Help me prioritize next steps (acceleration shudder)

[Jennshark]

I bought my lovely 2004 330ci about six weeks ago and love her. Shortly after buying her an occasional shudder would happen when accelerating between 75-85mph and she didn't pass smog inspection. I replaced the upstream 02 sensors, she passed smog, and the shudder abated (my E39 530 had the same issue and repair a few months ago).

I did my first HPDE in this car last weekend and had no acceleration shudders in two days of hard driving. It started again on the highway Monday, so I thought it couldn't hurt and put in some Lucas injector cleaner and all was well again until today.

The shudder only happens about once every 50 miles or so and between 75-85mph. When this occurs all is smooth to 75 then again after 85. Otherwise, the car runs like a dream.

I'm getting a code that could be due to 02s, MAF, injectors, and so on (01075? Don't have my reader with me). Should I clean the MAF next? Is there a most likely culprit to investigate?

[PetesZ]

Check the Fuel Filter.

[slater]

I bought my lovely 2004 330ci about six weeks ago and love her. Shortly after buying her an occasional shudder would happen when accelerating between 75-85mph and she didn't pass smog inspection. I replaced the upstream 02 sensors, she passed smog, and the shudder abated (my E39 530 had the same issue and repair a few months ago).

I did my first HPDE in this car last weekend and had no acceleration shudders in two days of hard driving. It started again on the highway Monday, so I thought it couldn't hurt and put in some Lucas injector cleaner and all was well again until today.

The shudder only happens about once every 50 miles or so and between 75-85mph. When this occurs all is smooth to 75 then again after 85. Otherwise, the car runs like a dream.

I'm getting a code that could be due to 02s, MAF, injectors, and so on (01075? Don't have my reader with me). Should I clean the MAF next? Is there a most likely culprit to investigate?

are you always in the same gear when it happens - 6th? if so, that RPM range with the stock rear end is about 2600-3000RPM, which some folks have had stuttering issues in. i also experienced it in my ZHP sedan.

what i've concluded is that it's caused by a worn DMF. my ZHP sedan did this, and after swapping the drivetrain into the Touring, it's gone. 100% gone. i changed the DMF and stock clutch out for the valeo SMF kit, but nothing else changed... not even the software! so i'm really wondering if that's it.

and i think spenser had the same issue recently, so once he gets the Blue Bandit back up and running with the SMF kit, we shall see if my theory is correct... :)

[Newjack]

Check the Fuel Filter.OP this is a good starting point. What's the mileage?

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[PetesZ]

https://repairpal.com/OBD-II-Code-P0172-and-P0175

[Newjack]

https://repairpal.com/OBD-II-Code-P0172-and-P0175Wait the thermostat would cause those codes? If it's happening at high speeds, maybe the tstat has failed and is stuck open?

OP do you ever notice your coolant guage showing below 12 o clock when on the highway after it's warmed up?

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[ryankokesh]

Wait the thermostat would cause those codes? If it's happening at high speeds, maybe the tstat has failed and is stuck open?

OP do you ever notice your coolant guage showing below 12 o clock when on the highway after it's warmed up?

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Wouldn't hurt to clean the maf, no? Doesn't seem like the culprit, but it's quick and free.

Also, your 530 had this same shudder? Same symptoms and everything?

[BADCLOWN]

Clean the MAF, check your plugs, check fuel filter

[ryankokesh]

Clean the MAF, check your plugs, check fuel filter

I like the plugs for this for some reason. I dunno why, though.


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[BADCLOWN]

If not, maybe coilpacks