I went to clean the throttle body on my 99 4wd 4.3 vortex engine and while it was running I went to take the air intake duct cover off the throttle body and as soon as I would start to pull it off the engine would start to stall and if I removed it completely off the engine would stall right out. Is this normal. How can I clean the throttle body with the cleaner if I can't take the air duct cover off it while it's running.

 

i think the MAF sensor has to have airflow or the engine will die. you will probably have to take off the throttle body and clean it that way.

 

I thought that also so I unplugged the MAF sensor to see what would happen and nothing happened. The engine kept running fine.
i could not understand why the engine would die when i went to pull the plastic air flow duct off of it. As i would just start to lift it off and make just a small crack the engine would start to die. It sounded like it was sucking in way to much air which makes no sense. I looked in my Haynes book and it says to remove the air intake duct from the throttle body while it's running. well I can't do it with this Blazer. lol

 

I had the exact same problem. Unfortunately it was not with my new 99 blazer but with my old 99 suburban (gmc). I was told the problem was a sensor on the fuel pump. I dont know if that helps you, but being such a similar issue I would check on it.

 

I'm pretty sure this might work a little better if you turn the engine off first. If you are running the engine the MAF cleaner will not have time to clean the parts. It will get sucked into the engine. I took mine off and cleaned it from both sides with MAF cleaner. It seemed to help a little. I put it all back together and now it idles better.

 

Just remove the throttle body and clean it. Much easier and less chance of something falling in your engine. Too bad I didn't do it this way and ended up spending around $700 to fix stuff afterwards because the tb cleaner ate through the toothbrush I was using and the head fell off and stopped in the lower intake.

 

As everyone else has said, just remove the throttle body and clean it.

As far as the MAF sensor goes, that is perfectly normal. If it is connected electronically, the duct work behind it MUST be connected for the engine to run. If the PCM isn't seeing airflow through the MAF sensor, it will shut down the engine. Unplugging the MAF sensor will allow you to remove the intake duct and have the engine stay running.

 

swartlkk
I did unplug the MAF sensor and when I go to remove the air duct from on top of the throttle body the engine dies. when I unplug the MAF sensor the engine keeps running just fine. but just as soon as i start to lift the duct off the throttle body you ca hear the engine start to die and the further i lift the duct off the more it wants to die.

 

Are you sure you unplugged the MAF sensor (large thing right after the air filter box) and not just the IAT sensor (little plug further back on the intake duct)?

The engine should run without the duct so long as the MAF sensor is unplugged.