during the compression test and don't get an accurate read. I've seen two different techs do the test back to back and get different readings...

What symptoms do you think a headgasket presents with?

Low power, running rich due to unburned fuel (rotten egg smell from exhaust), cylinder misfires all are symptoms of a head problem!

I'd still start with fuel ... fuel filter and then see how it runs...

[MasterKwan]

If you have 120 in one and 170 in the rest, you've got a big problem. You should get a leak down and try to figure out why that one is low. I wouldn't go any further with trouble-shooting till you figure it out. That's your mis-fire right there. It might be HG, it might be a bent valve, stuck ring or you might have broke a ring starting it for the first time in 2 years.

When you start a car that's been sitting, you should follow a procedure to minimize damage, you don't want to just crank it up. You take the plugs out, add oil to each cylinder and then turn the crank by hand slowly to try and free up the rings. Get it turning over smoothly with a wrench before you try cranking it. Maybe you did all this but, I didn't see it mentioned. When you park a car, typically some of the valves are left cracked open. Those are the cylinders that get rusty. It's one reason you using fogging oil on engines before you let them sit for extended periods.

I would get all new gas, I might re-do the compression check after squirting some oil into each cylinder. See if the compression comes back up.

[tummarabaap]

Its just crazy, the cars drives perfectly fine. After I did all of those things The car runs so much better.

I'm trying to figure everything out before I have everything taken out to get the Head taken out.

Mad dog is probably meaning that all cylinders should be equal ... plus or minus a few points. He's right about the head gasket potential.

Normally on a compression test if you have that reading...it's a headgasket. The problem I find is that some techs oops something during the compression test and don't get an accurate read. I've seen two different techs do the test back to back and get different readings...

What symptoms do you think a headgasket presents with?

Low power, running rich due to unburned fuel (rotten egg smell from exhaust), cylinder misfires all are symptoms of a head problem!

I'd still start with fuel ... fuel filter and then see how it runs...

[aht bmp]

So start with a few small simple things and then re-check...fuel filters are cheap and readily available and so is gas...lots of vendors have 'em...one link is:

www.bmpdesign.com

[Mad Dog 20/20]

Its just crazy, the cars drives perfectly fine. After I did all of those things The car runs so much better.

I'm trying to figure everything out before I have everything taken out to get the Head taken out.

Absolutely, re-test and confirm you have a head issue before yanking it out.

[tummarabaap]

thank you for all the info!

So start with a few small simple things and then re-check...fuel filters are cheap and readily available and so is gas...lots of vendors have 'em...one link is:

www.bmpdesign.com

Thanks for the help man.

Absolutely, re-test and confirm you have a head issue before yanking it out.

[MasterKwan]

Is it running better and still mis-firing or has the mis-firing gone away? You can get a misfire code if a cylinder if just down on power compared to the rest. Being 120 versus 170 means #6 is down on power from the rest. It's probably still doing something. It's not like the cylinder is totally dead.

[tummarabaap]

I did the compression test myself an hour ago and the cyl 6 was at 60 and the rest of them were at or around 120.

Its time for a rebuilt head.