1997 Ford F-150 small amount of black smoke at idle only

Tiny
AEOLIANRANE
  • MEMBER
  • 1997 FORD F-150
  • V8
  • 4WD
  • AUTOMATIC
  • 141,000 MILES
I have owned f150 for a week. When I was looking things over I noticed no converters. They have been added and the check engine light has been cleared with no codes to this point( about 100 miles). The engine seems to run much better except for the faint black smoke at idle. The water that is coming out the exhaust(it is also new), has what looks like soot in it. I wonder if an engine anilyzer will tell if it is running to rich(black smoke). Or is that a waste of time. 4.6l v8, aode trans. Oil is royal purple 5-30. Air filter new k&n. I have code reader, and most tools for major repairs including 9000lb lift.
Wednesday, May 28th, 2008 AT 6:58 PM

8 Replies

Tiny
MASTERTECHTIM
  • MECHANIC
  • 4,750 POSTS
A scan tool will tell you for sure if you are running rich. You need to look at the o2 sensor voltage, it should vary rather quickly from 000 to 999. Basically it needs to go above and below 500. If it stays above 500 then its running rich. You said there are no converters. What did they do with the o2 sensors that were behind the converter? You should be getting a code 420 for inactive cat converters. Get back to us and let us know
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Wednesday, May 28th, 2008 AT 7:33 PM
Tiny
AEOLIANRANE
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  • 16 POSTS
I have replaced the cats. O2 sensors are in the factory locations. 4 total 2 pre-cat, 2 post cat, all in pipes. Approx. 3inches from cats. I had codes for o2 sensors not working, after istalling cats I cleared codes and none have returned. Check engine lite is off(good thing). Truck is still running to rich I think, evidence by faint black smoke and soot coming out of tailpipe with water. 4.6 v8 aode 4wd.
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Wednesday, May 28th, 2008 AT 7:44 PM
Tiny
MASTERTECHTIM
  • MECHANIC
  • 4,750 POSTS
Ok. I though you said they were removed. You will definitely get codes like 173 if its running rich. Do you have access to a scanner to read the o2 voltage? Thats the next step
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Wednesday, May 28th, 2008 AT 7:50 PM
Tiny
AEOLIANRANE
  • MEMBER
  • 16 POSTS
I own the acton scanner but without check engine light on it will not tell me anything. Will an engine anilyzer at my ford dealer tell me what I need to know? They said they could read multiple systems on computer while engine is running. About 85$, good investement or not?
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Wednesday, May 28th, 2008 AT 7:56 PM
Tiny
MASTERTECHTIM
  • MECHANIC
  • 4,750 POSTS
Yes good investment. They should be able to tell you if its running rich and why its running rich, if it is for the 85 bucks. Get back to us if you need further help
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Wednesday, May 28th, 2008 AT 8:00 PM
Tiny
AEOLIANRANE
  • MEMBER
  • 16 POSTS
Let you know in day or two
major thanks
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Wednesday, May 28th, 2008 AT 8:03 PM
Tiny
AEOLIANRANE
  • MEMBER
  • 16 POSTS
On the engine anilyzer my mass air flow was telling the PCM that at idle my engine was at 39% load. After checking(prev owner dipped front end in water). I replaced MAF and everthing great, no smoke, smooth idle, great gas mileage.

Thanks appreciate the help!
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Monday, June 2nd, 2008 AT 6:33 AM
Tiny
MASTERTECHTIM
  • MECHANIC
  • 4,750 POSTS
Awesome
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Monday, June 2nd, 2008 AT 12:00 PM

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