Ive been reading the forums and have not found an answer to my issues. I recently had an issue where my blazer would stall out after about 15-20 minutes of driving. The engine would turn over again but not fire until a few hours later. I replaced the fuel filter, Distributor Cap, Rotor, Coil, and Crankshaft sensor before realizing the ICM was bad. I replaced the ICM and it ran great the rest of the day. I then put a full tank of premium into it along with a bottle of fuel injector cleaner. The next day I noticed the truck had almost no power during acceleration. I can floor it and the engine sounds like it has almost no airflow to it. If I turn of the A/C it is a little better, but nowhere near where it should be. I have not cleared my check engine codes so they still show the crankshaft sensor error, as well as o2 sensors and one for incompatiable ECM, whatever that means. ANy help would be appreciated as I dont have money to keep throwing at it.


2002 Blazer LS, 120k miles, 4.3L Vortec, 4x4

 

What are the exact codes?

When running a cleaner through a dirty system, it may cause somewhat poor performance while all of the junk is getting cleaned out.

Have you cleaned the MAF sensor & EGR valve (both covered in the Tech Article DIY section)?

 

I have cleaned the MAF sensor which did smooth out the idle, as far as the EGR valve I was told the 2002 and ups do not have one.

The codes are p1683, p0155, p0128 (beleive this was when I had a stuck thermostat a few weeks ago, been replaced), p0102, p1345 (crank sensor was cracked, been replaced), p0141.

I have asked a few auto parts placed to clear these codes so I can get new and accurate info, but they are telling me they are unable to clear them anymore. Used to not be an issue.

 

It may or may not have an EGR, I've seen trucks registered as a 2002 model year vehicle with them and without them. Pays to check. If you have it, it will sit right above the water pump in the center of the motor bolted to the lower intake manifold.

P0102 - Mass Air Flow Sensor Circuit Low Frequency
P0122 - Throttle Position Sensor Circuit Low Voltage
P0155 - Heated Oxygen Sensor Heater Circuit (bank 2, sensor 1)
P0141 (GMT360/370) - HO2S Heater Circuit Bank 1 Sensor 2
P1345 - Crankshaft Position [CKP] Camshaft Position [CMP] Correlation
P1683 - PCM Error - My reference states that if P0602 is not present, the PCM needs to be replaced. This may want to be the starting point for your repairs. Especially if the code comes right back up after each reset and/or battery disconnect. A tuned PCM from PCMforLess.com is $375 ($115 refundable core charge). Not sure what Wait4me or BlackBearPerformance costs are like for the s-series...

Sounds like you possibly have MAF & TPS problems. Do you have the capability of recording live data from the sensors? Or know someone with a scantool that can?

With two O2 sensor heater circuit codes, I would wonder if there is a problem with the wiring to the O2 sensor heaters on the passenger side of the truck (B2S1 is located between the passenger side exhaust manifold & the y in the y-pipe and B1S2 is located behind the catalytic converter for the '02+ (or is that '01+...).

I wouldn't worry too much about clearing the codes. They'll clear themselves once the problem is fixed.

For the P1345 code, did you do a CASE Relearn (aka crankshaft variation learn procedure) after replacing the CKP sensor?

Again though, I'm not sure I would invest too much time into trying to figure out the other codes with the P1683 code present. I have never seen this code just go away on it's own.

 

Sorry it took so long to get back. Was in process of closing on my new house.

I had not done a case relearn. I did borrow a scan tool from a friend and tried to do the relearn but the Snap-On scanner I had did not have that option. I did do some monitoring and the biggest thing I saw was at idle the timing is at 17 degrees, and at 1500rpm it was at 31.

I had it towed to the shop yesterday to do a case relearn and check out the PCM and of course they have done everything but. They just told me I have almost no vacuum, my exhaust is not clogged so they want to rip out the front of my engine to check for wobble on my Cam thinking the chain is jumping. They also said my engine may be toast! So I am very frustrated with them and told them before they rip anything else apart to do the damn case relearn. Especially since it ran great before I replaced the crank sensor (of course the ICM as well).

So hopefully they will listen to me and do the case relearn and I will update as I learn more in case anyone else has similar issues.