2000 Jimmy 105k miles

I've got an intermittent P0304 problem. It's related for fuel. I know this because all of my cylinders are running lean. They aren't all run lean enough to set a CEL, but they are running lean. My Short term and long term fuel percentages are in the acceptable ranges, but are on the higher end of the scale. Cylinder 2, Cylinder 4, and Cylinder 6's plugs are all showing as a lean cylinder. Cylinder 5 is also showing lean. Plugs are new OEM AC Delco's.
Few weeks ago I had a flashing cel come on going up a steep grade with a wicked head wind. After reaching the top of the hill, it stopped flashing and just stayed illuminated. ran the code, P0304. Looked at the freeze frame data, showed a massive load, 90 something percent throttle, 3700 roughly rpm. Short term fuel trim was about 16% if I remember correctly. I erased the code, put in some lucas fuel injector cleaner, and changed the plugs to the new AC Delco's.

A week or so after that incident, I had to floor it to get around some major traffic problems, and after flooring it, truck came back down to an idle and just started to shutter. Ran like ****. It took the PCM about 5 minutes to figure out the code and pop on the CEL. Ran the code and Had P0304 again. Freeze frame data showed no load, low rpm, and a 19% short term fuel trim roughly, and a 20-21% long term fuel trim. The reason for no Load and low rpm was because the cel didn't come on until the truck had been idling for a few minutes.
After this code, I ran Chevron techtron in the fuel system. About 2 miles down the road and the truck was running so smooth I couldn't even feel it. Floored it and it ran great, good power, was just very happy. This time I let the CEL turn itself off and by about 15 miles, if shut off.

So, since then everything has been fine. But I've been feeling it getting steadily worse again, and today My wife was driving it and said the CEL started flashing again while she was going up hill, but she insists she didn't have it floored or anything. the code i'm assuming is a P0304 again since that's been our problem and it seemed like the truck was starting to get worse again.

So my question is, should I run some more fuel injector cleaner through it or should I just start looking at replacing the fuel spider assembly.

Could a vacuum leak be causing my issues? Any common places for a vacuum leak?

Also it has a new fuel filter, I might change it again, since obviously the fuel system is full of crap.

 

Hmm! After I had to do an emergency shut-down:stomp & hold AND downshifting
had the same issue-but...it went away!

 

Have you read through this...P030x Explained (x=0,1,2,3,4,5,6)

 

Yes I have read through that.

We had the jimmy pop up a P0304 AND a P0300 today. Did a compression check, did the tune up with OEM AC Delco parts too.

Unfortunately, I'm at the point that I need a Tech II to diagnos it, so it's going to the dealer thursday. I need to be able to check the Signals at the PCM coming from the o2 sensors, and I don't have a fuel pressure tester, however, before it goes to the dealer thursday, I'm going to rent one from Advance and check fuel pressure. I think the fuel system is full of crap, and I think the injectors/poppet nozzles need to be cleaned, or replaced, but, again, still not sure. If the O2's are reading right, and the Fuel pressure is right, then that's all i can think of.

I will post the solution when I or the dealer figures it out.

 

Catalytic converter...jerry

 

Funny you said that, I actually thought of that on my way home today. My other thought was intake manifold gasket.

 

Catalytic converter...jerry-hopefully they'll check out that angle-that's where I'd go with the info you stated. Just a hunch-let us know of what you find out-good luck!

 

I will.

Fuel pressure checked out. KOEO 60 psi, KOER was 57 psi. Didn't do a driving measurement since I'm feeling like poop (flu, yay?). But, Yeah I'm gonna leave it up to the dealer at this point. I'm going to give their tech everything I've done thus far. The dealer it's going too is the same dealer I've ben going to for 5 years, and they've never screwed me over and they've always fixed my problem right away. So, yeah, I trust them to fix it right.

 

So, the solution to this problem is stupid. I checked it too, but it didn't do it when I checked, but now, at the dealer, it's doing it. Go figure.

So, my brand new AC Delco plug wires were bad. All 3 on one side were arcing across each other. I had the dealer show me right there. He sprayed it down, hid it from the light as best we could, and I watched the sparks dance across those wires like saturday night fever. When I put them on, I did double check them a few days later after the CEL came on again, and they checked fine. Now, they are arcing. Yes they were run properly. Odd, but whatever. I guess it does happen sometimes. Maybe when I checked them they weren't bad enough yet for me to see, who the hell knows....

Anyway, we'll see how long it's fixed for. Hopefully I just got = bad couple wires. He's also putting on new wire mounts (the little plastic things) just in case.

EDIT: They just called me to tell me the distributor is broken, probably causing the arcing, and the constant miss. Woohoo? How common is it for these distributors to go? Based on what he told me, it's broken right under where the rotor sits.... I musta missed that too when I did the tune up. Damn. I need to relax when I'm doing this stuff.How was it running with a broken distributor? Seriously?

 

Hows the car been? still doing the flashy? my blazer recently started doing this.