Major misfire

[dropinem2low]

At idle it misses on 1, 3, and 5, and when in the throttle it misses on 2, 4, and 6. This problem started overnight, first thing it broke the starter bolts off and push started it to find a P0300 misfire. It has gotten progressively worse since it started 5 years ago.

Replaced:
plugs, wires, cap, rotor, coil
ecm, egr, injector spider,
fuel pump, fuel filter, fuel pressure regulator,
upper intake plentum, camshaft sensor,
crank sensor, all 4 o2 sensors, MAF,
MAP, TPS, and starter ring.

Fuel pressure is holding at 55psi, getting spark on all cyl. at all times. Runs rich with white smoke and burns nose hair. I'm out of ideas, so any help would be amazing.

[danielsatur]

Running Rich with white smoke!
Check your coolant level, and look for coolant in oil.
Is the coolant reservoir tank contaminated with oil?
These are symptoms of a bad Inake, or head gaskets

[dropinem2low]

No coolant leaks, rebuilt the motor was the last thing I did. Oh yeah, and I put in a NEW wiring harness. I have replaced everything external at one point or another with new or known working used parts. The only things I havn't replaced or not completely sure of is the camshaft, distributor housing and shaft, and the balance thing under the intake.

[MT-2500]

What year and engine and engine code?
Any check engine lights or other codes?

[dropinem2low]

1996 S-10 4.3 vortec "X" vin (plastic intake plentum)

Had a P0300, P0301-P0306, all four o2 sensor codes for running rich, maf code. Thats all I remember right now, got the batt on trickle charger now. Will have to grab a scanner later to see if they're still there.

[rhandwor]

Try spraying some carburetor cleaner around the intake. If the motor smooths out that is where your leak would be located.

[MT-2500]

Fuel pressure is low.
Run a full fuel pressure check.
You should see 62-64 lbs engine running.

[dropinem2low]

I replaced the fuel pump and filter, had the lines out for inspection and blew them out with air and checked for kinks (none). 55 psi was found at engine not running. rigged up an old fuel pressure regulator to a fuel pressure gauge at the spider and got the same reading. gone through a case of carb cleaner since it started to check for leaks to no avail.

[MT-2500]

Originally Posted by dropinem2low

I replaced the fuel pump and filter, had the lines out for inspection and blew them out with air and checked for kinks (none). 55 psi was found at engine not running. rigged up an old fuel pressure regulator to a fuel pressure gauge at the spider and got the same reading. gone through a case of carb cleaner since it started to check for leaks to no avail.

The only true test on a fuel pump is to check the direct fuel pressure from fuel pump.
A quick test is to block off the return line and see if fuel pressure comes up to 75-85 lbs.
But do not run the pump at full pressure very long.
Also when testing fuel pump and pressure you need to tape a gauge to outside windshield or outside mirror and drive it on the road for 20 -30 minutes
until the pump gets has run a while to check for a pump fading out after hot.

Hard to start cold or hot and fuel pressure testing guide lines.
Check cold start fuel pressure.
Check engine running fuel pressure.
Check engine running on the road fuel pressure.
Then shut it off and watch for fast leak down.
Pinch off at rubber part or block off return line and check full pressure.
If pump has full pressure with return line blocked and low pressure without it blocked most usually the fuel pressure regulator is leaking or not holding pressure.
Later V6 and V8 gm engines should have 60-66 fuel pressure.
Cold start should be 64-65 lbs of pressure.
If you do not have full fuel pressure on a cold start the injectors will not squirt fuel.
Do not leave home without it.
Engine running should be 60-66 lbs pressure depending on engine load.
Full pressure with return pinched off should be 75-85 or more.
And if it has a fast leak down after shut off you have a leak in system.
Post back fuel pressure readings.

[dropinem2low]

Fuel pressure readings:

At fuel pump w/return line blocked: 110psi
At Check valve...
With ign. on: 63.5psi
With return blocked: 65psi
With engine running: 60-62psi
Cannot test driving fuel pressure, no power to get over 5 mph. and not legal.
No leak down found at any time during testing. Pressure was held for 5 min. plus for each test. (enough time to have a smoke)

[rhandwor]

Some pressure regulators can be adjusted try raising pressure slightly,as not all gauges are completely accurate and are off 5 to 10 percent.

[j cAT]

with these issues you have I would look at the spark plugs . any white tips on those plugs ? If so I suspect a coolant leak in the cylinder[s] this would explain the starter bolts breaking. this is because you can't compress a liquid..

compression test the cylinders using the proper method for a complete result.

[dropinem2low]

Spark plugs look like new. The starter bolts broke off six times total with one starter being broke in half due to the engine kicking backwards. I thought it was a timing issue but it is computer controlled and a timing light conformed timing is correct. The timing chain is also new along with new gears.

[rhandwor]

Originally Posted by dropinem2low

Spark plugs look like new. The starter bolts broke off six times total with one starter being broke in half due to the engine kicking backwards. I thought it was a timing issue but it is computer controlled and a timing light conformed timing is correct. The timing chain is also new along with new gears.

Check the plug wires with a wiring diagram this will cause a rough running engine.

[j cAT]

Originally Posted by dropinem2low

Spark plugs look like new.

runs rich,white smoke out the exhaust, missfires , and you expect me to believe the plugs look new ?

take a good color picture of those plugs and mark what cylinder they came out of then post here ..