1992 Chevrolet S-10 Exhaust Black Smoke

Tiny
REZA3AUTO
  • MEMBER
  • 1992 CHEVROLET S-10
  • 2.5L
  • 4 CYL
  • RWD
  • MANUAL
  • 240,000 MILES
Here is the situation :

The black smoke came out of exhaust ONLY when reving the engine up and down, but when accelerate and hold it, there is no black smoke.

Every one says check the sensors, injectors or regulator, but I think there is an evidence it's related to an incorrect ignition timing.

My question is, does the black smoke has any relation with the timing of sparks?
I assumed it because at high engine speeds, the sparks automatically advanced.
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Saturday, December 20th, 2014 AT 3:53 AM

2 Replies

Tiny
MHPAUTOS
  • EXPERT
The question is how much smoke, you may just be in need of a tune up, excessive plug gaps can cause this, timing will also but it must be out a long way and you would feel other symptoms, leaking injectors, check the tune and check comps, start here.
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Saturday, December 20th, 2014 AT 4:26 AM
Tiny
JOHNNYT73
  • EXPERT
Get a scan tool and read all your temp sensors to see if they are reading correctly. Especially check your engine coolant temp sensor.
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Saturday, December 20th, 2014 AT 8:15 AM

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