Hi. Im new to the forum and I have my first blazer, also my first chevy of any kind. It is an '01 Blazer LS 4 door 4x4 Auto. 125000KM/77000 Miles.It is in good shape, needed nothing to safety and put on the road. No rust. Clean.1 Owner. I paid $4000 cash for the truck....drove it for a day or two pretty easy and not being familiar with blazers or chevys i never thought much of the rougher running engine. SO now it starts easy and is very reliable, does not stall, idles low(500rmp or so) but steady. i burn a full tank of gas in less than 300 KM/185 miles. If I step more than 1/4 throttle the engine sounds horrible, like a loud furnace almost, it will chug, buck, surge and misfire on hard throttle or any rpm over about 3000. At the same time the rpm guage will spike all over the place. I brought it to the shop, plugged in the ecu, it said crank sensor , misfire on #2 cyhlinder, vacuum leak. OK, got the shop to fix that. Brought it home, it still runs exactly the same. Also the engine ticks at idle speed quite loudly.Brought it back for another diagnostic. Now it says something about the emmissions(which was vapour canister) and 02 sensor is bad(dont know which one) and miscommunication with MAF sensor. SO...I did a tune up-plugs, wires, air filter, pcv, cap/rotor. Now the truck burns SLIGHTLY less gas, but still runs like crap with the same problems. 2 days ago i changed the drivers side 02 sensor...it did absolutely nothing and costed 120 dollars for the part. I dont know what is wrong with the truck, i think it is hard to believe that there are that many sensors that arent working. The truck really runs bad, but otherwise is in mint condition and i would hate to sell it for a loss because i coldnt get it running rite. I am thinking there may still be a major vacuum leak somewhere. When i put my heater to def or def/floor it works fine, on the other settings it will come out of the vents like it is supposed to, but i hear a hissing sound(vacuum leak??)-no not the hissing of the air blowing through the vents. I dont know if this problem is related..and my 4x4, which the button works, i hear the motor engage the transfer case, feel the transfer case engage, but no power to my front wheels. ANY HELP WOULD BE AWSOME....i dont want to keep sinking money into it for nothing. THANX
James G
Ontario, Canada

 

ok first try changing the mass air flow sensor, and for the 4x4 (this happend to me ) take out the battery,remove the battery pan you should see a diafram looking thing that has a cable attached to it inside the wheel well you will see three bolts take them out go back under the hood turn over the pump and there should be a vaccum hose attached to it it there isn't one then your hose fell off find it (should be there close) reattach the hose and if you can put a hose clamp on it to hold it from fallin off again that should help and that should bee your problem as for you other problem good luck I'm still tring to fixx mine

 

Karma strikes! I complain about posters giving too little background.. now this.

We need a baseline.
Run the Fuel pressure at prime/leakdown test. Key on/ dont start pressure. and pressure 5 minutes after pump stops.
Write it down.
Disconnect all vacuum lines at intake and plug the ports. How does it run.
Now connect brake booster.. how does it run?
- take it for short drive.
Disconnect the IAC and start it.. effect?
Now reconnect other vacuum lines..effect?

 

My truck did the exact same thing, turned out to be a horribly carboned up MAP sensor! I mean it had almost an 1/8th of an inch of carbon on it, also took of the intake plenum and sprayed upper intake cleaner into the throttle body until the motor choked out then cleaned the throttle body itself. The throttle body was causing the vacuum leak due to carbon blocking the blade from closing fully. And I clean my MAF sensor monthly, cheaper than buying a new one for now. I get around 360km to a tank now of regular driving, still have the odd power surge/hesitation though.

 

OK, i think i will check out the MAF sensor first. Its VERY cold here this week...-15C, so i will do the easier stuff first, dont wanna play with vacuum lines in the freezing cold. I also read something about a KNOCK SENSOR or MAP sensor?? could that be bad? although there are no codes in the ecm for it. ......if i cant get it running rite soon ill have a low miles, loaded blazer for sale for REAL cheap if anyones interested....this is my FIRST and LAST chevy product for sure. Just cant seem to find the problem with this truck...oh and as of yesterday my cruise stopped working and my automatic lights no longer work for some reason. and the high speed on the fan burnt out. door started to sag pretty bad last week..belt squeals now, which killed the battery. compass no longer works, but temp does? NO fuses are blown. none. oh ya and although i cant tell if it gets cold, the ac compressor no longer comes on. THIS TRUCK LOOKS MINT and HAS ONLY 75000 miles on it....

CHEVY...LIKE A ROCK, you'll always be stuck there