s60 power drop

Castigleone · Post by **Castigleone** » 20 Jun 2018, 15:46

Goodafternoon, thank you for the forum right off the bat.
I am experiencing a drop in power while driving. The engine code told me that I needed to replace the Master Air Flow Valve which I did. I was told it may take 100 miles or so for the engine to recognize the replacement so the engine light may stay on even after I replaced it.
However, while driving the engine seems to stop for a couple of seconds while giving it gas does nothing. It is sporadic however it is sporadic everyday. Usually on the way home from work it will do this once, twice or three times. The thing is it is GOING to happen at a very inconvenient time at some point.
Anyone experience/solve this with their Volvo?
Thank you all for your time
-Castigleone

Post by **mrbrian200** » 21 Jun 2018, 00:11

Note: MAF codes can be set when there is a leak in the intake system. Rule that out first if you already havent...

When the throttle body is having trouble it will often trip the code for the MAF because the air being registered through the meter isn't what the ECU is expecting. But the problem is that the throttle plate isn't responding properly thus too little or too much air is getting into the engine, which the MAF sees (the MAF is fine).
You can try cleaning it. I was having trouble with my '06 2.5T S60 with DTCs for the MAF and occasionally fuel trim DTCs among other symptoms such as a very non linear engine response to gas pedal position and once or twice 'reduced engine power' (limp mode). I replaced the MAF, like you, with no change in behavior. Then I tried the upstream O2 sensor also to no avail. Once I replaced the throttle body the issue resolved never to return. The TB wasn't dirty in my case. Internal gears had worn down and the mechanism was binding/sticking. We're both the same model year. These Bosch TBs are reliable as anything according to some. I differ, or at least, like anything, a bad batch of plastic gears may affect a certain model year or stretch of chassis numbers.

It's not a cheap part, but I'm fairly confident this may be what you are having trouble with. If you have an OBD reader that shows the actual throttle plate position (VIDA graph mode is good for this), drive the car then review the data to see if the throttle plate appears to be sticking at certain positions as you slowly press the gas pedal then slowly let up on the gas pedal (do this on a long open stretch of highway). The throttle plate position should roughly coorelate with torque request/accelerator pedal position without 'flat spots' or sudden/instantaneous jumps in throttle plate position. I got the impression that the ECU software is better at sensing electrical issues with the TB position sensor circuit than it is at catching mechanical failures with the actual TB.

Castigleone · Post by **Castigleone** » 21 Jun 2018, 17:47

Interesting to know that reading the code for the engine light only goes so far. I tested it prior/after replacing the MAF and still got the same code. So you really have to dig deeper than the code result to find the problem. So the tester only goes so far to resolve the problem as the MAF, yet it can't go further than that. Very interesting.
Very succinct in your response and it makes sense to me. Looking forward to swapping this out soon and get back to a smooth ride.
I really enjoy this car, and want to get at least 3 more years out of it.
Mrbrian200 thank you kindly and have a wonderful summer.

Post by **abscate** » 22 Jun 2018, 02:53

Castigleone wrote: ↑21 Jun 2018, 17:47 Interesting to know that reading the code for the engine light only goes so far. I tested it prior/after replacing the MAF and still got the same code. So you really have to dig deeper than the code result to find the problem. So the tester only goes so far to resolve the problem as the MAF, yet it can't go further than that. Very interesting.
Very succinct in your response and it makes sense to me. Looking forward to swapping this out soon and get back to a smooth ride.
I really enjoy this car, and want to get at least 3 more years out of it.
Mrbrian200 thank you kindly and have a wonderful summer.

You captured modern mechanic diagnostics beautifully in one paragraph. If you just “replace by code” you will waste a lot of money replacing good parts.

Post by **chrism** » 22 Jun 2018, 08:49

Is "Master Airflow Valve" another name for the throttle body?

Castiglleone,
I'm not sure from reading the posts - Did you replace the throttle body or did you clean it? Also, what year is your S60? (Trying to determine if it's a Bosch or Magneti Morelli unit.)

Post by **abscate** » 22 Jun 2018, 09:16

Im guessing its MAF or Mass Air Flow Meter

An 2006 S60 will be a Bosch Throttle Body - yeah!!

Castigleone · Post by **Castigleone** » 22 Jun 2018, 17:54

Hey chrism. I replaced the master air flow valve to no avail. The problem popped right back up.
Mrbrian200 alerted me to the throttle body that may be the actual culprit.
Its a 2006 s60 which hopefully next week will be getting a new throttle body. Once that is done man this car is back to the one I simply love to drive.

Post by **mrbrian200** » 22 Jun 2018, 19:45

Castigleone wrote: ↑22 Jun 2018, 17:54 Its a 2006 s60 which hopefully next week will be getting a new throttle body. Once that is done man this car is back to the one I simply love to drive.

I would have been happier had you done some rolling tests while assessing live data between the throttle plate position and torque request/accelerator pedal position to confirm the problem with the throttle body before setting out to acquire a new one. However, based on your initial post I feel a new TB is fairly likely to fix it.