Sluggish 850 and poor gas mileage to boot!

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.
1992 - 1997 850, 850 R, 850 T5-R, 850 T5, 850 GLT
1997 - 2000 S70, S70 AWD
1997 - 2000 V70, V70 AWD
1997 - 2000 V70-XC
1997 - 2004 C70
Ronniedasaint
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Sluggish 850 and poor gas mileage to boot!

Postby Ronniedasaint » Mon Aug 27, 2007 4:14 am

I have a 1994 850 Non Turbo with slightly over 191 miles on it. Lately I've noticed that it doesn't have as much zip as I am used to. I first noticed it on Sat. when on the highway I wanted to pass someone but it just didn't speed up quickly. Usually in E mode I have more than enough juice to pass other cars. I assumed it had to do with being low on gas (I was under a 1/4 tank) when I first noticed this. However I filled it up last night and did mostly highway driving last night and today. Anyhow, I noticed this morning that at forty two miles on the trip odometer the car had already chugged about 2 gallons. This is uncharacteristic as I get about 30 miles to the gallon with highway driving. the best way I can describe this is I feel like I am driving with a brake locked up. Something else I've noticed is that sometimes (Once ever two or three days) when going from a complete stop to moving again the car won't react right away. I'll hit the gas and it won't react right away, then it'll jerk into motion and be on it's way. It's a slight but VERY noticeable hesitation. Any help or advice will be appreciated, thanks!


RJ
RonniedSaint



94 850 Non Turbo 2.4L

94 850 GLT

Tsquared
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Postby Tsquared » Mon Aug 27, 2007 12:06 pm

Not enough info to really diagnose over the internet, but here are a few things to consider:

Transmission - when was the last time it was serviced, current condition of fluid...
Fuel filter - last time it was changed?
Fuel - Are you using same fuel from same dealer - summer blend or unknown off the wall cheep gas? Good pressure at fuel rail?
Brakes - do you have a burt smell coming from any of your wheels? when was the last time you performed any brake work...

Have you performed any maintenance to the car recently?
'11 C30 T5

'96 854 - died an early death with 184K miles. Killed by the front end of an LTD on a suicide mission (T-boned and both cars totaled).

icelandic
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Postby icelandic » Mon Aug 27, 2007 4:13 pm

One very common problem with the 850 NA that goes largely unoticed is the hot air flap valve in the airbox. It causes a 15% drop in power and a very bad mileage. If left unchecked will lead to damage to the MAF sensor.
It also causes engine knocking or pinging around 2K rpms, if you use regular gas.

This valve is located at the bottom of the airbox. If you look at the airbox, you will see that there is a silver aluminum pipe going to the top center of the exhaust shield on top of the exhaust manifold. This pipe is connected to the hot air valve in the bottom of the airbox. The purpose of this valve is to close cold air admission into the airbox when the engine is cold. With a cold engine, exhaust heated air will come in only thru that silver corrugated pipe. As the engine heats up the flap valve closes the hot air intake and opens up cold air intake. Notice that the diameter of the silver pipe is small compared to the cold air intake ( the one close to the top of driver
1995 859 auto NA

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mwy
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Year and Model: 1996 850 wagon
Location: Philadelphia, PA

Postby mwy » Tue Aug 28, 2007 1:38 am

My car had been feeling sluggish the past couple of months, and hesitating when accellerating while cold. Yesterday it just died while driving, fortunately only 3 miles from a dealer who replaced the fuel pump. Now the hesitation is gone and power and smoothness have returned!

The wax capule for the cold air flap also went a couple of months ago. Made the car a little sluggish. the right shaped stone from the side of the road in its place is still holding that flap open to permit cold air intake until I replace the part.
96 850 Wagon, 5spd, normally aspirated

Ronniedasaint
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Postby Ronniedasaint » Tue Aug 28, 2007 2:57 am

TSquared,

I bought the car about two years ago. It is my second 850.

Transmission service = I haven't done anything to it in the time I've owned it though I've meant to. I keep being afraid that someone might wreck it.
Fuel Filter = Has not been changed while I've owned it.
Fuel = I usually use Regular and I am not sure what the mixture is.
Brakes = I don't think it's this because they were done very recently. I changed the rotors and pads less than six months ago and there's no burnt smell.
Maintenance = Nothing major done recently, I had the oil changed and the tires rotated. I did a major tune up maybe a year ago.

Also, I noticed something today, I noticed that at highway speeds when I had wanted to pass my RPM's would not go past 2500 rpms the needle seemed stuck. The speed increased very gradually but the rpms would not increase. I was driving at almost 70 mph and trying to pass to exit the highway.

Also, I meant to check the hot air flap today but I forgot.
RonniedSaint



94 850 Non Turbo 2.4L

94 850 GLT

Tsquared
Posts: 514
Joined: Sun Aug 17, 2003 11:54 pm
Year and Model: 11 C30
Location: Atlanta GA

Postby Tsquared » Tue Aug 28, 2007 3:31 pm

The two ares I would be looking at are the fuel system and Transmission. With it not going over 2500 RPM I would suspect the fuel pressure.

I would try the fuel system first, find out what pressure the fuel rail has whil running. Rebuilding the fuel pump and replacing the fuel filter are relatively easy and not that expensive.

Good luck,

TT
'11 C30 T5

'96 854 - died an early death with 184K miles. Killed by the front end of an LTD on a suicide mission (T-boned and both cars totaled).

Ronniedasaint
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Postby Ronniedasaint » Tue Aug 28, 2007 10:29 pm

TSquared, thanks for all the advice. It's been very insightful. My suspicion was something in the fuel system or tranny since the car has a lot of miles and I have not serviced either. I am taking it in to the shop tomorrow so I'll probably know by the afternoon what's up. I'll keep you posted.

I'm going to check the hot air valve right now and make sure that that's working properly.
RonniedSaint



94 850 Non Turbo 2.4L

94 850 GLT

Ronniedasaint
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Postby Ronniedasaint » Thu Aug 30, 2007 3:26 am

Well I got in there and fiddled around and didn't find anything broken or stuck. I played with the valve a bit, moved it open and shut, and the mechanism seemed to be working properly. I then took it for as spin and now it seems all good!

I didn't make it to the repair shop but I still intend on doing a tranny service and having my fuel system looked and or serviced.
RonniedSaint



94 850 Non Turbo 2.4L

94 850 GLT

Ozark Lee
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Postby Ozark Lee » Thu Aug 30, 2007 4:05 am

Well I got in there and fiddled around and didn't find anything broken or stuck. I played with the valve a bit, moved it open and shut, and the mechanism seemed to be working properly.


While it sounds like the car is running better for you the true test for the airbox thermostat is based on temperature rather than freedom of movement. Even if your airbox thermostat is good now at some point it won't be. Unfortunately it fails full time to the hot air position. Since you are now familiar with the way the valve works might I suggest that you jamb something in the mechanism to force it to the cold air side. Luketrash used dowel rods, I used Yellow Scotchlock electrical caps since they happened to be on my desk at the time. I do like the creativity of an appropriately sized stone from the side of the road although in some northeastern states I'm sure you could be prosecuted for theft of public property.

I did notice that it took an extra city block for the car to come up to full temperature on subzero days after I forced mine to full open but that is a price I will pay for 10 mpg.

...Lee
'94 850 N/A 5 speed
'96 Platinum Edition Turbo
'99 V70XC - Nautic Blue
Previous:
1999 V70XC - RIP - Wrecked Parts Car.
1998 S70 T5
1996 850 N/A
1989 740 GLT
1986 740 GLT
1972 142 Grand Luxe

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meine39
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Year and Model: 1995 850 GLT Wagon
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Postby meine39 » Fri Aug 31, 2007 1:18 am

The airbox thermostat is $28 at FCPGroton - part number 9142616. I replaced mine with the correct part rather than trying to MacGyver a fix. I installed mine on a 90 degree day - I put the new thermostat in the freezer for 10 minutes, which allowed me to compress the actuator rod enough to ease installation (you have to compress a spring to fit the thermostat behind it). After reassembly, I put the airbox back together, came back a few minutes later, and the air flap was in the correct postion (fresh air side open).

The rock by the side of the road is not an option for me here in the Northeast, since there is a Philadelphia lawyer behind every street sign waiting to sue for theft of public property...:wink:
1995 855 GLT 190K NA Auto
1998 BMW 528im 137K
2000 Toyota Camry 78K
2010 GMC Acadia 57K


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