[master486]

So I obtained a junked 96 4.6L so that I can take what I want from it, and I'm trying to see if I can get the engine to run. It turns over and occasionally seems like it wants to start, but the engine pretty much just cranks. I've yet to get it to start. I scanned for codes and got the following:

P0300 Random/Multiple Cylinder Misfire Detected
P0301 Cylinder 1 Misfire Detected
P0302 Cylinder 2 Misfire Detected
P0303 Cylinder 3 Misfire Detected
P0305 Cylinder 5 Misfire Detected
P0306 Cylinder 6 Misfire Detected
P0307 Cylinder 7 Misfire Detected
P0308 Cylinder 8 Misfire Detected
P0171 System too Lean (Bank 1)
P0174 System too Lean (Bank 2)
P1443 Purge Control Solenoid or Purge Control Valve fault

I already know about P1443 so I'm not concerned with that. P0171 and P0174 I assume to be either the MAF sensor or 02 sensors. I can't tell if it might be a vacuum leak because I can't get it running. But on to the misfire codes. I tested and I'm not getting any spark. I'm getting plenty of fuel (I can smell it, I can feel the injectors pulse when cranking, and the plugs are soaked with it), so I know the cam position sensor is working fine. I found the coil packs to be working (tried them in a working 4.6L) and also put known working coil packs in the car, but still no spark. The firing order is correct so that's not the problem. In investigating, I found the two wires for the crank position sensor to be frayed and touching, so I fixed that problem but still nothing. However the crank sensor is working right because the scanner can read the revolutions of the engine during cranking.

So is the problem the computer? I've checked and double-checked ALL fuses so that's not the problem. The coil packs and sensors are getting power. I cleaned the MAF and tried a known working one but that didn't get it to start. Any suggestions?

 

[Bangster]

cylinder 4 seems to be working fine, that should be enough!

Sorry, no help here.

 

[master486]

lol yeah maybe that's why it ocassionally jerks like it wants to fire when I'm cranking! Thanks though.

 

[master486]

Anybody have an idea?? I'm throwing a new computer on it in a couple days unless someone else has other insight.

 

[v8pwrdbird]

okay, you said you have no fire. then check the ignition control moduel connection for corrosion. also i just rebuilt a 3.4l grand am gt that was on tryiing to fire on one cylinder. culpret was a cracked in half camshaft. so check to make sure that when you turn the motor over that the rockers are moving. just something to check.

 

[The Great Obucina]

you try new plugs, wires, and o2 sensors?

 

[master486]

okay, you said you have no fire. then check the ignition control moduel connection for corrosion. also i just rebuilt a 3.4l grand am gt that was on tryiing to fire on one cylinder. culpret was a cracked in half camshaft. so check to make sure that when you turn the motor over that the rockers are moving. just something to check.

This car doesn't have an ignition control module. It's built-in to the PCM.

I did however think of the valve timing as being the problem (maybe broken timing chain or something) but I looked and there's definitely movement of the valves/rockers.

you try new plugs, wires, and o2 sensors?

I put in new plugs but haven't tried new wires or O2 sensors yet. I'm just trying to get it to start so I'll worry about the O2's later. I thought about the wires being the problem, but could they be so bad that the car wouldn't start at all? I checked at night and didn't see arching anywhere when trying to start it.

 

[The Great Obucina]

bad grounds for the starter or a dead starter could also be a problem. i replaced a set of wires back in october and they were "that" bad.

 

[master486]

Well the starter seems fine. It turns over just fine and will crank as long as I will try. It just won't fire. As it's turning, it'll sound like one or two plugs spontaneously fires and the engine will jerk a little, but it just won't start.

 

[Maxion$Mulla$]

well you figure it has to be a sensor. Iv herd ppl talking about the crank posistion sensor keeping the car from starting but i dont think that would set off all of thoughs codes. Maybe your vaccume lines are clogged?? Or im thinking all of the wires on your o2 sensors have corroted off... just a though. good luk

 

[master486]

It turned out to be a combination of things. No sensors were bad. The cuplrits: bad plug wires, bad coil packs, and a 95% clogged exhaust from broken up cats.