Yet another P1345...2002 Trailblazer

TailGazer

Original poster
Member
Jul 19, 2015
11
Hello!

So I've been googling and reading about P1345 all day, and I thought I'd give this forum a try before I hand over a wad of cash to a shop.

A little back story:

About a year ago the SES light came on, and the engine started running very rough. Took it to a shop (we were on a road trip) and they diagnosed that the CPAS was bad, and replaced it (plus oil change.) I believe it was P0014 back then. 10 days later, light comes back on. Wife took it to a shop (I was out of town) and they diagnosed a faulty crankshaft position sensor, and replaced that. A few days later...light back on. I managed to sneak it through emissions testing so I pretty much have been ignoring it for a year. I know, bad idea. I'm not nice to cars. But it runs mostly fine, a little rough on idle and not very good gas milage.

Well, registration time has come again, and that means I must make amends. I took it for an oil change, had them read the codes.
No P0014 but the beloved P1345 came up.

The camshaft position sensor hadn't yet been changed, so I changed that. Bought myself an OBD2 bluetooth scanner, cleared the code. Start the engine, P1345 comes right back up.

In summary: CPAS & crankshaft position sensor changed out a year ago, camshaft position sensor changed today. Still P1345.

The way I see it, my only recourse is to try changing out the CPAS again (maybe it was one of the cheap Dorman ones) and hope for the best. Every other possible cause (phaser actuator, timing chain, crank shaft, other?) is going to cost me a bundle.

Is that about right?
 

gmcman

Member
Dec 12, 2011
4,656
Welcome to the site.

First thing....what is the maintenance history? Mainly oil changes, how often, what type, are you the original owner?

When the engine is running, mainly at idle, do you hear any rattling around the front black plastic cover where the oil fill cap is? First thing I would do is make sure you don't have any loose wires at the camshaft position sensor. Remove the plug and check the pins, take a pick and see if they are all secured...ie, don't push back into the harness.

Seems odd that you replace the sensor and it's fine for a day, that may rule out a loose timing chain tensioner allowing the timing to skip a tooth.

Next step if that doesn't fix it is to pull the front cover where the oil fill plug is, not to hard. You will need to verify that the timing marks are aligned and that's easy to do also. The two dark links should line up on each sprocket at the timing dots.

If you want to save money, this is what you need to do, otherwise you will be out a few hundred at the shop to find out the same info.
 

TailGazer

Original poster
Member
Jul 19, 2015
11
I would say the maintenance history is probably not good. We inherited the vehicle from the in-laws, and I'm not sure how well they kept the oil chance schedule. Since having it one year, I changed it shortly after taking possession, and 2 days ago. So once in 8/14 and once in 7/15. On the last change they put was "Premium Synthetic-Blend" 5w30 in there but I have no idea about prior changes. It's probably fair to say the vehicle has been abused somewhat on the oil front.

By the way, it has 108k miles.

When the TPAS was changed out a year ago, the SES light stayed off for about 10 days. After the crankshaft position sensor what changed out, it stayed off for a few more days. Changing out the camshaft position sensor seemed to have no effect, though amazingly the bolt securing the CPS was not tight. Is it possible the PCM has to "relearn" something?

I've read the tech notes about the #1 cylinder at TDC and verifying the timing marks aligning with the dark chain links, but it seems like quite a bit of work to pull off the front cover as this actually involves removing the camshaft cover, if I understand things correctly. Also, it seems unlikely that the timing chain suddenly would't be aligned as per factory at 108k miles if no engine work has been done on that level - does the chain jump sprockets? Perhaps the tensioner is malfunctioning?

I'm going to pull the TPAS out and have a look, make sure that dirty oil hasn't appeared to compromise it. And clean all the sensor terminals. I have a feeling I'll still be looking at a P1345 at the end of the day though...
 
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gmcman

Member
Dec 12, 2011
4,656
It's been awhile but I think you're correct, the valve cover needs to come off as it's all one piece.

Forgot to ask....when you changed your crank sensor, did you get a CASE relearn? This is mandatory.
 

TailGazer

Original poster
Member
Jul 19, 2015
11
That I don't know, as it was done at a shop a year ago. I would assume they did? I suppose I could call them tomorrow and see if they have that on file.

Is a CASE relearn required when you change out the cam position sensor, or CPAS? And if you don't do one, is P1345 the expected code to come up?
 

gmcman

Member
Dec 12, 2011
4,656
The CASE relearn is required if the crank sensor is removed. This needs to be done with a GM Tech 2 scanner or a shop with a compatible scanner. If the crank sensor was removed at a later date then it will need another CASE relearn, same as if the PCM was replaced. This is not required with a cam sensor or CPAS solenoid removal.

I would first focus on loose or broken wires on the cam sensor. Did you ever change your serpentine belt? reason I ask is the cam sensor is just in the right spot for a breaker bar or other tool to whack it if someone isn't careful. I disconnect my harness before removing the belt for this very same reason.
 

TailGazer

Original poster
Member
Jul 19, 2015
11
I have never changed the serpentine belt, but I they would have to have loosened it at the very least to move the steering pump out of the way when they changed out the CPAS a year ago. I didn't see any broken wires on the cam sensor, but I'll check again today.

As a small rant, I don't understand why the firmware engineers don't include additional diagnostic information. For instance, with the P1345 code I understand that the computer has detected a difference of greater than +-2 degrees between commanded and sensed camshaft/crankshaft angle, so it would seem logical to record exactly what difference if measured, for how long, and under what circumstance (e.g. "commanded 6.5 degrees retard of the exhaust cam phaser, measured 8.6 degrees for 3 seconds" or "didn't command any movement of phaser, but measuring continuous variance of +-3 degrees in CKS" etc.) so at least we can know why the PCM doesn't like what it is seeing. Any idea why they don't do this, other than hoping for consumers to spend thousands of $ on "servicing"?
 

Mooseman

Moderator
Dec 4, 2011
25,260
Ottawa, ON
When I got that code on my TB, I did the same as you. I eventually tracked it down to the camshaft phaser itself. Once I changed it, all was good until I had to change the timing chain tensioner a couple years later and it came back. I might have damaged it when I removed it. It seems to work fine when I command it with the Tech 2 so I had the code disabled via a tune. Truck runs fine and passed the e-test.
 

gmcman

Member
Dec 12, 2011
4,656
You could try some BG oil treatment and see if that helps. With your infrequent oil changes, there's a chance there's buildup inside the cam phaser which has very tight tolerances.
 
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TailGazer

Original poster
Member
Jul 19, 2015
11
I was thinking the phaser as the next suspect. I would image with a tech 2 scanner you could command the phaser and see what happens. Would this be an adequate test? Is there a way to "flush it", perhaps by working it back and forth repeatedly with the CPAS until new oil flushes out the old?

I'm amazed how difficult the auto industry has made this. I should be able to hook up any laptop to the PCM with a USB port (hell, make it wireless!) and talk to the damn thing, and it should tell me everything. But I suppose that would put a lot of dealer shops out of business.
 

Mooseman

Moderator
Dec 4, 2011
25,260
Ottawa, ON
All auto manufacturers want to keep that to themselves with special scanners (i.e. Tech 2) so they can legally pickpocket you by forcing you to come in. It's legalized mafia if you ask me.

I wouldn't even try to flush that thing. Have you checked the CPAS recently? Maybe it got gunked up after the oil change.

It's a fairly involved job to replace the phaser. Took me a whole day.
 

TailGazer

Original poster
Member
Jul 19, 2015
11
So I took it to the dealer, and sure enough, they say it's the cam phase actuator. Now I knew pulling this thing out and replacing it was a big job, and they definitely confirmed that...to the tune of $3k. Apparently they also replace a few other things like the timing chain, water pump, and some other stuff as a matter of course, because I guess that's what you're supposed to do when you pull the front off.

Is $3k reasonable for a job like this? I expect to get a bit reamed by the dealership, but I'm not sure how much reaming is reasonable.

I asked them to price just putting a new engine in, which I can't image costs much more, and then at least I'd get a 100k mile warranty. What should I expect this to cost?

Any advice?
 

Texan

Member
Jan 14, 2014
622
I think gmcman in post #9 has a good suggestion.
Put a engine oil treatment such as KW or MMO (marvel mystery oil)
in the crankcase and drive a few hundred miles, and see if that
will solve the problem.
 

djthumper

Administrator
Nov 20, 2011
14,950
North Las Vegas
What dealer did you take it to?

I usually do an engine flush when I change the oil to help keep the build up down in the engine. Especially since my oil changes are not that often anymore.
 

TailGazer

Original poster
Member
Jul 19, 2015
11
The chevy dealer in town. They appear to be a fairly major one, servicing most of the area I live in.

Edit: Just noticed you're in Vegas too. Took it to Henderson Chevrolet on Gibson.

The oil treatment idea sounds appealing, does anyone know if this has successfully cleaned up a cam phase actuator before?

In any event, unfortunately I don't have huge amount of time to resolve the problem, as registration is coming due. I might just have to take it in the shorts.
 

djthumper

Administrator
Nov 20, 2011
14,950
North Las Vegas
There are 4 major Chevrolet dealers in town so to take it to the Chevy dealer in town isn't like taking it to a small town dealer. I would take it in for a second opinion.

When is registration due?
 

TailGazer

Original poster
Member
Jul 19, 2015
11
Aug 21. So I have a month. But we are going on vacation in 2 weeks, so I'm hoping for a resolution before then.

I took it to Henderson Chevy on Gibson.

I saw that thread, and a few others, which prompted a call back to the dealership requesting a detailed description of the work they are proposing. It seems like they wanted to do a whole lot more than seemed necessary, but then again I'm no expert. I'm still waiting to hear back.

A quick google search into MMO seems to suggest that it's just mineral oil (74%), mineral spirits (25%) and lard (1%) with little other than anecdotal evidence that it does any good at all. Not that I'm against trying a $10 solution over a $3000 one, but I don't think my expectations would be terribly high given there aren't thousands of stories about how this stuff fixes cam phaser actuators (which I would expect if it actually did so.)
 

djthumper

Administrator
Nov 20, 2011
14,950
North Las Vegas
I have never been a big fan of Henderson and fairway... Too bad you weren't near Bozarth or Finley. I have had great customer service at both.
 

TailGazer

Original poster
Member
Jul 19, 2015
11
Do you mean Findlay? I'm probably just as close to them as Henderson.

Do you think they are better?
 

djthumper

Administrator
Nov 20, 2011
14,950
North Las Vegas
I know I have gotten much better service out of them in the past. I have driven across town to pick up parts from them and not have to deal with Fairway and Henderson. They are both owned by the same people. If I had a Tech2 I would tell you to come over to check it out and the firmware in the PCM. There have been a few reports of needing the firmware updated to fix a similar issue.
 

TailGazer

Original poster
Member
Jul 19, 2015
11
I've not seen that, is there a tech bulletin about the PCM firmware? Seems odd that it should work for 100k miles and then stop.

Yeah I wish I had a Tech2 as well. I'd like to see for myself the cam phase actuator failing to move into the command position. I don't even know for sure if they actually ran that test, rather than just looking up the code and concluding "replace the actuator."
 

Mooseman

Moderator
Dec 4, 2011
25,260
Ottawa, ON
They are fleecing you if they say they have to replace the timing chain. That's a super big job, I did it and would rather cut my thumb off than doing that again. For the phaser replacement job, you need to replace:

- Phaser (obviously)
- valve cover gasket
- intake manifold gasket

You don't even need to remove the fan or shroud or even open the cooling system. You do need either a wedge tool or the hook tools to keep the tension on the chain while the phaser is out. IF you happen to need a new water pump, then the extra room is nice but not necessary. All you're removing really is the intake manifold and valve cover to get to the phaser.

I haven't seen anything about an update to correct an issue with the phaser or valve timing but as mentioned, why would it work fine until now?
 
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gmcman

Member
Dec 12, 2011
4,656
I would go by a dealership and ask for their BG oil treatment their stuff is pretty strong. Marvel Mystery Oil is good but I would try any of the BG stuff first
 
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gmcman

Member
Dec 12, 2011
4,656
Another option is after you used the BG oil treatment, is to run some Auto Rx through it. I believe it's mail order but has quite a following. The Auto Rx takes longer to work but alot of people swear by it. I would try anything before I started pulling the top end apart.
 

TailGazer

Original poster
Member
Jul 19, 2015
11
To follow up and in the interests of closure, here's what happened:

I went ahead and had the dealership do the work they recommended. The culprit, it seems, was one of the timing chain guides. The plastic guard had somehow broken off, and the chain had completely worn through a large portion of the guide, leaving a big gash where there should be metal.

This led to 1) the chain being too slack, as the tensioner could not keep it tensioned even at full extension and 2) a lot of metal bits apparently in my oil pan.

So they replaced the guides, and for good measure (since the engine was already torn apart anyway and the miles warranted it) the timing chain, tensioner, and cam phase actuator, and probably some other stuff as well (like the water pump, which apparently was leaking.) The thinking was that as labor is 2/3rd the cost anyway, might as well change things out while we can. Also, the fairly likely the actuator was damaged as well - though come to think of it I never really got confirmation of that.

It was a big costly job, but hopefully the right choice. I've been told that I should easily get another 100k out of this engine.

So there you have it.
 

Mounce

Member
Mar 29, 2014
13,667
Tuscaloosa, AL
Should've been able to get 100k+ more out of it without that work but still will with the work. Thanks for checking back and letting us know what went down.
 

Mooseman

Moderator
Dec 4, 2011
25,260
Ottawa, ON
First time I've heard of such a failure. Mine only had a bad tensioner making the chain flop onto the chain guide above the two cam gears while idling. The tensioner couldn't hold the tension without the oil pressure.

Did they show you the old parts or give them to you? Would be interesting to see the damage.
 

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