1986 2m4 5 speed I have posted in the past here about a rough idle every now and then and the replies was a vacuum leak, also it was a bit of a high idle. Sometimes when I drive the car it takes a fit of rough idle then it goes away and also the engine light comes on and goes out at random times. So while checking my alternator in the garage tonight while the car was idling it took a fit of rough idling and while it was rough idling there was black smoke coming out of the exhaust. So for 5 or 10 seconds or so it was black smoke and then it went away.
Any thoughts on what it could be or what to start checking? Also there is no codes on the computer.
I've had an '84 SE since new (now 363,000 km) that would occasionally significantly misfire. It would happen after a cold start during damp or rainy weather & disappear after a few kms of driving. It was like the ignition was being rapidly & erratically turned off & back on, the tach needle would bounce crazily around & the check engine light would flash.
The symptoms would also disappear when accelerating. I presumed that opening the throttle was advancing the timing and affecting the ignition in a way that mitigated the issue somehow.
I found that the contacts in the distributor had developed white deposits. If I cleaned the deposits off or replaced the distributor cap the problem went away until the deposits reappeared about a year or two later.
Sounds good, but wouldn't I get some other symptoms then every now and then, maybe I will take the cap off. would a weak/bad fuel pump give issues like that? Thinking on it now, it would be probably be starved for gas and backfire. So a flooding at certain times would mean an ignition problem or a sensor.
If it was a sensor what would give trouble like that every now and then?