After replacing wires, plugs, distributor cap, o2 sencor, mass air flow censor, fuel filter, fuel pump and fuel injection assembly my truck seems to miss fire. replaced these parts due to age of truck. the missfire was occuring prior to fixes. mechanic feels it is electrical. my truck is a 1999 gmc jimmy sls 4x4. please advise

change fuel filter.OBDI

Try a few if these ideas...

Priority Action Part Type Cause
1 Inspect Spark Plug Fouled, Damaged, or Broken Spark Plug(s).
2 Inspect Hose (PCV) Clogged or Collapsed PCV Hoses.
3 Inspect Wireset Worn, Damaged or Faulty Spark Plug Wire(s).
4 Inspect Distributor Worn, Damaged or Faulty Distributor.
5 Inspect Catalytic Converter Clogged or Faulty Catalytic Converter.
6 Inspect Fuel Pump Low Fuel Pressure.
7 Inspect TimingSet Slipped TimingChain or Worn TimingGear(s).
8 Inspect Knock Sensor Improperly Connected or Faulty Knock Sensor.
9 Inspect M.A.P. (Manifold Absolute Pressure) Sensor Faulty M.A.P. Sensor.
10 Inspect Throttle Position Sensor Faulty or Incorrectly Connected Throttle Position Sensor.
11 Inspect Mass Air Flow (MAF) Sensor Damaged, Loose, or Faulty Mass Air Flow Sensor or Circuit.
12 Inspect Air Cleaner Temperature Sensor Damaged or Faulty Air Cleaner Tempature Sensor.
13 Inspect Fuel Injector Pressure Regulator Faulty Fuel Injector Pressure Regulator.
14 Inspect Piston Ring Set Worn or Broken Piston Rings.
15 Inspect Timing Specification Incorrect Ignition Timing.
16 Inspect Fuel System Pressure Incorrect Fuel Pressure Being Delivered to Carburetor or Fuel Injection System.
17 Inspect Fuel Filter Clogged or Dirty Fuel Filter.
18 Inspect PCV Valve Plugged or Damaged PCV Valve.
19 Inspect Valve Burned, Worn, or Sticking Exhaust Valves.
20 check idle stop solenoid - if faulty, could cause rough idling
21 inspect distributor cap/rotor - if burnt, could cause loss of acceleration

Do you have any other codes along with the 0300 code? If so, it could pin point the problem

Clean the throttle body. Check the mass air flow sensor for corrosion of the wire harness connector.

normally a fuse burns out because of a short in the wireing and/or the item the fuseis running is defective...(check o2 censors, spark plugs"plugs,wires", and the ignition coil...

check for vacuum leaks, check distributor cap and rotor button, clean or replace as necessary. Use quality injector cleaner.

It sounds like it is running rich - possible injector poppets hanging open. Clean the injectors - You need to have a pressurized fuel injection done (which requires special tools). You will want to remove the mass air flow censor from the induction tube; remove the four torque bit screws; seperate two metal ends from plastic piece and clean the little wires on the censor with brake clean and used compressed air to dry.

Have the drive gear on the distributor checked, these are known to wear and cause a timing issue.

Hello,
your problem appears to be the idle control motor located on the air intake manifold it is a small motor that goes bad quite often. Other items that can cause this is a bad /clogged air filter or a tune up (spark plugs and wires), or clogged fuel injectors. to clean the injectors you can buy a container of fuel system cleaner and pour it into the gas tank and as you drive it cleans the system.

Once the fuel system is cleaned via a tankful of cleaner & gas then the idle controller motor would be next on the list to be replaced.

Good Luck !
Rich Lilja

Inspect Wireset Damaged, worn, or deteriorating spark plug or coil wire(s). in this list u will find a answer to ur problem Shaun 2 Inspect Spark Plug Fouled, damaged or broken spark plug(s). 3 Inspect Fuel Filter Clogged or dirty fuel filter 4 Inspect Distributor Worn, loose or incorrectly adjusted distributor. 5 Inspect Distributor Cap Loose or cracked distributor cap 6 Inspect Distributor Cap And Rotor Kit Loose, cracked, or worn distributor cap and ignition rotor. 7 Inspect PCV Valve Plugged or damaged pcv valve. 8 Inspect Air Filter Restricted or clogged air filter. 9 Inspect Catalytic Converter Clogged, damaged, defective or faulty catalytic converter. 10 Inspect Automatic Transmission Improperly adjusted kickdown cable adjustment or internal transmission problems. 11 Inspect Fuel Pump Improperly functioning fuel pump or circuits. 12 Inspect MAP Sensor Improperly connected or faulty m.a.p. sensor. 13 Inspect Mass Air Flow Sensor Improperly connected or faulty mass air flow sensor. 14 Inspect Throttle Position Sensor Faulty throttle position sensor or throttle position sensor circuit. 15 Inspect Timing Specification Incorrectly adjusted engine timing. 16 Inspect Fuel System Pressure Incorrect fuel pressure being delivered to carburetor or fuel injection system.