Misfire on #4 cylinder + evap emiss. code too

[no cigar]

Hey guys. Have been fighting a condition with rough warm-start for a while now. Cold starts are a-okay.

THis afternoon on the return leg of a 3 hours trip home, got a noticable shudder and misfire (blinking CEL). Stopped to read the codes and got a Cyl. 4 misfire and evap emiss. system leak and random misfires. Truck runs alright at highway speed but like a dog in city driving.

Pulled the #4 wire and poked it a bit with my hand and it's definitely firing. Not sure about the plug however.

I was going to check leakdown on fuel system first in order to check the spider and perhaps the FPR unit. This sound like a decent plan? Engine is practically fresh off of a rebuild with about 15k trouble free miles on it so far.

 

[SunlitComet]

Inspect the plug as well. Also check resistance of wire look and cap/rotor as well. If all are good then you could look at the fuel pressure. For the evap leak check to see if the hoses on the block or charcoal canister has come off.

 

[OR VietVet]

I sure would like to know the code(s) you pulled.

 

[SunlitComet]

At least a p0304 so far it seems.

 

[99Vortec]

If his number 4 plug is wet, and he has spark, the spider might be dumping fuel.

p0440 or p0455? For Evap?

So also p0300 code?

 

[SunlitComet]

P0300 is usually set when the misfires are not consistent on a specific cylinder or sometime under multiple cylinder misfire.

 

[no cigar]

I have been getting P0304. SES light is solid @ idle and around

Evap sensor was fixed. Broken disconnect @ the valve by the intake mani.

Pulled #4 plug and it was pretty gnarly (#4 on left, #2 on right). Checked all 7 others and they all pretty much looked the same as #2.



Replaced the plug with new NGK unit and gapped to spec. Still missing. Then put in new Delco cap/rotor and still missing.

This evening, swapped #2 and #4 wires and drove a short ways over to Oreilley's to see if the miss moved to #2 if it threw a new code and it's still throwing P0304. Not sure if it needed more time to 'reset' and throw a new code.

Haven't done any sort of testing as far as vacuum leaks but tomorrow had thought about getting carb cleaner or soapy water and spraying around the intake. A friend of mine suggested I do an injector balance test to rule out a bad spider. Keep in mind I did replace with a brand new MPFI module when I did my rebuild.

 

[SunlitComet]

If it smells like fuel on the plug then do the injector balance test by the way use Delco or Autolite platinums. And never gap them. Taken care of by the factory already for a reason.

 

[no cigar]

Well, got the diagnosis back from the shop: Bad injector driver in the PCM. Apparently the #4 injector is not firing from the PCM at all. I guess they got it to fire by using a pulser or something like that.

Which brings me to my next question... This is a Black Bear module I got in October 2013. It was clearly a core so I'm wondering what their warranty is like when the whole thing (pcm) goes bang and encounters a physical defect?

 

[SunlitComet]

I doubt they warranty a used core. However when the pcm is replaced I am sure They will have no issue reprogramming the next one free of charge. Contact them for details.