Check Engine Light came on.. car sputtering

[TechBoyJK]

Was out running errands today, when all of a sudden my service engine soon light came on, and my car started sputtering.. I could tell immediately. Car has about 65% of the power of normal.

Took it up to autozone, and one of the guys pulled the codes. Just one alarm stating

"misfire on cylinder 5"

cause could be

bad spark plug
dirty fuel injectors
bad vaccuum tube
other mechanical failure

Car is a 2004 bmw z4 with 68,000 miles. haven't changed the spark plugs since I bought it with 21,000 miles. Recently changed the oil.. nothing different, same synthetic oil I have always used (and suggested by the dealer). Oil change about 400 miles ago.

Engine is very rough on idle, very shaky. I've got it parked out in front of my garage.

Guy at autozone said it could just be a dirty fuel injector, maybe from a bad tank of gas. So I bought to GUMOUT fuel system cleaners. Put one bottle in right away. Car has about 30% tank left. I'm going to run it all out till its on empty, put in the other bottle of GUMOUT and about a 1/4 tank of premium. Then run it through again.

Also going for new spark plugs as well. If that doesn't fix it.. i guess it's going up to the dealer. ;(

ideas? advice? it's sitting outside running (idling in park) right now so it will burn through the gas.

 

[exdeath]

Check spark tubes and coil boots for moisture and blow them out with compressed air. There isn't a whole lot that can go wrong with a modern solid state coil on plug ignition system.

Pull the coil packs and check for spark after the boots, check plugs, and try swapping coil packs around.

Do a power balance test by pulling the spark from each cylinder one by one and verify that cylinder 5 is the only one not causing a change in engine smoothness.

 

[Meghan54]

Start with the simple junk....pull the spark plug and see what it looks like? Maybe even replace the plug....it'd be a cheap way to eliminate that as a problem.

Then, move up the chain. Remember, there are only three things that can cause the car to miss.....electrical, air, or fuel deivery.

So, eliminate the easy things first, like a bad spark plug.

You've already dumped a high concentration of cleaner into your gas tank (1/4 tank to full bottle that's recommended at a 15/20 gal to bottle mix....).

Then examine the plug wire. If OK, move up the chain.

Honestly, I'd think that if one injector was plugging up, more than one would be due to all of them being exposed to whatever would have plugged up the first one. I'm leaning more towards the problem being electrical. But you never know......

Also, replace your fuel filter as soon as possible after running those two bottles of Gumout through your tank. They'll have also, as a side benefit, "cleaned" a lot of the junk in your tank out and moved it to be captured by your fuel filter. Seen it happen more than twice that running a lot of cleaner through a gas tank clogs a fuel filter.

 

[TechBoyJK]

Start with the simple junk....pull the spark plug and see what it looks like? Maybe even replace the plug....it'd be a cheap way to eliminate that as a problem.

Then, move up the chain. Remember, there are only three things that can cause the car to miss.....electrical, air, or fuel deivery.

So, eliminate the easy things first, like a bad spark plug.

You've already dumped a high concentration of cleaner into your gas tank (1/4 tank to full bottle that's recommended at a 15/20 gal to bottle mix....).

Then examine the plug wire. If OK, move up the chain.

Honestly, I'd think that if one injector was plugging up, more than one would be due to all of them being exposed to whatever would have plugged up the first one. I'm leaning more towards the problem being electrical. But you never know......

Also, replace your fuel filter as soon as possible after running those two bottles of Gumout through your tank. They'll have also, as a side benefit, "cleaned" a lot of the junk in your tank out and moved it to be captured by your fuel filter. Seen it happen more than twice that running a lot of cleaner through a gas tank clogs a fuel filter.

ok thanks! thank god this car is CPO and still under warranty.

 

[StageLeft]

Well I've had bad coils on my 2000 Maxima and on my 2004 MPV necessitating a replacement of all 6. In the case of my MPV I WAS lucky enough to get a cylinder misfire and it was clearly a coil. Replacing the rear coils on my MPV is a wicked fvcking hassle. Is it on your car? If it isn't (like it isn't on my Maxima), then swap them out and see if the problem chases the Cylinder. If it is, you're good to go. If not, then try something like plugs.

Honestly though at this point you have 68k on the plugs I'd change them anyway even if they are supposedly good for 100k.

 

[radioouman]

I would be careful here. If it always misses at that cylinder, you could be dumping raw, unburned fuel into that cylinder. (If the fuel injector has failed and is causing the miss, obviously you don't have to worry about this.) But if a coil has failed or an ignition control module has failed, then you could be dumping fuel into the cylinder and out into the catalytic converter.

I just had this happen on a GM car and it caused the catalytic converter to glow red and it destroyed the catalytic converter and both oxygen sensors.

If it is an occasional misfire, then this won't be a problem. If that cylinder misfires continuously, I wouldn't run the engine for very long this way.

 

[allanon1965]

compression is also needed for a cylinder to work...minimum is 90psi anything less and it will definately drop out..

 

[sdifox]

Your 04 Z4 is still under warranty?

 

[TechBoyJK]

Your 04 Z4 is still under warranty?

certified pre owned.. cpo warranty expires in october.

 

[Hyperlite]

your 04 z4 is still under warranty?

cpo

 

[TechBoyJK]

certified pre owned.. cpo warranty expires in october.

I checked the owners manual. It says if the "service engine soon" light is on, but it is not blinking, then misfires aren't bad enough to stop driving. It then says if it starts blinking, pull over and stop driving the car. Mine isn't blinking.

 

[Hyperlite]

I checked the owners manual. It says if the "service engine soon" light is on, but it is not blinking, then misfires aren't bad enough to stop driving. It then says if it starts blinking, pull over and stop driving the car. Mine isn't blinking.

if a cylinder is occasionally missing you shouldn't have any problem driving the car.

 

[exdeath]

I would be careful here. If it always misses at that cylinder, you could be dumping raw, unburned fuel into that cylinder. (If the fuel injector has failed and is causing the miss, obviously you don't have to worry about this.) But if a coil has failed or an ignition control module has failed, then you could be dumping fuel into the cylinder and out into the catalytic converter.

I just had this happen on a GM car and it caused the catalytic converter to glow red and it destroyed the catalytic converter and both oxygen sensors.

If it is an occasional misfire, then this won't be a problem. If that cylinder misfires continuously, I wouldn't run the engine for very long this way.

No. OBD II systems cut fuel to that cylinder when it misfires continuously.

 

[TechBoyJK]

No. OBD II systems cut fuel to that cylinder when it misfires continuously.

I changed the spark plugs, it didn't help. You can hear a hissing sound coming from the engine. My friend said (before I told him what the codes read), that it sounds like bad compression, like a vacuum tube is leaking or something.

The codes said it was misfiring on cyl 5, which could be caused by a bad vaccuum hose. So that makes sense.

Called the dealer this morning. Taking it up there after work, picking up a loaner, and letting them deal with it.

thankful I bought a CPO. It was a few thousand more, but the convenience has been nice.

 

[StageLeft]

I checked the owners manual. It says if the "service engine soon" light is on, but it is not blinking, then misfires aren't bad enough to stop driving. It then says if it starts blinking, pull over and stop driving the car. Mine isn't blinking.

But "Car has about 65% of the power of normal." is not a good thing, if that's still the case.

I changed the spark plugs, it didn't help

You didn't swap the coils?

 

[TechBoyJK]

But "Car has about 65% of the power of normal." is not a good thing, if that's still the case.
You didn't swap the coils?

Swapped coils from 4 to 5 and back, didn't make a difference. Didn't buy new ones, because...

new spark plugs - $30.

New coils - $150

car is under warranty. I'll let them figure it out.

Dealer said CPO coverage will even have it towed up there if I'm worried about driving it. It's sitting parked about 2 miles from the dealer. He said he won't fault me for driving it up there if it's just misfiring and the service engine light isn't blinking. when it blinks, it means stop the car immediately. if it's just on but not blinking, you can still drive it. so as long as it isn't blinking, they can't fault me for driving it up there.

 

[LTC8K6]

Swapped coils from 4 to 5 and back, didn't make a difference.

Well, if it was the coil, only the code would change, not the way the engine runs.

 

[TechBoyJK]

Well, if it was the coil, only the code would change, not the way the engine runs.

True. Either way, the 5th cylinder plug had oil all over it (not dramatically), while the rest were completely dry. You can hear a hissing sound coming from the engine. Friend said it sounds like a vaccum tube/compression problem, and that's what the engine code said at autozone.

It's going to the dealer tonight and I'm getting a loaner. It's their problem now.

 

[StageLeft]

I suppose without pulling codes you wouldn't know for sure if the coil was to blame, but the hissing sound (assuming it wasn't there before; probably you were never listening for one) isn't a coil.

 

[Lotheron]

True. Either way, the 5th cylinder plug had oil all over it (not dramatically), while the rest were completely dry. You can hear a hissing sound coming from the engine. Friend said it sounds like a vaccum tube/compression problem, and that's what the engine code said at autozone.

It's going to the dealer tonight and I'm getting a loaner. It's their problem now.

If you have oil on the spark plug sounds like a rings issue which would also explain a lack of compression.

 

[TechBoyJK]

I suppose without pulling codes you wouldn't know for sure if the coil was to blame, but the hissing sound (assuming it wasn't there before; probably you were never listening for one) isn't a coil.

Well, as soon as the service engine light came on, there was an obvious lack of power. It wasn't a creeper problem. Something broke. Car was driving fine. I was on the road for about 15 minutes then all of a sudden when I went to accelerate it dogged down, light came on, and it's been sputtering ever since.

Like I said earlier, I had the codes pulled at Autozone and it says misfire on cyl 5, probably cause being related to vaccuum line/compression or other engine failure.

The 5th cylinder back, it's plug had a significant amount of oil on it. My guess so far is that a seal somewhere is bad, causing a compression problem (hissing sound) letting oil into the plug area, etc.

I'm not a mechanic though.

 

[LTC8K6]

The cylinder wasn't firing properly, so it's plug is going to be dirty or look different than the rest.

I would expect a vacuum line to affect more than one cylinder.

I'm curious as to what the dealer will say the problem was.

 

[StageLeft]

I'm curious as to what the dealer will say the problem was.

Me, too. I'm going to guess it is something substantial given Tech's last post.

CPO for the win.

 

[sdifox]

certified pre owned.. cpo warranty expires in october.

original was 4 year, they gave you another 2? lucky if it works out then.

 

[TechBoyJK]

original was 4 year, they gave you another 2? lucky if it works out then.

Yep. its a 2004 bmw. Its 2010, and i'm still in warranty. I'm driving a new 330ci loaner too (1,400 miles).