Hey guys - maybe you can help me figure out what the problem is...

My 1995 Volvo 850 Wagon (2.4L 5-Cylinder) has been getting poor gas mileage as of late - maybe 16-18 miles to the gallon when I'm used to getting around 25-27. About a year ago I had a new engine put into it and it's been running great - hell, it's still running great. No odd sounds or loss of power. The only thing I really notice is when it's in drive and sitting at a stop sign or light the idle will occasionally drop a bit and you can feel a kind of shuttering - it's quick, and random, and quickly returns back to normal. During the course of sitting at a stop light i'll feel it about 2-3 times. But then I hit the gas pedal and it's fine.

I change the oil religiously, recently flushed the coolant system, and cleaned the K&N air filter. I don't see anything out of the ordinary under the hood, no oil leaks, or overheating. Everything seems to be ok.

Could this just be in need of a tuneup? During the engine swap we had new plugs, a timing belt, and water pump put in.

Here in Denver we have these occasional "Car Health Meter" things around the exits - usually it says "Good Health" and the little car lights up a smile and says i'm "Saving Money" when I drive by it. Tonight however, it said "Fair" and the little car wasn't smiling anymore... so obviously the emission meter or whatever it is that detects it is noticing something wrong as well.

Any help? Thanks.

 

Tryfollowing thread to see if you've missed out something.

https://volvoforums.com/m_48928/tm.htm

See if there is a trouble code stored in the ECU, or the PCV is retiring, orspark is weak, or the throttle body needs cleaning, or the A/C is set at the defrost position, which keeps the A/C compressor on, or faulty O2 sensors, or...zzz.

This probably doesn't have anything to do with your problem but make sure the tyres are properly inflated & aligned and the parking brakes are not seized.

Tech would be able to give you a lot more accurate diagnosis than I possibly could, if you can wait until Tech kicks in.


JPN

 

The little car not smiling would be bugging me too. That means you are probably running rich. I doubt if it would be simply a tuneup if one was done a year ago especially. I would check for vacuum leaks, clean the throttle body and check the Mass Air Flow sensor.

 

Ok, i've been looking around on here for some more info. on the following:

1. Changing the fuel filter
Where is it? What's it look it? Got any more-detailed info. on this?

2. Cleaning the throttle body
I think I've found the info. for the throttle body on :
http://www.volvoclub.org.uk/faq/Engi...tyThrottleBody

But it doesn't really show me where it's located or what it's going to look like - you guys got any better info on this?

3. Servicing the PCV
Huh? What is this?

Thanks for the help.





Any help?

 

Fuel filter....

Ok, looking in my Haynes manual it looks like the fuel filter is located under the rear of the car, just forward of the fuel tank.... easy enough.

It says I need to release the pressure of the fuel system by disconnecting the sender unit and the fuel pump which is located under the luggage compartment in the wagon model. Is disconnecting this an easy thing to do?

Then I disconnect the fuel line from the filter and let it bleed from the system (shouldn't be too much fuel at that point right?)

Found the filter for $19 at the local Napa so I think i'm going to tackle this today as well as cleaning the throttle body. Got a couple buddies coming over to help out.

Any detailed info. on the throttle body would be much appreciated.

-Dave

 

Is the Check engine light on? I had a simialr problem a couple months ago, and it turned out to be the coolant temperature sensor located by the thermostat. Of course I had a check engine light and a 1-2-3 code.

Glenn

 

Make sure you pry the lines off the fuel filter with something like needle nose pliers. Don't just grab the lines and pull them off. I did this once and had to replace the line from the tank to the filter. It was expensive and a pain to do.

 

No check engine light.

 

Where is this throttle body? It's a non-turbo - so is it under this black cover with the single T-25 screw on it? To the front-right of the manifold? Next to the battery? Or is it under the car? Please help - working on this car as we speak!

Thanks.

 

I tried to find pictures but didn't have any luck. It's where you said on the top of the engine behind the battery undeneath the cover that has the T25 torx screw holding it on. Here is a link to volvospeed where the talk about cleaning the Flame Trap and mentions the Throttle Body;

http://volvospeed.com/Repair/ftrap.php

 

Don't just pull them off? Hmmm.... that seemed to be how it worked.... they just pulled right off.

And then they just slid right on.

I actually wanted to ask about that - is that supposed to be how it works? Slide on and slide off? They don't seem to snap on or anything.

Any ideas?

Got the throttle body cleaned, the flame trap cleaned, and the fuel filter changed. It might be too early to tell - but it seems to be running great.

 

Reminder: It's a 1995 Volvo 850 GLT Wagon (2.4L 5-Cylinder).

So while I was putting the throttle body back in I noticed that the flame trap was all gunked up. While trying to take it out to clean it up a bit (or to at least inspect it better out of the car) I was trying to get the small yellow vacuum hose off of it and snapped it right off the black vacuum hose relay thing it was connected to. I should've taken a photo of it but this is the basic description of the part.

It's a small (about 3 inches tall maybe) "tower" looking thing that bolts to the top of the manifold right next to where the throttle body bolts in, just to the left of it.

It has 2 vacuum hose connections on one side, and 3 on the other side. On the side with the 2 connections it had 2 hoses connected and just 1 on the side with 3 (with 2 plug caps closing the other 2 off). There are no electronics or anything to this piece - it looks like it's just a "relay" type device for the vacuum hose connections.

As a temporary fix I just ran 1 of the vacuum hoses to 1 of the connections that was closed off and used some epoxy to seal off the 1 I had broken. It's fixed, and the car runs great, but now one of the vaccum hoses is basically sitting right on the intake manifold and I'm afraid it'll melt with the heat of the manifold.

But I can't find this part - any ideas what it's called or where I can find one? I'll check the salvage yard but... any help?

 

Ok - so i'm starting to think that I'm going to need to take this bad boy in to the Volvo dealership and have them run diagnostics on it. Which I really don't want to do.

I went by the little "emission testing sign" again and again I got the sad face and it said "costing you money". I know it sounds stupid to use that sign to diagnose something as being wrong but I know something is wrong because my gas mileage is crap.

So far I have:

- Changed the Fuel Filter
- Replaced the Flame Trap
- Replaced the Vacuum Tree
- Cleaned the throttle body
- Cleaned the K&N air filter
- Removed the thermostat from the airbox and have the cold-air side of the airbox permanently open now
- Changed the oil and oil filter

And:

- Timing belt and tensioner pulleys changed a year ago
- Water Pump and Thermostat changed a year ago
- (Engine replaced a year ago with a used engine that had 58,000 miles on it)

So at this point i'm thinking of:

- Changing the spark plugs (I assumed they did it when they changed the engine out a year ago - but maybe that's a big assumption)
- Replacing the PCV system
- Checking the MAF sensor? (Where is it located?? And could this be causing my engine to run rich??)

It could be a problem with the A/C being on defrost, but wouldn't I hear it kicking on and off? I did notice this summer that my A/C wasn't working anymore and though I think it's the evaporator that's gone out, it could just be that it needs to be recharged. Would this cause a problem with how rich my engine is running?

Any ideas of things I should try before I take it to Volvo for diagnostics? I know they're going to rob me if I take in and i'm definitely not in a place right now that I can afford that.

Please help!

 

First of all, I would organise the info a bit, as I'm a bit confused.

Here's a repeat:
https://volvoforums.com/m_48928/tm.htm

See my 2nd post titled "ROUTINE TUNE-UP ITEMS".

If you don't want to pay the dealer, locate a local AutoZone or other parts shops that provide free OBD-II diagnosis.
http://www.autozone.com/store_locator/home.htm

If you haven't checked the spark plugs yet, I would go over the list in my post once again. Also, your PCV system may need replacement as a unit. This requires a new intake manifold gasket as you have to disconnect it.

As to vacuum elbows, see if you can find it at:
http://www.fcpgroton.com/volvo850vacuumelbow.htm

The MAF sensor is located by the brake fluid reservoir; follow the intake air hose:
http://volvospeed.com/Repair/maf_secure.php


JPN

 

I've read that "Noob" posted several times - it has helped but not specific to my problems.

I'm not getting any OBD-II codes, nor am I getting a check engine light warning. But I know there's something wrong because i'm getting like 12 miles to the gallon.

I'm planning on changing the spark plugs tomorrow - I think i'm going to go with the Iridium plugs. Should I change the plug wires (which have "95-38" written on them in yellow) and the distributor cap along with the plugs?

Vaccum elbows? I'm good there I think.

Ok - I've found the MAF sensor - but if it were going out would that cause my engine to run rich? Or wouldn't I at least get an OBD-II code from it?

 

I see, I'm sorry for making you frustrated, didn't meanto.

The plug wires are past due date, and they need to be replaced whether they're affecting the gas mileage or not. As to plugs, either iridium or platinum would do. I would choose whichever is less expensive, as there would not be a dramatic difference between iridium and platinum. Also, check the condition of the distributor cap & rotor. If you see erosion or carbon deposits, replacethem.

I just went through the previousreplies and Iassume the tower-looking thing close to the throttle body was the EGR valve. It opens a valve in the exhaust and re-routes a portion of the exhaust gas into the intake stream to lower combustion chamber temp, in order to reduce the amount of CO. It could affect the gas mileage, but not as badly as in your case.

The car may be running rich, as Jim has mentioned. Yes sometimes trouble codes are stored without triggering CEL. The self-diagnostic on 850s is not very well-designed. If if turn the ignition key to the 2nd detent and CEL lights, then the bulb is good. I would definitely do the PCV system replacement, unless it is a known good unit.

This may not help, but try dumping a large bottle of Techron fuel system cleaner into the fuel tank. Also, how old is the air filter? An air filter can look clean while infested with microscopic dusts. If all else fails, there may be some unwanted loads in the drivetrain (transmission, brakes, tyres, wheel alignment, etc...). Are the tyres wearing out equally?

Lastly, there may be some blockage in the exhaust, which is causing a build-up of back pressure.

I have a feeling that it is something simple, something we have not yet mentioned.


JPN

 

Don't worry about it- i'm not getting frustrated. I know you're trying to help and I appreciate it.

Plug Wires, Plugs, Cap, and Rotor - I was planning on changing all of this today, but i'm feeling sick and not sure it's going to happen today. But I definitely agree, it all needs to be changed. I'll look for the Bosch platinum +4 as it seems those have a good reputation.

The Air Filter - it's a couple of years old but it's a K&N filter and has been cleaned twice - each time being once a year since i've owned it. It's been cleaned recently.

The tower looking thing next to the throttle body was the vacuum tree. I found it through FCP Groton and already replaced it.

So the EGR valve isn't off the hook yet.

The PCV system is going to have to be replaced, just to give me piece of mind. I'll have to explore that more throughly. I've never done anything that involved.

I'll have the guys at the parts store scan my OBD-II and see if there's something that's showing up and not displaying on my instrument panel. It's worth a shot.

 

Check your airbox thermostat. I had the same issues and just jammedthe damperto the cold air side full time. It takes an extra 1/4 mile or so for the car to warm up from a cold start but the performance and the mileage improved dramatically.

A good thread on the subject (It wanders a bit) is here:

http://www.matthewsvolvosite.com/cha...pic.php?t=8830

EDIT: Sorry, I'm not used to the way this board lays out and I missed page 2 - Sounds like youve already dealt with the airbox thermostat. END EDIT

...Lee

 

Changed out all of the PCV parts this weekend. It's still bit a early, but I think I my MPG might still be suffering.

Could my A/C unit (which stopped working this past summer - probably needs a recharge, or it might be the evaporator/condensor) be stuck on? Or stuck to defrost? How would I know? And what can I do about it?

In battling this - so far I have:

- Flushed the Coolant
- Changed the Fuel Filter
- Replaced the Flame Trap
- Replaced the Vacuum Tree
- Cleaned the throttle body
- Cleaned the K&N air filter
- Removed the thermostat from the airbox and have the cold-air side of the airbox permanently open now
- Changed the oil and oil filter
- Replaced the spark plugs (Bosch Platinum 4+)
- Replaced the spark plug wires
- Replaced the distributor cap & rotor
- Replaced the PCV system (all hoses and oil trap, even the clamps)
- Cleaned the MAF sensor

And:

- Timing belt and tensioner pulleys changed a year ago
- Water Pump, Thermostat, Rear Main Seal changed a year ago
- (Engine replaced a year ago with a used engine that had 58,000 miles on it)

It's pulling NO CODES from the OBDII port

Or maybe it's not that bad... my fuel light comes on at 279 (18 gallon tank) - which is about 15.5MPG and completely empty (found out last week) at 335, which is about 18MPG.

But i'm used to alot more MPG - more than 400 per tank - hell I went almost 600 on a tank through Kansas last year (all highway+flat roads+lower speed limit+summer weather+higher standard octane in Kansas - 87 there vs. 85 in Colorado).

-Dave