2001 V70XC - struggles to idle when coming to stop light Topic is solved

[xHeart]

So basically the TCM asks ECM to reduce torque for the longevity of the shift. ECM does it by reducing fuel, boost and throttle. For some reason ECM thinks it has no control over air flow and has to compensate for too much air by reducing the fuel injection. The pressure buildup can happen, for example, if ETM turns the plate more than it has been asked for. Or if the turbo does not respond to TCV quickly enough.

Your comments above^ hinted to look elsewhere, thus...

Often drop in engine speed resulted in power generation symptoms including drop in voltage, flickering dash, headlights, engine cut-off etc. So, read through the OAP related discussions, and decided to service the pulley before next step, i.e. ETM.

I installed this Bosch 140 A rebuild generator in 2014. It has 60,000 miles on it, but the pulley doesn't freewheel anymore. Replaced the pulley with a new INA OAP. A drive cycle is coming later today.

MVS_OAP_1185.jpg (193.98 KiB) Viewed 1341 times

[vtl]

Check/replace the voltage regulator as well.

[xHeart]

Check/replace the voltage regulator as well.

Amazing improvement after the alternator OAP service. Reversing out of the inclined driveway is way more responsive, and lots of power -- awful bearing noise is absent. It use to give up reversing on a pile of ice. Driving this winter with snow on the ground will be way more joyful.

The following OAP (not INA) failed more than two years ago. Be prepare to replace it if your's have 30,000 miles on OAP.

MVS_FailedOAP_1186.jpg (174.59 KiB) Viewed 1331 times

[xHeart]

Unless you say otherwise, I am leaning TB is failing.
Three ECM freeze frames in the order of mileage when stored:

ECM-6806

ECM-904C

ECM-4801

[xHeart]

Some finer details after the OAP replaced, and few drive cycles -- runs way better.

The sudden drop in engine speed is absent, and jerk after taking foot off the gas pedal is minimal. Much cleaner shifting up and down during the normal urban drive.

BUT, rpm hunts between 900-1200 when slowing to stop. It burps each time after the car is fully stopped and idles in "D"; rpm rests at 700±. HOWEVER, it DOES NOT burp if I move the gear selector to "N" prior to coming to a full stop; rpm rests at 900±.

[xHeart]

Intercooler to ETM pipe

Crumbling at the ETM connection. Replacing this pipe will complete this service of end-to-end replacement of intake pipes and hoses. Ending with installing XeMODeX throttle body next.

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[vtl]

Hopefully new/improved ETM will do it. There's a reason why Volvo walked away from Magneti Marelli.

[xHeart]

Hopefully new/improved ETM will do it. There's a reason why Volvo walked away from Magneti Marelli.

Installed the XeMODeX. The air intake is now refreshed from the air inlet to intercooler-ETM pipe.
The MAF is new too, but I may have to clean/replace the MAF, other then that the drive this morning was Ah-ha!

The two departing MM 0-130,000 miles white label, and 130,000-202,110 miles yellow label.

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MVS_MM_1191.jpg (188.74 KiB) Viewed 1285 times

[xHeart]

The air intake and charging issues were mixed up -- clouding the diagnostic for this DIYer. Many small issues had creeped up too.

Listen to the Captain! In addition to the air intake pipes, hoses, and filter, I replaced was MAF, TCV, MAP, and ACT sensors too. The OAP freewheel function at the alternator had failed some 2 years ago -- battery was never fully charged. VTL says to check the regulator too.

LESSON: take care of air intake while popular items such as tb, pcv take your attention away. Be prepared to refresh air intake after 150,000 miles. I use new OE/OEM parts on my cars -- it can be cost effective with eBay and jy.