diagnostc code says MAF sensor

[brian c]

howdy all
this is the coolest forum. I just tore down my kid's 850 head- replaced a valve etc. This forum provided ALL the photos and info I needed to do the job. How cool is that?! thanks everyone

Now on to the question.... Originally the check engine light came on just as the engine began missing badly. Compression test said #4 cylinder lost all compression. So I tore down the head...replaced a badly burned exhaust valve put in new oil seals etc and put the head back on. The engine runs good now but the check engine light is still on. So I did the diagnostc check under the hood. Plugged in the self diagnostic thingy and see that A-2 gives me a 1-2-1 code. Acording to the code sheet I looked at (on this site) that means trouble with the MAF sensor.
Ok, so... I have a pretty good idea what the MAF is but what could be wrong? and how did a badly burned valve cause the MAF sensor to act up?

I cleared the code but the check engine light just comes back on. Not sure if this is at all serious as car seems to run fine. Tell me please what a smart person would do in this case.
thanks in advance..........

[jblackburn]

You can try either:
-cleaning the mass airflow sensor (they sell a spray at most auto parts stores)
-check for any holes in the air intake hose - even a small one can throw the sensor readings off
-ziptie the connector at the top - they can cause erroneous readings when they're not making contact well
-as a last resort, replace the sensor with a new one or a used one if you can find one that works.

[brian c]

thanks J .....I'll snoop around and see what looks bad near the intake. What trouble might the false reading cause...bad mileage?

By the way... I saw your video of before and after timing belt adjustment. Your engine sounds even noisier than mine. Though I suspect the recording has a little to do with the noise.

[misha]

...-as a last resort, replace the sensor with a new one or a used one if you can find one that works.

But ONLY with oem Bosch,not with aftermarket or with generic/universal ones.

[jreed]

I wrote up a short DIY on removing and cleaning the MAF sensor:

https://www.matthewsvolvosite.com/forums ... 1&p=218607

[brian c]

Thank you jreed. I read your tutorial.I'll be taking a look at the sensor this afternoon.