Throwing codes

gthphotography

Well-known member
Aug 27, 2008
317
3
chicago
www.greghanrahan.com
Hey guys, I really need your input. I just finished putting the engine back in the truck. Before I took it out, I had two codes, p0304 and a code with no number associated with it. Now I have them again.
Things that I replaced while the engine was out:
Plugs
Wires
Injectors
Maf

I did not change the coil
I did not change the 02 sensors

What am I looking at? Coil? I know the 02 sensors are going bad because of the misfiring and rich running from before I pulled the engine.
And why a code with no number?
 

squirt

Well-known member
Nov 13, 2008
824
13
Los Angeles
What is this code with no number? How do you know it exists if you don't have a number? What's the description from your reader?

Swap the coils side to side as a diagnostic step. If no joy, then I'd start thinking about the cam/lifter condition or possibly wiring to the injector..
 

gthphotography

Well-known member
Aug 27, 2008
317
3
chicago
www.greghanrahan.com
What is this code with no number? How do you know it exists if you don't have a number? What's the description from your reader?

Swap the coils side to side as a diagnostic step. If no joy, then I'd start thinking about the cam/lifter condition or possibly wiring to the injector..

code reader says two codes
only gives the code for p0304
reader is getting fixed
new coil is coming

if it were my cam, what would it look like when the piston is going up and down?
While the heads were off getting cleaned, I spent a lot of time cleaning the short block. This involved turning the engine by hand, and I will say that all the pistons rose and fell the same amount and it wasn't a difficult process, everything moved smoothly.
Now a lifter I get. I chose to not replace them.

Thank yoy for your help.
 

gthphotography

Well-known member
Aug 27, 2008
317
3
chicago
www.greghanrahan.com
UPDATE:
just finished looking at the coils. It appeared that my #6 and #4 HT leads were plugged into the wrong port on the coil.
I swapped them adn now I'm getting p1300 p0304 p0306. Any idea on the 1300? It's really rough. Now I expect my adaptive values to be off and need resetting. And I'm pretty sure the O2s are gone. I'm rechecking connections now.
 

gthphotography

Well-known member
Aug 27, 2008
317
3
chicago
www.greghanrahan.com
UPDATE to the update:
so i have no idea how this happened, but i just swapped 4 and 6 at the plugs and the codes are gone. i am thoroughly confused. LMAO.
hopefully they don't come back. the exhaust reeks, and for some reason i'm spitting coolant out at the heater core connector (no matter how many times i calm it down).
 

Rob371

Well-known member
Nov 29, 2016
150
1
Charlevoix, Michigan
Just a tip, codes have priorities. Start with the low number and work your way up. For example, if you have a misfire then you possibly have a rich condition because of un-burned fuel which may be setting the O2 code. The ECM cannot compensate for the un-burned fuel so it throws an O2 code. Or maybe it is lean because injector is not firing, is plugged or restricted and it throws an O2 code. So the fault might be an injector problem and the symptom is a misfire with an O2 code. Replace the O2 sensors but you aren't fixing the fault so you still get an O2 code.

It could potentially be worse, valve trouble, cam lobe worn, broken rings, cracked piston, coolant in cylinder, etc... Those will often have other symptoms like milky oil, excessive blow-by and oil consumption, popping through intake or exhaust. Could even be a cracked spark plug or defective plug. It happens. New doesn't always mean good. What does the #4 plug look like? Black and/or wet is rich, white is lean, medium brown is ideal. What do the other plugs look like? Inspect the porcelain closely. Very easy to crack a plug during install. Is there a line that won't wipe away in the porcelain, or an edge you can catch with fingernail?

Did you try rotating the coils to see if fault follows the coil?

Compression good? No sensor or coil will fix low compression.

The O2 sensor are really just sending info to ECM to do the fine tuning. They can't compensate for big variations. The ECM has inputs and outputs. The outputs are just that, turn on a solenoid (injector for example), switch, relay, etc,... but the ecm, depending on vintage, generally has no way of knowing if the solenoid, switch, or relay actually performed it's job so it has downstream sensors that may be throwing codes due to what is occurring upstream. The codes will appear in order of priority on your scan tool. Go from A to Z and don't skip over anything in the middle. Do it any other way and you may be wasting time and money.

Secondary firing voltage? That's in a different lesson.
 

gthphotography

Well-known member
Aug 27, 2008
317
3
chicago
www.greghanrahan.com
Just a tip, codes have priorities. Start with the low number and work your way up. For example, if you have a misfire then you possibly have a rich condition because of un-burned fuel which may be setting the O2 code. The ECM cannot compensate for the un-burned fuel so it throws an O2 code. Or maybe it is lean because injector is not firing, is plugged or restricted and it throws an O2 code. So the fault might be an injector problem and the symptom is a misfire with an O2 code. Replace the O2 sensors but you aren't fixing the fault so you still get an O2 code.

It could potentially be worse, valve trouble, cam lobe worn, broken rings, cracked piston, coolant in cylinder, etc... Those will often have other symptoms like milky oil, excessive blow-by and oil consumption, popping through intake or exhaust. Could even be a cracked spark plug or defective plug. It happens. New doesn't always mean good. What does the #4 plug look like? Black and/or wet is rich, white is lean, medium brown is ideal. What do the other plugs look like? Inspect the porcelain closely. Very easy to crack a plug during install. Is there a line that won't wipe away in the porcelain, or an edge you can catch with fingernail?

Did you try rotating the coils to see if fault follows the coil?

Compression good? No sensor or coil will fix low compression.

The O2 sensor are really just sending info to ECM to do the fine tuning. They can't compensate for big variations. The ECM has inputs and outputs. The outputs are just that, turn on a solenoid (injector for example), switch, relay, etc,... but the ecm, depending on vintage, generally has no way of knowing if the solenoid, switch, or relay actually performed it's job so it has downstream sensors that may be throwing codes due to what is occurring upstream. The codes will appear in order of priority on your scan tool. Go from A to Z and don't skip over anything in the middle. Do it any other way and you may be wasting time and money.

Secondary firing voltage? That's in a different lesson.

Thanks for the info.
I did have the heads machined and cleaned etc. Did a lot to the engine. All the cylinders are great.
I had P0304 before puling the engine out.
After putting the engine back in, I looked at the HT lead diagram, and I had thought that I swapped 4 and 6. I thought, 'ah ha!', that's the issue. So, my thinking was as such......
1-keep the current coils, and put the HT leads on correctly, if 0304 comes back then it's a bad coil. (all new wires and plugs)....this is my current situation
2-put in new coil and see if I throw codes (this is what I am going to start).....if no codes, then great, no prob. If code comes back, then try injector connector (all newish cleaned and checked injectors)
3-put in new injector connector.......if no codes, great, if 0304 comes back, then I'm stumped.
4-put in new O2 sensors (my driving with a heavily rich environment has fouled them I fairly confident

the O2 code is new. It shows up first.
 

Rob371

Well-known member
Nov 29, 2016
150
1
Charlevoix, Michigan
An inexpensive testing device is a "power/ground test light". It has two clips for connecting to battery power and ground. It has two LEds in it. Once connected an LED is illuminated red to verify it is on.

Touch the tip of test light to power and now another secondary LED shows red, touch it to ground and the secondary LED shows green.

When key is on there should be red LED on one side of injector connection. When cranking or engine running the ground side green light should be flashing.

The expensive version of this is called a NODE light and it plugs into the injector harness connector and does pretty much the same thing.

This light can also be used on 5 volt circuits in the same manner. This is how I test ECMs for driver failures. It's just another way to verify what you think before purchasing an expensive part.