2001 V70 Turbo and limp mode? (Loose hose) Topic is solved

[Daveliz99]

Hello

2001 V70 2.4T 230k miles. Stock.

I have a stage 0 nearly complete on the motor, except for oxygen sensors and this pesky engine system service required message.

On with it.

I was driving the other day and my car started surging a little. I could hear a noise coming from behind the dash that sounded like a turbo spooling up. That whistle sound. Not normal for my car. Also I could hear something that sounded a little like the noise I heard in a different car when the bearings in the water pump began to seize. But this noise didn't sound as "heavy" as that. It sounded more like debris got sucked up in the impeller or something. Or maybe a relay clicking very fast. Suddenly, there was a loud thump sound, only once, like a charge air pipe had blown off. And the exhaust was louder for a moment. The car went into limp mode, would not respond to the gas pedal at all, and the message center now says engine system service urgent.

I pulled into a parking lot and it died. I cranked it again and it idles very rough, but will idle fine after a second, then go back to rough. I can turn on the a.c. compressor and the rough idle will smooth out. In park, if I give it gas, it revs up smooth, but will only rev to 2500 rpm max, sometimes only 2000 rpm, and sometimes it will go from 2500 to 2000 and back again with the pedal on the floor.

I checked all the turbo pipes and they are on good. I pulled the maf sensor and it is intact, so I guess nothing got sucked up in there. I have plenty of fresh oil, just changed it. After it sat overnight i cranked it again, and had a lot of smoke from the exaust, and the exhaust was loud. I suppose it went right back into limp mode, and the smoke went away, the exaust sound went away, and it returned to the rough idle.

So, will a bad etm cause this? What about the surging and turbo sound followed by the smoke? That sounds like a turbo. I can't get it out of limp mode to try to trouble shoot any better.

Thanks for thoughts and help.

Dave

[jonesg]

Can you limp it home, if not I'd get it towed home, might take a while to fix it.

Could be turbo.
When I blew mine the inlet side felt ok but the exh side was broken off and sitting in the wastegate area.
Oil was flowing past the turbo seal into the exh. The flexpipe joint was showing oil at the gasket.

It can be other causes too, a compression test will indicate where to look.

[Daveliz99]

Thanks for the reply.

I unplugged the MAF and limped it home quite well actually. It drive fine, about 25mpg over about 8 miles home.

So I guess it's a bad MAF then?

And those are plug and play from the junkyard right?

Is it ok to drive it unplugged until I can get one? Seems to be.

Thanks for the help.
Thanks.

[jonesg]

As long as its OEM, not after mkt you should be ok, some people try MAF cleaner spray.
But without codes you are guessing. The bluetooth readers are cheap and capable if you have a schmart phone.
Autozone will scan the codes free and sell you MAF cleaner.

[Daveliz99]

Yeah i'll be sure to get it but there to get the codes scanned, but it was late last night when I got it home. I just cleaned the maf about 3k miles ago, with maf cleaner, as part of the stage zero I've been doing. I suppose it could need but I doubt it.

About the codes...

I cranked it last night, same problems as before. I turned it off, unplugged the MAF, cranked it again. It barely ran for about 10 seconds, then smooth, no limp mode. I turned it off; plugged it back up, and it went right back to crap again when I cranked it. So, turned it off again, unplugged it again, it was rough for about 10 seconds again, then good. Drove home fine.

So, codes or no codes, isn't that definitive? Bad MAF?

I understand the importance and good practice of always knowing what codes are stored, but in this case we have evidence. Just curious. I'll have them checked any way.

Thanks again for talking to me.

[jonesg]

Yeh you don't need codes to know you got a flat tire.

The MAF sensor can be removed from the tube, its not volvo specific, its mfgered by Bosch and used by other cars.
So you can buy that sensor new for less money than a volvo dealer.
Or play junkyard roulette.

[abscate]

Unplugging the MAF is not a definitive test for a bad MAF. Here's why.

The ECU uses the flow measured by the MAF to compute the amount if fuel to inject. When you unplug the MAF , the ECAu goes to a default lookup table of fuel injected based on engine rpm. This is NOT limp mode. I've driven 200 miles in my T5 at 65 mph at about 25 mpg on the look up table.

Unplugging the MAF forces the ECU to ignore the other inputs, so it Wil cover up many other faults

[Daveliz99]

Thank you both for the replies. So I will get the codes before spending any money.

I think it's worth noting that the exhaust is a lot louder than before this happened. Any thoughts on that? It sounds kind of cheap and aftermarket now, it's pretty noticeable especially if you know the car.

Unfortunately i'm moving pretty slow with this. Work sucks. But I do appreciate you both. Thanks again.

[Daveliz99]

I will have the codes pulled at advance or somewhere today when i get freed up, and report here.

Abscate, I guess if it ignores all other inputs, It could mask, a lot. But what can it NOT mask?

Initially i suspected either a bad turbo or a bad throttle body because of the surging and turbo sound. This car being a lpt you can't really hear the turbo spool, but before it quit I did hear something that sounded very much like the characteristic sound of a turbo spooling. And, with the MAF plugged up, it blows a fair amount of of smoke. On top of that, the exhaust is louder, and it sounds like it's coming from somewhere behind the dash, possibly up high.

So, could unplugging the MAF mask a failing turbo? If its blowing smoke because of oil leaking, it definitely wont mask that, so I Don't think so, but i'm asking.

About the etm, for a long time now, a couple years or so, I have had the engine system service required message. My research on the forums at the time suggested it was probably the etm on its way out. So I've been waiting for it to die. Now it says engine system service urgent. Initially I also thought the etm had finally died, and the tps was going bad and that's maybe what caused the surging. I bought the carvin 06 with 93k miles, now it has 230k. As far as i know, the etm is original, and it is the magnetti one that fails. So it isn't far fetched that it would be bad now.

But, I've never read anywhere that you can simply unplug your maf and your failed etm will then allow you to drive normally. I don't think that a bad etm is a possibility now though, do you?

I guess it's also possible that I have two problems now too, whatever the original problem was and also the loud thumping or thudding sound I heard was a backfire that damaged the cat or something, and that is what's causing the exhaust sound.

So I guess the question is this. Replacing a failed etm isn't hard, but it's expensive. I was planning to spend the next batch of money on suspension parts. Do we have enough to rule out a bad etm? Replacing a bad turbo isn't real expensive from a junkyard, but to me, that's real hard. Can we rule that out based on observation? If either of those items are bad, will unplugging the MAF mask either? How likely is it that a backfire damaged the turbo?

Thanks for reading, thanks again for helping.

[Daveliz99]

The only codes were p1238 and one for the MAF being unplugged. I'll look into the tcv. Any other comments appreciated. Thanks

Dave