I bought a 2000 Blazer project in the fall. I replaced the intake manifold, started the engine and had seven codes. Been working my through this, and now down to one code. P1345 - camshaft/crank correleation

I looked at the crank sensor, and cleaned it.

When I reassembled the engine, I took my time with the distributor, using my own paint marks for alignment, and I think I put it in correctly. Or at least, in the same position as when I bought the vehicle. The task was kind of tough on my creaky back, so I would like to avoid doing it again if possible.

My question is this: Does the computer need to be connected to a scan tool to relearn the advance, even if the distributor is installed correctly? Or should I pull the distributor out and start over?

The engine seems to run fine, although the gas in the tank is about nine months old! I need to get this thing on the road.

Any input appreciated

 

P1345 means the distributor is off at least one tooth, (at least 25 degrees). If the engine starts and runs fairly well, (no backfiring through the intake or exhaust) it's easy to fix. The timing marks and the rotor must be in the correct position simultaneously. Using a socket & ratchet, manually rotate the crankshaft clockwise until the timing marks are aligned like in the image below. While turning the crankshaft, DO NOT rotate it counter clockwise.


With the crankshaft marks aligned perfectly, AND the distributor rotor is less than ~90 degrees from the "6" on the distributor housing:




If the rotor is not within ~90 degrees of the "6", rotate the crankshaft one revolution clockwise until the crankshaft marks line up perfectly again.

When the crank and distributor are aligned, then remove the distributor. DO NOT move the crankshaft while the distributor is removed. Re-install the distributor so the rotor points within ~5 degrees either way of the "6" when the distributor is fully seated against the intake manifold. You may need to rotate the oil pump drive shaft, (with a large flat blade screwdriver) so the distributor will fully seat. Fire it up, if the P1345 is gone, the distributor is meshed correctly with the camshaft. This is only a "rough adjustment" for the distributor. Camshaft retard must be checked and adjusted with a scan tool. The scan tool MUST be able to access streaming data for camshaft retard. The adjustment is done with the engine running by slightly turning the distributor while watching streaming camshaft retard data. Spec is zero degrees, plus or minus 2 degrees.

The P1345 doesn't set unless camshaft retard is off ~26 degrees or more. If it's off, lets say, 25 degrees, it will not turn the check engine light on, and the engine may seem like it's running pretty good, trust me, it needs to be within spec to run well


Camshaft retard aligns the Camshaft Position Sensor, (inside the distributor) with the camshaft, hence the name. The camshaft position sensor data is used along with crankshaft position sensor data to detect & accurately identify cylinder misfire. When camshaft retard is within specs, crossfire inside the distributor cap is kept to a minimum to prevent misfires and destroying the distributor cap & rotor, (which need to be AC Delco). When camshaft retard is within spec, the camshaft position sensor can be disconnected with no effect on engine performance, so, the camshaft position sensor can NOT cause a no-start condition. Rotating the distributor has nothing to do with ignition timing on this engine.

On another note, if you had the timing cover or crankshaft position sensor removed, the crankshaft position sensor relearn MUST be performed, again, with a capable scan tool.

 

Thank you very much captain! I will dive back into this project this week. Step one: get some advil, because my back does not do very well leaning over that engine!

 

I can relate to the back issues
If the engine is running as well as you say it does, it's probably only one tooth off. Each tooth on the distributor gear accounts for ~27.692 degrees of rotation. With that in mind, when you line up the crank marks, the rotor will only be off that same amount, give or take ~5 degrees. So if it's ~170 degrees off, that means you're on TDC of the exhaust stroke and need to rotate the crank 360 degrees clockwise. If you have any questions, just ask.

 

Captain,

I lined up the timing marks on the crank, pulled the distributor cap, and the rotor appears to be sitting dead on the "6." Should I pull the distributor anyway? Because right now it seems like I will be putting it back in the same position. Also, the rotor has a little play in it, a couple of degrees, and I wondered if that was normal.
thanks

 

Are both timing marks lined up just like in the image?

Is the flat side of the distributor facing forward?

Is the original distributor hold down bracket still attached to the distributor base?

Is the rotor pointing at the "6"? (Some of the 4.3 distributors also have an "8", gotta look close).

Did you clear the P1345 from memory, then briefly bring engine RPM above 2,000?

When you reassembled the engine, were the timing gears or chain removed or replaced? If so, were the "dots" lined up perfectly on the gears?

The P1345 will only set if camshaft retard is off more than ~27 degrees, so, if everything above is good, and the P1345 still sets, the outer ring on the vibration dampener may have slipped. If that's the case, when you line up the marks, #1 piston is not at TDC. You can pull #1 plug and stick a plastic drinking straw in the hole. Then have an assistant manually rotate the crank (clockwise) and feel for the piston when it arrives at TDC. Then check to see if the marks are lined up. The option to that is check camshaft retard on a scan tool to see exactly where it is, and adjust accordingly.

Play in the rotor: Normal to have up to .250" axial, (up and down). When the engine is running, the gears pull it down so the axial play is not a factor. The rotor will also turn a few degrees, in one direction, and rise up, normal. There can not be any radial, (side to side) play in the distributor shaft.

 

I am confident that both marks are lined up like the picture. As you warned earlier in the thread, my first attempt was not right, and I needed to spin the crank another 360 degrees. By this time, my 15 year old son was home from school, and he was my spotter on top. So I got to do a little bonding with the kid, which was cool.

I will check the other things in the light of day.

For what it's worth, when I clear the codes, and start the engine, the p1345 code pops up almost immediately, no need to spin up to 2000 rpms.

I did not get deep enough into the engine to reveal the timing chain, so I am hoping it is OK.
The original hold down bracket seems to be fine. Virtually idiot-proof, which is a good thing.

I should have been more clear about the play in the distributor: it rotates clockwise/ ccw a bit, maybe 3 degrees.

Thanks again, I am not throwing in the towel just yet!

 

You mentioned it runs pretty well, and no other DTC's are present, so from that, short of pulling the front end apart, we have to "assume" the timing chain & gears are ok, and that it's timed correctly. Which brings us back to a slipped vibration dampener. Which is no big deal, but we need to get that P01345 to go away. Try the business with the straw and see what you find, (more bonding time) that will tell if the dampener has slipped. OR, either put it on a scan tool and check camshaft retard, which we already know it's out of spec, or pull the distributor and experiment one tooth in each direction until the P1345 goes away.

 

I did some testing, and I guess I am "inconclusive" right now. I advanced the distributor one tooth, and could not get the engine to fire. Then I retarded it one tooth back, and the best I got was a half hearted fire, would not stay running. Then I put it back on the gnats ***, and it fired right up, producing the same code.

Had a heck of a time lining up the oil pump with each attempt. Poking with the screwdriver - a little of that goes a long way. As I was beginning to curse, U2 came on the stereo with "I still haven't found what I'm looking for." I had to laugh, and that tune produced a calming effect. I suppose I might run it up the shop for a scan, based on what you have suggested. Does that sound wise?
thanks

 

What is the CMP Retard value as displayed by a compatible scan tool?