bank 2 O2 sensor was pulled and engine ran slightly smoother. Removed cats and installed test pipe only slight improvement at idle, ran rough above idle to about 3000 rpm then acted like it hit a fuel cutoff or rev limiter. MAF value does increase, wanna say it went to about 10.55 but engine kept dropping out at 3000 rpm.

 

Ok so exhaust is OK. If maf is 5 g/sec at 500 rpm idle, it should be at least 6x5g/sec = 30g/sec at 3000 light throttle in park. Spec is around 155g/sec at full throttle and 4900 rpm (1-2 shift). Lets work the MAF sensor issue further. Let me get back to you tomorrow after reviewing factory diagnostics. Are MAT sensor and coolant sensor readings making sense?

 

Latest live data showed ECT at 85c at idle holding steady within a degree or two, IAT @ 40c and MAP steady @36kPa. All readings at idle in closed loop.
Looking forward to what you might find. And thank you for the help.

 

No problem. A quick thought for tonight. Is the snorkel leading into the air filter box through the radiator support bent over (bent shut)? I have seen this before.

 

I will have to check that. Just put a new air filter in didn't notice anything out of the ordinary,but will double check tomorrow afternoon.

 

OK lets look at some of the sensors that can affect the MAF. I assume that Blue Driver is capable of logging data or displaying multiple PIDs for a screen capture.

I happen to have a 2001 Blazer 4x4 myself. Here it is at idle, 1500 RPM, and 3000 RPM. See if you can duplicate the same PIDs and conditions with the engine warmed up. Note that in park with no load (highest vacuum) that will give the lowest MAF readings. Any less vacuum from poor performance or misfire and the MAF should go up considerably. Let's see if we can spot anything goofy other than the MAF reading. Oops, I see the throttle angle PID I chose is inop.

 

Sorry I haven't got back sooner, been working 16 hr days. The @idle numbers are close to what you have shown except I don't have barometric pressure or MAF hertz. Hopefully tomorrow I will get home early enough to run tests at the higher rpms . Snorkel was fine no abstructions.

 

No rush on my part. At your speed.

Baro pressure can be tested using MAP sensor reading with engine shut off. Hertz not so important.