'97 Hx gettin' 28MPG. Whats wrong?

[HeX]

i cant wait to see you results maybe i need to change my pvc again its been awile. i bought a brand new egr valve about a year ago and thats when my mpg jumped up to about 45 on average but then it dropped back down about 6 months later to what it is now. how did you clean out the egr valve? i still have my old one maybe i will clean it and test and see if it helps

Dont bother changing your PCV valve. Just clean out the EGR chamber, not just the EGR valve. Chances are thats your remaining issue, hence the MPG reduction 6 months later. You can clean them both out with carb cleaner. The EGR chamber is located under the fuel rail. Below is a link to someone on HondaTech.com who cleaned out theirs. Thats pretty much how mine looked as well. Make sure to clean out those ports as well. The whole job shouldnt take more than 1.5 hours, maybe 2 for the less experienced DIYer..

http://honda-tech.com/showthread.php?t=2151691

 

[mc360]

Wow I didn't even know that removable lid piece existed lol well I for sure will have to do this. I checked last night and I bought my egr from Honda exactly 1 year ago yesterday and I also realized its been almost 2 years since I changed my cap and rotor so I better get on that with the $4.29 per gallon for gas now

 

[HeX]

Wow I didn't even know that removable lid piece existed lol well I for sure will have to do this. I checked last night and I bought my egr from Honda exactly 1 year ago yesterday and I also realized its been almost 2 years since I changed my cap and rotor so I better get on that with the $4.29 per gallon for gas now

Your Cap & Rotor typically should be changed every 40k-60kmiles or so, depending on your driving habits. Before you spend more money you may not need to spend, just make time for the EGR chamber cleaning. That may be all you need.

 

[DarkCreep]

Have you checked your timing?

I got amazing MPG on my Civic after I got my timing done. PCV valve should help, it helped a lot on my accord.


What formula are you using to get your MPG?

 

[mc360]

I've put well over 60k since I changed my cap and rotor so I forsure need to check it out at least. I will probably do my egr some time this week. Idk if your talking to me but I fill up then drive over half a tank then fill up again then divide by number of gallons it took to fill

 

[HeX]

Have you checked your timing? I got amazing MPG on my Civic after I got my timing done. PCV valve should help, it helped a lot on my accord.

What formula are you using to get your MPG?

MPG = (Miles driven since last fill-up) / (Gallons filled up)

In my case, Im inclined to doubt timing is a significant issues as my car accelerates quite well. Normally when timing is an issue, you can feel the sluggish acceleration and/or sputtering. Is there something else I may be missing in regards to timing?

 

[HeX]

U p d a t e

After changing the PCV Valve & changed the oil to Royal Purple 5w30 with the Mobil1 Performance Oil Filter, my MPG has increased to just under 33MPG, roughly 280 miles per tank (up from the original 28mpg & 250mpt). Ill be checking the Timing next. I may just try to adjust it at the Distributor if the bolts look noticeably off.

I also forgot to mention at the start of all this that I mainly drive all city. I may hit the highway 2-3 times a month on average and not for longer than 20-30 miles roundtrip.

 

[Mern]

I'm also getting not so great mileage.. 375kms from full to gas light which equals to about 235 miles... 10.3 gallons to a tank is
23.81 mpg. My driving habits aren't great and I drive an automatic but i never use AC so there has to be something wrong! i think this weekend i will check my tire pressure and soon i will try new plugs and wires. I have no engine lights on so i dont think its an o2 sensor.

 

[HeX]

I'm also getting not so great mileage.. 375kms from full to gas light which equals to about 235 miles... 10.3 gallons to a tank is 23.81 mpg.

If youre filling up at 10 gallons, you are driving your car to near empty because it only has an 11.3 gallon tank. Thats not good! At my worse, I fill up at no more than 9 gallons.

 

[HeX]

This thread is building up a pretty good checklist on what to consider. Here's the list so far...

1. Driving Habits - staying under 60mph & shifting at or below 2k RPMs
2. Local weather factors (heat = less MPG)
3. Rim Weight - consider your rims material & diameter
4. Tire Pressure & Quality - crappy tires dont help
5. Cabin weight (more weight = more gas consumption)
6. Air filter - clean regularly and/or upgrade
7. Gas Filter - should be changed every year or 2
8. Proper Oil & Filter - not just proper viscosity, but quality oil may help at least clean up old gunk inside
9. "Check Engine" Codes
10. Spark Plugs & Wires - check the plug gap
11. Distributor Cap & Rotor - change every 60k miles or so
12. Clean out EGR Chamber or Change EGR Valve - code P0401
13. O2, IACV, PCV or TPS Sensors - some Bad sensors should throw a code
14. Suspension/ Alignment Issues - some worn parts can impede your ability to move easily
15. Check/ Adjust Engine Timing
16. Reset ECU - not recommended unless necessary; ECU may take several days/weeks to recalibrate while driving.


Feel free to suggest more potential MPG-robbing causes outside of basic maintenance.