2000 chevy blazer no start P0300
 

I bought the truck for $500. Did head gaskets, and all other gaskets from the heads up.
Mom drove it for couple weeks and radiator blew. Would not run , checked spark plugs and coolant came out of number 4 plug. pulled the head and it was cracked from a mounting bolt to the valve area. Got used head from pullapart, resealed, redid lower intake gaskets, new plugs,wires,distributor, rotor, new ignition control module connector, new ignition coil connector, new crankshaft sensor connector. only things i HAVEN'T done are new cam sensor, cam sensor connector.
I'm still getting P0300 sometimes it starts sometimes it doesn't. Got a used ICM/Ignition coil same result.
I did my 2000 GMC jimmy the same way and it is running just fine. Dont know what is wrong with this one.
Before the radiator blew i had it pass emissions and got tags on it, week ater is when it blew the radiator. ive tested and changed everything i knew what to do from the last time except for the cam sensor, cam sensor connector and/or crankshaft sensor.
Timing is where its supposed to be.
getting spark to coil just not to distributor. i had it running earlier with rough idle and P0300. now cant get it to start.
let me know if theres other things i should check.
missing alot of work because of this.
Thanks in advance.
Jay

The first path for spark is from the coil to the distributor. You don't have spark there but you have it somewhere else? Do you have a primary ignition signal to the coil?

George

So i double checked everything and turns out my fuel injector connectors were not seated all the way in. Put it all the way in and it started right up.
I'm using a Innova 3040c scanner, in the global scan I'm getting a P0301 Misfire cylinder #1. In the Chevrolet enhanced scan I'm getting P0300.
I've double checked my connections, changed the plug from #4 into #1 and still same result. Took intake plenum off checked #1 injector and cleaned all injectors with carb cleaner, new gaskets on plenum and throttle body. Double checked spark plug in #1 looked fine. Took off valve cover and rechecked the valve lash, valve lash was ok. I have compression. Timing is good. EGR valve has been cleaned.
Checked the wires to injector #1 and no kinks or bad spots. I have no fuses gone bad.
Still misfires, will start up just fine, will run for awhile and after about 10-15 it starts to bog down.
Only thing left to change is cam sensor and cam sensor connector and/or take it to shop and have them scan it but running out of money for both options.
Thanks in advance for your time.
Jay

also replaced both upstream 02 sensors also

A misfire code indicates a hick up in the crank rotation near the time of that cylinder firing. Could be spark, fuel, vacuum, compression. Can also be a neighboring cylinder.

Have you swapped ignition wires?

Inspect the distr cap for carbon tracks.

Do you know your CMP retard?

On live data how frequent is the misfire?

Have you checked the strength of the spark?

Have you done a cpmpression test?

What are your short and long tern fuel trims at idle and 2500 rpm?

George

You're sure your timing is right?

Not advanced or retarded?

with a new crank sensor YOU NEED TO A CRANK RELEARN. That is how the timing is done on these trucks. And there is no adj. for the valves lifters

Scanned this earlier today @2196 RPM

Your short term fuel trims are out of bounds. They are positive so the computer is adding fuel (actually injector pulse width) to compensate for a lean condition (vacuum leak, stuck injector, bad MAF/MAP, bad O2, etc). I would measure them at idle cold, 2500 cold, idle hot, and 2500 hot. Another good test would be to floor the truck to wot in first gear and get the two pre cat O2 sensor voltage levels just before you shift into second gear. They should be pegged above 0.8V. Under normal driving they should be alternating between under 0.45v and above 0.45 volts.

George