Good day folks, I just purchased a 2003 Blazer ZR-2 with some running issues. We have got it to run like 75% better as we bought it in full limp mode. Anyhow, it will fire fine when it's cold and drive pretty well. About half way through the throttle it will bog, have no power and lose speed. Top of the pedal it accelerates ok like the slowest it will accelerate pretty much. I have code p0101 and I have replaced the MAF and the wiring to it. I cleaned the throttle body and also changed the throttle position sensor. We are digging in to the cat being blown out as it's rattling very badly inside the exhaust. Was going to do the whole unplug o2 sensor thing. Anyhow just looking for any tips or tricks. Starts well idles rough and has no power. Any help is appreciated!

 

The first two things that you should rule out are excessive exhaust back pressure and the quality of the power and ground to the MAF sensor.

George

 

We have replaced the connector to the maf unless it would be the wires at the beginning that are shot? I am unsure of how to test back pressure but sure I can look it up. The cat is in terrible shape but still rolling around inside.

 

You need to get a voltmeter on the 12 V and ground wires at the MAF while it’s connected and the truck Ignition is on. Regarding the cat you have two choices, the best choice is to remove an O2 sensor and put a back pressure gauge in there and see what your exhaust back pressure is. The low-cost option is to remove the O2 sensors and run the truck and see if it improves which implies that there’s a back pressure problem if it gets better. There’s also some evaluation you can do with a vacuum gauge but the exhaust back pressure is a much more definitive test. George

 

Thanks so much, I was planning on doing the remove o2 sensor thing but couldn't get the downstream out last night before dark been soaking in blaster so hopefully when I get home today it will be free.

 

It has to be the O2 sensors upstream of the cat(s).


George

 

Thanks, have yet to try the o2 sensor thing but planning on it. Will get back.

 

Want to confirm with the upstream 02 sensors out she runs amazing! Along with new spider injector for codes p0300 and maf. Just to finish this off correctly, the duralast maf that the previous owner purchased didn't operate the vehicle as well as the AC Delco one I replaced it with. Fuel filter and plugs, wires, cap were also replaced. I have to put an ABS module in it for code C0265. This turned on the brake light and the abs light. I currently just have an air bag light on. I ran it through drive cycle with the o2 sensors out and it didn't turn CEL on for maf again. Thanks for you George!

 

My pleasure, let us know if you need any help with the rest of your punch list. I love fixin' s&*t and solving problems, especially if no one else can figure it out. lol.


George

 

Now it is just to reseal the entire engine because every gasket is leaking and will figure out the chatter in reverse when we get the engine going its strongest. Seems pretty strong now but hate a leaky engine. I was reading it may be diff related with reverse and I did the engine break test and it engine breaks so leads me to believe it's hopefully not reverse going out. Going to change the fluid in the near future and see if that helps. The carfax states the previous owner only changed the oil every 10k so I am replacing every fluid. The oil filter was too small of one that we just took off the vehicle also so someone had no idea what they were doing. Lol basically saving this thing from scrap. Hahah