A few months ago, the SES light went on in my Jimmy, which turned out to be a P1345. Other than the light, there wasn't any issues with how the truck was performing. The light went off soon after, then came back with the same code, then turned off again. Haven't gotten the same code since then, which was a few months ago. Now, a few weeks ago, the SES light came on again, now with a P0300. I have rough acceleration, and at highway speeds there is a lurching or jerkiness to the way the engine is running, which causes a vibration. Also, there is no overdrive, which I have read on here is probably due to the misfire. A few days ago while on the highway the light actually flashed for around a minute or two, which was troubling. The P1345 code has not reappeared.

While trying to solve a different misfire issue about 4 years/20,000 miles ago, a mechanic replaced the following: spark plugs, wires, rotor, distributor cap, fuel filter, PCV, ignition module/coil, MAF sensor, and finally, the fuel injection assembly, which was the culprit in that case.

I am thinking that there might be something wrong with the distributor, maybe worn shaft or gear or something. Does this sound right? It's odd that the P1345 hasn't returned though. I'm going to test the fuel pressure to make sure that's alright, and replace the fuel filter while I'm at it. I don't want to jump to conclusions, so I'll run through the article on P0300 on this site to try to eliminate other things.

 

Boy, the random 300 code. Search the site & see what you find.

 

About 4 years ago, had the same problem with my '97 (which has had an additional EEM put in to no avail).
I had replaced the the distributor, cap, rotor, coil,cam sensor, and still got the 1345 code, along with 0300s. Took it to a local mechanic, who replaced my cap and wires.
It's still going strong today. Puzzling, but the mechanic said I had a bad cap.

One other possibility is you may have the distributor off by one tooth (or the timing chain jumped 1 tooth). Highly unlikely if you didn't take the dist. out, but depending on milage, the chain is a possibility. A timing light would verify if the timing is off.

 

Thanks for the replies. The only thing I don't understand is why the P1345 hasn't reoccured since those two times a couple of months ago. If the timing was off would this code be constant?

 

When my 97 had a bad distributor the light came on & did not go off until distributor was replaced. But check & see if you have any play in the distributor top bushing. If you can move the rotor side to side. The distributor has a plastic housing & they can be tricky.

 

Crap. I had hoped the two codes were related and it would be a straight forward repair. Maybe not the case.

 

P1345 sets when camshaft retard is off by ~27 degrees or more. Apparently it's close to that or the light would remain on. Worn distributor bushings and/or worn distributor gear can cause an intermittent P1345. A capable scan tool is required to view camshaft retard data. Spec is zero degrees +/- 2 degrees at 2000 RPM. Rotating the distributor adjusts camshaft retard by aligning the camshaft position sensor to the camshaft. When P1345 is set, it can also cause P0300 to set due to crossfire in the distributor cap. Camshaft retard directly affects ignition timing that the PCM can apply: if camshaft retard is incorrect, ignition timing is incorrect. A timing light is an obsolete tool on this engine, there are no index marks on the dampener or timing cover. Ignition timing is viewed on a scan tool only.

 

Very informative, thanks. IF the distributor is worn like you say, does this mean that in order to install a new one that I would have to use the procedure that assumes the crankshaft has been turned? In other words, since the timing is possibly close to being outside tolerance at the present, would that mean the timing would have to be reset when installing a new distributor? Is a fancy scan tool needed to verify this is done correctly?

 

In this case, I would manually turn the crankshaft clockwise, (using a socket and ratchet) until the distributor rotor lines up with the "6" in the distributor housing as shown below:





AND both marks on the dampener and timing cover are lined up as shown below:




Then replace the distributor, making sure the rotor is aligned with the "6" when the new distributor is fully seated against the intake manifold. WARNING: Do not move the crankshaft while the distributor is out. You'll need a "fancy scan tool" to check/adjust camshaft retard after replacing the distributor. If you follow these instructions, P1345 will not set.

 

Thank you Captain Hook. Unfortunately, I was busy working on my wife's car today, so the only thing I got around to doing on the Jimmy was checking fuel pressure (okay) and a quick scan of the underhood wiring to make sure nothing was out of the ordinary.