Arrrrghhh... p0306!! out of the blue.?

UUggghhh... :banghead: why am I getting this p0306??!?

ok.. I recently had a freeze plug leak.. couldn't see it at first and thought it was the water pump....

so.. I replaced the water pump.. in doing so I disconnected the battery.. (I always do this out of habit when working on the truck)... Replaced the water pump.. reconnected the battery.. (engine still leaked.. (freeze plug .. got it fixed already..))

I started the truck back up and it ran =very= rough... after a few minutes (was trying to heat up the engine to get the thermostat open to get some coolant in there...) boom.. check engine light comes on... I haven't had a single check engine light problem in the last 2 years since rebuilding the top half of the engine.. (head gasket leak)...

took it to Autozone the next day.. and as i drove it there the SES light started flashing.. got there and it came up p0306...

the truck was running soo good before I took the water pump off (and disc. battery) I was getting about 20 mpg for the 2 years after I redid the heads

now it idles rough.. and runs rough and low rpm. and i get a p0306. grrrr..

Things I've checked so far:
replaced all plugs/wires/distributor cap/rotor/ (even the distributor itself due to stripped cap securing holes) still gets p0306..

what am I missing!?!
driving me batty.. really wanted to go on a road trip in the coming weekends and not going to be able to with truck in this shape...

Help!?! Please. :runaround:

UUggghhh... :banghead: why am I getting this p0306??!?

ok.. I recently had a freeze plug leak.. couldn't see it at first and thought it was the water pump....

so.. I replaced the water pump.. in doing so I disconnected the battery.. (I always do this out of habit when working on the truck)... Replaced the water pump.. reconnected the battery.. (engine still leaked.. (freeze plug .. got it fixed already..))

I started the truck back up and it ran =very= rough... after a few minutes (was trying to heat up the engine to get the thermostat open to get some coolant in there...) boom.. check engine light comes on... I haven't had a single check engine light problem in the last 2 years since rebuilding the top half of the engine.. (head gasket leak)...

took it to Autozone the next day.. and as i drove it there the SES light started flashing.. got there and it came up p0306...

the truck was running soo good before I took the water pump off (and disc. battery) I was getting about 20 mpg for the 2 years after I redid the heads

now it idles rough.. and runs rough and low rpm. and i get a p0306. grrrr..

Things I've checked so far:
replaced all plugs/wires/distributor cap/rotor/ (even the distributor itself due to stripped cap securing holes) still gets p0306..

what am I missing!?!
driving me batty.. really wanted to go on a road trip in the coming weekends and not going to be able to with truck in this shape...

Help!?! Please. :runaround:

Check the #6 spark plug and plug wire connections.
One of them might be bad.
Could also be a piece of crud in the #6 injector. (If injector was bad, you'd get another code for "low voltage injector #6).

Side note; I recently replaced my distributor with as remanufactured unit.
The cap screw hole was stripped out on the new one. Looking closely at the base, I noticed it's made of a fiber material, not metal, and the screws for the cap are wood - type screws, not machined. Cheap stuff indeed.

Get a larger wood screw, would be my suggestion.

Check the #6 spark plug and plug wire connections.
One of them might be bad.
Could also be a piece of crud in the #6 injector. (If injector was bad, you'd get another code for "low voltage injector #6).

Side note; I recently replaced my distributor with as remanufactured unit.
The cap screw hole was stripped out on the new one. Looking closely at the base, I noticed it's made of a fiber material, not metal, and the screws for the cap are wood - type screws, not machined. Cheap stuff indeed.

Get a larger wood screw, would be my suggestion.

new plugs... new wires... new rotor... new cap... new distributor (the 'fiber material' wasn't stripped but -cracked- so a bigger wood screw wouldn't have worked this time.. (only $69 after core return but still a pain just cause i can't put the cap on))

I looked at the injector 'poppet' for that cylinder while i had the plenum off.. it 'looked' clean.. wasn't gummed up or anything (that I could tell.. this engine has that CPFI 'spider like' injector... can't replace individual injectors.. have to do whole injector assembly.)

Anyway.. after all that still the p0306 shows up.. I thought.. maybe not getting any compression.. (stuck valve.. or lead in head gasket or excessive ring wear) so checked that too... and compression on all cylinders is -good- since the head jobs...

Just don't know what to do from here, short of taking it to a shop, and I really don't want to fork out the $$ for that right now.. but need the truck.


Would this be indicative of a VCM problem?

new plugs... new wires... new rotor... new cap... new distributor (the 'fiber material' wasn't stripped but -cracked- so a bigger wood screw wouldn't have worked this time.. (only $69 after core return but still a pain just cause i can't put the cap on))

I looked at the injector 'poppet' for that cylinder while i had the plenum off.. it 'looked' clean.. wasn't gummed up or anything (that I could tell.. this engine has that CPFI 'spider like' injector... can't replace individual injectors.. have to do whole injector assembly.)



Would this be indicative of a VCM problem?


I had a similar problem with my Chrysler. Replaced the spark plug, no more misfire codes.

Doen't matter if you have all new wires, plugs. Most like this is where your problem is.

As far as the injectors, I also have the spider set-up, and you can buy the injectors individually (about $80.00 each), or as a set (over $300.00).


By crud in the injector, I mean in the fuel feed internal to the injector.
That's why I mentioned the "low voltage" code if the injector caused the misfire.
When I had an injector go out on my Pontiac, 2 codes were generated, not just the misfire code.

Did you get the right distribitor?It should say V6 where the rotor screws on to.The V8 and V6 distribitors are differant.Another thing to do is hook up a scan tool,go into data loooking for cam sensor retard.The spec is 0 degrees.

When I stated all those new things.. (plugs, wires, rotator, distributor (actually called a High Voltage Switch now) & cap.. I mean I've already replaced those things -trying- to eliminate the p0306.. so I've tried replacing the plugs.. then I tried replacing the wires.. then the rotor and cap... then I -had- to replace the HVS (distributor) due to the cracked/stripped base...

Engine runs rough now at idle (truck slightly shakes).. (it didn't before I disconnected the battery when replacing the water pump...) I can clear the code and it will run a rough idle in the driveway for 20 minutes without throwing a code... As soon as I go for a drive around the block and hit about 25 mph @ 2300 rpm I'll get the flashing SES and p0306.

....

Yes.. the distributor (high voltage switch) I got was exactly same as original I pulled out.. and actually it is used for either the v6 or v8 (as it has little molded in 'arrows' with a 6 and an 8 on them where the point is supposed to 'point' when cyl 1 is top dead center on v6 (the '6') or a v8 (the '8') (altho there was a stamped '6' on where the rotor screws on.. (unless it was a '9' :)) but no 'v')

The scan tool I have doesn't have the feature you mentioned ( I don't think.. will have to look tonight when I get home) it just pulls/clears/and get a freeze frame...

Sounds like you're having fuel spider trouble of some kind...

I probably missed make, model...I offer you what's on the Factory Shop Manual flow chart for PO306 (Cylinder # 6 misfire) for 95 Blazers- Before clearing DTC(s), use scan tool to record freeza frame and failure records for reference;as data will be lost whenClear Codes function is used.
1. ARE THERE ANY OTHER DTC(S) stored ? If yes DIAGNOSE THOSE CODES FIRST. IF NO- install Tech 1 (scan tool) Duplicate conditions at which misfire occurred. IS DTC CURRENTLY ACTIVE ? IF NO- Misfire is intermittent,and could be caused by Spark plug/coil wire(s), Contaminated/ low fuel level, Misinstalled/loose or cocked crankshaft position sensor.IF YES- 2. Install spark plug tester in-line on # 6 and test at idle. A strong/ consistent spark should jump the gap. Was adequate spark present ? 3. If YES- check spark plug itself, air gap, cracks or fouling. If NO- check your IGNITION SYSTEM. Is the spark plug OK? 4. If NO- Replace plug. If YES- Analyze fuel delivery using fuel pressure gauge and injector tester. Pressure should be (55-61 PSI). Note fuel pressure as you energize injector- If no drop in PSI check injector coil, If PSI drops to less than 37 indicates a Faulty Central MFI poppet nozzle so replace Central MFI Unit, If PSI drops to 37-43 indicates: remove upper manifold assembly, connect poppet nozzle testers, apply battery voltage via 10 Amp fused jumper to fuel pupm test connector, energize injector and check each poppet for fuel spray. No fuel spray from one or more indicates replace Central MFI unit. 5. If injector poppet is ok- indicates problem is Engine mechanical. Sorry for the book, but sometimes it helps. Good luck.

Thanks for the chart steps...

Looks like only thing on that chart left for me to try is the coil, fuel pump, and injector.. I've got good compression and have replaced everything else (plugs/wires/distcap/dist/rotor)

I guess I am just so frustrated because it was running so well before I had disconnected the battery...

I wonder.. are poppet testers something I can pick up at advance or autozone? hadn't heard of them before.

will update later this weekend with what i find.

Sounds like you're having fuel spider trouble of some kind...

That's exactly what it was....

I havn't had time to work on it much lately.. only an hour or two for one night a week.. but it turned out to be that the poppet that was in Cylinder 6 was stuck open.. so that when the injector would pressurize the 'hose' it would just squirt right into the cylinder.. even tho it wasn't on a compression cycle...

I was certain it wouldn't be the fuel injector.. because I've had problems with that before.. and always the problem was leaking regulator.. (indicated by drop in fuel pressure)... so when I had -good- fuel pressure I was sure it couldn't be the spider....

Kudos leeann94astro!!

I swapped the poppet going to cylinder 6 with the closest one .. cylinder 4.. and when I started it up and started running.. sure enough I got a p0304.. instead of the p0306

$300 later from Autozone.. and it appears to be running fine...

thanks for the help all..

-Tim

Cool! Glad you got it fixed.

Sorry (for your wallet) I was right, though...