Help, please, 1991 Accord Check Engine light and poor running.

Hello, all, I have a couple of problems with a 1991 Accord that I
can't seem to find a definite answer for. It's a 4 cylinder,
automatic with 220,000 miles.

This my girlfriend's car, so I don't drive it that much, but I've
driven it enough to see both problems.

First, the check engine light comes on from time to time. It may come
on and then go off after restarting the car. I've checked the engine
code (by jumpering the little connector under the glovebox and
counting the CEL flashes) and I get a code 1, which is supposed to be
the O2 sensor (not sure if that's the upstream or downstream sensor (I
think there are both on this car but I have not visually verified
that). This problem has been occurring for several months, even
before I did some work on the car's engine, so I don't feel it is
related to any recent work on the car.

Before I mention the second problem let me say that one month ago I:
replaced the timing belt, timing belt tensioner, spark plugs,
distributor cap, distributor rotor, spark plug wires, and the valve-
stem seals. Afterwards it ran fine, no problems evidenced at all, but
I probably should mention that work, just in case it matters.

The second probem occurred last Saturday. The car had been driven and
warmed up and then parked for about 2 hours. After starting the car
we drove it about 6 miles and the car exhibited loss of power. We
stopped at a store and killed about 30 minutes and then went back to
the car. We were going to my home about 60 miles from where we were
and I drove. The car ran fine until the last 3 miles or so. I was
driving about 80 mph when the speed started dropping and it felt like
it had lost power, yet it didn't feel like the engine had died, it
just decellerated gradually. I pressed the accelerator to no avail,
however, when I pressed the pedal all the way to the floor the car
downshifted and surged hard, full power. So, it ran fine at wide open
throttle (WOT). I lessened the pressure on the accelerator and let it
return to about where it should be for 70-80 mph and the car upshifted
and then exhibited the loss of power again. I repeated the WOT,
downshift, ease-back, upshift sequence twice more before I reached my
exit from the hiway. However, once I had slowed down for the exit,
and for the remaining 1.2 miles or so to my house, the car ran
flawlessly. It never died, I never killed/restarted it, nothing.
Just slowed down, exited the hiway, boom! ran fine.

Any ideas or suggestions on what is going on with these two problems?
Is it worthwhile to replace the O2 sensor, or should I remove it,
inspect it, check the connections, etc. and try to finesse this
thing? Anything relate that to this newer problem of power loss?

Thank you for your help.

--HC

 

This Honda is old enough (both in years and miles) that a
pre-emptive change of the O2 sensor is wise. The symptoms
all seem to support it as well. We're talking about the
upstream sensor here, given the symptoms, though I think
your Accord has only one O2 sensor.

Buy only an OEM O2 sensor. https://www.automedicsupply.com/
sells them at the best prices I have seen. I used this
company. I was very pleased with the service of this online
company a few years ago when I replaced my 91 Civic's sensor
pre-emptively.

The power loss would be related to a failed O2 sensor. Could
be other things, but the O2 sensor is a strong candidate.
You can unplug the sensor and compare how the car runs
without it to the way it runs now, to possibly get more
insight.

 

Thank you for your reply. I will probably replace that. The problem
I'm facing now is that maybe, and I'm not sure, the O2 sensor might
freak out if the readings are out of range, but maybe what's driving
them out of range is that the fuel pressure is low to the injectors.
Maybe that's a stretch, but it *might* be. I'm trying to go at this
in a step by step manor and it occurred to me to check the fuel
pressure. But....HOW? I can't find a port to check it. Maybe I'm
dense. My Chilton's manual is of no use. Suggestions?

Thank you again for your reply and your time.

--HC

 

I am not inclined to believe the O2 sensor would cause an
engine code due to abnormal fuel pressure. Seems to me you
also have a kind of vicious circle going here: Suppose the
O2 sensor is failing. Then the signal it sends to the ECU is
going to cause whack-o (the industry term) fuel pressure.

You have a good thought process going, though. Just be
careful of overanalysis. In this case, I'd rely more on the
collective group's experience here. O2 sensors do fail.
Rough running is a classic symptom. Add in the engine code,
and the age of this Accord, and that's three strikes.
You can try the online factory service manual for your
Accord at http://www.honda.co.uk/car/owner/workshop.html .

BTW, is the O2 sensor the original one? Or did some silly
put in a new (and non-OEM??) one.

O2 sensor wrenches may be borrowed at no charge (ultimately)
from Autozone.

Use OEM, I (and the group's archives) will tell you.

 

Fill the reservoir (since you had the coolant out) and run some injector
cleaner through it.

Check the reservoir again in two days and top up to MAX again so you can
observe how much is 'sips' overnight.

'Curly'

 

Elle, thank you for reply. I have ordered a new O2 sensor (having
gone and removed the one from the car and finding that it looks like
it's the factory original (it's a NGK-brand sensor). I figure if it's
original it can't hurt to replace it. Unfortunately, the mechanic who
had done all the work on this car for several years before I began
dating the owner, and took over maintenance of her car, was quite
precise in what parts he used (even the timing belt he had put on was
a Honda part) so, it's possible he might have changed it at some point
and he probably would have used whatever was actually a factory part.
Hard to tell for sure. However, there appeared to be no thread
treatment on the sensor and I think that the conventional wisdom is to
dope the threads with some kind of anti-seize when installing a new
one, so if that's right, then it's probably the factory original.

The O2 sensor I ordered is a Bosch 15-710 OEM-style. I ordered it
this morning before I saw your reply and the words about OEM. I'm
hoping that this Bosch is going to be okay. Is that okay, or have I
screwed myself up here?

I also ordered a new fuel filter. 1) the one in the car looks old and
dirty (outside, of course) which makes me think it might be quite
old. 2) I figure for less than 20 bucks it can't hurt to do it. If I
am getting abnormal fuel pressure then the fuel filter *might* have
something to do with it. Mostly, I feel good about doing it "just in
case" and it's not expensive.

Thank you for the link to the manual, that helps.

I feel these two things are the simplest and most obvious starting
points, before a long list of little (and not so little) irritating
doohickeys (I know the industry jargon, too. <wink>).

Thanks again. I'll post tomorrow after I install the parts and take
it for a trip (I'll take it to lunch with my girlfriend while she's on
lunch break, about 60 miles from here). That'll be about 120 miles
round trip and should be sufficient to determine if I've solved the
problem or not.

--HC

 

I do not think NGK is the factory original. I would have
thought it was Denso or Walker. That's what it was on my 91
Civic.

Indeed, if NGK is not OEM, then you may have found the
problem.

Right. Reports on the internet indicate that an O2 sensor
that has not completely failed nonetheless may be degraded.
It's possibly you'll see better fuel mileage with the new,
OEM one.

Unfortunately, the mechanic who

?!

You rascal you.

Hm. I hear you. See if others chime in here about the NGK
sensor, though.

Unfortunately you screwed yourself up here.

Cancel order. Go to aforementioned web site. Buy either of
the ones specified as OEM. Bosch is way not OEM here. This
group has bad reports on Bosch for O2 sensors here, if
memory serves. Really bad ones.

Excellent idea. It's due 60k miles/4 years according to my
91 Civic's owner's manual. Some sources say 24k miles/2
years.

Consider dumping a bottle of Chevron Techron into your
Accord's fuel tank when it's near empty and you are filling
up, as well.

2) I figure for less than 20 bucks it can't hurt to do it.
If I

Agreed. Go for a full tuneup, with OEM Ignition parts, too,
unless (I can't remember) you recently did one.

Agree with the other poster about topping off the coolant
system, too. Sensors not fully immersed in coolant will mess
up the signals to the ECU.

 

Thank you for your reply. I have checked the coolant level and it was
low. I have topped it off and will test it to see if it makes a
difference.

--HC

 

Thank you all for your help and input. I added coolant (as one person
suggested (it was low)) and drove it about 70 miles with no change, so
that was not the solution this time. I then replaced the O2 sensor
(with the Bosch since I had already committed myself to it) and that
was it. It has been driven several hundred miles now (about 300+)
with no check engine light or poor running.

Thank you all again.

--HC

 

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