2004 v70 MAF and idling issue

nyteacher · Post by **nyteacher** » 09 Jun 2014, 18:59

My v70 has 189K. I have been trouble-shooting a CEL that is MAF related. Originally, no problems with car other than CEL. Cleaned MAF. Still CEL on. Replaced MAF. CEL went off for a week, but came back on along with the dreaded 'hunting at idle' problem. Cleaned throttle body. Still rough idle and CEL. Disconnected MAF and ran car without it attached. ROUGH IDLE WENT AWAY! I was able to drive around with the MAF disconnected for awhile and it drove fine and idled fine. My other volvo is a 2004 s60 so it has the same MAF which is working fine. Tried swapping that one in for the one on the v70. Same rough idle came back when that one was connected. So what's the deal? MAF must be bad, but why would a working MAF from my other volvo not solve the problem? Stumped in NY.

Post by **abscate** » 09 Jun 2014, 19:20

It can take some time to adapt to the new MAF..did you try a few days if driving?

If you have a vacuum leak, disconnecting the MAF makes the car run on a default set of parameters which will work well. Putting a working MAF back in will cause rough running.

What code were you getting to start this all off?

nyteacher · Post by **nyteacher** » 09 Jun 2014, 19:55

The guy at the auto parts store said I had a MAF code and a couple more codes. Unfortunately I forgot to write them down because I was thinking about the MAF. I think they were an I and O issue and bank 1 too lean codes. He said they were both related to the air/fuel mix. I will check for vacuum leaks next.

Post by **abscate** » 10 Jun 2014, 03:23

Its important you get the actual code, like P1234.

The OBD system does not tell you "replace this part" but rather gives you guidance to what system is reporting an error. You still have to use your head to determine root cause, but that is what MVS is for - bringing heads together to fix cars!

Post by **JRL** » 10 Jun 2014, 05:01

Why are you up at 4:30 in the morning?
(and lucid)!

Post by **abscate** » 10 Jun 2014, 05:15

I can't get my HU. 850 'to turn off...the HU650 directions are wrong.

(Seriously, 1/2 my clients are +12 hours and I'm much more lucid in am than PM.

Post by **oragex** » 10 Jun 2014, 10:31

I've heard that some aftermarket MAF would do that.

nyteacher · Post by **nyteacher** » 19 Jun 2014, 15:14

I got a pulled throttle body/ECM and replaced mine and the problem got worse! Now, it stalls going around corners. The hunting at idle is still there (not when the car is cold) and now hunts at lower RPM's and goes to zero, causing the stalling. I had the fuel pressure sensor replaced under recall years ago and this reminds me of that, but the code is different.

Post by **oragex** » 20 Jun 2014, 10:16

I don't know if it's related, but the throttle body must be well sealed when placed back. I used some rtv to make sure it's sealed and there's no vacuum leak since that could foul the sensors reading. Also from what I remember, pulling the throttle body has to be done with the battery disconnected, as there is a reset procedure or something. Try pulling both battery terminals for about 12h, that resets the computers, and before connecting the battery make sure the ignition key is in position II - important procedure for Volvo so it doesn't allow a surcharge to bust electronic components.

Post by **abscate** » 26 Jun 2014, 05:27

None of manuals recommend sealer near the MAF..the connector is well engineered to seal with the OEM clamp.

Is key on for battery reconnection a P2 mantra? You certainly don't do this on P80 cars.