Misfire, Cel

[pcy]

After the car ('97 328i) was parked in the parking lot for 12 hours
(normally it is parked in the garage) in cold temperature, when the
car was started, the whole car was shaking (similar to misfiring)
and after a minute or so, the CEL came on. The shaking continued
on, wife drove the car home like that.

I started the car in the morning, same story. Misfiring, CEL came on.
Took the car to the Autozone so that they can read the codes.
Code 1 - P0302: Cylinder 2 misfire detected
Code 2 - (forgot the #): Fuel Trim Malfunction in Bank 1.

By the time I drove to Autozone, the misfiring stopped; the car ran fine.

The autozone employee reset the check engine light.
I put in a can of Fuel Injector cleaner and filled up the tank with 93 Octane gas.

Since then, no problems observed. What happened??
I know things don't just fix by themselves; Symptoms might show up again.
I will check the Spark Plug and Ignition Coil Pack on Cylinder 2 and see
if I notice any fouling on the spark plug and cracks on the coil pack.

Have you seen a problem like this? If so, please share your thoughts.

[thekid]

Checking the Ignition Coil and Spark plug willl let you know about misfire. It is not hard to do, and it sounds like you have that under control. I am a little more interested in the second code, I honestly dont know what that code means... I'll have to look it up or some one really nice can tell me what it means...

But any way, it is possible for the car to mis for a little bit and then stop. Basically if there was a minor blockage in the spark plug chamber, for instance a little bit of water or if there was some built up carbon ect, it can cause the car to mis until it clears the obstruction out. Let us know what you find.

[pcy]

Originally posted by thekid@Jan 10 2005, 10:36 AM
Checking the Ignition Coil and Spark plug willl let you know about misfire. It is not hard to do, and it sounds like you have that under control. I am a little more interested in the second code, I honestly dont know what that code means... I'll have to look it up or some one really nice can tell me what it means...

But any way, it is possible for the car to mis for a little bit and then stop. Basically if there was a minor blockage in the spark plug chamber, for instance a little bit of water or if there was some built up carbon ect, it can cause the car to mis until it clears the obstruction out. Let us know what you find.

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I believe the second code is related to O2 Sensor.

Your second paragraph might really be the explanation of what
really happened. When the CEL first came on, the tank had less than quarter tank of gas. I think moisture got in there. That caused misfire (along with possible gunk in the fuel system). The misfire resulted in unburnt fuel, that in turn tripped the O2 sensor (Fuel Trim in bank 1, by the way this corresponds to the Cyl 1).

That is my logical explanation.

From what I read in other posts; when you have the symptoms as I did,
pour a can of Heat (moisture remover) and a can of Fuel Injector cleaner.
That might solve the problem. So, I tried the easy things first.

Thanks for your input.

[///Matt]

The second code is not an O2 sensor fault, the code for the bank failure is either p1174 or p1175, this is probably due to a vacuum leak, usually from a manifold gasket leak.....a VERY COMMON problem when there are temperature changes....the leak stops when the gasket heats up and expands....

[pcy]

Originally posted by ///Matt@Jan 10 2005, 11:49 AM
The second code is not an O2 sensor fault, the code for the bank failure is either p1174 or p1175, this is probably due to a vacuum leak, usually from a manifold gasket leak.....a VERY COMMON problem when there are temperature changes....the leak stops when the gasket heats up and expands....

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Thanks matt, for your input.
Your explanation sounds logical. The car was parked in a parking lot during night when the temperature dipped in to single digits.

Were you refering to INTAKE MANIFOLD gasket? I am thinking of ordering a new one.

Thanks again

[///Matt]

Yes, it would be the intake manifold gasket.....

[thekid]

Originally posted by pcy+Jan 10 2005, 02:28 PM--><div class='quotetop'>QUOTE(pcy @ Jan 10 2005, 02:28 PM)</div><div class='quotemain'><!--QuoteBegin-///Matt@Jan 10 2005, 11:49 AM
The second code is not an O2 sensor fault, the code for the bank failure is either p1174 or p1175, this is probably due to a vacuum leak, usually from a manifold gasket leak.....a VERY COMMON problem when there are temperature changes....the leak stops when the gasket heats up and expands....

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Thanks matt, for your input.
Your explanation sounds logical. The car was parked in a parking lot during night when the temperature dipped in to single digits.

Were you refering to INTAKE MANIFOLD gasket? I am thinking of ordering a new one.

Thanks again

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[/b][/quote]
I would go along with that. Sounds like we have it figured out.

[pcy]

Matt, theKid,
You guys might just be right about the gasket leaking. Read on...

For the past several months, in the morning, when I start the car, the car would idle very roughly for about 10 to 20 seconds or so. And then after that would run perfectly. Same thing every day. I didn't take it seriously because it only did that during first 10 to 20 seconds only.

Your explanation about the gasket leaking while it is cold and once it warms up, the gasket expands... good analysis.
I am ordering the gasket tomorrow. While I take out the intake manifold, I will clean the ICV as well.

Thanks guys

[TECH]

A vacuum leak COULD cause a misfire, but not absolutely. I'd suspect an ignition coil. Swap number 2 with number 1, and if the problem comes back, the fault should then read a misfire on cylinder 1-IF the coil was the problem.

The mixture fault could be a by-product of the misfire. When the engine misfires, the oxygen in the mixture isn't burned, so the oxygen sensors see that and register as being too lean.

If you have a vacuum leak, spray some brake cleaner around the intake manifold, vacuum lines, intake boot, etc, with the engine RUNNING. If a leak is present, the brake cleaner will get sucked into the engine, and the speed will raise up abruptly.

[thekid]

Originally posted by pcy@Jan 10 2005, 08:06 PM
Matt, theKid,
You guys might just be right about the gasket leaking. Read on...

For the past several months, in the morning, when I start the car, the car would idle very roughly for about 10 to 20 seconds or so. And then after that would run perfectly. Same thing every day. I didn't take it seriously because it only did that during first 10 to 20 seconds only.

Your explanation about the gasket leaking while it is cold and once it warms up, the gasket expands... good analysis.
I am ordering the gasket tomorrow. While I take out the intake manifold, I will clean the ICV as well.

Thanks guys

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With the rough idling it could be a vaccum leak as TECH said, so do just as TECH said, check the coils and plugs, in the manner that TECH described, then do the vaccum leak test. That and the gasket should cover it. The rough idle would have helped with the vaccum leak diagnosis because both rough idle and missing are symptoms of a vaccum leak.

[Rooz]

Just to let you know, if you know your car is misfiring, fix it quick, otherwise, if it ends up running rich (too rich) while it's missfiring, you'll probably end up poluting your o2 sensor...

[pcy]

Originally posted by Rooz@Jan 11 2005, 01:53 PM
Just to let you know, if you know your car is misfiring, fix it quick, otherwise, if it ends up running rich (too rich) while it's missfiring, you'll probably end up poluting your o2 sensor...

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Rooz, I am planning on working on the car during the upcoming weekend.
- Inspect #2 spark plug and Ignition Coil pack on #2.
- Swap #2 Ignition Coil pack with #1.
This will help me in diagnosing in the future if the same problem comes up.
- Check for vacuum leaks
- Check for any hoses that came loose
- Check crankcase ventilation hose.
- Install Intake Manifold gasket (time permitting)

I agree with you, running the car rich will foul the O2 sensor, they are not cheap.

Thank you ALL for your input.

[Rooz]

am assuming your check engine light is on, if you an ob2 scanner, use it, it will tell you exactly what spark plug is missfiring