2002 Chevy Blazer Engine Surging At Highway Speeds

FLASH703

MEMBER
2002 CHEVROLET BLAZER
6 CYL
4WD
AUTOMATIC
82,000 MILES

My 2002 Chevy Blazer surges when it is in overdrive. It starts fine, idles fine and runs well until I get it on the highway. Once the overdrive has kicked in the engine starts to surge. The tachometer will fluctuate as much as 400 to 500 rpm's. I have taken it to a mechanic and he worked on the fuel injectors and changed some spark plug wires but this did not address the problem. I first noticed this problem after I had filled up with gasoline from a discount fillling station. I usually use Amoco, Shell or Mobil.

Wednesday, March 11th, 2009 AT 8:37 AM

1 Reply

RASMATAZ

MECHANIC
75,992 POSTS

Could be caused by the following:

Dirty fuel injectors (cleaning the injectors often fixes this).
Bad MAP (manifold absolute pressure) sensor
Bad TPS (throttle position) sensor
Bad or dirty MAF (mass airflow) sensor
Low fuel pressure (leaky fuel pressure regulator or weak fuel pump)
Vacuum leaks (intake manifold, vacuum hoses, throttle body, EGR valve)
Bad gasoline (fuel contaminated with water or too much alcohol)

Sometimes, what feels like a hesitation is actually ignition misfire rather than lean misfire. The causes of ignition misfire may include:

Dirty or worn spark plugs
Bad plug wires
Weak ignition coil
Wet plug wires

Was this

answer

helpful?

Yes

No

Wednesday, March 11th, 2009 AT 8:50 AM