2006 Volvo S60 2.5 AWD, Endless search of problem

[mrbrian200]

The pigtail on the engine harness is just long enough to plug in this TB (don't try to start the engine), just turn the key to KPII, wait one minute for the ECU to run it's calibration sequence. You'll see the throttle plate move from that resting/idle position to fully closed, then the ECU will run a quick sweep out to near wide open and return to this idle position. Then plug in your scan tool and watch live data for the TB position while you work the accelerator pedal.
A quick check for internal wear without taking it apart is to (disconnected from the vehicle) move the throttle plate slowly back and fourth by hand paying attention whether you feel any 'notchy' spots in the part throttle range or if it doesn't always want to return all the way back to the idle position. Note, it will not naturally sit fully closed, the idle position, approximately 7% open, is a set by an internal spring loaded mechanism. The ECU applies reverse current to the internal stepper motor to act against this mechanism to achieve fully closed. At 'rest' this mechanism holds the throttle plate open at around 7% open plus/minus ~1%.

Be careful with cleaning - one of my suspicions is that harsh cleaners may work into the mechanism under the plastic cover and soften/damage the internal gears which are a form of poly-plastic. I was having intermittent trouble with mine. I tried cleaning it, after which problems became noticeably worse/all the time. I think what you don't want to do is spray cleaners with the throttle body oriented as in your picture where gravity will pull the cleaner down into the mechanism. Rotate it half way from how it is sitting your picture so that the plastic cover is 'up'.

[Unownreality]

thanks for the advice. I oriented it to a way where the plastic pieces are at the top, allowing the solution to drain down the metal portion of the TB.

[Unownreality]

So I changed out the Throttle body and its running amazing again! Took me about an hour, and one bolt gave me a ton of trouble but it was well worth the time! Throttle positioning is running amazing, no more shaking, sputtering, and most importantly no more codes reappearing! Oxygen sensor readings have normalized as well. Hopefully I'll get some good life with this throttle body!

Here's a picture of the one I took out. I personally cant feel or see anything wrong, but obviously its broken.


Thanks to everyone who helped me trouble shoot and figure out what was going on! You're all awesome!

[XC70Rider]

Glad a used ETM (throttle body) solved your issue!

My ETM failed also but wasn't as serious as your issue. My ETM butterfly valve wasn't positioning correctly which caused an air leakage. Like yourself I threw on many of new parts before I could detect the ETM was causing the ECM-121B code (P0101 OBDII code). I'm going to open up the defective ETM and examine the gears.

If these were cable TBs I would of thrown on a used one myself. Being controlled by the ECM which receives data from several other sensors to determine the ETM valve position I decided to throw on a new & lifetime warrantied ETM I got at www.fcpeuro.com.

[EngineeringBloke]

Unknownreality, as your older TB is not usable, would you please open the plastic cover and inspect the plastic gears to see if any of the cogs are missing. This would be so useful to know.

I currently see very poor mileage with my TB plate not closing below 11.4%. However, my car is not stalling at this point. My Torque app shows the two absolute throttle positions fairly closely (this is the reading from the paired potentiometer tracks. However, my ECM has calibrated the TB so that 11.4% absolute is considered 0% throttle relative. I do not think a cleaning will help, although I have not inspected my TB.

[mrbrian200]

Yes, as the original throttle body is now relegated to scrap, remove the plastic cover. The gears that wear are underneath. With the plastic cover off you'll see a larger gear in the middle that just lifts out. Wear occurs on the smaller diameter gear on the bottom of that big one that drives the small gear attached directly to the throttle plate. You'll see 2-3 teeth of about 8 which are a little misshapen compared to the rest. They don't strip completely off before problems occur. 2-3 teeth on the throttle plate gear also wear. Between the two they don't mesh together cleanly and start binding up instead of turning.

[EngineeringBloke]

Anyone seen any spare replacement gears, or know of a source?

[Unownreality]

It doesn't look like mine had too much wear on the gears, and I'm thinking its just an electrical failure of some kind. Mechanism moves, no skipped teeth or anything.

[abscate]

Hmmm, the motion of the motor is reduced by gears by the ratio of the motor gear to the plate gear.

It looks like the idler gear has the same diameter as the motor gear, so no effect there.

[EngineeringBloke]

The gearing is 10 cogs to 47, applied twice (motor spins the middle gear, middle gear spins the throttle plate partial gear). 22.09:1 from the motor to the throttle plate.

I really do not see the significant damage to the cogs that I expected.

From the symptoms, I would expect damage to the cogs on the throttle plate gear (the left picture). It is interesting that although the plate should be at rest (ie, 7% open), the gear is at 5 of 16 (31%) but that is wider than the 12% reported.

I don't see the resistance tracks that the 4 contact fingers on the left picture run on, reporting the actual throttle plate rotation. Perhaps there is damage there to the tracks. I thought that was only an issue with the 2000 and 2001 Italian TBs.

I do not expect any damage to the motor, as that should not be position dependent.

So, still puzzled, but very glad you are no longer seeing the issue.