1989 Volvo 240 rough idle, running rich—Yes, another one.
Thread Starter
|
Member
Joined: Jul 2019
Posts: 32
Likes: 1
Installed the IAC with no improvement. Arguably, might be worse as its periodically stalling when coming to a stop now.
Last edited by FantasticGarlic; Feb 21, 2021 at 10:19 AM.
Thread Starter
|
Member
Joined: Jul 2019
Posts: 32
Likes: 1
Replaced the exhaust pipe directly after the exhaust manifold today and installed a new O2 sensor (I had reasonable suspicion my first one was not good.) No change.
I did discover a small exhaust leak from where the manifold meats the pipe at the flange that I didn't pick up on before—the gasket doesn't quite make up a small ~1/4" long gap where you can feel small amounts of exhaust gas puffing out. Maybe act1292 was onto something here? I'm unsure if the leak was there previously and I just missed it or if it is new from this install.
I did discover a small exhaust leak from where the manifold meats the pipe at the flange that I didn't pick up on before—the gasket doesn't quite make up a small ~1/4" long gap where you can feel small amounts of exhaust gas puffing out. Maybe act1292 was onto something here? I'm unsure if the leak was there previously and I just missed it or if it is new from this install.
Do you have any exhaust leaks up-stream of the O2 sensor? Any leaks up-stream of the sensor will allow oxygen to get sucked into the exhaust stream and cause the ECU to read that as a lean condition and enrich the fuel mixture. I use a plastic tube as a stethoscope to listen for leaks along the exhaust path.
Last edited by FantasticGarlic; Mar 3, 2021 at 01:01 PM.
Senior Member
Joined: Jan 2006
Posts: 1,797
Likes: 52
Long thread and I didn't go back and read through it. The leak might be the cause of an overly rich condition/poor mileage. I doubt that it will help in the rough idle though. Is the idle sorted out?
On the last 240 I had I worked for a year trying to get my mileage to the point where I was satisfied (~23mpg mixed driving). That included replacing the O2 sensor (Bosch) and fixing all of the exhaust leaks. The point where yours leaks isn't uncommon after performing work in that area. Just wanted to check, is the bracket right after the bend in the downpipe that bolts to the engine right where the engine/transmission meet. Many times that will rust out (I live in the rust belt) so if it is broken you need to get that sorted out. When connecting the downpipe to the exhaust manifold, make sure the bracket I described is loose when you tighten the bolts where your leak is. After tightening the bolts connecting the downpipe to the exhaust manifold, tighten the bolt to the bracket.
On the last 240 I had I worked for a year trying to get my mileage to the point where I was satisfied (~23mpg mixed driving). That included replacing the O2 sensor (Bosch) and fixing all of the exhaust leaks. The point where yours leaks isn't uncommon after performing work in that area. Just wanted to check, is the bracket right after the bend in the downpipe that bolts to the engine right where the engine/transmission meet. Many times that will rust out (I live in the rust belt) so if it is broken you need to get that sorted out. When connecting the downpipe to the exhaust manifold, make sure the bracket I described is loose when you tighten the bolts where your leak is. After tightening the bolts connecting the downpipe to the exhaust manifold, tighten the bolt to the bracket.
Thread Starter
|
Member
Joined: Jul 2019
Posts: 32
Likes: 1
Long thread and I didn't go back and read through it. The leak might be the cause of an overly rich condition/poor mileage. I doubt that it will help in the rough idle though. Is the idle sorted out?
On the last 240 I had I worked for a year trying to get my mileage to the point where I was satisfied (~23mpg mixed driving). That included replacing the O2 sensor (Bosch) and fixing all of the exhaust leaks. The point where yours leaks isn't uncommon after performing work in that area. Just wanted to check, is the bracket right after the bend in the downpipe that bolts to the engine right where the engine/transmission meet. Many times that will rust out (I live in the rust belt) so if it is broken you need to get that sorted out. When connecting the downpipe to the exhaust manifold, make sure the bracket I described is loose when you tighten the bolts where your leak is. After tightening the bolts connecting the downpipe to the exhaust manifold, tighten the bolt to the bracket.
On the last 240 I had I worked for a year trying to get my mileage to the point where I was satisfied (~23mpg mixed driving). That included replacing the O2 sensor (Bosch) and fixing all of the exhaust leaks. The point where yours leaks isn't uncommon after performing work in that area. Just wanted to check, is the bracket right after the bend in the downpipe that bolts to the engine right where the engine/transmission meet. Many times that will rust out (I live in the rust belt) so if it is broken you need to get that sorted out. When connecting the downpipe to the exhaust manifold, make sure the bracket I described is loose when you tighten the bolts where your leak is. After tightening the bolts connecting the downpipe to the exhaust manifold, tighten the bolt to the bracket.
Thread Starter
|
Member
Joined: Jul 2019
Posts: 32
Likes: 1
BY THE BEARD OF ZEUS, IT'S FIXED!
A local area junkyard just happened to get another '89 240 into their yard. Just for trying its sake, I went up and grabbed the MAF out of the car. It was another remanufactured non-Bosch one, but figured it was worth a shot anyway for $35. I'll be damned if as soon as I put it in it ran like a top. The replacement original MAF I got from RockAuto was not any good, leading me on this year-long goose chase after that being the very first thing I replaced.
What a roller coaster of emotions this has been and thank you everyone for your help. If anyone else has these symptoms, try replacing the MAF (again)! I'm not sure how long this junkyard one will last me, but I'm going to plan on getting an OEM Bosch one for the future.
On the bright side, everything around the motor has now been replaced
A local area junkyard just happened to get another '89 240 into their yard. Just for trying its sake, I went up and grabbed the MAF out of the car. It was another remanufactured non-Bosch one, but figured it was worth a shot anyway for $35. I'll be damned if as soon as I put it in it ran like a top. The replacement original MAF I got from RockAuto was not any good, leading me on this year-long goose chase after that being the very first thing I replaced.
What a roller coaster of emotions this has been and thank you everyone for your help. If anyone else has these symptoms, try replacing the MAF (again)! I'm not sure how long this junkyard one will last me, but I'm going to plan on getting an OEM Bosch one for the future.
On the bright side, everything around the motor has now been replaced
Senior Member
Joined: Oct 2010
Posts: 4,540
Likes: 137
Great! The MAFS are very often the problem and they are hard to diagnose even by the best shops. I bet many have given up on their cars because of inability to solve MAFS issues, and sometimes the "new" MAFS sold are defective.
Thread
Thread Starter
Forum
Replies
Last Post
tox_slaughter
Volvo 240, 740 & 940
17
Aug 26, 2014 12:46 PM
jpawww
Volvo 240, 740 & 940
5
Nov 15, 2010 11:32 AM