O2 Sensor Placement

zdriver123 · 07-23-2012, 09:35 PM

So, I have to replace the entire exhaust on my 90 244. I'ts got a cracked manifold, cracked header pipe and junk exhaust. I found a manifold, header pipe and built my own 2.25 inch exhaust. The only difference is that the new exhaust has the O2 sensor in the manifold, not the header pipe down by the catalytic converter. would economy or performance be affected by installing my sensor up in the manifold instead of the header pipe. I could care less about performance, i'm looking for economy.

vvpete · 07-23-2012, 10:02 PM

Quote:

Originally Posted by zdriver123

So, I have to replace the entire exhaust on my 90 244. I'ts got a cracked manifold, cracked header pipe and junk exhaust. I found a manifold, header pipe and built my own 2.25 inch exhaust. The only difference is that the new exhaust has the O2 sensor in the manifold, not the header pipe down by the catalytic converter. would economy or performance be affected by installing my sensor up in the manifold instead of the header pipe. I could care less about performance, i'm looking for economy.

The sensor is most sensitive when it is hottest, which is in the catalytic converter, even hotter than the ex manifold.
I would suggest getting the Magneflow 2.25 freeflow cat with the O2 bung in it, I and many others run this one and cheap. IIRC the p/n is 94135
http://www.magnaflow.com/02catalytic...niversal=94135
The O2 sensor was in the cat in '91-up, and my LH 3.1 has it there, the best mpg 240 I've had.

John2x240 · 07-23-2012, 11:33 PM

I don't know about a '90, but my '89 244 has the O2 sensor in the cat.

volvoboy90 · 07-23-2012, 11:53 PM

My '89 240 has the o2 bung in the down pipe just before the catalytic flange...

John2x240 · 07-24-2012, 12:00 AM

Hmm. Maybe it's my '88 244 then ... I do get them mixed up some times.

volvoboy90 · 07-24-2012, 12:04 AM

*shrug* when I ordered the downpipe, I had to pay extra to have a shop weld a bung into it since it didn't come with one, and my cat doesn't either.

John2x240 · 07-24-2012, 02:41 PM

I just checked my '88 and the sensor is in the exhaust manifold just above the connection to the down pipes. I can't get at the '89 right now, but I'm pretty sure that when I replaced the cat a few years back we re-installed the O2 sensor in to it.

erichobart · 06-26-2022, 05:20 PM

Hi all,

My 81 242 turbo is getting rehabbed. I replaced the in-tank fuel pump with the larger later pump from ipd and a new sending unit as well. The sending unit was reverse polarity at manufacture, so i cross-wired. Now the main fuel pump is whining, so I'm planning on replacing it. But I'm wondering if the problem is the 02 sensor. I had a custom shop install a 2.25 turbo back stainless exhaust and they didn't bother to weld in a bung nut but just used sealant instead. Thoughts?

dl242gt · 06-26-2022, 06:32 PM

The stock location of the o2 sensor is under the manifold behind the turbo. So if there is a sensor in there with stock kjet. Then it's time to make sure it's working. The exhaust shop probably didn't have a stainless steel hole saw. If you do move the sensor to the downpipe. Change to a heated sensor so it won't cool off while cruising or idling.

erichobart · 06-26-2022, 07:56 PM

Thanks Dave,

I'll put it up on stands and take a closer look, have to replace disks and pads anyway. By the way, how did you get 3-inch exhaust on your 82? I'm putting a ton of time in on my 81 and need all the advice i can get. i did all the suspension upgrades, chassis braces, sways, bilsteins, etc but am hoping to push the boost safely as well. Tips are much appreciated.

Best,
Eric

erichobart · 07-02-2022, 05:35 PM

ok i'm in trouble. Upgrading 1981 242t, replaced the in-tank sending unit and pre-pump with the larger version.
Fires up but fuel leaks galore. Fuel running down one or more hoses to the ground. In-line pump and hoses not leaking. Leaking fuel accumulating on top of in-tank fuel bung. All hose clamps there are secure. Also, turbo dash light is on. help? Maybe the old girl wants to move on?

07-23-2012, 09:35 PM	#1
zdriver123 Board Member Join Date: Sep 2010 Location: Sequim Washington	O2 Sensor Placement So, I have to replace the entire exhaust on my 90 244. I'ts got a cracked manifold, cracked header pipe and junk exhaust. I found a manifold, header pipe and built my own 2.25 inch exhaust. The only difference is that the new exhaust has the O2 sensor in the manifold, not the header pipe down by the catalytic converter. would economy or performance be affected by installing my sensor up in the manifold instead of the header pipe. I could care less about performance, i'm looking for economy.

07-23-2012, 11:33 PM	#3
John2x240 Board Member Join Date: Oct 2010 Location: Sarsfield,ON	I don't know about a '90, but my '89 244 has the O2 sensor in the cat. __________________ '88 Volvo 240 auto (now a parts car), '89 Volvo 240 5 spd. (now a daily driver), '92 245 5 spd. (new my car), '80 Holiday Rambler/Ford E350 (tow vehicle and track crash pad), '95 GMC K2500 (local hauler/back-up tow vehicle), '83 Mazda RX7 (race car when I have the funds), '99 Miska 20' car hauler. The man's prayer: "I'm a man, but I can change, ... if I have to, ... I guess."

06-26-2022, 06:32 PM	#9
dl242gt Old and boxy but good. Join Date: Jun 2002 Location: S NJ, a suburb of Phila.	The stock location of the o2 sensor is under the manifold behind the turbo. So if there is a sensor in there with stock kjet. Then it's time to make sure it's working. The exhaust shop probably didn't have a stainless steel hole saw. If you do move the sensor to the downpipe. Change to a heated sensor so it won't cool off while cruising or idling. __________________ Dave, 1982 242 turbo. 338k miles. MVP coilovers and 3" exhaust. Flowed 405 with a V15. Cossie turbine housing with upgraded compressor housing. 90+, IPD remote oil filter. Some other goodness, too. Been lots of fun over 25 years. Restored in 2k. Now ready for a 2nd restoration. 1993 245 Classic, 440k miles, enem V15. IPD bars and chassis braces. Simons sport exhaust from Scandix. sbabbs ezk chip. Been a good road warrior. Genuine Volvo rebuilt leaky M47.

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07-24-2012, 12:00 AM	#5
John2x240 Board Member Join Date: Oct 2010 Location: Sarsfield,ON	Hmm. Maybe it's my '88 244 then ... I do get them mixed up some times.

07-24-2012, 12:04 AM	#6
volvoboy90 sanna kärlek är svensk Join Date: Jun 2011 Location: Dayton, Ohio	shrug when I ordered the downpipe, I had to pay extra to have a shop weld a bung into it since it didn't come with one, and my cat doesn't either.

07-24-2012, 02:41 PM	#7
John2x240 Board Member Join Date: Oct 2010 Location: Sarsfield,ON	I just checked my '88 and the sensor is in the exhaust manifold just above the connection to the down pipes. I can't get at the '89 right now, but I'm pretty sure that when I replaced the cat a few years back we re-installed the O2 sensor in to it.

06-26-2022, 05:20 PM	#8
erichobart Board Member Join Date: Oct 2011	Hi all, My 81 242 turbo is getting rehabbed. I replaced the in-tank fuel pump with the larger later pump from ipd and a new sending unit as well. The sending unit was reverse polarity at manufacture, so i cross-wired. Now the main fuel pump is whining, so I'm planning on replacing it. But I'm wondering if the problem is the 02 sensor. I had a custom shop install a 2.25 turbo back stainless exhaust and they didn't bother to weld in a bung nut but just used sealant instead. Thoughts?

06-26-2022, 07:56 PM	#10
erichobart Board Member Join Date: Oct 2011	Thanks Dave, I'll put it up on stands and take a closer look, have to replace disks and pads anyway. By the way, how did you get 3-inch exhaust on your 82? I'm putting a ton of time in on my 81 and need all the advice i can get. i did all the suspension upgrades, chassis braces, sways, bilsteins, etc but am hoping to push the boost safely as well. Tips are much appreciated. Best, Eric

07-02-2022, 05:35 PM	#11
erichobart Board Member Join Date: Oct 2011	ok i'm in trouble. Upgrading 1981 242t, replaced the in-tank sending unit and pre-pump with the larger version. Fires up but fuel leaks galore. Fuel running down one or more hoses to the ground. In-line pump and hoses not leaking. Leaking fuel accumulating on top of in-tank fuel bung. All hose clamps there are secure. Also, turbo dash light is on. help? Maybe the old girl wants to move on?