I have a 2001 blazer 4x4 that is losing power and couching while driving.It's undriveable.It will crank and idle fine.I just replaced the fuel pump with ac delco about 4 months ago.I check the fuel pressure at the rail its jumps to about 62 when you turn the key over and 53 while idling.I replaced the distributor cap and rotor button.I pulled spark plug wires 1,2,4 and 6 and tested for spark with a hei tester all are getting good spark.I took it to auto zone and they cant get no codes out of it even though the cel is on.OBD might be unhooked? Any help is appreciated.

Thanks

 

Check the CIG fuse. If it's blown, the DLC will not receive power which will result in no communication with a scan tool.

 

Thanks swartlkk!! I got a code out of it after i replaced the cig fuse.The only code i got was p0101 (PD) MAF mass air flow or VAF volume air flow sensor circuit range/performance.Does this mean my mass air flow sensor is bad?How can i test the MAF?Thanks for the help.

 

Replaced the MAF with one off a friends truck just to see if it would fix the problem.It didn't help.The truck idles fine but when you put into gear and accelerate it fall flat on its face.It wont go over about 20mph now with the pedal to the floor.Do you think a clogged catalytic converter would cause this?THanks

 

P0101 - Mass Air Flow System Performance

Could be a wiring problem. Could also be a leak in the intake piping between the MAF and the throttle body. If the fresh air make up tube is not connected to the back of the intake hat (what attaches to the top of the throttle body), it could cause the problem.

 

Thanks for the reply!I think the problem is a clogged catalytic converter.I disconnected and pulled the oxygen sensor right in front of the catalytic converter.Now it's running great with no sputtering or loss of power.just loud as hell.What are the recommendation on getting the catalytic converter replaced.Thanks for the help

 

I'd say go to a muffler shop or if you have the reciprocating saw, cut it out & get a replacement with clamps. A high flow cat may help with a couple ponies but unless other things like free flowing exhaust or headers it would be a waste of money IMO.
I can't remember if the downstream 02 sensor is before or after the pre cat. If it's before then it may be the pre cat.

 

It was definitely the catalytic converters.The pre cat completely broke up and clogged the cat.I had the pre cat removed and replaced with a straight pipe.The rear cat was replaced with a 2 1/2 magnaflow from advance auto.Its doing great now