Rough idling black smoking 87 Integra

[Mauricio Tavares]

Friend of mine has an 87 Integra which is acting up. First of all, let's say the battery is dead, but since she is not driving the car right now (more on the reason alter), we are just jumpstarting it as needed. Second, it has new (NGK) spark plugs, wires, rotor, and distributor housing. Once we connect it to a working battery (insert here my comments about the tiny size of the battery used in some Hondas), car starts right up without an issue nor check engine (pgm-fi?) light. Though, the idle rpm is a bit high.

After a few minutes it starts to do some sort of idle hunting. As the tach needle does not move (I wonder if it is boink or somewhere in between is dead. I guess I could try to use my tach/dwell meter. However, I also wonder if the tach is seeing the same signal something else important is seeing; if the signal is not there something else is also pissed), my guess its idle goes from around 800 to 1300rpm and it sounds like someone is just revving up the engine and then letting the gas pedal go. Then, if I press the brake pedal, the rpm will drop some, the engine light will come up, and the idle starts to hunt. The same happens when I put it in gear (it is an auto). I also noticed that once that happens, there is black smoke comming from the exhaust.

When I bought my scirocco, the idle was doing something very similar and was smoking (I do not remember if it was black like the Integra's though). I took care of that by adjusting its air/fuel mixture. I wonder if something similar is going on.

Suggestions?

 

[TeGGeR®]

After a few minutes it starts to do some sort of idle hunting. As the tach needle does not move (I wonder if it is boink or somewhere in between is dead. I guess I could try to use my tach/dwell meter. However, I also wonder if the tach is seeing the same signal something else important is seeing; if the signal is not there something else is also pissed), my guess its idle goes from around 800 to 1300rpm and it sounds like someone is just revving up the engine and then letting the gas pedal go. Then, if I press the brake pedal, the rpm will drop some, the engine light will come up, and the idle starts to hunt. The same happens when I put it in gear (it is an auto). I also noticed that once that happens, there is black smoke comming from the exhaust.

Check your coolant level. Low coolant can cause unsteady idle.

How does the car behave after you've driven it for at least 15 minutes?

Also, pull the carpet back from the passenger footwell until you can see the ECU. Turn the ignition to ON (not to START!) and count the short (and maybe long) blinks from the ECU's red light. The code may help narrow this down.

 

[Mauricio]

Check your coolant level. Low coolant can cause unsteady idle.

Should I also run the car with the coolant filler cap off to see if any bubbles show up?

How does the car behave after you've driven it for at least 15 minutes?

Hmmm, I will have to get back to you as we have not driven the car that long. =)

Also, pull the carpet back from the passenger footwell until you can see the ECU. Turn the ignition to ON (not to START!) and count the short (and maybe long) blinks from the ECU's red light. The code may help narrow this down.

Will do!