Rough idle and black smoke upon startup. 1996 850 Turbo

BelitaMI · Post by **BelitaMI** » 31 May 2009, 12:20

I just went to start my car and though it ran just fine all day yesterday driving all over the city, it is idleing extremely rough and there is black smoke pouring out of the tailpipe.
I recently replaced the thermostat housing, thermostat, spark plug wires, spark plugs and distributor cap. Doesn't black smoke usually indicate a misfire? The check engine light is not coming on oddly enough. I really need some help ASAP.
Thanks in advance.

Post by **vegasjetskier** » 31 May 2009, 12:50

Black smoke indicates that unburned fuel is going through the engine. So yes, it is likely that you have a misfire. What did you gap the plugs to?

BelitaMI · Post by **BelitaMI** » 31 May 2009, 13:04

I gapped the plugs at .028 (.7mm).
I just tried to start the car again and it turns over but will not actually start now.

Post by **jblackburn** » 31 May 2009, 13:42

Mine did this! Unplug your mass air flow sensor - the plug on top of the air filter housing and try to start the car and see if it'll stay running. Likely, you will still have some black smoke, since the car doesn't know how much fuel/air to mix now, but if it runs, then you probably just need to clean/replace the MAF.

BelitaMI · Post by **BelitaMI** » 31 May 2009, 14:25

Ok, I unplugged the MAF and tried to start it but it wouldn't start. I only cranked it a few times for a few seconds and then the fan turned on. I'm puzzled. On one of these forums I read that the battery can cause a lot of strange problems. Could the battery be causing any of this? I was told 850s are very voltage tempermental and if your battery is not running near 100% it can cause a lot of chaos.

Post by **jblackburn** » 31 May 2009, 14:27

Could be - do you have a voltmeter to check the voltage at the battery terminals/another battery you could swap into the car to see if it works? Even so, disconnecting the battery for 5 minutes or so may cause the car to "forget" what it thinks is wrong with it and run again.

Post by **misha** » 31 May 2009, 17:21

Could be bad o2 sensor,fuel pressure regulator,maf sensor or even bad Air pump or sas valve.
Check your codes...even the check engine light isn't on,there could be some codes stored.
Read the codes and post'em here and we will be able to help you more.

Post by **Ozark Lee** » 01 Jun 2009, 19:50

I only cranked it a few times for a few seconds and then the fan turned on.

ECT Sensor. Change the thermostat while you are there.

...Lee

Post by **eroosa** » 07 Jun 2009, 15:42

I agree, change the ect sensor. It was $35 dollars at advance auto. Be careful for the part is brass and can be stripped easily.
Also be careful with the T40 bit you will need to get the thermostat off. I found some bits at Advance that were lifetime gauranteed that were about five inches long. Also be careful where the wires go into the sensor. The first one had a crack in the plastic molding and I just replaced it again.

Ed