OK here is the situation I am in I have a 2007 Chevy Impala LS 3.5 FlexFuel car has been running good for the 2-3months I've had it now and just today I stopped at a red light and the car Stalled/Died so I put it in park and start it back up it starts nothing seem wrong at first then when I put it in gear it Stalls/Dies again. So I try restarting it again and the same thing runs in park but the second you put it in gear it dies it will even die when shifted into Neutral. The only way to keep it running is if you can get into neutral and you just about floor the pedal it will run but horribly it just spits and pops and the speedo jumps all over the place even though it's in neutral. I have a Foxwell full function scanner and checked there are no codes other than a small evap leak that has been there forever. I was told by my neighbor who works on cars as a side job from home that it's possible this could be a bad or severely plugged catalytic converter? If there is anyone out there in the Chevy forum that can please shed some light on this issue it would be greatly appreciated. Thank you.

 

OK Checked the wiring today going from the sensor into the harness and that all checks good can't find any breaks of any or exposed wires even had someone in the vehicle watching the speedometer and no change. I have replaced the Output/Transmission VSS (Vehicle Speed Sensor) and this did not resolve the issue. Please if anyone can help I am at a loss and am about to go out of my mind as I need a Vehicle so I need to repair this one as I don't have a budget that alows to just go get another vehicle and I have Medical obligations that are 120 Miles from me that I can't get too without a vehicle. Thanks.

 

measure your fuel pressure

 

could anyone tell me is it in any way possible this could be a severely plugged Catalytic converter? @mountainmanjoe Fuel pressure checked out fine reads 58-60psi. with the key on

 

No it doesn't sound like a bad cat con. Are there any trouble codes?

 

No there are no trouble codes except the Small Evap leak that has been on since right after I got the car. I just can't seem to figure what would cause this issue. I thought about cutting the exhaust a little before the catalytic converter and just punch it though anyways just to try it and I'm probably gonna anyways as I feel its worth a try at this point, and if it by some miracle makes a difference then I will replace the catalytic converter all together.

 

You're barking up the wrong tree
plugged exhaust usually causes problems at higher RPM, not idle. You said it runs better when you gun it.
It also doesn't care about which gear you're in.


You need to go after the clues that the car actually shows, like this. Smoke test for vacuum leaks, especially in the EVAP system. A vacuum leak would cause the exact symptoms you describe.

 

I appreciate your opinion but was told by a chevy dealer mechanic that I kinda know nut no real well when I ran into him at the store near me and he says a small evap leak will not cause the issue I'm having, he couldn't tell me anything beyond the VSS without actualy going through the car in a garage but I can't afford $165/Hour just for a diagnosis then $165/hour for the repair. I guess I'm just Sc*ewed and now have no vehicle as I am lost because there is nothing I can find causing the issue. the only thing left is the Computer so and I don't have the means to have that fixed.

 

Just a Thought could this be a Transmission Controll Module?

 

Then don't go to a stealership. They usually cost the most and don't actually fix the problem. Find an independent mechanic.

VSS and TCM don't cause stalling. You have a dozen more tests you should do before you can conclude it's a computer.
Have you checked any live data with your tool?

Fix your leak. If you think you know better then what are you doing asking on a forum?