Yesterday driving home from work i noticed a power loss and then the rpms started surging around 2500 up and down. It finally threw the p0101 code for the maf sensor. I went and bought a new maf sensor and no change. i changed it back to the old maf sensor and removed the air filter and ran it from a dead stop to a 1-2 shift and the output on my code reader never got above 7.5 lbs per minute which converts to about 56 grams per second. This would seem to indicate a restriction but theres nothing left to restrict? I took the air filter out and removed the air box and found nothing blocking anything. please help. This is on a 1997 bravada

 

P0101 - Mass Air Flow System Performance

I would verify that the power & ground from/to the PCM are good.

 

well I checked for voltage and it seemed good, i reinistalled the new maf with no air box hooked up or air filter and ran it and the car started surging again and this time gave me a P1406 code for the egr pintle valve. I looked at the thread for it but for the life of me can't figure how they would be connected? any ideas?

 

P1406 - EGR Valve Pintle Position Circuit

A bad ground to the PCM/MAF?... Both also use a 5V reference from the PCM. Not the same pin on the PCM, but if there were a problem with the PCM, it could cause an intermittent problem with a number of sensors.

 

that was what I was leaning towards myself, if i were to get a pcm from same year bravada in a junkyard, would i need to have it flashed or would it be ok?

 

I've been searching through the site and a couple of people have said it turned out to be a clogged catalytic converter. Is there anyway to check this thru live data on my obd2 scanner? I can look at oxygen sensor outputs and fuel ratio. I just don't know what I would be looking for, thanks for any help!

 

The easiest way that I have found to diagnose a restricted catalytic converter is to pull one of the pre-cat O2 sensors. Disconnect the wiring and tie it up and out of the way then remove the O2 sensor from the exhaust pipe and drive the truck. There should be a code set for the missing O2 sensor and it will be louder due to the rather large exhaust leak, but if it runs better, that means that the cat is clogged and is in need of replacement.

 

I know this thread has some age now but I am having a simular issue and it only starts when the vehicle is warmed up. My cat has been making noise for almost a year now. Did that end up being your issue?

 

97 4dr 4wd Blazer

About a month ago the computer threw up a P0420 code; catalyst system efficiency below threshold (bank 1)

Pep boys said to take it to a muffler shop.

I went on a long road to Colorado from Texas and on the way back I stopped by the auto parts store and bought a K&N air filter and installed it. After some driving the computer threw up a P0101; mass air flow (MAF) circuit range/performance problem.

Before I read this thread I did notice some surging around 2500 RPM. Ever since the truck came into my wife's possession I hated it because the brakes always seemed weak and the truck never had much pickup, power, or throttle response. Anyhow, I came across this thread and did the test above and wammo, lots of pickup, power, and throttle response (brakes are still crappy) plus a P0140 code; 02 sensor circuit no activity detected (bank 1 sensor 2).

The oxygen sensor I pulled is the single before the catalytic converter. I didn't touch the two that branch to the tops of the Y before the catalytic converter nor did I touch the one between the catalytic converter and the muffler. The question is, would my catalytic converter be clogged or my muffler?

The truck spent the first 11 years of its life in up state New York. Looking at the muffler I noticed a sort of spider crack on a bubble if you know what I mean. There is definitely a noise leak (one thing I've noticed for a while, always thought it was louder than it should be). I kind of feel like if I replace one (cat) then I should replace the other (muffler). Would this be the normal procedure? I need recommendations for a part, I have autozone, pep boys, and O reilly's nearby. I was thinking of doing this myself since my wife and I are on a tight budget. Is this a simple job? It appears simple from my initial inspection of the under carriage..... What would the labor charges be like? My wife and I are looking for good gas mileage, (i'm looking for that "git up and go"). Looking at autozones parts I saw they sell a walker and magnaflow. Suggestions?

 

OK ,I would recommend bringing it to a muffler shop unless you have air tools ,like cut off wheel ,torch ,etc!! It can be all rusted up!! I saw a high performance kit from summit racing for cheap a while back but im not sure if its still cheap!! I do recommend getting the parts from a supplier if you plan on going to a shop to save yourself some money!! try rockauto.com also there great and the cheapest on everything.