97 s10 P0301 cyl #1 misfire, no power, rough idle, bad gass mileage
I have a 1997 S10 Automatic 2wd V6 - 4.3L. I am getting a P0301 code consistently. It has 105,000 miles that is idling rough, has a loss of power at highway speeds, and terrible gas mileage (around 10mpg or less). In the past year I have changed the cmfi unit (fuel injectors/lines/poppets), the fuel pressure regulator, throttle positioning sensor, coil, fuel filter. In the past month I have changed the plugs (correctly gapped), plug wires, distributor cap, rotor, fuel filter. I have put in several fuel injector cleaners of various types including seafoam with no improvement. I am trying to figure out what to do next. The fuel pressure is 63psi with the key on while priming (key on and buzzing/whining heard) then drops to zero - while running it is 54psi. This is within specs according to the manual - aside the initial drop which causes a hard start sometimes (not an issue for now). There is a minor exhaust leak between the catalytic converter and the muffler - (seemingly a small issue unless effecting the O2 sensors). I have cleaned several sensors in the past..... I am at the point where I am trying to figure out if I should fix the truck or junk it. I am out of ideas.... I don't have the tools to check compression. I am thinking O2 sensors, or catalytic converter - or a sensor.... Any thoughts????
Register today for free or log-in if already registered to remove this ad!
How does the plug in the No. 1 cyl. look? Does it look like it is firing at all?, does it have any carbon burn on it? Does it have a fuel smell to it? It leads me to think of going back to the basic three principals of the operation of an internal combustion engine Air/Fuel, Spark and Compression. Each one has to be checked and eliminated as a problem. It could be a wiring issue causing the plug not to fire or the injector not to fire. It's just a proccess of elimination if it can be found and fixed than the truck is worth keeping.
Thank you both for your responses. I will check your suggestions again tomorrow. I appreciate your help during the busy holidays! I have not checked the plugs since I installed them a few weeks ago. I will check tomorrow and let you know. I will spend some time tomorrow troubleshooting a few last things before bowing out to the professionals with the proper diagnostic equipment. I am taking the truck to a shop on Tues. to officially troubleshoot this issue - it has been causing problems for too long. This is a test to my pride...but sometimes you must choose the path of least resistance. I will post what I learn/find out tomorrow and after the shop visit.
Have you found the problem with the Blazer?? I am having the same issue and I have 186000 miles. I got a p301 code (#1 cylinder missfire)and a p420 code (catalyst effiency below threshold) how did you fix your issues or did you take it to the professional. I am at that stage right now. Not sure what to do>
So I got it running better the night before I was going to take it in the the mechanic. I cleaned all the sensors, checked for vacuum leaks, and everything else. Then I noticed that the plug wire for the #1 plug didn't go up as far as the others - by just like 1/16th of an inch or so. I got it to seat all the way like the rest of them and the problem was solved. After all the stuff I checked and cleaned - it was that the whole time. It just couldn't get a strong enough spark I guess. Hope this helps. I overlooked this several times beacuse I thought that the little bit that the boot was pushed back couldn't make a difference. Check it out - it's worth a shot. The boots on the wires seem awful thick - which makes it difficult for them to seat all the way. I used wd-40 to make them slide on all the way .... not sure if that's the right thing to use but it worked. Good luck!