99 Blazer LS. 4.3 Vortec. Code W. 4 door. 2 WD. 158 K. Problem: Distributor cap indicates a timing issue. Contacts are pitted extreem to one side. (I am assuming it is too far advanced as it runs so well ). This model distributor is not adjustable. The triggering sleave mark on shaft appears to be in line with gear dimple. Have early service manual, it does not show CPS relearn procedure. My scan tool is a one way anyway. Question: Is this engine's timing geared or chained? Or can it be either? Suggestions? Thanks, Crusty.

 

I doubt your timing is off. The computer controls it. Sounds like you just need a new cap & rotor. Get a quality set (AC Delco or an aftermarket unit with copper terminals) and drive!r

The cam is chain driven by the crank. The distributor is gear driven off the back of the cam.

 

I appreciate that you gave a response. If you had read my post a little closer; I indicated it was firing 'extreem' to one side. This indicates a timing issue. Changing the cap, regardless of contact alloy, will not address the problem. If the cam is chain driven; wear is a possibility leading to tooth skip or breakage. This of course may lead to varying degrees of damage to engine. I posted the thread hoping to unveil a 'common problem' that others may have had with this model. Unless someone else has something constructive to add; I'll have to bite the bullet and go through the diagnosis set by painfull step. Thanks,Crusty.

 

If I had kept all of the distributor caps I have replaced on these vehicles, I would show you that they all look very similar to what you describe... These trucks do run quite a bit of advance during normal operation, but it isn't anything to fret over. If you have a scan tool you can see what the timing is...

Is the truck running poorly or do you just have this feeling that there is something wrong? Typical first step in diagnosing an ignition system issue is to do a complete tune up consisting of plugs, wires, cap, & rotor...

If the timing chain were to skip even 1 tooth, it would throw the timing off to the point of having a barely running engine not to mention a CEL. Wear in the distributor drive gear would cause the distributor to be retarded more.

But damn man... "Something Constructive"... Really. Do you want help with this or not? You can go pay for advice...

How about you provide some details about how the vehicles is running and what has lead you to think there is a problem...

 

:lttd: change the cap and rotor and go on driving. They all fire to one side and he is the most helpful and constructive person on these forums.

 

swartikk and robert728; Forgive me if either of you were offended. It is clear I do not have enough information to give to make an accurate diagnosis. I will take it to dealer and pay to put on 'the machine'. My scan tool readouts do not match the service manual's rundown even remotely. We will see if that helps. Thanks Crusty.

 

We can provide help, but you have to provide details... You could just answer the questions...

 

If the timing was off more then 2% you would get a code instantly. The Cam and Crank Sensors check against each other in corelation with the actual Firing.

A P1336 I think.

That last thing you want to do is run the Sh*t out of your engine as part of the Relearn process.

 

I too want more details. I have an appointment at dealer for Monday. In the meantime; I'll give you the whole truth. That's right there is more to it. But I'm not sure if they are related. I wanted to clear up the timing issue first THEN address the code I am getting. Timing first: as I said b4 it is firing extreem advance. Runs VERY good. As it should. My POS Auto Xray scanner says it is running 19 Degrees advance @ idle and as much as 35 @ 3/4 throttle from the dig. Now the code: P1351-short or power interuption in IC circuit. ( I have a factory service manual ) Checked everything I could. VCM pins, wiring, ohmed everything. Even ran redundant jumpers. NOTHING! To make things worse; the problem is INTERMITTENT!. Daily scenario: In the morning it may take as many as 8 tries b4 it lites. Once it does lite; it will fire off the first time, every time. Coming home from work: the same thing. NOTE: one out of five days the thing will start normally and the MIL is off! Totally bizarre! I explained this all to service mgr. @ dealer. He said it makes no sense. He probably thinks I'm a stupid Redneck that smoked too much dope in my younger years. ( some of that may be partially true. ) That's why I'll gonna pay him 80 bucks to narrow down the issues. For the hell of it I checked the fuel pump. Pegged at 60 when I touched the key, 56 on crank and 53 idle. Like I said b4 I was hoping it was a common problem and someone had the name of the guilty gremlin so I could have him arrested. I'll know more Monday or Tuesday evening. Will post results. Thanks Crusty.

 

Have you monitored the continuity on the wires to/from the ignition coil and ignition control module while moving the harness around? Sounds like you have a broken wire inside the harness.