Hello,
I have an 1986 Civic Si, it's currently my only running car, but I don't drive it much. It has a couple problems. The main one is that the idle is erratic. When it's cold it's not too bad it fluctuates a little bit, but after it warms up it goes up and down up and down, fluctuating between 1200 and 1800 rpm. The temperature normally runs about 1/5 to 1/4 of way up. If it idles for long enough on a warm day (temperature reading close to 1/2 scale) the idle smooths out considerably.
The coolant level seems fine. From what I've been able to find out online it sounds like it's a temperature sensor or the IAC. Where is the IAC physically located on this car, relative to the throttle body?
I've tried spraying a canful of really strong carburetor / throttle body cleaner into the throttle body, but it didn't help.
The other strange thing I've noticed is that the tachometer seems to read high most of the time. Typically when I'm cruising at 75 mph it's reading around 4500 rpm.
Every once in a while it will seem to read, what I'm guessing is a more realistic 3500 rpm. The engine sounds more like it's actually turning 3500 rpm when it's reading 4500. It's not that the tach is varying when I'm cruising at 75 mph, it stays steady. I'll start up the car, drive it normally a few block until I get on the Interstate and then in fifth gear on the Interstate it will be reading 4500.
Another time, I'll start the car, get on the Interstate and it will be reading more like 3500 rpm at the same speed. When it's reading high I really have it in fifth gear (I've checked) and I'm sure the clutch isn't slipping.
The car seemed to have lost a little power over the years I've had it, I think I know why now. The other day I needed accelerate quickly from a stop light in first gear. I noticed that the engine seemed to be pulling much more strongly than normal, when I glanced down at the tach and it was reading 7500-8000 rpm.
I think that a stock 1986 Civic Si would rev to those kinds of rpm, but I'm pretty sure that the power would have tailed off quite a bit by that point, but probably not if it was really reading 1000 (or more) rpm high.
-Eric
I have an 1986 Civic Si, it's currently my only running car, but I don't drive it much. It has a couple problems. The main one is that the idle is erratic. When it's cold it's not too bad it fluctuates a little bit, but after it warms up it goes up and down up and down, fluctuating between 1200 and 1800 rpm. The temperature normally runs about 1/5 to 1/4 of way up. If it idles for long enough on a warm day (temperature reading close to 1/2 scale) the idle smooths out considerably.
The coolant level seems fine. From what I've been able to find out online it sounds like it's a temperature sensor or the IAC. Where is the IAC physically located on this car, relative to the throttle body?
I've tried spraying a canful of really strong carburetor / throttle body cleaner into the throttle body, but it didn't help.
The other strange thing I've noticed is that the tachometer seems to read high most of the time. Typically when I'm cruising at 75 mph it's reading around 4500 rpm.
Every once in a while it will seem to read, what I'm guessing is a more realistic 3500 rpm. The engine sounds more like it's actually turning 3500 rpm when it's reading 4500. It's not that the tach is varying when I'm cruising at 75 mph, it stays steady. I'll start up the car, drive it normally a few block until I get on the Interstate and then in fifth gear on the Interstate it will be reading 4500.
Another time, I'll start the car, get on the Interstate and it will be reading more like 3500 rpm at the same speed. When it's reading high I really have it in fifth gear (I've checked) and I'm sure the clutch isn't slipping.
The car seemed to have lost a little power over the years I've had it, I think I know why now. The other day I needed accelerate quickly from a stop light in first gear. I noticed that the engine seemed to be pulling much more strongly than normal, when I glanced down at the tach and it was reading 7500-8000 rpm.
I think that a stock 1986 Civic Si would rev to those kinds of rpm, but I'm pretty sure that the power would have tailed off quite a bit by that point, but probably not if it was really reading 1000 (or more) rpm high.
-Eric