kamelred408
TYF Newbie
- Joined
- Jan 12, 2020
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Hello all i am new to this forum and am looking for some help.
2002 chevy-suburban 5.3 4wd p0300 Problem
Parts That we have replaced with new OEM.
All Spark Plugs
All Spark Plug Wires
All Ignition Coils
All Fuel Injectors
Fuel Filter
I had not done those and the car has 200k Miles so i figure its about time anyways .
I do not want to just buy parts and hope for a fix.
I have an Autel mkx808 car scanner and can do live data and several other things with it.
What i have found is the misfires are happening on BANK 1 only
Cylinders 1 , 3 ,5 and 7 Misfire
Cylinders 1 and 7 Misfire the most.
When i drive the car it has a major loss of power and the CEL flashs at me.
here is what i have tested so far.
Live Data shows
Car at operating temp and at idle
Bank 1 Heated o2 sensor 1 Moves up and Down from 100 mv - 900 mv like normal
Bank 2 Heated o2 sensor 1 Moves up and Down from 100 mv - 900 mv like normal
Bank 1 Heated o2 sensor 2 Moves up and Down from 100 mv - 900 mv THIS IS NOT Normal
Bank 2 Heated o2 sensor 2 Stays steady 750ish mv
I thought maybe the cats where bad so i did a temp test and it seems fine im going to do another temp test tonight to make sure ill edit in the exact temps later.
Could it be the bank 1 cats are bad and causing a misfire on bank 1?
My fuel trims stay around 0 and move to -10
Bank one fuel trim moves towards -10 more then bank 2
Fuel Psi
Checked after car sat all night 0 psi
checked when key is turn but engine is not running 58-60 psi then starts to drop
Checked when car is running stays stead at 60 psi
fuel injector psi ( i have this feature on my scanner)
All Injectors Shoots up to 67 psi then down to 44 psi ( they are all new)
now some times after the car sits i have to prime the fuel lines to start the car so i know the pressure is dropping.
I dont see how that would cause a misfire one bank 1 only tho.
A new fuel pressure regulator is my next item but may need a fuel pump?
im building a smoke tester and have not done a compression test yet.
what could this p0300 random misfire be. its driving me crazy and i need the truck for a family trip soon.
any and all help would be great thank you
2002 chevy-suburban 5.3 4wd p0300 Problem
Parts That we have replaced with new OEM.
All Spark Plugs
All Spark Plug Wires
All Ignition Coils
All Fuel Injectors
Fuel Filter
I had not done those and the car has 200k Miles so i figure its about time anyways .
I do not want to just buy parts and hope for a fix.
I have an Autel mkx808 car scanner and can do live data and several other things with it.
What i have found is the misfires are happening on BANK 1 only
Cylinders 1 , 3 ,5 and 7 Misfire
Cylinders 1 and 7 Misfire the most.
When i drive the car it has a major loss of power and the CEL flashs at me.
here is what i have tested so far.
Live Data shows
Car at operating temp and at idle
Bank 1 Heated o2 sensor 1 Moves up and Down from 100 mv - 900 mv like normal
Bank 2 Heated o2 sensor 1 Moves up and Down from 100 mv - 900 mv like normal
Bank 1 Heated o2 sensor 2 Moves up and Down from 100 mv - 900 mv THIS IS NOT Normal
Bank 2 Heated o2 sensor 2 Stays steady 750ish mv
I thought maybe the cats where bad so i did a temp test and it seems fine im going to do another temp test tonight to make sure ill edit in the exact temps later.
Could it be the bank 1 cats are bad and causing a misfire on bank 1?
My fuel trims stay around 0 and move to -10
Bank one fuel trim moves towards -10 more then bank 2
Fuel Psi
Checked after car sat all night 0 psi
checked when key is turn but engine is not running 58-60 psi then starts to drop
Checked when car is running stays stead at 60 psi
fuel injector psi ( i have this feature on my scanner)
All Injectors Shoots up to 67 psi then down to 44 psi ( they are all new)
now some times after the car sits i have to prime the fuel lines to start the car so i know the pressure is dropping.
I dont see how that would cause a misfire one bank 1 only tho.
A new fuel pressure regulator is my next item but may need a fuel pump?
im building a smoke tester and have not done a compression test yet.
what could this p0300 random misfire be. its driving me crazy and i need the truck for a family trip soon.
any and all help would be great thank you