Engine Woes

[SheepDip]

Right, last ditch cry for advice on the last forum I expect a solution on, no offense though

I have a Honda Civic 1.6LS from 1997. Fitted with Honda model D16Y3 engine.

Ever since last summer my mpg has been dropping. I've had the valve timings checked, sparks, distributor positioning, it's had a service, and passed its MOT within the last 6 months.

I am absolutely out of ideas, failing it being the O2 sensor in the exhaust, but surely if that were going wrong I wouldn't have passed emissions test?

Currently, I get around 90 miles for 20 litres (4.3 UK Gallons) so at the moment I'm getting 20mpg. From a 1.6 reputed to be able to do double that.

Any suggestions appreciated

 

[Ralfst3r]

My bro drives a Civic from 97 or 98 I believe. I could ask him what MPG he gets when I see him, for comparison.

Did you check tirepressure? Is your idle rpm too high? Maybe your tank gauge is faulty, and your tank is actually fuller than it says? You would notice that when tanking though. Sry, not an expert either

 

[SheepDip]

lol, nah I monitor the fuel as it goes in and then see how many miles it gets me. Idle RPM is around 750-800, tyres were a little low but inflatied them to the exact psi but no joy

 

[Deeival]

Hole in the tank or fuel lines?

 

[SheepDip]

Nope, everything about the car looks and smells right. It's all as it should be, it does seem underpowered also.

I'm beginning to wonder if it could be a problem with the engine management.

 

[Dumba [cro]]

I'm beginning to wonder if it could be a problem with the engine management.

Could very well be. Airflow sensors tend to go crazy... or the vacuum line from the air intake....

Try getting it to a garage and hooking it up to a diagnostic machine.

 

[REZ]

Fuel injectors been looked at? Though I dont know how that would affect fuel consumption but may explain the underpowered feeling? NOT an expert.. I always take my Honda to the dealership.

 

[User Name]

Your O2 sensor can be bad and still pass emissions. I had an '86 Mustang GT that passed with flying colors and it's O2 sensors were barely functional if that. I replaced them and my gas mileage and power went up.

This is pretty far fetched but is it dropping or did it drop and stay there? A change in tire diameter can do that.

 

[fiftyone]

You're burning more than you're running sounds like, as opposed to flooding which is when you can smell the loss.
Ticking over nicely are we ?
What happens when you put your foot down,(stationary) does it miss or flatten before picking up ?

Bet its something electronically regulated not working as it should.

Cars ain't wot they used to be I'm afraid, computers on wheels.

 

[Grobut]

With this kind of problem, there are so many things that could cause it there is just no way to be sure what it really is, for that matter, the engine could just have been a lemon, a real early monday morning build that was just waiting to wear itself out.

But lets hope not eh?


If it where me, i'd check the exhaust, then all the electrics, if that didn't work i would remove the.. the english word escapes me here.. the top of the engine block and start looking for clear signs of wear or damage to cylinders or pistons, but if that still doesen't yield any results, hmm, tough one then..

 

[Peter.Steele]

Just for sh&ts and giggles, you've changed the air filter and fuel filter, right?

 

[SheepDip]

Yeah all the filters have been checked and are ok

I've had the cylinder head off when the valve timings were done, all looks in great nick.

Stationary RPM is steady and consistant when applying the throttle.

I do need new front tyres as I'm approaching 2mm of tread, my mpg has stopped dropping as far as I can tell.
If I can't figure out the problem I'll be picking 2 new tyres up before part-ex-ing it in. They only cost

 

[fiftyone]

Note that the price of petrol has somewhat increased this last 18 months or so.
30% less for a tener's worth.

 

[SheepDip]

Yeah I put my petrol in to the litre, not to the

 

[DONT_SHOOT]

I would check your cylinder compression, timing, check for exhaust blockage, catalytic converter blockage, stall converter functionality (AT only). Clutch slippage (manual only). Check all your vacuum lines for cracks and fit. I would also check the quality of the gas and for debris in your tank. Don't forget to check the fuel sock on the pickup tube inside the tank, if clogged it can cause problems. After all that, make sure your brakes are not dragging, and clean out your car if you are carrying around useless weight.

If you are still having trouble then check out this forum its the best I have found for Hondas.

http://www.redpepperracing.com/forums/index.php

 

[UncleDrax]

Probably someone else said it, but if you're really interesting in correcting it, jack into the computer.. see if what it says is what is really going on.


Also, because I've heard a story about this before.. any chance you're getting water (or some other contaminate) in your fuel? (do you gas up at the same station all the time?).. likely not purposeful, but who knows.. like I said, I did hear about it happening 1x.. (like in all my almost-long-life.. so it's still pretty undamnlikely.. ))

 

[Pavel]

All you need is a OBDII diagnostic scanner. Plug that thing in, read the error code and go from there. Most mechanics will charge over $100 just to do this. It should take 5 minutes to do, however you will need to get the scanner somehow. Buy one or borrow one.

 

[Coaxial_Puppet]

All you need is a OBDII diagnostic scanner. Plug that thing in, read the error code and go from there. Most mechanics will charge over $100 just to do this. It should take 5 minutes to do, however you will need to get the scanner somehow. Buy one or borrow one.

The cheap 100 buck ones don't let you pull up all the nice things though.

Like others said it could be your o2 sensor and still pass emissions.

It the mechanic world they call it a lazy o2 sensor. I have changed many an o2 sensor based on readings that did not make it fault but was causing performance problems.

 

[Pavel]

Perhaps the catalitic converter is clogged or melted?

 

[Capt.Marion]

How does the engine sound? Does it skip or anything like that? Possible things could be a head gasket, but then again, that would show with a compression check. Also, and crankcase-to-air-intake vent, maybe plug that up? Clean air should do some good...

I know that a new headgasket after a blown one on my 1962 Dodge w/ 230 c/i straight 6 got me from 1/4 mpg to about 6-7 mpg, while still in need of an honest-to-god tuneup.