I need some help and advice on my 99 GMC Jimmy SLS 4.3L. I have P0338, P0452 current codes I had P1345 but its now fixed (off on distributor timing). I bought this blazer with the hopes of a daily driver for 800 bucks, it needed a new fuel tank and fuel spider and she started and ran fine ( I drove it home about 30 miles). I pulled the enigine to replace the oil pan seal and the timming cover, also replaced the head gaskets and all the seals, along with the thermostat that wasnt event in the truck, new complete exhaust from headers back including O2 sensors. the engine has 170 compression in all cylinders (with no drop) the fuel pressure is strong at 62 with key on and holds pressure after key is off, all plugs are getting good spark. If I spray fuel in the throttle body it will run but not good (rough) and it dies if the pedal is pressed at all. All parts were replaced with AC Delco. I have destroyed one starter already trying to trace the problem. Some research points to replacing the crankshaft sensor which will get replace tomorrow, but not sure if that will fix this since I already have spark but will hopefully stop eating starters.
ANY sugestions would be a great help thanks.

 

I haven't looked up the codes you presented but are you sure all the wires/sensors are hooked up? I'm thinking TPS & the EGR can reek havoc on a lot of things.
You're obvioulsy capable to pull an engine & replace items.
If you're lucky swartllk (our admin) or Captain Hook will catch wind of this & he is a 32 year or something like that GM Certified Mechanic.
Then it'll be like All State - in good hands!

Has the PCM been reset IE: pull the + for 30 mins, drive & let it get to "know" the new changes?
Might be a GM security issue as well.
You can search for the remidy for that 'cause I have no clue lol

 

P0452 - Evaporative Emission Control System Pressure Sensor Low Input
P1345 - Crankshaft Position [CKP] Camshaft Position [CMP] Correlation

Found these 2 Hope they get you somewhere

 

With replacing the timing cover and crank sensor you will need to do a relearn of the crankcase. I know the gm tech 2 scanner can do it. Otherwise, its using the old data. Hope that helps.

 

Update, thanks for all the replys. I replaced the CKP sensor and that fixed the P0338. Engine runs strong no skips at all RPM's. Only code left is the P0452 really don't want to drop the tank, already checked/replaced the fuel cap. Also found the park brake doesn't work.