Code P1345 / P1351

1998 Blazer w/ 4.3 is popping up these two codes. Ignition switch harness has been replaced, ignition module has been replaced, and the crank shaft sensor has been replaced. Is there a cam shaft sensor ?

A second note here, "Sometimes" when it starts up it goes into the fast idle and then slowly comes down to the slow idle, ( which seems appropriate )other times it seems to start off on the slow idle and when this happens it will occasionally die and when re-started go on to the fast idle mode. Bad idle motor maybe ?

Yep, we found it. Distributor has not been removed or touched, can it jump timing but still run great except at start up ?

Very much so.

Thats what I was thinking, the codes you are seeing is a base timing problem.

"IF" the distributor jumped even as little as one tooth, would the computer and anti knock sensors pick up this timing issue and compensate for it ? We are thinking of setting it back one tooth to see if that doesn't eliminate the start problem because the engine sounds like it is ready to take off and then it is almost like a cylinder hits out of order and kills the engine. But one it gets started it is absolutely perfect. Also, we did notice on both the old and the new distributor cap that it looks like the "Sides" of the terminals are getting the spark,( which gives the impression of firing spark to soon ). Every other cap we have ever replaced, the area of burn was the surface directly across from the rotor. We bought this Blazer about two weeks ago and at that time the motor would have this hard start like once every 8-10 starts, now we are at about once every 3-4 starts.

No, the engine's computer is made to adjust from a correctly set base timing.

It will go right out of wack adjusting it and trying to figure itself out if it isn't set perfectly.

Kinda what we thought, but didn't know how much artificial intellegence they built into it.

I know, wish they had more. Tehehehe....

Being how the distributor cap was brand new and the contacts were showing burn marks on the sides rather than the area across from the rotor contact, we decided to pull out the distributor and set it back one tooth. Now it starts like it should. Started and shut it off numerous times and did not have any problem. Real test was this morning, ( -7 and not counting the windchill ), started on the first try, (knock on wood). Cleared all the codes last night and none popped up and this morning the Check Engine Light was still off.

Excellent, timing really can screw around with an engine.

Thanks for all your help and ideas, this is really a great place to throw out your problems and get feedback as to what and how to fix. Now that we have almost throughly searched every square inch under the hood of this Blazer, and know it so well, we are thinking about getting a second one while all these repairs are still fresh in our mind, plus now we have some extra parts.

True, once you know, the repairs are very easy.

Trouble is just getting the knowledge to accurately diagnose.

This forum is full of knowledge,that is for sure, and having all the right tools make it a whole lot easier.

glad to see you got yours fixed too we had to start from the beginning but got it I was just checking to see if you did too.