DTC P1345 ?

ang94541 · Post by **ang94541** » Mon Aug 25, 2008 7:07 pm

Hello everyone,
Long time lurker, first time poster.

I have an 03 CrewCab and an 02 Blazer. Both are 4.3L, 4wd, beige with blk leather. A "His and Hers" if you will.
My problem is with the Blazer, but since these trucks are almost identical and I'm more familiar with this site, I'll post it here. Here goes...

We wife complained that her blazer started to stummble and run rough after starting it. She had been driving it all day, so the engine was warm. She also said that it was overheating, gauge showing 3/4 hot. No MIL.

I plugged in my Scangauge and could not find any trouble codes. There were a couple of things that were strange when compared to the CrewCab. The CrewCab always shows zero or maybe a few degrees of Knock Retard, no matter what I try and do. The Blazer is showing 30, 40, 50, up to 90 ?? of KR. It also will go into OPEN Loop if I'm pushing down hard on the gas for a few seconds. Right about then the temps start to climb.

After a few starts, I then got a P1345.

The only thing I can find in my 2003 S10 Service Manual is if I install the distributor improperly this code will show.
On the web I find "Crankshaft Position (CKP)-Camshaft Position (CMP) Correlation" and talk about the dist. drive gear wearing.

Any ideas?

roadrunner · Post by **roadrunner** » Mon Aug 25, 2008 7:40 pm

Sounds like more than one problem. Possible fuel/lean out problem. (Would account for extreme knock retard and elevated temps.) Since you have the service manual perhaps a manual check of the cam position sensor is also in order given the code displayed? The open loop would be a normal result of fuel/timing too far outside operational parameters. I would advise a fuel pressure check both static and under duress operational while experiencing driveability problems. Have you changed your fuel filter lately? Have you run a good injector cleaner through it lately? 90 degrees is serious retard and this problem is serious as well. Engine damage/failure may result if not diagnosed and repaired. If all above fails to resolve the problem I would advise you take it to a shop with re-flash scanner and have them do a crank position re-learn procedure as a last resort. (I doubt this would be needed.) If you are running a reprogrammed or high performance computer module make sure that's all they do or you'll lose your performance settings in the PCM.

Also, Welcome to the forum

. Hope this is useful to you and if not perhaps some of the other members will chime in and have other/better ideas.

Post by **HenryJ** » Mon Aug 25, 2008 7:56 pm

Heat and spark knock are the things ringing bells here.

First check the basics. Start with the ignition. Check that cap and rotor. While the cap is off check for slack in the distributor drive. This would be the wear you mentioned. Maybe check one plug.

Fuel filter? Fuel pressure if you can.

There are good threads on those topics.

Now find the plugged precat thread and see if the symptoms look familiar.
Remove the two forward O2 sensors and start it up. Take it for a drive and see if it runs better. If it does , you have a plugged cat or precat. That is my best guess with what little I can see from here.

ang94541 · Post by **ang94541** » Tue Aug 26, 2008 8:46 am

Thanks for the quick replies. I now have a little more direction.

I already have a fuel filter on order. I'll be checking the other things out as well.

Post by **HenryJ** » Tue Aug 26, 2008 9:12 am

If you can not do the O2 sensor removal, drop by a good muffler shop and have them pressure test your cat. It will not always set a light when it is bad. Do this with the engine hot.

roadrunner · Post by **roadrunner** » Tue Aug 26, 2008 11:35 am

Good call on the pre-cat Brule. That one slipped my mind at the time of the posting!

ang94541 · Post by **ang94541** » Sun Sep 21, 2008 3:20 am

Ok, so I've noticed that when I squeeze down on the gas and the Knock Retard goes up, after a few seconds the computer goes into OPEN Loop and the A/F ratio starts to go rich. This is also when the Water Temp starts to climb. When in CLOSED Loop it stays at 14.6. I don't think it's leaning out. I will eventually change the fuel filter anyway.
The engine will stumble and misfire if you rev it a little (2k) and hold it or if I'm cruising and just touch the gas. No misfire codes.
The only code I keep getting is P1345 and at one point the MIL was flashing at me. I think the computer was getting angry.

Today I set out to inspect/change the distributor cap and rotor. Inside the cap I found a little build up on the pins. Nothing bad. The cap and rotor looked normal for 77k miles.
I grabbed the rotor and tried to turn it back and forth. I figure there should be almost no play. Wrong. Lots of play. WTF?
I pulled the distributor and found this...

I'll replace this and see what happens.

I'm curious if the noise from this is what the Knock Sensor is hearing.
I'm holding off on the fuel filter and pre-cat for now.

To be continued...

Post by **HenryJ** » Sun Sep 21, 2008 7:05 am

Looks like you found your problem. Nice work! Quite a few have had this problem.

What oil are you using and what service interval?

ang94541 · Post by **ang94541** » Mon Sep 29, 2008 1:48 am

Ok, so I changed the dist gear, cap and rotor.
DTC P1345 is gone.
I don't think the cap/rotor had anything to do with this since nothing looked burnt, broke or missing.
I was still getting the high KR numbers, some stumbling, etc as before.
Comparision,

Next up, replace fuel filter.

I think the engineer who designed this clever bracket needs his arse kicked.
There is a noticable improvement in the way the truck drives. No more stumbling while cruising on the freeway between 2000 and 2500 rpm. The KR numbers are a bit lower as well. Also, the computer is not going into OPEN LOOP, unless of course, I floor it.
At least there was an improvement in exchange for a little gas in the face, stiff neck and little carpal tunnel syndrome.
Good call on the fuel filter.

Finally, I disconnected the battery for 15min. Again it seems to have improved slightly.

The overheating also cooked the Dexcool. So I have been flushing the cooling system out. 2 times so far. Lots of mud. The coolant wasn't in good shape before but it got real bad, real fast after all the overheating (250°F).

The Blazer (78k miles)has been a little down on power for a while. What makes it noticable is the CrewCab (35k miles). I'm sure the Crew is lighter but the Blazer just doesn't seem to have the same "get up and go". So I'll continue troubleshooting. The pre cat is next.

Oil change intervals have been between 3k and 6k miles. I'd also like to point out that I checked the oil level when all this started and it was down 2qts. Ooops. I send my wife to the local quick lube to get the oil changed and I never check when they get back. I'll be changing or at least checking the oil more frequently from now on.

I feel that I'm back to how things were before.
Thanks for the help guys.

And yes, I too am wondering where the rest of that distributor gear went.

roadrunner · Post by **roadrunner** » Mon Sep 29, 2008 3:46 pm

What oil you using? Inquiring minds want to know.

Post by **HenryJ** » Mon Sep 29, 2008 4:21 pm

What quick lube chain?

ang94541 · Post by **ang94541** » Mon Sep 29, 2008 5:49 pm

I have some Castrol 5w-30.

We usualy go to a Chevron QuickLube. I have no idea what they put in.