2000 v70xc To MAF (again) or not to MAF?

albertoVO5 · Post by **albertoVO5** » 01 Sep 2015, 12:42

To MAF (again) or not to MAF?
I have a 2000 v70xc with 160K miles, Eng: B5244T, 2.43 L.
After a 45 minute highway drive and then on surface roads for 10 minutes at slower speeds I had a pop/backfire (uh-oh I thought, never heard that before); at the next start up a few minutes later (after a stop for an errand) idle was wildly erratic and car was undriveable. I disconnected the MAF; it started up, and I drove it home normally (more or less) a few minutes away.
My Acton code reader showed one fault, P-1238, “Fuel Air metering”. I ordered and installed a Bosch MAF from ‘Stocklifts, LLC” (from their site: “Stocklifts, LLC is a re-distributor of NEW automotive after-market parts”) The new and old MAF #'s matched: Bosch, 0 280 218 108 86 70 112. Unfortunately, new MAF didn't make a difference – same symptoms.

So: Bad-from-stock Bosch MAF? Fake Bosch part? Doubt it’s the ETC; no fault light, and it was changed a year ago by the local go-to Volvo shop here in Seattle (Daisywagen); I talked to them and they also doubted ETC, they only install ETC’s with mechanical & software upgrades.
How would one bench-check a MAF? Resistance reading pin-to-pin on a normally functioning MAF?
Any help would be appreciated!

Post by **RussB** » 01 Sep 2015, 13:08

You've ruled out the MAF sensor, so no need to keep beating that dead horse. The loud pop/backfire you heard may very well be a turbo hose that tore or popped off. Look at all of them carefully, especially the one on the bottom of the intercooler. Symptoms would be in line with what you're seeing now

albertoVO5 · Post by **albertoVO5** » 01 Sep 2015, 14:04

Russ, thanks for the fast reply. I did look at them previously, but on a level somewhere between casual glance and thorough inspection; I will take a close look ASAP.
Out of curiosity after I posted the problem, I went out and re-connected the MAF, mostly to erase and then pull a fresh code. I was surprised - at first it was running almost normally, but the warmer it got the worse it ran.
I'm a moderately versed in mechanics, but this is a 'new' car to me and I'm not very familiar with the particulars. When you say "the bottom of the intercooler" - there is a large hose at the 6 o'clock position on the radiator assembly, and I assume the intercooler is in that sandwich of radiator/AT cooler/intercooler. Is that the one you mean?

Post by **scot850** » 01 Sep 2015, 14:52

If you look down the back of the radiator when standing in front of the car, there is a black rubber pipe about 3-31/2" in diameter coming out from the intercooler (as you correctly surmised) in front of the radiator from the middle top. This pipe turns 90 degrees and then clamps to a plastic pipe that runs down into the intake manifold via the ETM. Still looking down the back of the radiator, the inlet pipe to the intercooler should be to the bottom right as you look at it. If fitted, remove the 2 x 10mm bolts that hold the plastic under tray in place under the radiator to see better. It is the larger of the 2 pipes at the bottom, the other is the lower radiator pipe.

The pipe to the bottom, runs up the front of the engine into a metal pipe and then up over the top and back down the back to the top of the turbo. There is a short (4") rubber connection there that can split with age also or come off it not tightened correctly. Finally, check the plastic 'corrugated' cold air pipe from the air box to the turbo inlet. These can also split with age at the turbo end.

Neil.

Post by **scot850** » 01 Sep 2015, 14:53

Oops! Should also have said check the bottom of the intercooler for cracks as this can also happen with age.

Neil.

albertoVO5 · Post by **albertoVO5** » 01 Sep 2015, 17:31

Russ & Neil, excellent call.
Neil, your description of the pipe layout was spot on. I checked each with mirror and tugging, pushing/pulling on the various pipes. All seemed to be in good shape and looked/felt Ok - until the last one I checked at the ETM (I said 'ETC' in my post, my bad) Hard to tell, but it didn't look right in the mirror, and then confirmed that it wasn't secure to the bottom of the ETM (this was the ETM changed a year ago).
That is a particularly tough spot to get to the clamp, tough enough that after trying from above & below I'm thinking taking it back to Daiseywagen and say 'Hey, I think I'm due a little warranty work here'. Alternately, any recommendations of an easier way to work on that spot?

Post by **RussB** » 01 Sep 2015, 18:21

It's a tight fit in there. I recently replaced my ETM and stuffed my left hand up in there securing the hose to the ETM while slithering my right hand to the hose clamp with a 7mm nut driver.

At this point you want to fully remove the hose from the ETM, take the clamp off and loosen it a bit, then put the clamp back on the hose get it up onto the ETM

albertoVO5 · Post by **albertoVO5** » 01 Sep 2015, 19:03

That's actually what I ended up doing (fully removing the hose etc) but while in the midst of that got to thinking - I'm guessing I had an overboost and the loose pipe going into the ETM was a result, not the cause. I heard a pretty good 'pop' just before it started to run wobbly. So, now I'll be searching for causes/cures of over overboosting...

Post by **scot850** » 01 Sep 2015, 22:12

I always believe in being cautious and it would be wise to check the possibility if an over-boost occurring, but I think it is more likely that the plastic intake pipe was never re-fitted correctly and has worked loose over time. It is fiddly to access the 7mm bolt head of the clamp, and when I fitted a new intake pipe on my car I had to use a LOT of strong engineering words and about an hour before the dam thing would go on. The original had worn and was a piece of cake in comparison to install. I used a long 1/4" 7mm socket and a 1/4" ratchet. I fitted the bolt head to the right of the ETM body facing to the front of the car to tighten. Even with my large size (ahm!) I was able to reach down from the RH side of the radiator (looking from the front of the car into the engine bay) and get my arm/hand in along the side of the intake pipe.

Remove the top rubber pipe first before trying to fit at the ETM.

A small extending bendy mirror on a stick can help see what you are trying to achieve.

Neil.

Post by **abscate** » 02 Sep 2015, 01:35

...these hose clamps need to be TIGHT on the induction hoses.

The only way to inspect induction hoses to troubleshoot, I believe, is removal and replacement.

We have had many here he did a visual and missed a loose induction hose and then threw parts set the wrong place...myself included.