- This topic has 9 replies, 6 voices, and was last updated 12 years, 1 month ago by
.
- Topic
I drive a 2005 Dodge Durango, I recently put in an engine with 50k on it in place of my 116k mile engine with a blown head gasket, previously I was getting around 13mpg (pretty much all city driving) but last night I filled it up from empty for the first time since the engine swap and basically it went 267 miles on 26 gallons of gas, so pretty much 10 mpg, I have 5w30 royal purple in it, my tires are inflated, no check engine light, 4 new oxygen sensors, stock tire size, nothing real heavy except for pulling my 5×9 utility trailer every once in a while. I don’t floor it or anything like that, the one thing is… it has the tow package which means it has 3:55 gears instead of 3:92 so I don’t know what to think, Any ideas how I can get a little better mpg? Thanks!
- Replies
The trained ASE certified approach
What I would do is put a scan tool on your vehicle and observe live PID data. Focus on the “big 5:”
- O2 sensor
- TPS (Throttle Position & engine RPM)
- ECT (engine coolant temp)
- MAF/MAP
- IAT (intake air temp)
interpretation of the above parameters will allow you to determine what factors are influencing your fuel efficiency. Also look at short-term and long-term fuel trim data. An old-school 5 gas analyzer up the tail pipe might also offer some insight into the situation.
The DIY’er approach
- throw some fuel injector cleaner in the tank
- change the air filter
- check tire pressure
- hope that 1 of the above helps.
My wife had a 99 with the 5.9 and the tow package. It always got about 12 mpg even at 180k when we sold it. There must be something wrong to have poor mileage like that.
well like I said all my o2 sensors are new, my coolant temp is a constant 95C it has a new MAF sensor, I will check the rpm with the scanner but its about 600 to 700. The air filter is brand new tires aren’t low, I just put fresh gas in from empty so I guess I will see if that makes any difference, Overall it runs great, no lights or anything, all my driveline fluids are new, I pretty much did everything when I changed the engine. I will hook it up to the scanner and put the number up later, Thanks!
[quote=”Durango8766″ post=44281]I drive a 2005 Dodge Durango, I recently put in an engine with 50k on it in place of my 116k mile engine with a blown head gasket, previously I was getting around 13mpg (pretty much all city driving) but last night I filled it up from empty for the first time since the engine swap and basically it went 267 miles on 26 gallons of gas, so pretty much 10 mpg [/quote]
Expect it to be craptastic for the first 3-5 fill-ups at least, even if it’s an engine in great shape. The sensors will have to re-learn the trims tables over again. That means going over each rpm and load range during certain conditions multiple times. In many cases where there’s been a prevalent vacuum or exhaust leak toasting the volatile table memory will improve gas mileage, but in this case not so much for a bit.
well like I said all my o2 sensors are new, my coolant temp is a constant 95C it has a new MAF sensor…
I think you have missed the point. The condition of the sensor itself is irrelevant; with exception of GM products, it is safe to assume that most modern day manufactured goods will actually work more often than they “don’t work.” It’s the data you receive that is important, even if a sensor is lying to you. The art of deciphering pid data can be difficult to learn, but I will offer a common scenario:
Based on the following pid data, is the engine running lean or rich and why:
*To all of ye’ who know the answer, please keep the answer to yourself; learning in progress.
It is possible to look at scan tool data, observe your fuel trim and determine why your engine in running lean so your PCM is dumping fuel into the engine to compensate and subsequently take corrective action and improve ye’ gas milage.
Sorry I haven’t replied back in a few days, I’ve been sick, and have been driving my dads 20 mpg 94 regal since he’s out of town. I probobally need to just drive some more and I think it will correct itself back to its normal 13 mpg. I will look at the live date sometime this weekend just to be sure, Eric, just on a side note, do I have to have a PayPal to get the premium membership? Thanks, -Darren
- You must be logged in to reply to this topic.