need some advice, my 03 SS 3.8 non supercharged has been a great car bought it from Tennesee last year now its in Utah, I have been able to take good care of it and nothing out of the ordinary, except I made he mistake of putting drilled slotted front rotors on it....very very noisy, anyway recently it has been "coughing" and it has died at freeway speeds several times now, no check engine, no msgs, I have checked loose wires, plugs, relays reseated everything I can think of, it always starts back up even before I come to a stop but Im baffeled, its so quick, not at idle or going down grade, is it fuel pump, some sort of electrical issue, anyone else run into this, help

 

Hmmmm....check fuel filter, fuel lines...if theyre clogged could cause it to run lean and stall....also check throttle body to see if its clogged with carbon, can also cause stalling...those are just the easiest three things to start with

 

Could be a failing fuel pump!
Id check fuel pressure at fuel rail...also the filter...you may also be experiencing a bad catalytic converter(Clogged)... Whens the last time you changed the air filter? somethings to consider!

 

Hey guys, thanks for the input, as much as I probably need or should replace inline fuel filter(s), some other info I got was the MAP sensor could be giving me similar symptoms, I drive 100 miles a day and this "coughing" and stalling has been consistantly worse and daily, last night I pulled the electrical connector off the MAP and tapped on the body of it, looked again for loose wires etc., low and behold my drive home from work at 230a was absolutely eventless! no coughing or quiting/stalling, so this points at the MAP sensor, I do appreciate the feedback.

 

I was going to suggest the MAF...
But they are expensive! It is "HIGHLY" recommended to "NOT" drive it with it unplugged...that's designed for test purposes "ONLY"!!!!
I recommend replaceing it Immediately so as to not cause any further issues.... Unplugging it only tricks it into believeing everything is normal...to see if theres any other issues related to the problem!
Its a pre programed ...program in the pcm for testing...
Glad you figured it out!

 

Also, make sure you can get a delco brand dont go for a cheap aftermarket

 

Are we talking about the MAP sensor or the MAF sensor? One monitors manifold pressure and the other monitors air flow.

I know a lot of members think that unplugging the MAF is a way to test it, but that is not correct. When you unplug it the PCM doesn't receive input from it. If it doesn't receive input then it forces the engine to run in open loop mode - meaning it relies upon default tables to operate the engine. The engine will run rich (like cold start) which will effect drivability and fuel mileage. Unplugging it also eliminates the entire circuit, so if the problem is in the wiring (and not the sensor itself) you have falsely identified the sensor as the problem. Your customer pays big bucks to replace the sensor and the problem still exists. The only accurate way to test a MAF sensor is with a multimeter and a flow chart.

OP - a malfunctioning MAP sensor would cause stalling. If it isn't monitoring manifold pressure correctly it would effect fuel delivery. You might get away with cleaning it, but be very careful so you don't damage it.