My blazer has developed a nice ping under acceleration from a stop. If I take off very easy or stomp it it does not do it. I had the codes pulled and it has a PO1345, PO440 and a PO0155.

I replaced the gas cap that was shot. I will replace the pass side 02 sensor this weekend.

As far as the 1345, I have checked the timing alignment. It was dead on. Could I have too much play in the dist causing this? It is the dist from my old engine. It is also the CKP sensor from my old engine. I put this engine in well over a year ago and it has run fine until the last few weeks. It idles fine and I can rev the snot out of it in the driveway and no ping or rattle. Is there a check to see if the CMP or CKP are bad? Would it run fine if either were bad?

When it pings I can feel it loose power. It also seems intermittent. I do not notice it at all for the first 5 minutes after i start it.

 

Yeah the distributor can have play in it, take the cap off and pull up slightly on the rotor and then turn it back and forth, see if there is any play, if there is excessive play you can buy a replacement gear for the end of the distributor, or of course you can buy a new distributor but the gear is much cheaper.... You also can get or borrow a scan tool capable of reading CKP/CMP correlation values and see if it is within spec, if the gear on the end of the distributor is shot and the deg is too far off the CKP/CMP values may be to far off and will not be able to correct it

 

I will check the gear this weekend. I do not seem to have time until then. Thanks for the point. I will let you know what i find. It is odd that it does not do it when I first fire it up. Can I assume that the CKP/CMP are working since the truck runs fine? This is more of a wear or adjustment?

 

On the distributor gear it gets worn... when you first start a vehicle it will be in open loop meaning it will be running on the preset defaults from the computer, after it warms up and goes into closed loop the computer takes various inputs from all the sensors to make the correct adjustments.. hope this helps

 

It does. I will let you know what I find.

 

OK, I set the engine to TDC and popped the cap of the distributor. It was dead on the "6" on the rim of the dist. I went ahead and pulled the dist to check the gear. It looked ok. It may be worn some. I reinstalled and double checked the position of the timing marks. Bolted the dist down and buttoned up the cap and wires. Fired up and ran great. I test drove and noticed all of my power is back. It was kicking out of converter lock for the past week or more and is not doing that now. It feels great. One problem, it still pings while leaving from a dead stop. I suppose the gear could be worn. I will pick up a new gear and compare it to the one on my dist this weekend. If it looks the same I will return it. How much play is allowed in the shaft and rotor? It moves a little when I twist it with the cap off.
I am thinking that my dist was a little loose when I removed it. It is tight now which is probably why it is running so much better. I will stop by AZ to see if the code is still there. Any ideas????

Thanks guys.

 

Are there any active codes? Sounds like your Knock Sensor is not doing its job if there is pinging...

 

P1345 is the only code still showing. I assume that a code would be thrown on the knock sensor was faulty or disconnected. I will double check connections today.

 

I suppose that the P1345 code could limit the overall timing changes that can occur and allow for detonation to occur...

 

I am just not sure where to go from here. Could the CMP of CKP be faulty? How do I determine if either is faulty? Any thing else that would cause this code. I went through
the post you linked to. I did not check the timing advance with a scanner. I may need to pick one up. Any recommendations? Thanks Kyle.