Repost
Only getting 22mpg HELP!
Hi guys,
After reading the sticky on gas mileage, I've started to replace a few things that could be the culprit to my terrible gas mileage.
Let me start with the specs of my car.
Its a d15b block, d15b7 head, si headgasket (8.55:1 compression)
Automatic transmission
Oem everything.
Tires @ 40psi
No tuning modifications at all.
New NGK Spark Plugs and Wires
Before I was getting an average of 22mpg. I just changed the fuel filter with an autozone replacement and now only got 190 miles out of the next tank of gas!! I verified there's no leaks after the replacement.
I pulled the o2 bung in the cat (obd2 cat on obd1 car, so bung closing the second O2 sensor hole) and it was BLACK as was the exhaust tip.
This leads me to a bad O2 sensor which I am going to change tonight.
I honestly have no clue how to check timing at the distributor, or valve lash so I'll be looking those up shortly after I finish this post. I highly believe it could be the distributor as I noticed recently it was only being held in with 1 bolt. I've since fixed that, so no more oil leaks at least.
From there if anyone has some ideas as to what could be causing such a major drop in economy I'll appreciate the support. I'll also be checking compression and would love to do a leak down test, but I say that term to all the tool rental places around here and they look at me as if I have 3 heads.
Thanks again in advance.
James
P.S. I have an intermitent sputter while the car is warming up, I would go as far as to say it sound like a misfire. NO cel lights
P.P.S I definitely think I have at least a distributor timing issue after reading a thread on how to set it.
After reading the sticky on gas mileage, I've started to replace a few things that could be the culprit to my terrible gas mileage.
Let me start with the specs of my car.
Its a d15b block, d15b7 head, si headgasket (8.55:1 compression)
Automatic transmission
Oem everything.
Tires @ 40psi
No tuning modifications at all.
New NGK Spark Plugs and Wires
Before I was getting an average of 22mpg. I just changed the fuel filter with an autozone replacement and now only got 190 miles out of the next tank of gas!! I verified there's no leaks after the replacement.
I pulled the o2 bung in the cat (obd2 cat on obd1 car, so bung closing the second O2 sensor hole) and it was BLACK as was the exhaust tip.
This leads me to a bad O2 sensor which I am going to change tonight.
I honestly have no clue how to check timing at the distributor, or valve lash so I'll be looking those up shortly after I finish this post. I highly believe it could be the distributor as I noticed recently it was only being held in with 1 bolt. I've since fixed that, so no more oil leaks at least.
From there if anyone has some ideas as to what could be causing such a major drop in economy I'll appreciate the support. I'll also be checking compression and would love to do a leak down test, but I say that term to all the tool rental places around here and they look at me as if I have 3 heads.
Thanks again in advance.
James
P.S. I have an intermitent sputter while the car is warming up, I would go as far as to say it sound like a misfire. NO cel lights
P.P.S I definitely think I have at least a distributor timing issue after reading a thread on how to set it.
21 - 36 of 80 Posts
never even thought of that honestly, guess it was a full tooth.With OEM everything as per your OP, how can you possibly change the belt half a tooth, unless you mean one tooth on the cam being half a tooth on the crank.
ok well I guess my excitement was too soon; at half tank of cautious driving it's only at 90 miles, so it's on track for the same 19/20 mpg ugh
well my plugs were rich so I have to check if I am still running richPoor fuel economy due to the engine is normally associated with rich mixture, fuel leaks, retarded ignition, miss fires or poor compression.
Due to chassis it is most often due to dragging brakes but can be low tyre pressures, external accessories like wings, or very large wheels and tyres.
no fuel leaks I'm aware of
ignition is on where it needs to be now (was ridiculously retarded before)
compresssion is 175+ on all cylinders
Tires are at 40psi
no additional external accessories or large wheels
is there any way to lean out a stock car? If i'm still running too rich could it be a case of simply swapping ecu's?
oxygen sensor is brand new.Is your AIT sensor working correctly.
Is your oxygen sensor working correctly.
IAT I dunno ... will be doing all this testing tomorrow after work as I have college tonight.
Just a thought, while i have 175+ compression numbers, according to the zeal calculator I do have 8.55:1 ish compresstionPoor fuel economy due to the engine is normally associated with rich mixture, fuel leaks, retarded ignition, miss fires or poor compression.
Due to chassis it is most often due to dragging brakes but can be low tyre pressures, external accessories like wings, or very large wheels and tyres.
not having any cooling issues, not sure how that would apply (excuse my ignorance)t-stat stuck open?
hmm I did check the lower rad hose and it stays cold at first and then warms up once it reaches operating temp so i think its working correctly.could make the car run cold - the car would run a little rich like when your car warms up on a cold day. and you wouldn't have a cooling prob if it were stuck open
I agree...Just because something is new, that does not absolutely mean it works.
ugh this car is so annoying its getting 16 mpg out of a damn d series!
First I need to look up what readings I'm SUPPOSED to be getting, cause I have no clue what they should be.it sounds like you need to pull out the multimeter and start taking in readings while the vehicle is at operating temps...
As you can see by my spark plugs and the fact my exhaust tip is BLACK its definitely adding fuel somewhere!it could be a bad IAT (intake air temp) sensor. reading cold and adding fuel.
Hi guys thanks, I picked up a haynes and a multi tester.... everything was within range (iat, ect, o2) the only thing i couldn't test was the map sensor as i didn't have a way to induce vacuum on it.
I replaced the cap and rotor as on further inspection I saw my current rotor was starting to get corroded.
The thing i'm noticing now is a distinct clicking or tapping sound coming from the distributor. Using the "screwdriver" stethoscope it's loudest at the middle of the cap... what on earth could that be? I removed the cap several times to check for any possible contact on the rotor; there was none. It's the same frequency as the valves/ injectors (which are all clicking as they should btw) however its MUCH more pronounced.
Same distributor just different cap and rotor; didn't click before and now does.... no signs of anything hitting...
I replaced the cap and rotor as on further inspection I saw my current rotor was starting to get corroded.
The thing i'm noticing now is a distinct clicking or tapping sound coming from the distributor. Using the "screwdriver" stethoscope it's loudest at the middle of the cap... what on earth could that be? I removed the cap several times to check for any possible contact on the rotor; there was none. It's the same frequency as the valves/ injectors (which are all clicking as they should btw) however its MUCH more pronounced.
Same distributor just different cap and rotor; didn't click before and now does.... no signs of anything hitting...
errr any ideas?
Almost positive but i will be checking again today.Are you sure the rotor is aligned properly and all the way down.
Are you sure the carbon rod in the middle of the cap is in place properly and it's spring is OK
It almost sounds like valve lash thas resonating through to the distributor i dunno just a crazy theory :wacko:
bumping this up still only getting 22mpg HIGHWAY!!!
I still think I have bad piston rings. I may juyst swap in a d16z6 since i want to convert to manual anyway
I still think I have bad piston rings. I may juyst swap in a d16z6 since i want to convert to manual anyway
21 - 36 of 80 Posts
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