Hi all, first post here. I am about to start work on a Blazer that roughly three weeks ago whilst being driven started misfiring and has sat since. No service/check engine lights on at all, hooked the OBDII and it gave the following codes: P0300, P1481, C0520, and finally C0000. (The C-series codes only came on once out of four key turn ons.) The only code I had expected to see was P0300 for the obvious multi-cylinder misfire it has going on.

All that out of the way, as far as how the engine itself runs; it feels and sounds like its firing on only four out of six cylinders. It will rev up, but no change at all. It also smells HEAVILY of gasoline upon 5-10 seconds of start-up. However there are not any visible leaks. The Blazer is currently at a confirmed 154000 miles. From what I understand the owners may have been a little iffy on getting service intervals done as they should be.

Anyways, if anybody has experienced this or can point me to what it may be I would be very appreciative. It currently seems off the limited time I have had with it that it could be something super simple, or could be something more severe. Whatever the case may be, I have reasons to get it figured out and repaired as soon as I can. It looks like it will be Saturday before I will have the Blazer, but I wanted to get the ball rolling now.

Side-note: this is my first time owning/working on a Chevy. Lots of mechanical experience behind me, but I haven't done much wrenching on Chevys So if there is anything worth mentioning about them that sticks out that would be helpful. Also, wanted to mention that it has had a new fan clutch within the last year and the owner replaced them cam sensor in hopes of remedying the issue with no change. And from what I was told the timing chain has not been replaced, so not sure if there may be something to that or not.

 

Welcome to the forum. A misfire problem can definitely be solved but there are so many potential causes that some work may be required to find and fix your issue. Many others can offer parts swapping advice if that's how you want to proceed but my approach would be a methodical analysis through testing and then targeted repair. If you want to go my route then I will be more than glad to help you and I will stick with you until the end. You can start by reading my thoughts here and then we can get started if you wish:

https://blazerforum.com/forum/2nd-ge...72/#post732722

This might also help:

https://blazerforum.com/forum/2nd-ge...k-flow-103979/

Since you are smelling gas, start with the fuel pressure test in the sticky, my guess is that you may fail the leak down portion. Also, lets look at your fuel trims.


George

 

Thank you for the response, very fortunate to have folks like you willing to assist. I figured that what I know currently about it would be pretty vague, and have a big range of possible causes. Rspecially mainly just having the P0300 code as the only code to go off of. I will have the vehicle tomorrow and I am expecting to have my hands on a scanner that is capable of running fuel trim reports by the start of this next week. I will give an update once I've been able to get my hands on it. Also, this may well be foolish questions or a misunderstanding on my part. But again, since I am new to Chevys I just don't know better. Anyways, it seems that the 2002 4dr blazers have two different engines from what I have seen. (The 4.3 V6 and the 4.2 l6 4200 that mine has) Am I misunderstanding something or is this true? And what are the bid part differences between them? Thanks again for the assistance, those are good threads to read off of.

 

Some model years of the platform offered a 2.2L 4 cyl but the 2002 only came with the 4.3L V6.


George

 

Gotcha, just a quick update- I had to install a new battery this morning as the old one was flat and old. With new good battery it's starting up and obviously still misfires. Right now it is giving me a change engine oil light and the SES light. Nothing else. Waiting on the scanner and fuel pressure test kit to get here in a few days. When I started it up it's hovering at around 500RPM give or take. Stalls when put in gear after moving a few feet, and is only peaking about 1000RPM when given throttle. Fuel pump seems to give a pretty heavy whine upon turning the key to on. Not a whole ton I can do until those tools get delivered I know. But is this sounding possibly like a fuel pump, fuel filter. Or still one of the many other things good old P0300 can mean?

 

You are on the right track. Scan for codes and perform the fuel pressure and leakdown test first.

Sounds like the truck is running like crap so P0300 is almost automatic. We will need to determine why you cannot get above 1000 rpm. If it’s not fuel pressure then we just need to run down the list. Ignition, compression, sensors, etc. Codes may give us some clues to narrow it down.


George

 

Just installed a new OEM fuel filter and battery, scanner will finally be here tomorrow. Started it briefly after and still ran horribly, but given some throttle it was able to reach closer to 1500-1600 rpm compared to topping out at 1000RPM