Acceleration stutter + idle : MAF? Sparks? Injection/fuel filter?

[marmotteNZ]

Dear all,

Any advice would be welcome. I searched in the existing posts but nothing seem to fit exactly my symptoms.

2004 XC90 2.5T AWD, 185Kmiles
The other day I had a "check engine light" coming up whilst driving in a national park 2hrs+ from home. No other symptoms, nothing obvious under the hood, levels OK, temperature OK - I took the way home while keeping an eye on everything.
Mid way back we started noticed some "stuttering" on acceleration/uphill. Checked again under the hood and all levels - still nothing unusual. I though "probably spark plugs, MAF sensor or injeciotn issue....let's get home and get a code reader"

Bought a code reader. Read indeed P0101 - MAF Sensor fault.
I fiddled with the connector - and had a look at the change procedure to make sure I could do it with the tools I had. The fiddling (I guess) cleared the check engine light - but not the symptoms. I noticed that:
1. The stuttering on acceleration / uphill is really around of 2k to 2.2k rpm, on light acceleraiton and light uphill. It does not appear at higher rev / throttle at all
2. There is now some roughness also at idle which was not here the first 2 or 3 days.

Ordered MAF from Amazon - Bosch OEM. Box came in today. Seal was broken, but the part looks brand new , Bosch code on holographic label checks out fine on their website. At the same time I changed my air filter and gave a good clean to the air box.
I replaced it easily. Still no check engine light . Took the car for a ride - the symptoms are still there
I tried fiddling more with the cable/connector...no change.

Any clue of where to look else next? If it was a misfiring due to coil or spark plug, wouldn't it be detected by the OBCD ?

Same question for an injection issue? (This is really a subsystem i have NO knowledge about at all

Return this MAF sensor?

I may well replace the spark plugs and fuel filter whatsoever as it seems to be easy and the parts aren't too expensive, but if anybody has any idea of what else to check that would be greatly appreciated!


PS:
Previous history - that I know of - before that pretty much unknown except that the timing belt (and I hope the water pump) have been done at 115kMiles:
I had to replace an intercooler hose which had broken. A few days have lapsed before I have noticed it I suspect.
I have disconnected the vacuum sensor as it it faulty and was making the vaccum pump (brake system) run continously - which it is not intended for. I've been running like that for sometime now...should definitively change it
Throttle body has been cleaned recently.



THX

[weespoon]

Is it still throwing the same code?

The spark plugs are probably a fine thing to replace anyways,
if it has been over a year since they have been replaced.
Although it seems like I am more likely to get a miss under load
with a bad plug.
If you look at each plug as you pull it, it may give you more information as to what is going on.

Regarding injection, I had similar behavior with a fuel pressure sensor gauge at then end of the fuel rail.
Which was an easy fix. But... I replaced it because the engine code told me it was at fault.

[FLXC90]

usual suspects would include vacuum and air intake lines and hoses, to include intercooler hoses, for leaks, splits and tears. Coils and plugs usually set a code and tell which cylinder (or random) for the misfire. Fuel issues likely limit revs/load and affect startup as well.

Edit: How good a code reader did you get. Swedish is still foreign to a lot of the less expensive ones. Run by a parts store and have them hook up a good reader, look for 0300 codes, pending or set.

Is yours a 5 or 6 cylinder? I have changed all 6 coils on mine over the past year due to coding and failing between 120-135k miles. Watch for a "flashing" CEL while it stutters, that is the prime indicator of a misfire. And the fuel filter and plugs are routine maintenance.

Have fun!

[FLXC90]

Also, try a MAF from a wrecking yard if there is one nearby. they may warrantee the part, if it doesn't change things, they'll refund your money. Can't hurt for troubleshooting.

[marmotteNZ]

Thank you all. Apologies for the lack of replies...I have been moving house on top of that....
Bought a cheap Bluetooth reader from Amazon...gave me a 103 or 102 code for MAF
I changed first the MAF sensor with air filter, and cleared the code.
But the stutter was still here.

New plugs solved it!

not sure whether the reader cannot read any misfiring code (Amazon reviews included good reviews from Volvo owners) or whether the monitoring circuit of the car is fried....

Thx a gain