Solving P1345 on a 1999 Suburban

[V-8Fan]

I developed this persistent P1345 code on my '99 Suburban a few weeks ago and had done some searching for solutions on the web. Surprise, surprise...I ended up right here in these forums.

There had been numerous threads where it is revealed that
1. the P1345 code means that the camshaft and crankshaft appear to the computer to be out of sync,
2. the distributor drive gear wears prematurely on 5.7s in Suburbans (perhaps others too? Why NOT?) for the years '98 and '99 and maybe other years during this era, and
3. you do not set ignition timing on these vehicles as was done in the good ol' days and special equipment is required.

So, I ordered a distributor drive gear and a camshaft position senor. I do not have any sophisticated diagnostic equipment other than an ordinary OBD2 code reader. When I set out to tackle the installation of the new parts I knew I had to be very cautious and deliberate.

I removed the ignition wires from the distributor cap and used a straight edge to index the distributor cap via a pencil mark on the firewall. As it turned out, this got me in the ballpark. I then removed the distributor cap from the distributor and noted the position of the rotor.

Next, I removed the distributor entirely. I removed the old rotor and drove the roll pin out that secures the gear to the shaft of the distributor. The gear was definitely worn. Since the gear can be put on the shaft in either of two positions, I made note of how the original gear was installed on the shaft and then installed the new one.

When I began to put the new rotor on the distributor it appeared as though it could go on two different ways, but this was not so. I put it on the only way it can go. Then I began installation of the distributor back into the engine. I had made note of which way the rotor was pointing when I removed the distributor, and danged if the assembly didn't want to go back in the way it was supposed to. I think the oil pump rotates very easily so I had to keep fiddling with it until the distributor fell into place with the rotor oriented as it was before I removed it. I finally accomplished this.

I put the distributor hold-down clamp back on snugly, but loose enough I could still turn it by hand. Then I put the new cap on and oriented the whole thing in accordance with the mark I had made on the firewall using a straight edge. I then reconnected the ignition leads and fired the beast up.

Satisfied that it would run, I cleared the P1345 codes. I then started the engine, whereupon the code reappeared. I twisted the distributor ever-so-slightly clockwise, cleared the codes, and fired it up again. The code reappeared. I kept twisting the distributor clockwise and clearing codes and they kept reappearing, so I then started moving the distributor counter-clockwise. After a few repetitions of the cycle I finally got the distributor positioned so that the code does not come up any more.

I really would rather have the equipment to make sure the distributor is perfectly positioned, but I do not and I was able to make do with less.

Maybe this will help someone else deal with this P1345 code.

[777stickman]

Very interesting. Glad you got it going. You might consider talking with a good local repair shop to get the "base timing" (cam offset/cam retard) checked. Should be 0 +/- 2degs @ 1200 rpm.

[V-8Fan]

Since there is no longer a P1345 code being set, I am inclined to believe that the distributor is now positioned within specifications.

[j cAT]

Originally Posted by V-8Fan

Since there is no longer a P1345 code being set, I am inclined to believe that the distributor is now positioned within specifications.

you did a very good job of repairing this issue ...using the fixed pointer to the mark on the distributor cap will get you very close.

even when I can adjust the timing using the distributor marks make it easier to get the engine going .

I have found many recommend only using the OEM GM cam gear ...other part makers use, a material that has damaged the cam shaft gear.

this usually don't take too log to occur...

since the code is gone I agree it's good..don't take much to throw this code when timing is off...

[V-8Fan]

Thanks, j cAT. I appreciate the complement.

Actually, I had absolutely no trouble getting the engine to run after the distributor repair. That may be due in part to the fact that the vehicle ran fine before I undertook the fix...I'd never have known anything was amiss had there not been the SES light (I do think the thing is running a little better than it did before, though). I hate the damned things when they're on, but getting them to extinguish is so satisfying that it's almost worth it.

I had not heard anything bad about any of the replacement drive gears, but it has been my philosophy for some years now that I am best off using OEM parts if they're available so I ordered an AC Delco replacement gear (and cap, rotor, and camshaft position sensor). Good choice, huh?

[slo99sierra]

Thanks for the write-up...My 4.3 is throwing P1345 and I just ignore it (because it runs good) but I may have to tackle this when I have time.

[Rafaeldavid1]

Good day and thank you for your post, I also have a 1999 Suburban (k1500) with the 5.7 engine and we are having the exact same problem. Originally the only reason we replaced the distributor is because we were in the process of replacing spark plug wires and noticed that there was no screw holding down the distributor cap, it was glued! The last people to work on the truck 3 years ago were Pep Boys and they striped the screw and instead of curing the problem they just glued it. Since I use this truck strictly for the desert I decided I could not ignore the issue so I ordered a new distributor online. I didn’t go with the factory distributor because of the cost and it’s an old truck, I bought a Cardone distributor it had really good reviews. We installed it and the truck as before ran great but the P1345 code emerged. We tested everything and thought it was a bad distributor so we ordered a replacement one, it arrived and we installed it and again the P1345 code emerged.
Since I couldn’t get to the bottom of it I sent it to a buddy’s shop who does everything including rebuilding engines and has scan tools etc, and they can’t seem to get to the bottom of the issue.
My question is: from what I can tell in my Suburban you cannot turn the distributor to adjust the timing; it only drops in one way so I don’t see how turning the distributor clockwise can help cure the issue. Please any help would be appreciated my buddy at the shop is thinking bad computer etc. but the truck ran perfect before any of this began.
Thanks in advance,
Rafael

[Rafaeldavid1]

Good day and thank you for your post, I also have a 1999 Suburban (k1500) with the 5.7 engine and we are having the exact same problem. Originally the only reason we replaced the distributor is because we were in the process of replacing spark plug wires and noticed that there was no screw holding down the distributor cap, it was glued! The last people to work on the truck 3 years ago were Pep Boys and they striped the screw and instead of curing the problem they just glued it. Since I use this truck strictly for the desert I decided I could not ignore the issue so I ordered a new distributor online. I didn’t go with the factory distributor because of the cost and it’s an old truck, I bought a Cardone distributor it had really good reviews. We installed it and the truck as before ran great but the P1345 code emerged. We tested everything and thought it was a bad distributor so we ordered a replacement one, it arrived and we installed it and again the P1345 code emerged.
Since I couldn’t get to the bottom of it I sent it to a buddy’s shop who does everything including rebuilding engines and has scan tools etc, and they can’t seem to get to the bottom of the issue.
My question is: from what I can tell in my Suburban you cannot turn the distributor to adjust the timing; it only drops in one way so I don’t see how turning the distributor clockwise can help cure the issue. Please any help would be appreciated my buddy at the shop is thinking bad computer etc. but the truck ran perfect before any of this began.
Thanks in advance,
Rafael

[j cAT]

bring to a repair shop that can set the timing to zero..

[777stickman]

The P1345 code is very simple. The "base" timing is off by more than 3-4 degs. This is a crank sensor vs cam sensor correlation issue. I have never seen a bad VCM throw this code, nor a new fix it.

With a proper scan tool, not a code reader, base timing can be set by accessing "Cam Retard" or "Cam Offset" or something very similar to that.

The Dist, if installed properly, will get you close. It should also have a +/- 5-6 deg rotational adjustment.

Base timing is 0 degs +/- 2 degs at 1200 rpm.

[Rafaeldavid1]

Originally Posted by 777stickman

The P1345 code is very simple. The "base" timing is off by more than 3-4 degs. This is a crank sensor vs cam sensor correlation issue. I have never seen a bad VCM throw this code, nor a new fix it.

With a proper scan tool, not a code reader, base timing can be set by accessing "Cam Retard" or "Cam Offset" or something very similar to that.

The Dist, if installed properly, will get you close. It should also have a +/- 5-6 deg rotational adjustment.

Base timing is 0 degs +/- 2 degs at 1200 rpm.

Thank you I will absolutely due that Ill let you know how we end up.