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Rough Idling

Help, Advice and DIY Tutorials on Volvo's extremely popular car line -- Volvo's 1990s "bread and butter" cars -- powered by the ubiquitous and durable Volvo inline 5-cylinder engine.
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1997 - 2000 S70, S70 AWD
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Rubberfig
Posts: 22
Joined: Fri Aug 11, 2017 9:54 pm
Year and Model: 1995 850
Location: Portland, Oregon
United States of America

Rough Idling

Post by Rubberfig » Fri Aug 11, 2017 10:23 pm

I purchased a used 1995 Volvo 850 2.4l 5 cylinder from a neighbor, and I have been dealing with a rough idle ever since. If the car is going under 5 miles an hour, and is clocking less that 1k rpm, its pretty rough. No matter how fast I am going, if im braking it gets rough as soon as i get under ~5 mph. As soon as i accelerate, it clears up. The check engine light was on, so I took it in and got the codes checked. I didn't get the actual code from the gentleman, just what the code read. It came up with misfires in cylinder 3 and 4, and a random misfire on top of that. I thought that was odd because misfires normally cause rough riding in all speeds and rpm, which my car was not doing. I have replaced the spark plugs and the spark plug wires, and also cleaned out the place where the spark plugs are screwed into the chamber. I read something about the IAVC causing a problem, but i took it out and it rotated freely. I cleaned it anyways, and later came back with some oil dissolver and cleaned it thoroughly. I have yet to test this recent clean, but I have a feeling it wont change anything. I'm not that car fluent, so if possible could all responses be in layman's terms? I still have the car, and can check all different parts of it. Also, its very easy to get the codes if needed, which i will probably do and add to the post. What could be causing it? I really want to figure this out, im willing to put some money and moderate amounts of time into fixing this. I have limited tools.
Finn

scot850
Posts: 3652
Joined: Mon Apr 05, 2010 2:46 pm
Year and Model: 2000 V70 R
Location: Calgary, Alberta, Canada
Canada

Re: Rough Idling

Post by scot850 » Sat Aug 12, 2017 10:27 am

Sorry no one has responded to you. There have been a lot of similar issues recently. These cars are getting older so parts become worn and can be a bit random in performance. Firstly, to confirm the car is a non-turbo (NA) engine?

What brand(s) of plug wires and plugs did you use? These cars are finicky on what they like.

Have you replaced the distributor cap or rotor arm yet? If not, you need to remove them and have a look at the condition of them. A small hairline crack in the distributor cap can cause this type of issue as can a worn rotor arm.

When you have the distributor cap off have a look for any oil residue in the distributor.

Are you getting any oil leaks up near the top of the engine near the oil filler cap?

Neil.
1993 850 GLT -Sold
1998 V70 XC - Sold
2000 V70 R - still being an endless PITA
2006 XC70
1997 Volvo 850 SE NA - Went to niece in California
2000 V70 SE NA - New project and test bed

User avatar
Nevada1906
Posts: 98
Joined: Wed Sep 07, 2011 6:01 pm
Year and Model: 1995 850 Turbo
Location: Ohio
United States of America

Re: Rough Idling

Post by Nevada1906 » Sat Aug 12, 2017 11:53 am

If the engine is running rough at low RPMs but smooths out as you accelerate - and gets worse as you brake - try cleaning your MAF. They can get weird without throwing a code.

That was my exact same problem this past week.

I had installed a brand-new Bosch unit in 2013 but hadn't cleaned it EVER. I hosed the shit out of the sensor element with CRC MAF cleaner and the problem went away.

A tuneup might be in order as well, because who knows how long your existing plugs and wires have been in there.

ONLY USE THE BOUGICORD WIRES AND Volvo PLUGS, THOUGH.

These cars are solid but they're real snobs about parts.
"...and yet another evening out ends with the words, 'you guys gotta leave, NOW!'"

Rubberfig
Posts: 22
Joined: Fri Aug 11, 2017 9:54 pm
Year and Model: 1995 850
Location: Portland, Oregon
United States of America

Re: Rough Idling

Post by Rubberfig » Sat Aug 12, 2017 7:42 pm

scot850 wrote:
Sat Aug 12, 2017 10:27 am
Sorry no one has responded to you. There have been a lot of similar issues recently. These cars are getting older so parts become worn and can be a bit random in performance. Firstly, to confirm the car is a non-turbo (NA) engine?

What brand(s) of plug wires and plugs did you use? These cars are finicky on what they like.

Have you replaced the distributor cap or rotor arm yet? If not, you need to remove them and have a look at the condition of them. A small hairline crack in the distributor cap can cause this type of issue as can a worn rotor arm.

When you have the distributor cap off have a look for any oil residue in the distributor.

Are you getting any oil leaks up near the top of the engine near the oil filler cap?

Neil.

You are correct, the car has a non-turbo engine. I used Bosch wires and plugs, as I have heard from multiple sources that they provide reliable parts, and also some parts in the engine are currently Bosch so I took that as a good sign.

I have a distributor cap that I was planning to replace, but I could not get the bolts loose holding the current distributor cap in. I will be checking the local O'Reilly's for a part that can help take out stripped bolts.

I am losing some oil out of the top of the engine, but it doesn't seem like a lot. I was told that the very top "valve cover" (I dont think they know what they were talking about) was almost purely aesthetic, and didn't have any real value to the car. I've recently purchased a gasket maker silicone thing, so I will be applying that asap to prevent further oil loss. However, that requires a full 24 hours without use of the car, and currently I am using it daily. However, directly around the oil filler cap does not seem like it is losing any more oil than the rest of the cap.
Finn

Rubberfig
Posts: 22
Joined: Fri Aug 11, 2017 9:54 pm
Year and Model: 1995 850
Location: Portland, Oregon
United States of America

Re: Rough Idling

Post by Rubberfig » Sat Aug 12, 2017 7:46 pm

Nevada1906 wrote:
Sat Aug 12, 2017 11:53 am
If the engine is running rough at low RPMs but smooths out as you accelerate - and gets worse as you brake - try cleaning your MAF. They can get weird without throwing a code.

That was my exact same problem this past week.

I had installed a brand-new Bosch unit in 2013 but hadn't cleaned it EVER. I hosed the shit out of the sensor element with CRC MAF cleaner and the problem went away.

A tuneup might be in order as well, because who knows how long your existing plugs and wires have been in there.

ONLY USE THE BOUGICORD WIRES AND Volvo PLUGS, THOUGH.

These cars are solid but they're real snobs about parts.
What is a MAF? Where is it located in the engine? I have considered a tune up, but I would rather pay less and do the labor myself.
Finn

scot850
Posts: 3652
Joined: Mon Apr 05, 2010 2:46 pm
Year and Model: 2000 V70 R
Location: Calgary, Alberta, Canada
Canada

Re: Rough Idling

Post by scot850 » Sat Aug 12, 2017 9:01 pm

The maf is the Mass Air Flow sensor and it sits in the pipe between the air box and the intact manifold. It regulates the air/fuel ratio and has a hot wire sensor in it that gets a build up of crap over the years and needs to be VERY carefully cleaned. Use only the correct cleaner for a MAF like CRC. Never touch the hot wire. These also degrade over time (like a light bulb filament).

I see someone else made the point also that these cars a finicky on what parts they work with. Bosch plug leads may work but we only ever recommend Bougicord which was the OE manufacturer. Even spark plugs are a fine line. I only use Volvo plugs but there are others that will recommend some cheaper brands. As I have no experience of them I will leave that to someone else.

Sucks on the distributor cover bolts. They can usually be udone with a very small socket like 7mm I think? They can sometimes be undone with a flat blade screw driver (all 3 of them. Easiest done with the air box removed for access.

Oil leaks. The top cover over the spark plugs and leads is cosmetic. Some say to remove it and leave it off.

The most regular point of leaks is the oil seal ring on the oil filler cap. Cheap aftermarket ones can last as little as a year. Volvo maybe 2-3 years. If it feels like hard plastic it is way past replacing! Next oil issue if the oil capture system called the PCV system. This blocks up with age and causes excessive pressure build up in the crankcase and can blow out oil seals, usually starting with camshaft seals like the one behind the distributor. Easiest way to check for too much pressure is to put a latex or rubber glove over the oil filler hole (cap off) and run the engine. If the glove inflates, the system needs serviced before damage is done. There are several how-tos on here.

If you do have lots of pressure, then pull the dip-stick out slightly and it will reduce the pressure for a short time until it can be fixed.

Neil.
1993 850 GLT -Sold
1998 V70 XC - Sold
2000 V70 R - still being an endless PITA
2006 XC70
1997 Volvo 850 SE NA - Went to niece in California
2000 V70 SE NA - New project and test bed

Rubberfig
Posts: 22
Joined: Fri Aug 11, 2017 9:54 pm
Year and Model: 1995 850
Location: Portland, Oregon
United States of America

Re: Rough Idling

Post by Rubberfig » Sat Aug 12, 2017 9:19 pm

scot850 wrote:
Sat Aug 12, 2017 9:01 pm
The maf is the Mass Air Flow sensor and it sits in the pipe between the air box and the intact manifold. It regulates the air/fuel ratio and has a hot wire sensor in it that gets a build up of crap over the years and needs to be VERY carefully cleaned. Use only the correct cleaner for a MAF like CRC. Never touch the hot wire. These also degrade over time (like a light bulb filament).

I see someone else made the point also that these cars a finicky on what parts they work with. Bosch plug leads may work but we only ever recommend Bougicord which was the OE manufacturer. Even spark plugs are a fine line. I only use Volvo plugs but there are others that will recommend some cheaper brands. As I have no experience of them I will leave that to someone else.

Sucks on the distributor cover bolts. They can usually be udone with a very small socket like 7mm I think? They can sometimes be undone with a flat blade screw driver (all 3 of them. Easiest done with the air box removed for access.

Oil leaks. The top cover over the spark plugs and leads is cosmetic. Some say to remove it and leave it off.

The most regular point of leaks is the oil seal ring on the oil filler cap. Cheap aftermarket ones can last as little as a year. Volvo maybe 2-3 years. If it feels like hard plastic it is way past replacing! Next oil issue if the oil capture system called the PCV system. This blocks up with age and causes excessive pressure build up in the crankcase and can blow out oil seals, usually starting with camshaft seals like the one behind the distributor. Easiest way to check for too much pressure is to put a latex or rubber glove over the oil filler hole (cap off) and run the engine. If the glove inflates, the system needs serviced before damage is done. There are several how-tos on here.

If you do have lots of pressure, then pull the dip-stick out slightly and it will reduce the pressure for a short time until it can be fixed.

Neil.
I believe I just saw this as I was replacing the distributor cap (!!!) How would I know if it needs to be cleaned; just crud building up upon the actual wire?

I use RockAuto as my car parts dealer, and what I can't get there or don't want to wait to ship I grab from the O'Reilly's down the street. Both of these companies recommend certain parts, wouldn't they work fine if they are recommended for the car?

I am going to keep it on, and put a silicone seal around the edge asap to prevent possible oil leakage.

Will definitely try the rubber glove trick, posting results asap! I can do that right now actually. Would I leave the dip-stick out while driving if the glove does inflate? If not, how would I drive the car while not causing further damage to it?


Edit: Tried the rubber glove test, it inflated. Wat do?
Finn

User avatar
Nevada1906
Posts: 98
Joined: Wed Sep 07, 2011 6:01 pm
Year and Model: 1995 850 Turbo
Location: Ohio
United States of America

Re: Rough Idling

Post by Nevada1906 » Sun Aug 13, 2017 12:04 am

Rubberfig wrote:

"How would I know if it needs to be cleaned; just crud building up upon the actual wire?"

The MAF sensor element needs to be completely exposed to the airflow to work. After a while, various contaminants build up on the surface of the sensor element and insulate it from the airflow. When that happens, the computer can't calculate the AF ratio correctly and the car goes into a sort of default operation, which works fine for idling but quickly turns into a rough idle, hesitation when trying to accelerate and a tendency to want to stall out upon braking.

MAF cleaner strips the contaminants from the sensor element and dries without leaving a residue that would inhibit proper operation - that's why you want to use only MAF Cleaner, like that made by CRC. Any other cleaner, even electrical contact cleaner, will leave some residue when it dries. Not much, but enough to cause problems.

What you do is remove the MAF sensor from the car, thoroughly blast the sensor element with cleaner from both ends of the tube and let it air dry. DON'T TOUCH THE ELEMENT. Give it a few minutes to dry and reinstall it, then go for a drive. You'll know pretty quickly if it worked or not.
"...and yet another evening out ends with the words, 'you guys gotta leave, NOW!'"

Rubberfig
Posts: 22
Joined: Fri Aug 11, 2017 9:54 pm
Year and Model: 1995 850
Location: Portland, Oregon
United States of America

Re: Rough Idling

Post by Rubberfig » Sun Aug 13, 2017 12:12 am

Nevada1906 wrote:
Sun Aug 13, 2017 12:04 am
Rubberfig wrote:

"How would I know if it needs to be cleaned; just crud building up upon the actual wire?"

The MAF sensor element needs to be completely exposed to the airflow to work. After a while, various contaminants build up on the surface of the sensor element and insulate it from the airflow. When that happens, the computer can't calculate the AF ratio correctly and the car goes into a sort of default operation, which works fine for idling but quickly turns into a rough idle, hesitation when trying to accelerate and a tendency to want to stall out upon braking.

MAF cleaner strips the contaminants from the sensor element and dries without leaving a residue that would inhibit proper operation - that's why you want to use only MAF Cleaner, like that made by CRC. Any other cleaner, even electrical contact cleaner, will leave some residue when it dries. Not much, but enough to cause problems.

What you do is remove the MAF sensor from the car, thoroughly blast the sensor element with cleaner from both ends of the tube and let it air dry. DON'T TOUCH THE ELEMENT. Give it a few minutes to dry and reinstall it, then go for a drive. You'll know pretty quickly if it worked or not.
Thanks, ill order some MAF cleaner and gives the element a good dousing, will update post with result when it happens. I read in multiple posts about people disconnecting their MAF and driving around, would that hurt the car at all?
Finn

User avatar
Nevada1906
Posts: 98
Joined: Wed Sep 07, 2011 6:01 pm
Year and Model: 1995 850 Turbo
Location: Ohio
United States of America

Re: Rough Idling

Post by Nevada1906 » Sun Aug 13, 2017 12:21 am

Rubberfig wrote:

"Edit: Tried the rubber glove test, it inflated. Wat do?"

Sounds like a plugged flame trap (PCV system). When they get old and full of crud, they cause backpressure to build up in the crankcase, blowing oil out the dipstick tube and possibly - eventually - causing the rear main crank seal to fail.

The flame trap is a black box on the front of the engine with a few hoses coming out of it. You have to replace it. Both IPD and FCP Euro sell the kits for this, and you should do this operation periodically if you want the car to run right.

https://www.ipdusa.com/products/11269/1 ... system-kit
https://www.fcpeuro.com/products/Volvo- ... 850-850t96

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