99 S70 Turbo AWD - Low idle and smoke from the back, misfire

subbaraa · Post by **subbaraa** » 20 Oct 2007, 18:11

Folks
here is the problem

99 Volvo S70 AWD Turbo
~124K

today, when I had stopped at a light, the engine was idling at around 400 RPM! The car was jerking. Then when I put it into neutral and raised th engine RPM a little, I could see some smoke coming from the back.

A little while later, the check engine light came on with a P0171.

The MAF was replaced about a year and a half ago. What could this problem be?
The fuel filter has not been replaced in a while, nor has the plugs and wires. I was thinking this was a misfire, but no misfire code....

The smoke from the back was not similar to the heavy gray smoke that comes out of a car with an oil burning engine, this was a black smoke..

please help!

subbaraa · Post by **subbaraa** » 20 Oct 2007, 18:14

Oh yeah, both the o2 sensors was replaced not 8 months ago

Post by **Ozark Lee** » 20 Oct 2007, 19:22

Step 1 is to look for a vacuum leak. Look for a broken / cracked hose or a hose that just fell off of its fitting. Spraying starter fluid OUTSIDE around the vac lines can often help in locating the leak.

...Lee

subbaraa · Post by **subbaraa** » 20 Oct 2007, 19:51

Thanks Lee,
What should I be looking for when I spray starter fluid around?
Is the turbo models also supposed to have these vacuum hoses? Any idea where they are located?

subbaraa · Post by **subbaraa** » 20 Oct 2007, 19:53

ok this is annoying

I just turned on the car, and all the symptoms mentioned above are gone!
My wife said that she noticed the car jerking (as I mentioned in my first post) as well 2 days back, but only once!

Hmm....

Post by **Ozark Lee** » 21 Oct 2007, 16:19

What should I be looking for when I spray starter fluid around?

The engine will race when you get in the vicinity of the leak. Keep in mind that starter fluid is ether so you don't want to breath it in concentration.

The vac hoses are numerous on a turbo. Start at the vac tree on the intake manifold.

...Lee

subbaraa · Post by **subbaraa** » 22 Oct 2007, 10:38

ok, will give this a shot and update the thread

Post by **MadeInJapan** » 22 Oct 2007, 10:56

I agree with leaks in the vacuum lines or hoses. The cracks if small will not expand to allow air to penetrate them until the car is warmed up and the hoses get hot. That is most likely why right after a cold start the symptoms you were seeing have disappeared. Give it time....I've very rarely heard of Murphy's Law working in reverse.

subbaraa · Post by **subbaraa** » 22 Oct 2007, 11:41

Thanks for the tip guys...
I have never seen these vacuum hoses, any idea where in the engine bay I might find them? (figured I would ask this, before I go spraying starter fluid all around the engine bay)

edit: NM, its near the intake manifold...
Bay13 has a write up on this

Post by **MadeInJapan** » 22 Oct 2007, 14:04

Lift your hood and under it should be a diagram of your vacuum hoses. Hope this helps.