Hey. After much searching and reading, and reading. We are running out of ideas as to what the problem may be for a 2001 Blazer that keeps running erratically, and stalling; and there seems to be quite a few of us with similar problems with these trucks. (Posting this for a friend. He is pulling his hair out and crying as we speak).

Vehicle: '01 Chevy Blazer w/ 4.3 - 190,000 KM's

Problem: Start vehicle. Sometimes it runs fine. But lately has had a recurring problem of stalling while driving, running erratically at idle and stalling at idle. This has been on going for over a year. It used to only do it in the summer, but is now doing it in the winter as well.

Local temps when it happens: Varies from +30*C to -30*C




Codes: (these are still coming up WITH a new EGR installed)

• P0141 - O2 Sensor Heater Circuit Bank 1 Sensor 2
• P0404 - Exhaust Gas Recirc Control Circuit Range/Performance
• P0405 - Exhaust Gas Recirc Sensor A Circuit Low
• P1404 - Manofactorer Control EGR Closed Position Perf.

What we've tried to date: Last summer/fall - First, MAF sensor cleaning done. Then, replaced it with a used one. Replaced entire throttle body with a used one. New EGR installed. New PCV installed.

During all of this, coolant was discovered in the oil. Removed intake, cleaned, and reinstalled with new intake gasket along with new spark plugs (thanks to this forum). This seems to have fixed the coolant in oil problem thus far. But the vehicle still stalls at park and while driving as well as random idle while parked just after starting (warm or cold engine).

Today: We tried the fuel leak test (again thanks to this forum for the info).

Results of fuel leak test: Key on to prime pump w/ initial pressure reading of 62 PSI. Let sit for 10 minutes, and it dropped 6 PSI to 56 PSI.

Ran the vehicle with pressure tester still attached - while the vehicle sputtered and idled randomly, the pressure didn't bump around really. Stayed right around 55-60 PSI. So according to everything we've read on these forums, we may have ruled out the fuel pump at least, as well as spider? (read something about that here too).

Trying tomorrow: Disconnect MAF sensor and test drive w/ disconnected. Will post results.

What we are considering: Pick up coil? Cap and Rotor? Crank Sensor? What next?

After fuel leak test today, a sound was detected at the exhaust while running at idle.


Any suggestions would be greatly appreciated as this poor Blazer is minutes from being parked in a field and shot at with shot guns, rifles and flamethrowers....JK.

Thanks in advance.

 

Clogged Cat?

 

That's what I was thinking, but not too sure. There was discussion about cutting it out completely a couple days ago and replacing with a straight pipe (resonator).

Still considering it as a culprit though.

 

Do this outside in fresh air. Open the exhaust up before the cat and run engine up to temp. Or remove cat and insert a piece of pipe. They call it a test pipe. See if the popping tin can noise stops and the engine runs smooth.

the o2 sensor, diconnect and test heater circuit loop, is it open or shorted, if open replace it. If shorted, it maybe causing issues with the power coming from the pcm.

EGR - with those codes I would look for:

Did you replace the EGR valve with AC/Delco/Delphi manufactured valve?

1.) a wiring problem, visual inspect for broken wires by the connector at the EGR valve.
2.) check circuit continuity from plug back to PCM connector.
3.) check with EGR plugged in for the right resistance at the pcm connector

I would like to recommend one other thing. If the age of the truck is 10 years and mileage is ~> 100,000 miles that you replace the fuel injection assembly. Mine - the tubes were brittle, number 6 poppet was leaking bad, number 3 leaked but not as bad, fuel wash down #6 and #3, fuel also pooling at the back of the manifold.

Get the new design complete MPFI with the injectors at the very end of the tubes.

 

****Its the CM that is mounted on the heat sink right at the top passenger side of the engine.( Aluminum heat sink...cant miss it..right at the top. the icm is attached to it)

Buy a new one($74), and buy the silver heat paste at radio shack ($14).
take the whole assamble ( heat sink and CM mod) off the braket its mounted to because this is the cause of the problem. The bracket is mount to the engin and IT conducting heat back up from the engine causes all the problems.

After replacing the CM and applying the new heat paste, tye wrap the entire thing on the cables coming from the gas peddle to the top of the engine that are right in front of it , in such a manner that the air flow from the radiator will run down the length of the heat sink fins.

Simply tye wrapping will work fine and there is just enough length on the wires to the CM to allow it to reach.

This WILL finally solve this vexing problem. Simply put it is a design fault.
The CM is heat sensitive and is mounted to a heat sink. the problem is the bracket that ITS mounted to is hotter than hades and conducts the heat back into the CM via the heat sink.....crazy but do what I suggest and THAT problem is fixed...