2000 Blazer -- Distributor One Tooth Off(?)

[Josh Smith]

Hi folks,

I recently did some work on my Blazer which required me to pull the distributor.

When I put the distributor back in, it fired up but threw code P1395. Checking, I had it one tooth off, about 28 to 30 degrees advanced.

When I reinstalled it with the teeth aligned as they were before dis assembly, the code went away but the motor picked up the P0300 code.

I advanced it one tooth again. Perfect idle, smooth acceleration, no misfires whatever. It ran like a new 4.3, but the code came back.

The motor wants to run best with advanced initial timing.

I'm wondering now if perhaps the distributor gear was worn. It didn't look it, but neither did I clean it to really check.

Do you folks have any thoughts on this? Should I just have a CASE done and call it good? Inspect the distributor gear better?

Thoughts are welcome.

Thank you,

Josh

[Blue Bowtie]

When I put the distributor back in, it fired up but threw code P1395. Checking, I had it one tooth off, about 28 to 30 degrees advanced.

When I reinstalled it with the teeth aligned as they were before dis assembly, the code went away but the motor picked up the P0300 code.

I advanced it one tooth again. Perfect idle, smooth acceleration, no misfires whatever. It ran like a new 4.3, but the code came back.

I'm not clear on which code returned. Was it the 300 or 1395? Are you sure it wasn't a 1345?

Even if the gear has some wear the oil pump should take up most of the lash and keep it from wandering badly. It would probably have to be noticeably worn to a knife edge to allow enough differential to affect CMP timing. However, the gear could be worn and it warrants another look just to be sure. Replacing the gear is not a difficult task. If the timing chain is stretched the solution won't be so easy.

Whether or not the gear is replaced it's likely that the distributor will need to be rotated slightly to get the CMP trigger in phase with the CKP. There is only a little rotation available on the V-6, with just the slack in the bracket and bolt hole to play with. The CKP trigger can be read with a meter, scanner, or can be mechanically aligned. Once that is established the CMP can also be read with a meter or scanner to set the distributor position.

[Josh Smith]

Originally Posted by Blue Bowtie

I'm not clear on which code returned. Was it the 300 or 1395? Are you sure it wasn't a 1345?

Even if the gear has some wear the oil pump should take up most of the lash and keep it from wandering badly. It would probably have to be noticeably worn to a knife edge to allow enough differential to affect CMP timing. However, the gear could be worn and it warrants another look just to be sure. Replacing the gear is not a difficult task. If the timing chain is stretched the solution won't be so easy.

Whether or not the gear is replaced it's likely that the distributor will need to be rotated slightly to get the CMP trigger in phase with the CKP. There is only a little rotation available on the V-6, with just the slack in the bracket and bolt hole to play with. The CKP trigger can be read with a meter, scanner, or can be mechanically aligned. Once that is established the CMP can also be read with a meter or scanner to set the distributor position.

Hello,

It runs correctly when it's advanced by a tooth. However, when it's advanced by one tooth, it throws the P1395.

When I take it back one tooth (as it was previously set) it misfires and throws a P0300 code.

It almost looks like, sometime in the past, ran a CASE relearn while the distributor was a tooth off. The distributor gasket was missing, so it had been pulled sometime prior to me owning it.

Just a bit of background: I was trained in auto technology, mostly diagnostics, on the late carburetor car models, TBI, and some earlier multiport, around 1994-1995. The SFI and just a slight step up from what I know well, but having not ultimately decided in auto mechanics as a trade, I've not kept up. This is why I'm here asking dumb questions!

Regards,

Josh