96 GMC sierra p0172 and P0300 and flashing ses

[69 chuck]

New tune and o2 sensors with a rough idle. No cats, and o2 cheater for downstream o2 sensors. Idle rough and super rich. No intake pcv leaks. Occasional flashing ses light vortec 5.7. Have seen some posts about relearn of crank sensor after tune up. Just wondering if anyone else has encountered this issue and a possible solution before friend throws any more parts at this thing.
Thanks! I'm sure I'm missing something here.

 

[Schurkey]

1. A "FLASHING" SES light means the engine is running so bad that the catalyst is in danger. You may have removed the cats, but it's telling you something is VERY wrong.

2. Connect a REAL scan tool. Look at codes AND the data stream.

3. When using a piece-of-crap "code reader" or bottom-feeder scan tool, the P0300 is probably not the REAL code. A higher-quality tool would likely tell you the true code--a specific cylinder that's misfiring.

I dealt with this not two weeks ago. My own Trailblazer started surging during a gas stop. Stalled. Re-started, ran rough. I was away from home, so I pull into an Advance Auto Parts store. Counterman connects their junk code reader and proclaims "P0300, random misfire". If he'd have told me which cylinder was misfiring, I'd have bought a coil and installed it--but since his tool couldn't narrow down which cylinder was faulty, I drove home and connected my scan tool. Mine gave the TRUE code--P0301. I replaced the #1 coil, and it runs great again.

Running rich enough to set a code? Leaking injector? Have you replaced the terrible "Spider" injection system? What is the fuel pressure?

 

[Supercharged111]

P0301 isn't even manufacturer specific. That's some weaksauce right there.

 

[69 chuck]

1. A "FLASHING" SES light means the engine is running so bad that the catalyst is in danger. You may have removed the cats, but it's telling you something is VERY wrong.

2. Connect a REAL scan tool. Look at codes AND the data stream.

3. When using a piece-of-crap "code reader" or bottom-feeder scan tool, the P0300 is probably not the REAL code. A higher-quality tool would likely tell you the true code--a specific cylinder that's misfiring.

I dealt with this not two weeks ago. My own Trailblazer started surging during a gas stop. Stalled. Re-started, ran rough. I was away from home, so I pull into an Advance Auto Parts store. Counterman connects their junk code reader and proclaims "P0300, random misfire". If he'd have told me which cylinder was misfiring, I'd have bought a coil and installed it--but since his tool couldn't narrow down which cylinder was faulty, I drove home and connected my scan tool. Mine gave the TRUE code--P0301. I replaced the #1 coil, and it runs great again.

Running rich enough to set a code? Leaking injector? Have you replaced the terrible "Spider" injection system? What is the fuel pressure?

 

[69 chuck]

I was leaning toward bad injector as the fuel pressure is fine, volume is good as well. All 8 cylinders firing correctly. Unfortunately the real diagnostic tool is what we need . Thankfully, I think I know a guy. Thanks for reaching out.

 

[69 chuck]

170k miles on original injectors. So I'm sure its way past time.

 

[97K1500Silverado]

I have 212k on my 97 k1500. Original spider injectors. Runs excellent! Of course had to do vortec intake gasket. On its 3rd fuel pump. Recently replaced ignition control module since the original one was failing. Engine would cut out in rpm range and would only do it in hot summer temps. Cool weather it ran fine.

Only time I got a flashing SES was after an engine pressure wash. two spark plug wires came loose just enough to cause misfires.

I recently got the $100 BlueDriver code reader. Besides changing the factory radio clock to 1:00 every time I use it, it reads more codes on newer vehicles like body and abs codes than the $20 cheap code scanner. However my $20 BAFX worked fine on ol 97 when I had misfires and TCC lockup issues.

Have you replaced all 4 o2 sensors? I got better mpg and when I did.

 

[69 chuck]

Yes, o2 sensors new. And a fresh, complete tune. Intakes done 2 years ago. We gotta get a real scanner on it and look at misfire counts and data streams . Only showing rich on one bank. My guess is the spider injection, but I'm not sure failing ignition module would just cause rich on 1 Bank.
Will post an update when we get it plugged into a proper diagnostic tool

 

[97K1500Silverado]

Yeah a better code reader can hopefully narrow it down.

Could be a failing coil or bad spark plug wire. Have you ohm’d out all the plug wires? I’ve seen new wires have a bad one out of the box. Also see a sparkplug fail and not fire plug looked fine but code reader said misfire cylinder 5. Replaced plug and was GTG

 

[69 chuck]

Yeah, have seen these failures over the years. Have yet to double check the new wires . Will hopefully have some time to mess with this weekend