NEED HELP 03 Trailblazer multiple codes

[TADave]

Hello, and thank you for this very informative forum.

Last week I bought an 03 Trailblazer, I6, 2wd with 155K miles on it. The truck hadn't had the best of maintenance over the years. When I bought it, it had a slight exhaust leak, a dead miss (sounds like 2 dead cylinders) and the exhaust smelled very rich.

Last night I ran a scan,
P0107
P0300
P0014

Today I pulled the CPAS, it was clogged, I replaced it with a new unit from a GM dealer.
I also installed new 41-103's (all 6 looked normal with slight deposits, #4 was cleaner than most) and inspected the coils and boots. (3 coils were original delco units, 3 were newer aftermarket). I also removed and cleaned the throttle body (with the battery disconnected) it was pretty bad as well.

Got it all back together and no real change in the way it ran. The miss, lack of power and smell were still there.

Re scanned it and P0300 and P0014 were still listed?

Next step removing coil wires one at a time, then a compression test.
Its worse at idle, seems to smooth out as the load decreases. I suspect the motor mounts are adding to the feel at idle. The exhaust leak is at the flange, so a doughnut gasket should fix that.

Any thoughts or advise? I'm new to this platform.
Thanks!

 

[djthumper]

How does the oil look? That will affect the CPAS.

 

[TADave]

Sorry, meant to include that. It was a fresh change when I bought it.
You could tell by the build up in the oil cap that it wasn't always done on time.

 

[djthumper]

Did you happen to do an motor flush? I meant to ask that as well. Mine was a rental so it does not have the oil life light, I run synthetic and if I forget to check it when it is starting to get old and gets too dark I get a P0014.

On the P0300 that is kind of a tough one at this point. I am not a fan of many of the aftermarket coils. My money is on cylinder 4 being the core of your problem.

 

[TADave]

No I didn't flush the motor, just learning that I should have. The oil itself is clean but I'm sure there is sludge on the inside.
I'll add that to the list for tomorrow. Thanks!

 

[triz]

You might have to do more frequent oil changes. Looks like they failed to perform proper maintenance.

 

[TADave]

Update for today.
I pulled the connector for the coils one at a time, I found #4 made no difference. I switched it with #3 and the dead cyl followed it.
Swapped in a new coil to #4, some improvement, still rough idle. Test drive now shows P0306, confirmed and P0014. So replacing #4 allowed the computer to locate #6 for me. New Coil in #6 and even better performance, and the smell went away, but still a rough idle.
I'm still getting P0014, even after installing a new CPAS and oil change. I picked up some mystery oil, I will change the oil again tomorrow and add 32oz of Mystery oil and drive it to see if it clears up.

Still open to all suggestions

 

[Mooseman]

Try cleaning or replacing the camshaft position sensor.

For the misfires, I never liked the aftermarket coils. Had one on mine that failed before the other originals. Put in a used original, still going.

 

[TADave]

Thanks! I actually picked one up on the way home from my sons basketball game this morning. I agree on the coils, but 6 new OEM coils aren't in the budget right now.

 

[TADave]

Update: 2.3
Installed the cam position sensor, runs even better now, but there is still a rough idle, hesitation off idle.
The CEL flashed for about a minute, a few minutes into the test drive, but went away and didn't flash again. (The code was P0300)

 

[Mooseman]

When it flashes, that means that the misfire is occurring. So probably a coil is still failing somewhere. I'd get another new coil and replace one at a time. If no change, return the one you took out and replace the next one. Eventually you will find the defective one. There may be more than one too.

 

[TADave]

I noticed something odd, cylinder 2, if I pushed the connector on all the way the coil would have a miss. If I pulled the connector slightly back the miss cleared up. Is this a known issue when the connector is going bad?
Thanks again!

 

[TADave]

Update 2.4
Tonight I finally got a cylinder code for the misfire, P0306, the same cylinder that I installed the new coil. Its intermittent, only misfires randomly. Wiring issue?

Thanks!

 

[Mooseman]

Is the new coil OEM? Swap it to another position and clear the codes. See if it follows.

 

[TADave]

Unfortunately no. impatience got the best of me and I took what the local store had.

I'm still curious about the cyl 3 harness/clip. When pushed on all the way the cylinder starts missing, if you pull the clip back off a little the miss goes away?

 

[Mooseman]

Could be that the contact pin inside is loose inside the coil itself or the connector is failing. Definitely something to investigate further. Swapping that coil would confirm one or the other.

 

[TADave]

Thanks, I'll do that today.

 

[TADave]

I re-tested the coils by removing the connectors one at a time. #6 and #3 stay dead even with swapping coils. I have new plugs so they're ok.

Can you replace the coil harness, or just replace the connectors?


Starting to get discouraged.

 

[BlazingTrails]

You could put a very slight twist in the tabs on the coil side? that may restore the connection. also you can probably buy replacement plugs and splice them in. I recommend soldering the connections but splicing is ok.

http://www.ebay.com/itm/GM-ACDelco-...ash=item3cfd9a1e34:g:ig8AAOSwd4tT0rSR&vxp=mtr

 

[TADave]

I have two ac delco connectors on the way, I'll solder them in and see what this brings. LOL

 

[Inferno333]

Are the pins inside the connector bad? If they aren't then you could try repinning the new connector versus cutting and soldering. That's always the preferable way.

I used to do repair on large John Deere tractors. Lots of electrical troubleshooting.

 

[TADave]

Well things didn't go my way. I trusted the seller, lives up the street from me. After replacing the coil plugs and no improvement I performed a compression test. I know better, and normally would have done this first, but...

1. 185
2. 185
3. 90
4. 188
5. 186
6. 35

Ran out of time tonight to pressurize the two cylinders to see where the leak is coming from. Hopefully its the valves and not in the shortblock.

What are heads going for now?

 

[Mooseman]

It's not so much the cost of the head but the work involved. Biggest headache is the bolts breaking in the block. There have been a few reports of bad valves usually causing this but a leakdown test will confirm this.

 

[Inferno333]

One of my DoD lifters broke and stuck a valve open.

I had to have all of them replaced. Few grand later and it's running good at the moment.