2001 Blazer back/misfiring, P0300
#1
2001 Blazer back/misfiring, P0300
Hi guys,
Replaced the entire rotor and shaft (the old one had badly worn gears) about 6 months ago. At that time it ran great.
The truck sat over the winter, and is now causing all sorts of problems. It starts up fine and idles while cold, but once hot it starts backfiring/popping in the exhaust. It throws a P0300 code.
What can I do to start diagnosing this problem? I do have a scan tool with live data.
Thanks!
Replaced the entire rotor and shaft (the old one had badly worn gears) about 6 months ago. At that time it ran great.
The truck sat over the winter, and is now causing all sorts of problems. It starts up fine and idles while cold, but once hot it starts backfiring/popping in the exhaust. It throws a P0300 code.
What can I do to start diagnosing this problem? I do have a scan tool with live data.
Thanks!
#3
Positive fuel trims indicate a lean misfire. Either too much air, (vaccum leak is a possibility), or not enough fuel, (inoperative injector, low fuel pressure or volume are possibilities).
Start by checking fuel pressure and leakdown at the service port and at the fuel filter outlet. There is a How to thread at the top of this sib forum. Post all 4 readings and we can analyze them for you.
Start by checking fuel pressure and leakdown at the service port and at the fuel filter outlet. There is a How to thread at the top of this sib forum. Post all 4 readings and we can analyze them for you.
#4
Positive fuel trims indicate a lean misfire. Either too much air, (vaccum leak is a possibility), or not enough fuel, (inoperative injector, low fuel pressure or volume are possibilities).
Start by checking fuel pressure and leakdown at the service port and at the fuel filter outlet. There is a How to thread at the top of this sib forum. Post all 4 readings and we can analyze them for you.
Start by checking fuel pressure and leakdown at the service port and at the fuel filter outlet. There is a How to thread at the top of this sib forum. Post all 4 readings and we can analyze them for you.
What can I do to eliminate a vacuum leak as a possiblity?
As noted I will be replacing the fuel filter today on the off chance that it is plugged.
#6
With the fuel trims at +25, if it were a vacuum leak, it would most likely set a lean DTC on one bank or the other. Low fuel pressure may or may not set a DTC, but if or when it does, it's almost always P0171 & P0174 simultaneously. Here's the link: https://blazerforum.com/forum/2nd-ge...eakdown-88305/
Last edited by Captain Hook; 04-21-2015 at 03:48 PM.
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