13 mpg on 1994 Caravan

[EVH5150]

Checking my mpg on my Caravan, I've noticed that I only get an average of 13 mpg! I recently changed the plugs, cap, rotor, air filter. The van just passed emissions, so I'm not sure if it's the O2 sensor. Anybody have an idea what I can do to fix this problem???
Thanks

[conncarl]

"Not enough information to compute".

If you've got a loaded Grand with a 3.8, a heavy foot, and you do mostly city driving with the A/C on, you're in the ballpark.

OTOH, if you've got a 3300 lb. base Caravan, with a 2.5 and a 5-speed,
driving mostly on the highway, something is definitely wrong.

Carl

[EVH5150]

Sorry about that Carl,
Forgot to mention that it's a 3 Liter. I take it pretty easy on the acceleration. the a/c is on sometimes. It just doesn't seem right that the milage would be that bad even in the city.
Thanks for the input. I'm changing the coolant temp sensor and the thermostat today to see if it helps a little. If not, oh well. With the gas prices being the way they are, I just get a little concerned about the milage

[conncarl]

I think you're on the right track. If the thermostat isn't operating properly, the engine may never warm up fully, so your mixture could be too rich. If the coolant temp sensor fails, the computer may think that the engine isn't warming up, which amounts to the same thing.

Unfortunately, since the van passed emissions neither of those conditions is terribly likely, but they're still worth a try.

If you haven't already, I would definitely try reading any codes stored in the computer. They may point you to the culprit. My advice would be to stop at any AutoZone store when they aren't too busy. They will read your trouble codes for free, saving the cost of a code reader.

If there aren't any failures, there are a few tips that should help your gas mileage a bit;

The Caravan typically has a very quiet, very restrictive muffler and a resonator. If you don't mind a louder exhaust, it's easy and cheap to replace the muffler with an aluminized "turbo" or other free-flowing design, and to have a shop cut off the resonator and replace it with a length of straight pipe.

Change your engine oil to a full synthetic, you can buy Mobil 1, a PAO4 100% synthetic oil available in several weights, at your local Walmart for about $19 for a five-gallon jug.

Change your transmission fluid, do a complete change (not a power flush) to Chrysler ATF+4, a synthetic fluid that should improve your shift quality, lessen heat and friction losses, and extend your transmission life.

Follow those steps and keep your tire pressure at the maximum, and you should see a small but definite gain in MPG.

Good luck! Carl

[EVH5150]

Thanks Carl,
Yeah the tranny's due for a fluid change anyhow, so I'll try that. I ran the codes using the "Check Engine" light method and I ran a code 22 stating that there was either high or low voltage reading on the coolant temp sensor, so after I changed that and the thermostat, the code went away. There is a code, however that I'm not too sure of and that's a code 37, stating that there's an open or shorted condition detected in the torque converter part throttle unlock solenoid circuit Do you have any idea what that is, and should I be concerned about it?
Once again thanks for your help.
Jason

[conncarl]

Going by the seat of my pants, I assume that this is the part that kicks off the lockup torque converter under part-throttle acceleration.

If it's showing up as open, perhaps the wiring is disconnected. Check the transmission for any loose wires.

I would disconnect the battery for ten minutes or so. That should clear any trouble codes and put the computer into learning mode. You can always check the codes again in a week or so.

[bob1234]

If you have anymore questions please watch TV