Chrysler LHS mpg issues--HELP!

[erobb]

We have a 99 Chrysler LHS, with the 3. 5 v-6, 108k, Same car as the 300M except a little longer different front and rear end treatments. The car is rated 22 city 27 hwy. We can only achieve a best of 21-22 with a mix of city/hwy driving. The car has had a recent tune-up, plugs, air filter, etc. the engine runs smooth, does not lack power, does not smoke or use any oil, the check engine light is not on. A few years ago we had a Chrysler Concorde with the 3. 2 same engine only slightly smaller it would get 25-26 and on one weekend trip got 34. We love the LHS if it would only get the 27 it;s rated for I'd be happy. Does anybody have any ideas, what about professional fuel injector cleaning wherein they hook up the canister thingy and use air pressure to force cleaner through the injectors??? another web site mentioned that low fuel economy in a Ford could be the Mass Airflow Sensor in Chryslers the MAP sensor. A new one is close to $100 is it worth trying?????? Any info would be helpful or maybe you have a similar Chrysler product whats your mpg???

 

[Matt400]

I don't think anything is wrong. I frequent LX platform sites and read where the 3. 5's in those body styles get same as you, some less.



Your 99 has OBDII so its constantly monitoring itself at all times. If the fuel mixture is not right were it needs to be the oxygen sensor will let the pcm know and up goes the check engine lamp.

A bad map sensor would cause fuel mixture troubles.



Running 35-44 psi in the tires depending on what they are rated for will yield a little better economy than using the pressure listed on the door plate.



As for my mpg, I got 22 mixed mountain & freeway last I checked but thats in a Charger with 5. 7 v-8 but from what I read there are allot of 3. 5 owners that wish they got the 5. 7 for more power on tap with same economy.

 

[jtwcummins]

Wife had a 95 LHS and when we first got it would get about 26 hiway running 80mph. When the oxy gas, MTBE or Alcohol, became the standard in Calif mileage dropped to around 22 hiway. So you are getting about what you should be. The 3. 5 is a high performance V6, in the 95 it was 1 hp per cubic inch. The newer 3. 5 get about 250HP from same displacement, 214cubic inches.



The 3. 2 isn't really a smaller 3. 5, it's a totally different engine. . Getting injectors clean might help but very little, I ran Redline injector cleaner thru about every 6 months.



Just like the diesel today, gasoline btu rating is lower for the new emissions blends and has been for a few years. The current gasoline blend was the winter blend for a long time and the tree huggers fixed that and made it the only gas all year.

 

[AllianceDiesel]

are you running ethanol or anything thing higher than 87 octane?

 

[erobb]

We live in Iowa so Corn and 10% Ethanol are king. We do use the E10 blend which is rated at 89 octane. I have thought (but haven't yet) to try a couple tanks of just plain 87 octane with no ethanol, my dad claims it gives him 1 to2 mpg in his Chevy gasser pick-up. But when you figure the state subsidizes ethanol here it is always 10-20 sometimes 25 cents cheaper per gallon at the pump than 87. Still I might give it a try, the last car we had was a Volvo and we tried the 87 in it, no difference. This all might be for not anyway there was an older Mercedes diesel in the local paper tonight, called on it the guy is moving and must sell, but the car has been sitting for most of the winter. His asking price wasn't to far out of line, says he has a stack of recipts to go with it, going to look at it tomorrow night after work. Still the thing has 320k on it so it could lead to a whole can of worms I'm not sure I want to open up. Still going to look at it just for couriousity's sake.

Eric

 

[Matt400]

thing has 320k on it so it could lead to a whole can of worms I'm not sure I want to open up.

OMG Eric... you should be happy with your current mpg.

 

[AllianceDiesel]

well theres your problem right there, don't run ethanol at all espcially in older cars, ethanol burns slower so you don't get the btu's and power like regular gas. also the higher the octane the worse mileage your gonna get.

 

[zstroken]

We have a 2000 LHS and on the highway we see 27 at around 80mph. Usually around town gets about 22.

 

[jtwcummins]

You must be using real gas not vegetarian!!

 

[Joe G.]

We have a '99 LHS. It gets about 19 running around town. Somewhere in the 20s on the highway. The best we have had so far was between Fernley and Wells, NV. I think there must have been a tail wind that day, because we got 37.



The LHS is the same as the 300 but 345 lbs lighter if I remember the specs correctly. I can't figure out where the weight difference is.