93 Honda Civic Mileage gone bad

shipping mark.

After market, hmm. Let the group know how it goes. I'm
afraid the aftermarket coils I've had did not last nearly as
long as the original, OEM one.

Way to troubleshoot!

 

Thanks much for the URL.
I looked,and they did not list the 94 Integra GSR motor,just the RS,LS,SE
models. I suspect the O2 sensor would be the same,though.
Also,quite a big price difference between the OEM sensors and the
universal.I guess you would have to "adapt" the wiring on the uni
sensor.(no connector match)

 

In my experience, universals come with crimp splices to re-use the connector
of the OEM.

Mike

 

| > the best thing to do is put in a new one and be done with it.
Then why not buy new car & sell off old car ? I heard japs export
all their cars >5yr old, in whole or as components, to less developed
countries with lower labour cost [ii] in Japan, new cars are cheap &
repair costs high. Doesn't USA have the same situation ?

| will a 3rd party sensor suffice?
only if it has the same capacitance value ( usually in µH i.e. micro
Henry ) as the OEM part, so your ECU will not detect any difference

 

UH,microhenry is an INDUCTANCE measurement,capacitance is in microfarads,or
picofarads.

the O2 sensor might be rated in millivolt output (per oxygen unit).

 

Right about the units, and the output is rather a moot point. The
capacitance is immaterial, since it is used as a DC device. All use the same
chemistry and are as very nearly identical, with the exception of the heater
characteristics. Even at that the heaters are all 12V DC.

The essential characteristics (as I understand them):
*open circuit when cold, they are biased to 0.45 VDC to signal an
inoperative condition
*once they reach something like 450 degrees, they become conductive. If the
exhaust has enough CO compared to the outside air, the device becomes a fuel
cell and the output rises to approx 0.9 VDC. If the exhaust is lean, the
output drops near zero (about 0.1 V is the figure usually given).

If the mixture is close to correct initially, the ECU drives the mixture
back and forth across the transition point as rapidly as the feedback
allows - thus the need for rapid response. Seven transitions per second is
considered good, but I don't have a good handle on how slow is really
considered bad. Maybe four... three?

Mike

 

Top Notch Shipping. Ordered itSunday night, recieved it Tuesday
morning.

Anyway, it looks exactly like the coil that was in there already, it
measures in spec (resistances of the coil), and has worked fine now
that I've put it all back together.

 

Top Notch Shipping. Ordered itSunday night, recieved it Tuesday
morning.

Anyway, it looks exactly like the coil that was in there already, it
measures in spec (resistances of the coil), and has worked fine now
that I've put it all back together.

 

Well.. I seem to have found the problem.

It was, as many have suspected, an old Oxygen Sensor. I was getting
about 25ish MPG, and then I replaced the O2 sensor and now I have gone
about 150 miles with the needle still above the 3/4 tank mark. I'll
let you know the actual mileage when I finish the tank.

Thanks to everyone.

 

Well.. I seem to have found the problem.

It was, as many have suspected, an old Oxygen Sensor. I was getting
about 25ish MPG, and then I replaced the O2 sensor and now I have gone
about 150 miles with the needle still above the 3/4 tank mark. I'll
let you know the actual mileage when I finish the tank.

Thanks to everyone.

 

Especially thanks to Elle, who has been championing the O2 sensor issue for
a while now. I'm coming to believe there are a lot of cars that are
suffering degraded O2 sensor performance that haven't degraded enough to set
the "check engine" light. My daughter's '93 Accord with 220K miles is a
prime example. It doesn't make sense to assume a sensor that old is still
working well. I hope to replace that one this spring - it's just too chilly
now.

Mike

 

Especially thanks to Elle, who has been championing the O2 sensor issue for
a while now. I'm coming to believe there are a lot of cars that are
suffering degraded O2 sensor performance that haven't degraded enough to set
the "check engine" light. My daughter's '93 Accord with 220K miles is a
prime example. It doesn't make sense to assume a sensor that old is still
working well. I hope to replace that one this spring - it's just too chilly
now.

Mike

 

cars older than 1996 when OBD2 went into effect might *never* trigger
the check engine light. i know my moms 1993 eagle summit never did.

im sure someone here with more knowledge would know whether itll even
blink a code if/when checked.

 

cars older than 1996 when OBD2 went into effect might *never* trigger
the check engine light. i know my moms 1993 eagle summit never did.

im sure someone here with more knowledge would know whether itll even
blink a code if/when checked.

 

Yeah but I may have messed him over by casually mentioning
my temptation "to pull off the ignition wire of the suspect
cylinder (with the suspect fuel injector) and see if engine
power sounds like it goes down." Shoulda been more complete;
told him to follow a manual or Tegger's site on this point
(which I believe mentions your experience on this, Mike);
warned him about cranking the engine with any wire
disconnected. It may very well have cost him the coil as
well as time lost.

Gotta come clean, so maybe, with enough repetition in the
archives someone else won't have this happen.

Sorry Danny.

 

Yeah but I may have messed him over by casually mentioning
my temptation "to pull off the ignition wire of the suspect
cylinder (with the suspect fuel injector) and see if engine
power sounds like it goes down." Shoulda been more complete;
told him to follow a manual or Tegger's site on this point
(which I believe mentions your experience on this, Mike);
warned him about cranking the engine with any wire
disconnected. It may very well have cost him the coil as
well as time lost.

Gotta come clean, so maybe, with enough repetition in the
archives someone else won't have this happen.

Sorry Danny.

 

you have convinced me to change mine as well (probably i'll check it first
then change)
as i am sporting a '93 civic si @ 195k with original sensor

btw is the accord having any oil trouble ? i am loosing about 1/2 qt
between oil changes ?

was ther a final consensus on where to get good quality O2 sensors ?

robb

 

you have convinced me to change mine as well (probably i'll check it first
then change)
as i am sporting a '93 civic si @ 195k with original sensor

btw is the accord having any oil trouble ? i am loosing about 1/2 qt
between oil changes ?

was ther a final consensus on where to get good quality O2 sensors ?

robb

 

How much times is that in miles and months?

Doesn't sound too serious, but I'd still be checking for
leakage around the valve cover; under the distributor; and
into the spark plug tubes. How old's the valve cover gasket
and the several other seals in the valve cover (spark plug
tubes, oil filler cap, rubbery washers for the hold-down
bolts)? Ever had the distributor O-ring seal (IIRC)
replaced?

I did all of these not long ago, and my 173k mile, 1991
Civic's oil consumption seems way down, from about 1/2 quart
between oil changes. Plus the exterior of the engine and the
spark plug tubes are cleaner.

sensors ?

In 2004 for my 1991 Civic, I used
https://www.automedicsupply.com/ for an OEM oxygen sensor at
a significantly better price than the usual online OEM parts
sites. Good service. The sensor seems fine--still getting 40
mpg most of the year on my 1.5L engine, manual tranny. So I
have been recommending this company here when the subject
comes up.

 

How much times is that in miles and months?

Doesn't sound too serious, but I'd still be checking for
leakage around the valve cover; under the distributor; and
into the spark plug tubes. How old's the valve cover gasket
and the several other seals in the valve cover (spark plug
tubes, oil filler cap, rubbery washers for the hold-down
bolts)? Ever had the distributor O-ring seal (IIRC)
replaced?

I did all of these not long ago, and my 173k mile, 1991
Civic's oil consumption seems way down, from about 1/2 quart
between oil changes. Plus the exterior of the engine and the
spark plug tubes are cleaner.

sensors ?

In 2004 for my 1991 Civic, I used
https://www.automedicsupply.com/ for an OEM oxygen sensor at
a significantly better price than the usual online OEM parts
sites. Good service. The sensor seems fine--still getting 40
mpg most of the year on my 1.5L engine, manual tranny. So I
have been recommending this company here when the subject
comes up.