I have an '89 civic that I bought for $1 (yes, $1!). Needless to say, I’m more willing than I usually would be to spend money on a car this old.
Its symptoms are:
* very rough idle
* slightly rough running
* underpowered
* slightly better after about 1 hour of driving.
* idle speed seems to change.
In addition, there seems to be some kind of clatterish engine noise which I hear especially when the engine is working too hard at low rpms (< 2000).
I had the timing belt replaced (they said it slipped 7 notches), as well as the catalytic converter. Since then, I’ve been suspecting the fuel injectors (the check engine light came on indicating fuel injectors, but after resetting it, it doesn’t come back on), and I’ve used in-tank fuel injector cleaner. The fuel injector cleaner has helped immensely, but not cured the problem. Additionally, it seems to help more during the tank containing it (octane boost?).
Usually the car is pretty drivable, even on the highway, mountains, etc. But it did stall once while stopped and refuse to start until I moved it and ran the starter with the clutch in (jumped and died, of course, next try started it).
I’ve been thinking of just replacing the fuel injectors, but I’m not really sure that they could be the whole cause of my problem. The mechanics who replaced my timing belt were guessing a bent intake valve (and I don’t want that to be the answer, since I definitely can’t fix that myself). Maybe even this could just be spark?
Any help would be much appreciated.
Evan
In a shop setting, the first thing I would do is run a compression check given the fact the timing belt was off. It was probably not installed correctly rather than slipped. This could have bent some valves slightly and in turn could cause the valve lash to be looser. This might be your clattering.
Ignition timing is also critical. Since the timing belt was replaced maybe there is a chance the ignition timing was not set correctly by using the test plug.
The compression test would be step no. 1 IMHO and go from there. Nothing wrong with a cheap car at all. I’m still using my 20 dollar car I bought 1 and 1/2 years ago.
You probably just need a new set of plugs and wires. Make sure to get OEM.
Don’t forget a cap and rotor as well. I agree with using OEM on Hondas. Aftermarket ignition parts on Hondas are the #1 reason for poor running Honda engines.
Is that the DPFI induction system civic? Some of your symptoms sound like a bad injector - and in the DPFI cars one bad injector can cause all sorts of headaches since it’s not individually injected - - the 2 injectors both squirt into the TB, which on those cars is really a glorified carb.
The clattering noise under load at low RPM is probably engine pinging, which means either your timing is off a bit (maybe) or your injectors aren’t dumping enough fuel into the (sorry, I gotta call it like it is 
) carb. I’m guessing it’s the second possibility based on the other symptoms.
I don’t for a minute believe that the belt jumped 7 notches. If it jumped that far the car wouldn’t have run at all, and you’d probably damage something if you tried.
You should be able to pick up an entire DPFI manifold including injectors for 20-30 bucks at a junkyard or one of the honda forums. I’d personally start by replacing that and see where it takes you.
Although not related to performance, the engine “clatter” could be a number of things. If the engine is shaking due to poor running, the noise could be a heat shield or other part bumping against something. I even had a water pump go bad (in my 89 accord) which made a noise at low rpm. Try to isolate the noise with a mechanics stethoscope. As far as the rough running and poor performance, start simply . . . check the timing, change the plugs/wires/cap/rotor, change the fuel filter(s) . . . there should be 2 on this 89 civic. Air filter? PCV? All cheap and easy, and with a $1 car, not a bad investment. Good luck! Rocketman