Sudden drop in gas mileage....horrible!
 

BEFORE I START, I'M SURE THIS QUESTION HAS BEEN ANSWERED AND THERE IS ENOUGH INFO BUT FOR SOME REASON THE SEARCH FUNCTION ISNT WORKING!

Hope someone can help me out...I usually get about 12 km/l thats about 540km out of my 99 si 5s speed. About 75% highway and 25% road driving. Since I got the last oil change my last 2 fill ups is giving me about 8 km/l. I have never had that bad mileage. I'll try to give you guys as much info as possible.

Just a little info on the car:

si stock motor only a V2 intake, 153,000km, changed fuel filter 4 months ago, changed spark plugs with ngk iridium about 8 months ago, replaced wires with ngk wires and cap & rotor about 3 months ago.


More info:


And I have checked the oil level is fine after the oil change although I doubt that would really have an effect. Used Castrol GTX high mileage and an original Honda oil filter.

2 things I did this oil change which I don't usually do.......1) I did an oil flush before the oil change....and did not drive the car with the flush in the car, watched my mechanic do it, ran it through the car for about 5 min then drained the oil.....2) after the oil change I put in some additive to help with the oil burning that I'm having.... could the flush have fowled something????

I have a bad tranny bearing which I'm gonna get fixed soon, but thats been around for a year now and never had gas issue before.....

I have been having a issue with sluggish driving over the past 6 months. Sometimes it drives well, sometimes it really hesitates especially in lower gears from a stop....and also on the 401, if I'm going around 110 or so, then I let off the gas, it really tries to slow down really fast, then if I touch the gas again, it hesitates a little then goes....but still this has been happening for a while now, but I was still getting 12 km/l

Hope you guys can help me out

Thanks

im on my way to work so dont have time to read the whole post.

But I would check for a fuel leak if its that sudden of a drop (even though thats not the most common prob.) but its a start. If you have a fuel gauge its easy to check, if not.. just see if you smell fuel under the car, in the bay, etc.

If not.. amybe its time to do a tune up