"CMP Retard" on Vortec 7400 for P1345

[rationull]

Got a CEL with code P1345 ("cam sensor/ crank sensor relationship error") today on my Suburban with the Vortec 7400 engine. Finished putting it back together after replacing the LIM gasket a couple weeks ago and apparently I didn't put the distributor in quite exactly right (at least that seems like the most likely cause).

The truck runs just fine, and has about 200 miles on it since getting it put back together, so the timing must be close. I cleared the code and it hasn't come back on yet (only about 15 miles of driving since clearing it).

Now, in order to adjust the timing on this engine you're supposed to use a scanner to monitor "CMP Retard". All I have is a generic OBD2 scanner (ScanGauge2). I'm guessing if I had the specs I could read this w/ the ScanGauge's "XGauge" custom PID functionality, but I don't have and haven't been able to find any details. I do have XGauge info for a "Knock Retard" PID but that doesn't seem to return any data on this vehicle.

I'm debating whether the best thing would just be to take it to a shop and have it timed w/ a "real" scanner, but if it's so close already it seems like a lot of trouble to go to. Any recommendations for scanners that will read this?

I'm also half tempted just to adjust it a little and see if there are any changes, but I'm not sure that's the best idea since I don't know in which direction it's off.

 

[rationull]

The pickings seem slim for scan tools that will read CMP Retard. Looks like the cheapest option is the stuff sold by scantool.net, but even that would end up at least around $250. Would be nice to be able to do it myself, but it would probably be cheaper just to take it to someone. Hmm...

 

[rationull]

What irks me most about this is that the Scangauge2 actually has the ability to send/receive whatever custom PIDs you have coded (the XGauge feature). If I could find PID code info for CMP Retard it's possible I could make this work without buying anything else. Haven't been able to find it yet, though.

 

[AVB]

The cmp retard actually has nothing to do with the ignition timing, but it sets your fuel injector timing. The engine speed needs to be held above 1100 rpm for the reading on the scan tool to be accurate to set the cmp retard. I have heard of people setting them with out a scan tool. Trucks can run suprisingly well with the cmp off, but they do run better when set correctly. The setting should be between -2 to +2.

 

[rationull]

Yeah, I get the process (it's actually documented pretty well in the Chilton's manual), but getting the CMP Retard reading seems to be a little difficult since it's such a niche, GM specific code.

Maybe it would be worth just turning it a little and seeing what happens, but I'm nervous about moving the dist at all without being able to measure it, since I already put it back in as best I could and apparently it's off. Will be much more of a pain to rotate it and retighten now with everything back together.

 

[AVB]

Yeah, I tried to find a scan tool for a friend of mine who is working out of state that would display the cmp setting. I didn't find any of the cheaper generic scan tools that were able to. We have a old OTC Tech/ForceII at my shop that does. We have the only Tech/ForceII I have ever personally seen. I am guessing it was a earlier generation of the Genesis scan tool because it looks similar.

 

[wtd]

I have an AutoXray 6000 scan tool that reads CMP retard but this is not a very cheap scan tool. I would just take it to a shop and have them do it. It doesn't take very long to do with the correct scanner. To get it to run correctly and to keep the CEL off, you will have to set it correctly.

Wayne