driveslow

94 civic ex d16z6 187k mileage all stock

Getting about 23 mpg. 280 per tank.

No cels,timing has been done, car is a little sluggish in first gear, no oil in coolant, no coolant in oil, on occasion the car will start rough but then will idle like normal. Its daily driven mostly hwy miles. I switch gears around 3k, during my 3 test going from full tank to empty I never went past 6k. What can be causing this bad MPG?????

Recently replaced items with all OEM honda parts:
air filter
plugs
plug wires
fuel filter
dizzy
o2 sensor
pvc
timing belt
new radiator
new thermostat
Techron fuel injector cleaner added.

dumpsterbaby

tps sensor maybe? and make sure nothing is dragging like your brakes, i had a bad/mal-adjusted brake booster start to apply slight pressure on the brakes, and check yo tire psi

driveslow

Like a bad TPS sensor? How can i check that?

brakes were just done and when in neutral on fairly flat road i can easily roll foward and back no problem. tire pressure was checked also.

Former User

Does the O2 sensor have 180K miles? If so, you might consider replacing.

Stuck open fuel injector(s)?

Malfunctioning fuel pressure regulator?

Exhaust leak near O2 sensor?

I have heard claims that a bad PCV valve can reduce gas mileage.

driveslow

Ronj, first i would like to say that you have been very helpful in helping me out with restoring my ej as well as the other members on this forum. I think you might have missed my replacing parts list. I have replace 02 (nippon denso) and pcv vavle, however, I did notice a small oil leak right before the pcv valve. I can see a lot of oil build up below the manifold and around the that pcv vavlve chamber area.

what would be the best way to check for stuck fuel injectors and malfunctioning fuel reg

Former User

Sorry, I read your post too quickly.

You might start by checking whether all the fuel injectors make the same clicking noise. An engine stethoscope is best for this test. Not sure, but a stuck open injector might not make a clicking sound.

You need to make fuel pressure measurements with and without the regulator vacuum hose attached to check its function.

driveslow

Will i need special tools for this?

Raggedyman

I apologize if I'm jumping in here asking something but uh....what ecu are you running? Is this a swap that you've just installed or have you just suddenly run into this bad mileage on a motor that you've had for a while now?

Dangousity

I have a near stock Civic ex, I just recently took the head off due to timing belt failure. I was getting 32 mpg, but oh man i don't know how. The injectors were clogged beyond belief, and they seemed to be dripping and making sludge in the intake manifold. There was a goo inside the runners, and the exhaust valves were in bad shape, and the exhaust port were caked in carbon something fierce. Wondering if any of you have any of this same conditions.

driveslow

all stock, all original, original motor, bought the car used with 186k and restoring it. 1 owner, old man that used it to drive cross country for his business

Raggedyman

Hmmm....I was hoping you were gonna say it was a swap and you were using a chipped ecu but that's obviously not the case. I've always done all my own work and I usually hear the stories of swaps gone bad so I'm gonna throw some things at you. Open the ecu cover and and make sure the ecu you're running is stock and not chipped. If you honestly trust the guy you got it from, skip that part.

Double check the timing and check the plug wires for the correct firing order....and don't laugh! I bought my del sol for $1600 bucks 'cause they said it had 2 dropped valves and was running like crap. I listened, pulled the head, found a small part of the exhaust valve broken off and decided to slap on a different head. I had the plug wires identified to the cylinder and never checked the firing order....it was wrong and I was stupid enough to believe it was right when I got it.....go figure. Needless to say it still ran like crap until I figured that part out.

Next, rev to around 4k and hold it there for a few seconds and then immediately turn off the ignition and pull the plugs one at a time. I'm sure you can find plenty of sites for what a good plug should look like and maybe you'll find some inconsistencies among the 4 plugs that'll tell you what you want to know.

And last, if you can't find a stethoscope for listening to the injectors like RonJ mentioned earlier, use a long screwdriver. Wood handled ones work best but the plastic ones will do....just listen closely while the engine is idling and you'll hear the clicking.

Good luck!

driveslow

I also pinged my mechanic friend to see what he thought.
just thought it was so strange that everything is running fine and just getting bad gas mileage.

rogue420

Bad catalytic converter?

Former User

As suggested above, also check the ignition timing with a timing gun.

Jimster480

where can you get a timing gun? I hvae gotten bad gas mileage with my civic since i got it. ALthough i just swapped in a new motor and boosted it and am getting really abd mileage until i get it tuned. But even after the swap i still got around 18-20MPG. Which i found to be a very big coincidence because that is the same mileage i got on my car with its **** condition motor when it was automatic. Built a new motor (for boost, stock head) and converted to manual and got the EXACT SAME mileage?

Former User

You can buy a timing gun for ~$30 or possibly rent one for free from an auto parts store.

Jimster480

how do you use one though? I dont think my timing is bad, it was put on timing by this guy who has been into honda's for a long long time lol.

Former User

Your engine must idle to spec and not be misfiring. Warm the engine and then turn it off. Jump the service connector (same one used to pull CEL codes), connect the timing light red clamp to the + battery terminal, the black clamp to the engine, and the inductive clamp to the #1 spark plug wire. Start engine and point the timing gun's flashing light at the crankshaft pulley. If the timing is correct, the pointers on the timing belt cover will align with the red mark (middle of three marks) on the pulley.

driveslow

so without having to throw parts at it, what should I tackle first. Timing is good

Former User

Have checked an exhaust leak, such as from a cracked header?

Also check the 2-wire coolant temperature sensor under the distributor:

Jimster480

oh damn. YOu need covers? i have no covers on my motor at all. When it got built the covers on the block i had were cracked and shitty. My old one was pretty nice but the bolts that held it on were broken or rusted into place so we couldnt get it off. So i have no cover. I have some timing belt top cover laying around but its not on my motor.

driveslow

I will start with that. I did have to remove the j pipe to replace the oil pan gasket...

joelmatt89

You need to just determine what you kept when you swapped in the new engine. This could mean something in your wiring is bad if you kept that. Have you put the car on jacks to make sure none of you breaks or grabbing or you don't have bad bearings or something like that, very little things like that can affect your gas mileage significantly.

BTW To the op, my car runs fine and i am getting like 14mpg and 16 if i drive like a granny. So just cause it seems like it is running fine doesn't mean a thing.

booboo nation

i have a b16 head with a gsr head im going about 300 to tank but a friend of mine he has a d15z1 hes going about 500 to tank city mileages

Juan_Mitosis

When you are coasting downhill. . do you leave it in gear or do you switch to neutral?


TPS Adjustment is done with a multimeter. There are quite a few write-ups here about how to calibrate, its very easy.


Also, when you replaced the Distributor, did you adjust the ignition timing? Or just slap it on?