Why does the engine miss on cold startup and not when at operating temperature?

Tiny
ROBERTD55
  • MEMBER
  • 2000 CHEVROLET BLAZER
  • 190,000 MILES
2000 blazer 4x4 has new tuneup, new TPS, new IAC, new MAP sensor, checked EGR valve for carbon buildup, very little and function. Did not check for electrical, though. It was in closed position and seated when I pulled it. On cold startup in morning, starts fine, idles fine, idles down fine, when I start driving it, it has a severe miss until it reachs operating temperature. It runs fine after reaching peak operating temperature. It is now 78degrees in morning and 100degrees in the afternoon. Hope you can make some sense of this, and give me some solutions. Thanks, Robert
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Wednesday, September 5th, 2012 AT 11:58 PM

7 Replies

Tiny
ASEMASTER6371
  • EXPERT
Could be injectors needing service. Could be carbon on the intake valves.

Did you replace the wires and cap and rotor?

Roy
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Thursday, September 6th, 2012 AT 12:14 AM
Tiny
ROBERTD55
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Yes and this missing did not start till 3000m later.
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Thursday, September 6th, 2012 AT 1:54 AM
Tiny
ASEMASTER6371
  • EXPERT
Have the injectors professionally cleaned. Gas tank additives have little or no effect.

Roy
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Thursday, September 6th, 2012 AT 1:55 AM
Tiny
ROBERTD55
  • MEMBER
Since Ive had the vehicle Ive always added Lucas or something similar to tank. Thanks, Robert
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Thursday, September 6th, 2012 AT 2:07 AM
Tiny
ASEMASTER6371
  • EXPERT
Not good enough. Theyy need to be direct injection cleaned.

Roy
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Thursday, September 6th, 2012 AT 3:09 AM
Tiny
ROBERTD55
  • MEMBER
Then, why would it not miss all the time, after it warms up also?
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Thursday, September 6th, 2012 AT 3:56 PM
Tiny
ROBERTD55
  • MEMBER
If it had a dirty injecter would it not miss all the time?
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Thursday, September 6th, 2012 AT 5:55 PM

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