random miss fire

Asked by Sep 12, 2016 at 07:21 AM about the 1999 Chevrolet S-10 2 Dr LS 4WD Extended Cab SB

Question type: Maintenance & Repair

I have a 99 s10 4.3 i have replaced cap rotor wires
coil maf map egr gasket throttle position sensor
the problem will go away for a bit when i replaced
something but would eventually come back what
am i missing ???

4 Answers


P0300 CHEVROLET - Cylinder Misfire Detected Random Cylinders --- Possible causes - Faulty spark plug (s) - Faulty ignition coil (s) - Clogged or faulty fuel injector (s) - Intake air leak - Fuel injectors harness is open or shorted - Fuel Injectors circuit poor electrical connection - Ignition coils harness is open or shorted - Ignition coils circuit poor electrical connection - Insufficient cylinders compression - Incorrect fuel pressure --- The P0300 code means that a cylinder(s) is misfiring or is randomly misfiring. Start by checking for intake leaks, intake gaskets are common caused of multi-cylinder misfiring. If no leak are found the next step is to replace the spark plugs. If the problem persist more tests needs to be done to diagnose problem. Also there is a service builtin on this....2000-2008 Chevrolet Factory Service Bulletin OBDII Code P0300


Do tests, don't buy parts! Test EGR for back pressure because the number 1 reason for random misfire is a plugged cat or exhaust.

So i did some more testing and i had just replaced my map sensor and now if i unplug the sensor theres no miss but as soon as i plug it back in it starts missing the scaner says 10 for my manifold pressure doni have a manifold gasket leak?


If you have checked the vacuum pressure at an idle and you are only getting 10 inches vacuum, then there is a problem. Manifold vacuum should be around 17 to 20 in. at an idle. Ether a vacuum leak, or low compression in the cylinders.

Your Answer


Looking for a Used S-10 in your area?

CarGurus has 998 nationwide S-10 listings starting at $999.


Chevrolet S-10 Experts

  • #1
    Andrew Olsen
  • #2
    John Saffrahn
  • #3
View All

Related Models For Sale

Used Chevrolet Silverado 1500
2,199 Great Deals out of 151,084 listings starting at $1,499
Used Ford Ranger
119 Great Deals out of 4,676 listings starting at $1,495
Used GMC Sonoma
335 listings starting at $1,695
Used Toyota Tacoma
428 Great Deals out of 41,122 listings starting at $2,600
Used Ford F-150
2,558 Great Deals out of 220,223 listings starting at $1,222
Used Dodge Dakota
65 Great Deals out of 3,131 listings starting at $1,600
Used Chevrolet Blazer
722 listings starting at $900
Used Nissan Frontier
349 Great Deals out of 24,549 listings starting at $1,200
Used GMC Sierra 1500
887 Great Deals out of 59,331 listings starting at $1,980
Used Dodge Ram 1500
327 Great Deals out of 9,602 listings starting at $800
Used Chevrolet C/K 1500
738 listings starting at $2,995
Used Chevrolet Camaro
242 Great Deals out of 30,118 listings starting at $4,980

Content submitted by Users is not endorsed by CarGurus, does not express the opinions of CarGurus, and should not be considered reviewed, screened, or approved by CarGurus. Please refer to CarGurus Terms of Use.