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bmw_toronto

Replaced MAF, now I see Misfires on all the cylinders

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Hi all!

 

Many months ago I had a problem with the MAF shutting down the engine/staffing it on startup (tried cleaning it no luck).  I disconnected the MAF and it ran fine on the default values, just burning more fuel.   Now its time to get my emissions test so I bit the bullet and bought a new Bosch MAF.  I installed the MAF, and the durametric software cleared the fault codes and the new MAF is giving off normal values hovering around 10-13 on car idle.

 

The issue I am having is that I am receiving multiple misfires on all the cylinders through the Durametric software when the new MAF is connected. When I disconnect the mass airflow sensor I obviously get a check engine light, but I get 0 misfires on any of the cylinders.  I know that the maf is brand-new and is putting out valid values so I don't think that is the problem.

The car is about 9 years old as it is a 2005 base Boxster 2.7 L engine and has never had its spark plugs coils for replaced (old owner was an idiot!).  The car has 83,000 km on it.  My initial guess is that the spark plugs need to be replaced or potentially the coil packs.

Is this assumption correct?

Two other items to take into account is that the old MAF was covered in oil and there was a small puddle of oil in the intake system/velum.  Also when the mass airflow sensor was disconnected the engine would start obviously a little rougher but there was a plume of white smoke coming out of the exhaust.  Now that the sensor is replaced, the white smoke has disappeared. I thought that this may have been up potential AOS problem, but maybe it was just an issue with airflow sensor in disconnected. 

 

The other item to take into account is that I have a constant issue with the cooling system flushing the coolant out of the car (near the right rear wheel) when I shut off the engine I checked the coolant tank and it appears to be fine with no cracks but I was told that it may be the coolant CAP Issue - not sure how a coolant cap makes a difference, but this is what I was told.  I have not investigated this issue yet as I'm trying to deal with the codes that are generating the misfires now (priority as I need to pass the emissions test) that I replace the mass airflow sensor which I am assuming once again that it may just be spark plugs and or the coils.

What do you think? Any help is much appreciated!

Edited by bmw_toronto

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1. There is nothing that I can think of that would cause oil in the intake other than a leaking AOS or bellows leak on the engine.

2. Coils and plugs cab be inspected for cracks and high resistance. But I would replace the spark plugs anyway since they are likely well past due.

3. All the fault codes will have to be clear and the will need "drive cycles" to set the emissions readiness flag (that allows emissions tests). In some cases this can take a week of driving - and you must not get an emissions fault during that time.

 

My suggestions...

Fix the oil in the intake issue.

Clean the new MAF and verify that it is the correct Bosch part number for your car. There are a number of vendors selling on the web that do not understand the subtle differences and we have seen some that just plain don't work. If you want a guarantee go with OEM from a reliable discount Porsche dealer (like Sunset Porsche in Oregon).

Change the spark plugs and any bad coils.

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Loren, thanks for the detailed response, much appreciated.

 

That being said, I'm seeing strange things on the Durametric tool.  When I start the care and run the tool in realtime Actual Values mode, the Cylinder misfires are detected immediately on random cylinders anywhere from 0 to 7 misfires, but then the values do not increase from idling or driving?   Could it be perhaps just misfiring on startup?

 

Also when I check for Fault codes or the Fault memore, the care registers with Durametric "No Fault codes".  So is there a chance I'm just reading the values incorrectly, and perhaps there should be a few misfires on startup as the numbers don't rise? - maybe I'm using the tool wrong?

 

Also without the missfires registering a Fault Code in the care, would there be a chance that my emission test pass the way it is, so I have some more time to look into these issue?

 

Also, is there anyway in Durametric 5 to check for the Rediness of the Drive Cycle?

 

Any help is much appreciated!

Edited by bmw_toronto

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Loren, thanks for the detailed response, much appreciated.

 

That being said, I'm seeing strange things on the Durametric tool.  When I start the care and run the tool in realtime Actual Values mode, the Cylinder misfires are detected immediately on random cylinders anywhere from 0 to 7 misfires, but then the values do not increase from idling or driving?   Could it be perhaps just misfiring on startup?

 

Also when I check for Fault codes or the Fault memore, the care registers with Durametric "No Fault codes".  So is there a chance I'm just reading the values incorrectly, and perhaps there should be a few misfires on startup as the numbers don't rise? - maybe I'm using the tool wrong?

 

Also without the missfires registering a Fault Code in the care, would there be a chance that my emission test pass the way it is, so I have some more time to look into these issue?

 

Also, is there anyway in Durametric 5 to check for the Rediness of the Drive Cycle?

 

Any help is much appreciated!

 

There should be an I/M Readiness test in a real  Durametric 5 (not so sure about knock off clone versions), but I would highly recommend updating your system as the version 6 offers a lot of additional features and bug fixes.

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I have the original Durametric 5 but there is nothing about Readiness or anything similar to that in the manual or anywhere in the tool.

 

I no longer use 5, having switched to 6 a long time ago, but if you look under "engine module" you will find "Ready Status".

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