New owner here.... just purchased and shipped a 1998 C70 Coupe (T5) to Hawaii.

My 1998 S70 without turbo got 24 mpg's reliably years ago when ithad the same mileage on it (47,000). I'm not smelling any gasoline fumes nor is there any leakage noticed on the ground under the car.

Did I get fooled into buying this car? It's a magnificent car...is there some common expensive fix that the seller avoided by selling it off? The car was well kept....and is in very good condition. The running condition is good, but the acceleration isn't what it could be. It did just undergo a 2,500 mile sea voyage. I'm only getting 9.8 mpg's with an automatic transmission, suburban driving, easy on the pedal. [] I can't afford this car if this problem is permanent.

If anyone has any helpful suggestions, please reply to this post...I'm wary of running toa mechanic immediatelyin this kind of situation. This weekend I'll go over the car front to back and check the fuel lines.

Stephen in Maui, Hawaii

 

Last tune up?
Any check engine light?
Also make sure the check engine light comes on when you first turn the key on.

 

Aloha,

Follow Tech's advice.

I'm not privy to the C70s so my opinion is based on general knowledge.

The car has now reached 10 years, and if tune-up items have been neglected, the car's mileage could drop. Make sure the following items have been done lately:

- Spark plugs (genuine Volvo).
- Ignition wires (not unless it has direct/distributorless ignition system).
- Distributor cap & rotor (same as above).
- Fuel filter.
- Air filter & induction hoses. Make sure there is no blockage.
- Throttle body cleaning.
- No blockage in the exhaust line.
- Dump a large bottle of Techron fuel system cleaner into ahalf-filled tankand drive until the tank is near empty.
- Make sure the PCV system is in good condition.
- Check 4-wheel alignment.
- Make sure the parking brake is fully releasing.
- Make sure the engine temp is reaching normal. Cold engines use more fuel.
- Try using full synthetic oil with OEM filter.

If none of these is causing the problem, then the ECU is commanding the injectors to spray more fuel than is necessary due to incorrect sensor signal feedback. Incorrect fuel-related feedback is usually either the O2 sensor(s) or coolant temp sensor but could be other things. Find a reputable shop and have codes pulled via OBD-II and give us the findings. Do not cheap out on servicing Volvos, find a reputable shop and let a fully certified ASE Master Technician work on your car.

Good luck,


JPN

 

c-70's do not receive accolades for their mileage! My 02 with 30,000 miles in the winter can barely manage 12 MPG in the city. They do shine on the hi-way, 'though. Incidentally my MAF and throttle body are new............Bosch platinum plugs about 10,000 miles, air filter new, Shell premium with their attractive additives used 100%.

r.

 

Thanks, Reg.

Before buying this car, I researched just about everything about it. Most owners said they got very good fuel economy (20 mpg in today's world). Perhaps I got bad information. My climate is perfect....70-78 degrees this time of year, 75% humidity average.

I'm going to have it plugged in soon, my gut feeling is the oxygen sensor is REALLY far off on its reading... the computer is likely dumping tons of extra fuel into the cylinders.

You response was appreciated.

Stephen

 

Last tune-up 30,000 miles.

SEA VOYAGE last week, the rocking of the boat must have alerted a fuel system discrepancy...check engine light is on. I'll have it scoped ASAP. Thanks for your suggestions.

 

Thanks JPN.

The fuel loss is so severe that I'd think ALL of those conditions were not being met. I'll have it scoped ASAP, and will print out your list and go through it. My suspicion is that a sensor (oxygen, perhaps?) is WAY off on its reading, causing the computer is overcompensate.

You advice was much appreciated.

S.

 

I would go with JPN's list. I agree with the exception that I am a dyed in the wool Bosch single electrode platinum plug guy. HOWEVER there are soooooo many responses to the "plug" issue on this forum that you have to make up your own mind. HOWEVER keep in mind that Volvo uses Bosch platinum plugs (under their own name) in their 'big' autos. Lastly, use a can of MAF cleaner on that unit............it truly works on bringing up the mileage.

r.

 

Then something must be wrong. 12 mpg is incredibly low. We're talking about hummer gas mileage here...

 

My 1988 Dodge Ram van gets worse milage than that. I only get 10MPG in it.
Thats with a 318 motor and it takes about $150.00 to fill it up.(At todays prices)

 

Yes, I agree, reg's car had a major problem at 12 mpg. Mine is doing 9.8 !!!!

This is not my first 70 series...but I'm dismayed that this happened the first week I've owned it. Tech's advice is good....read over the list again just now....cat converted could be blocked, or some such. I'll make sure to post the diagnosis here next week.

Thanks for your input.

 

JPN, I'll be posting what happened to the car next week. The lagging accelleration makes me suspect the cat converted is clogged, or as said previously, sensor problem(s). You alluded to both, will follow up soon. Thanks. S.

 

Yes seems like there is a power loss somewhere, which is causing the two troubles. I'll wait to hear your findings, and in the meantime I'll copy & paste '08 C70's performance just for the heck of it:

Gas Mileage on 2008 C70:

Fuel consumption (city)
Six-speed manual gearbox
18 mpg

Fuel consumption (city)
Five-speed Geartronic transmission
18 mpg

Fuel consumption (highway)
Six-speed manual gearbox
27 mpg

Fuel consumption (highway)
Five-speed Geartronic transmission
26 mpg

I hope the problem would be solved soon.


JPN

 

12.5 or so in the city in the winter time. That's not bad at all! My wife's Japanese auto (6 cylinder) is the same. Now, in the summer things improve dramatically. I appreciate the original poster is in a warm climate and he should experience better mileage. However, the c70 weights almost 4000 lbs! It will on the hi-way obtain quite decent mileage..........in fact one time as I was traveling through Ohio obtained almost 36 mpg. I was not using air nor were the windows down. I had just given the old boy a fresh set of plugs and cleaned the MAF. You will note that JPN proffered a list of "to-dos" for the poster and if he accomplishes that list he will see better mileage. I have determined that Volvo's (at least the H.P. 236 horse engine) enjoy fresh plugs every year..................irregardless of miles. When I change plugs I see an increase in MPG. However, I am not all that concerned as I do have a German auto that on the hi-way gets in the single digits and runs on Shell premium plus a can of 106 octane booster! I suppose the fact that it has Weber side drafts and a Schrick 316 cam contribute to that issue??

r.

 

Why don't you try a can of seafoam through the vacuum tree? It can't hurt........

 

Are you jesting or is there a product called "Sea Foam"?

Enlighten me.

r.

 

It's a product that is supposed to clean out carbon deposits and such. On a 30k mile car, I don't know if it will help, but with 12mpg, It's worth a try.

http://www.seafoamsales.com/