Changed O2 Sensor removed Hot Air Pipe now Smoke???

dosmainframe · Post by **dosmainframe** » 25 Apr 2012, 15:45

Hello, I changed out my o2 sensor today it was a huge pain but I eventually got it out put in a new bosch oem replacement, after that I didn't try to start the car because I wanted to take off the hot air foil pipe to my air box previously the thermostat in the air box broke and was only letting in hot air fried my MAF sensor.

I changed out the MAF sensor and air box thermostat today hooked everything up plugged up the open hole on the air box and took the pipe completely out, started the car up and noticed that there looked like there was smoke spewing out from where the pipe was previously I thought originally that the o2 sensor wires were being melted immediately turned the car off investigated it doesn't look like the wires were being melted the white exhaust type smoke seemed to be coming from the where the hot air pipe was located.

so I put the hot air pipe back on and aimed it upwards, it looks like the smoke is flowing through the pipe it got insanely hot the short period of time the car was turned on, I can see now why that fried my MAF sensor, my question is, is this normal? did I do something wrong when I installed the o2 sensor?

There was alot of oil and grease all over my arms I wonder if this is just oil being burnt that I smeared everywhere?

Is this going to be a big problem because it seems like if I put the hot air pipe back on it gets crazy hot and it was touching one of my spark plug wires I am worried that it will fry or melt them?

Any one have any ideas on what I should do?

Should I keep the pipe on or is it okay to take it off and put aluminum duct tape over the outlet that the pipe goes on? this has me really worried as I think this hot air is going to damage something....

On the plus side since fixing the MAF and Air box thermostat the car runs at idle a lot smoother no more up and down revving I think this is fixed but now this hot air issue makes me not even want to drive the car... let me know what you guys think.

BTW the white smoky exhaust doesn't have any smell to it which is strange and makes me think (hope) this is just what was originally flowing through that pipe.

Post by **jimmy57** » 25 Apr 2012, 16:26

There shouldn't be any smoke other than from oil leaks or your handling of exhaust.
The hose does carry really hot air.
Hot air tube and the door system is a worthless pile of hardware on a car in FL.
Use a sheetmetal screw to lock door open to fresh air side and closed to hot air pipe side.
They dropped the hot air pipe in 89 or 90 on turbos.

lummert · Post by **lummert** » 25 Apr 2012, 19:07

While the O2 sensor was out you should have removed the screws holding the 2 parts of heat stove together and removed it from the down pipe.

dosmainframe · Post by **dosmainframe** » 25 Apr 2012, 20:05

Well I can still do that I'll take it off tomorrow I don't think I need the o2 sensor out to remove it right? just a tight squeeze in there, any ideas on what the white colored odorless smoke is or was? I'll remove that thing tomorrow and try to run the car again and see if it happens again.

lummert · Post by **lummert** » 25 Apr 2012, 20:39

The O2 sensor goes through a hole in the lower part of the shield.

dosmainframe · Post by **dosmainframe** » 28 Apr 2012, 19:04

I took out the o2 sensor and removed the hot air pipe and the hot stove housing, I'm not sure if that was the original problem but no more smoke after starting her up and driving around the block a few times so looks good no more stupid hot air to worry about new maf sensor, now when I was down there I noticed I have an open nipple coming off the engine block right across from the oil filter, this thing isn't connected to anything I'm wondering does anyone know what that thing is? should it be open like that? the guy who owned this car previously did alot of backyard mechanic maintenance and really screwed this thing up I'm just now piecing it back together, every time I fix something I find something new I've been having a problem with a rough idle situation where the car will surge at a stop light or stop sign rev up and down like it's choking out, I think it's a vacuum leak but I cannot locate the source of the problem I wonder if this open nipple has anything to do with it. let me know if you know anything about this nipple if not I'll take some photos and start a new thread, thanks for your advice it's been really helpful

lummert · Post by **lummert** » 28 Apr 2012, 19:47

Locate the power stage (ignition module) on the drivers side inner fender above the battery. I had a problem similar to yours due to the wiring plug not being securely plugged into the power stage after it was replaced. I finally found the plug completely unplugged after the car stalled in the middle of the street. After making sure that the plug was locked securely in place I didn't have any more problem with it.

The best way to explain it is that the plug would briefly lose contact when taking my foot off the gas pedal and the idle would drop to about 500 rpm then it would again make contact and the idle would go back to 750. Sometimes it would stall, but was easy to start back up.

lummert · Post by **lummert** » 28 Apr 2012, 19:48

The pipe nipple that you mentioned may be a block drain for draining the coolant.

dosmainframe · Post by **dosmainframe** » 28 Apr 2012, 20:27

ya know I read about that issue when I was first trying to diagnose this car, I did change the ignition module with a new one and just went out to make sure it was plugged in completely started the car up just to see if anything changed, nope still surging when I idle, I do know that the coolant temperature sensor is bad, and I need to replace that, I need to find a big enough deep socket to fit it, I can't get a crescent wrench in there because of the knock sensor in the way, I'm planning on spraying some carb cleaner all over tomorrow too see if I can find a vacuum leak I'm just out of ideas I thought the MAF would fix this issue, atleast it's driveable now before it wouldn't want to go above 2k rpms now it really has alot of pep, as long as I don't idle this thing cut out on me in the middle driving before too, that's why I rarely use it except for short trips, it's really a shame I love this car and want it too work I live in a small town so no one works on volvo's here and taking it to the nearest shop is too scary to drive 30 miles on the highway in this condition if it breaks down I'm done. Do you think the coolant temp sensor could be causing any of these issues or do you have any other ideas, I'll tell you what I've done so far

Replaced:
Ignition module
Complete PCV system including oil trap box
Hoses that come off the intake to the A/C
Brake booster check valve and brake booster hose
MAF
Air filter
Fuel pump External main pump new oem bosch part
fuel filter
Spark plugs and Wires are new
Tightened all hose clamps focusing around turbo area everything is good
checked air intake hose for collapsing effect, seems to be good

I know I need to replace the Coolant temperature sensor and I think there is a vacuum leak I've spent a ton of money and still haven't fixed this surging issue it really sucks. oh btw the car has about 176k miles on it so most of those parts needed to be replaced anyways I just wish I could get this thing working right.

lummert · Post by **lummert** » 28 Apr 2012, 22:21

My car was hard to start when very cold. When I tried to unplug the coolant temp sensor part of the sensor came out with the plug. It had probably been corroded for many years. I used a 3/4' (or 19mm) socket about 3 inches long to remove the sensor. a short (4 inch) extension will make the job easier. There is a copper crush washer that goes between the head and the sensor, don't lose that.