93 Honda Accord with problems

I have a '93 Accord 10th Anniversary Ed. Automatic. I've owed the car
for about 6 months and I have a couple of different problems that I
hope someone can help with.

1) The engine has a rough idle when warm (500-750 rpms). When I shift
out of gear and into Neutral or Park it smooths out quite a bit, but
not completely. It also goes away when driving or pressing the
accelerator.

2) When I am cruising at a steady speed (say between 60-70 mph) on
level highway, I've noticed that the rpms will jump up about 500 rpms
for no reason. It feels like a minor gear shift, but with the level
terrain and the constant speed it shouldn't be shifting. It does this
"shift" continuoisly back and forth.

3) I've recently noticed the smell of burning oil when the car is
parked, but no signs of an oil leak. I had the valve cover and spark
plug gaskets replaced a few months ago, but this has only started with
in the past few weeks. Occasionally, there is a puff of white/blue
smoke that comes from the exhaust on start up.

If you have had similar problems or have suggestions to correct them
please let me know. Thnx.

 

This one sounds like a motor mount problem. Same happened to my '92
Accord. All of them have been replaced now.

 

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Even without knowing the mileage, I'll bet your Throttle Position Sensor
is worn out. High mileage and Cruise Control, Prairies? That's the
formula for wearing out a TPS, which will cause the RPM fluctuation. It
will go away if you drive into a headwind.

You don't have to change the whole thing. Search it out thoroughly
before paying somebody to fix it.

'Curly'

 

You can also easily check it with a voltmeter. Backprobe the middle wire
and check for smooth voltage transition from closed to wide-open throttle.
Use an analog VOM. Autoranging digital ones can switch ranges part way
through, causing what appears to be a hitch in power.

 

check the ecu for codes before even bothering. i've had experience with
this, and a dodgy tps /definitely/ sets a code.

 

I've done some research on what that part does and it does sound like
it could be the problem. I will check it out soon and let you know. Do
you think simply cleaning the contacts fix it? I don't know if it goes
away when i'm in a headwind, but it does usually stop if I punch the
throttle or cruise above 80 mph. It mostly occurs between 50-70 mph.
Since my original post, I've been watching it a little closer and have
determined that the rpm fluctuation is only about 250-300 rpm instead
of the 500 I had said before.

 

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It is SO EASY to confirm. Just go to an open area or road where you can
drive SLOW in first gear. When you hit the exact same RPM that it shows
up at, it will start 'bucking' as it goes faster / slower. I had a Ford
Aerostar with a manual tranny and a bad TPS. You had to wear a seatbelt
while hunting for a parking spot or it would nearly throw you out of the
seat. Previous owner apparently didn't think it was worthy of fixing!!

'Curly'

 

I tried what you said and the engine ran normal. The problem normally
occurs around 3000 rpms. I put the car in first gear and slowly got it
up to as high as 3500 and there was no bucking, jerking or anything.
Does this mean it's not the TPS? Is there another way to confirm?

Thanks

 

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You may not have been patient enough. (if) It's a tiny gap in the
rheostat, and you could miss it easily if you slipped past it.
Everything has to be warmed up just like it is on the highway too. We
still don't know the mileage, do we?

'Curly'

 

based on that description, it shouldn't be the tps. but yes, you can
confirm: check the ecu for codes. the ecu most /definitely/ registers
faulty tps's.

other things to check are:

.. throttle cable - snagging can feed back into the movement the throttle
experiences.
.. ignition system. dodgy plug leads can cause all kinds of bizarre
behavior.
.. engine mounts, particularly the big one behind the engine. i've never
yet seen a honda this vintage that didn't have this mounting torn to blazes.
.. timing belt tightness. when i got my 89 civic used a couple of years
ago, i was dismayed to find the timing belt crazy loose. tightening it
correctly made all kinds of weird behavioral issues go away [because
there's no longer any "wow" in the sensor inputs].

also do a general check for other mechanical health, vacuum control
hoses, etc.