2.5T (S60) Observation regarding engine vibration Topic is solved

[JudgeRat]

People often jump to the engine mangement systems as faults way too early.

I'm gonna go with you on this one; I think there is enough evidence that he has correctly diagnosed a need for a new (hopefully high quality) MAF replacement. I'd say do that and reset everything and then see what you get back over the next week or two and go from there.

I certainly didn't wish to obfuscate things even more than they were by offering the link, but was simply passing along a resource that I've found helpful during troubleshooting.

[mrbrian200]

If you can't tell I seem to be itchin' to pull apart that TBA. But that will wait for the moment. Bosch TBAs across generations/makes/models all similar internal design just tailored to the application. At some point they switched from pots for the position sensor to a contactless MEMS sensor with a PCB just complex enough I suspect might accommodate back-compatibility (if all else is equivalent spec). Don't quote me on that, both would need to be reverse engineered. Want to check plastic gears for wear (and apply film of good synth grease as "maintenance"), also check for moisture that can condense in there and presumably cause problems at temperatures below freezing. I haven't seen specific references about moisture/freezing problems but it certainly would make sense. Several pictures and a video I've come across show varying amounts of water in there when people crack them open. One of them (off a truck) pretty excessive. ..Plus check the stepper motor for mechanical resistance, and sweep the position sensor pots with an ohmmeter. There's definitely something a little more going on that just a bad MAF. It doesn't necessarily seem like an ignition problem to me.

[mrbrian200]

Update- New MAF, car idles good and smooth now. MAF reading at idle changed from 0.6 lb/min to 0.4 and watching live data the MAF reading responds much more quickly to changes (tapping the accelerator pedal etc). Still seeing a problem, intermittent in nature. Sometimes the car is somewhat sluggish, other times it zooms. Drove around awhile eyeing live data I'm not happy with the fuel pressure readings. I'm just not seeing consistent fuel delivery/pressure behavior when performing repeated throttle/speed maneuvers. During the "sluggish" times the pressure reading doesn't spike under hard acceleration as it's supposed to (stays at 42-44 or dips down to 38-40psi) I'm zeroing in on the PEM on this one. Opened it up and decided I wanted to rant. I sure don't see anything inside there to justify $300+ (just sayin'). As far as SMC work goes I've seen better. Top side of board looks ok, but the bottom side looks like something from the late '80s. Under a magnifying glass I see 3 or 4 places looks like solder didn't fill the gap (board trace to SMC). Not enough solder? Not enough Flux? Incorrect working temp/time? Sticker on outside says "Ford" (and Bosch). Shaking my head. We'll see...could yet be looking at a wiring/pump issue.

[mrbrian200]

Reworked the PEM board by hand (don't try this at home unless you're !**experienced**! at board level repairs). Now seeing expected/constant fuel pressure behavior while performing driving test maneuvers. 43psi while cruising, varies (up) with throttle, 61psi under sustained WOT. I also note a dramatic change in cold start behavior. Before it would rev up to around 1500 rpm and drop down to low idle almost immediately (within 10 seconds). This morning after re-installing the PEM (cold start at 20F) it dropped the idle speed more gradually over the course of a minute or two.

Last question. Installed that new MAF yesterday. I noticed the seal on the box (attached pic) had been previously broken, which sounds an alarm bell. CEL that came on when I disconnected the old MAF didn't go off right away with this new one, but went off today (at about the 5th restart), and though the idle quality/part throttle performance was restored immediately, there seemed to be a lot of adaptation until WOT felt good (first try actually triggered 1500 rpm limp mode but recovered after about 5 seconds). After a few tries it "learned/adapted" and seems pretty good, unfortunately being a new car to me I don't have a good reference as to whether it feels "right". Testing today watching live data @ sustained WOT I'm seeing 89% absolute throttle position @ 18.1 lb/min MAF (490 kg/hr). Is that in the neighborhood/right? ..or did I get somebody elses' bad one (aka switch fraud returns)


http://i.imgur.com/mUYqrfFundefined.jpg

[precopster]

A Bosch 0280 218 088 would probably last longer. What cost was that MAF?

You can also find just the OEM sensor without housing which is made by Pierburg.

Dorman also make a 917-877 sensor for this car; just food for thought

Great info about the PEM resoldering/reflowing. This is right up my alley!! Just like ABS modules they are well worth repairing.

[mrbrian200]

$120 for the MAF, amazon (sold directly by amazon not 3rd party). I went with them because reviews seem to indicate they were good/new and with prime I could get it quickly. IPDs price was about the same but they both charge shipping and use fedex ground which takes forever unless you live west of the rockies or pay high dollar for faster shipping methods.
Amazon's return policy I think is the problem- They would have no way to test incoming returns and probably just do a visual inspection (like everyone) ...so once in awhile you get hold of a return switch item that's bad...or about half the time in my years of experience. I could return this one but that likely puts it in the hands of some next poor guy. I'll just lick my wounds and put a stop to this one making the rounds. It's an experience that as been repeated over the years since my first MAF equipped car, an '87 Cutlass ES/Vin3. Thinking back that was a really nice car for the day. Mine was Burgundy. Don't say "buy it from a dealer" I've had this happen there too (not specifically Volvo, but dealers all being privately owned/managed a random dealer pick = chances only somewhat better than anywhere else).

Much warmer today the old maf only had trouble only at temps well below freezing, but would seemed to function perfectly on a warmer day like today (smooth idle, highway econ would spike to around 37mpg). With this one I'm not seeing that mpg jump and I've decided the hard throttle performance just isn't there. I certainly noticed that the probe is removable on these, available just about everywhere online from various suppliers (Dorman, Standard, Delphi, Delco, unbranded from China). Several PN variants of this sensor/housing (presumably calibration/probe design differences) leaving some question of which will work properly in this exact vehicle. I'll look into the Peirburg part. Thank you for the bit.

[mrbrian200]

Two different MAF P/Ns supposedly compatible (at one time specific to engine codes ending T2 or T4). Is that interchangeability dependent on an ECU software update?

[mrbrian200]

Is the BCV control signal from the ECU strictly "on/off" or is this fed variable DC voltages? I bench tested this valve early in all this (12vDC/1A wall adapter and a switch). It seemed to function perfectly, but if its controlled as a variable valve or the ECU feed is current limited on the low side such a test may not mean much.

[mrbrian200]

My policy: When OE parts are known for repeated failures, give aftermarket/competing OEM/reman a shot at it. Bosch MAF sensors are nothing but problems in my experience often with 3+ replacements until you finally get hold of a good one that lasts the remaining life of the car.

So.. I'm giving Pierburg a shot at it. No getting these fast (at least in the States) they don't seem to have an aftermarket presence here in the US. Looks like it's built to last (Heat sink on the back side of the hot film element!)
P/N 7.22701.05.0 for the 2.5T engine.
WOT performance is back. As for the other symptoms (intermittent surging and poor throttle response/low highway econ/rough idle/occasional stall at startup) being intermittent in nature I can't make that assessment until at least a few days have passed and I run it on the highway a few times.

If those issues return I'm just going to have to invest in a better diagnostic tool.

[precopster]

If you open up a Bosch 0280218088 you'll find a Pierburg sensor in there