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wtf is this thing?

alewis92

New member
Joined
Dec 14, 2009
hey everybody.

i have a 1990 740 turbo. Im repiping the intercooler and induction lines cause the rubber hoses were all rotten and i thought id gain some hp and some cool points with aluminum intake tubing and spectre fittings. Well, i took the non pressure side stuff off, and right before the MAF is a little sensor inline with a vaccuum line. what is this? i was thinking ambient temp sensor, but idk. Is this nessacery to plumb inline with the air intake, or can i just wire it to a switch or can i put it outside the air channel (to avoid drilling holes and gluing it in)

thanks in advance!

andy
 
Temperature sensor. Not necessary, but may be required by smog. Needs to be coming from the PCV hose. You do need PCV hooked up, so i would keep this part functional. You could cut it out of the stock hose and fit it in a tube, somehow.

Edit: BEFORE the MAF? Uhh, no idea, wouldnt' be stock, that's for sure. (DD a '90 745)
 
well i say before as in closer to the turbo. I live in maine, so i dont give two turds about smog, but if i disconnect it will it screw up the compy?
 
how big is this vacuum line of which you speak? is it 3/8" hose? if so, and it comes from the intake side of the car, but closer to the cylinder head, its gotta be the PCV breather hose that goes pre-turbo to allow crankcase fumes to be burned up by being sucked through the intake into the cylinders.

got a picture?
 
yeah, its the bigger 3/8 hose. I cant get a pic now, but ill try to get one tonight. if i just have to run that pcv hose that would make my life much easier...

thanks for the help!
 
its not a sensor, its a heater. it keeps the oil varpor more vapored. loose it. un plug it and runa either a catch can with a draft tube or just a draft tube.
 
right, i looked it up at work today. supposedly its a "manifold pressure sensor" and it controls the idle... Ive heard alot of different things, and my buddys 88 740 turbo wagon dosnt have one....

i am confused....
 
right, i looked it up at work today. supposedly its a "manifold pressure sensor" and it controls the idle... Ive heard alot of different things, and my buddys 88 740 turbo wagon dosnt have one....

i am confused....

Wrong, it is a heater for the PCV system, 100% not needed

its not a sensor, its a heater. it keeps the oil varpor more vapored. loose it. un plug it and runa either a catch can with a draft tube or just a draft tube.

Correct

Temperature sensor. Not necessary, but may be required by smog. Needs to be coming from the PCV hose. You do need PCV hooked up, so i would keep this part functional. You could cut it out of the stock hose and fit it in a tube, somehow.

Edit: BEFORE the MAF? Uhh, no idea, wouldnt' be stock, that's for sure. (DD a '90 745)


again 100% wrong on the sensor part


I thought this was common knowledge by now
 
What is a "Draft Tube"? Will be attempting to replace the soft rubber intake hose in the near future. I know the heater/sensor thing is not needed but do you need to have some sort of vaccum to help in the PCV system?
 
you thought wrong sir. keep in mind that every one on here is not a volvo guru and dose not recite verbage from factory work shop manuals in there sleep.

It is old knowledge, I guess I just do not realize how many people here are new.

Those of us that figured it out did it from messing with the cars, not reading any books
 
well, i ditched it, fixed a few vaccuum leaks, and the car runs better than ever
new plugs, wires, oil, oil filter, fuel filter, and most of the vaccuum hoses have been replaced.

the check engine light is on, but i dont really care. the new intake and exhaust system seem to have really helped with the throttle response, and it takes off wayyy quicker in a 0-60 shot, especially in 2nd and 3rd gear.

very happy person, thanks for all the help guys!
 
does anyone that has ditched this have a pic of what they did?. or did you just remove the electrical and call it a day?
yes new to the forums.
 
We're talking about one of these guys, right? I've been curious myself... and the Haynes manual for the 700-series (-88) doesn't talk about it. That hose is off a ('91) 940SE, so it might be a later addition, of course.
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