Howdy, everyone

I've got an issue with my '02 Chevrolet Malibu with 189 000 kilometres on the clock, and it's intermittent, which is extra "fun"!

Occasionally, after starting, the engine will stutter and nearly stall when it's put into drive. It never stalls out completely, it just chokes up for a second or two before the RPMs climb back up. After that, it's perfectly fine. The engine is responsive, there's no codes, the transmission shifts as expected, shifting into park and then back into drive doesn't cause any problems whatsoever after the initial stumble. The PASSlock system was disabled and the security light isn't coming on anyway, so I doubt that's got anything to do with it.

This happens even when the tank has just been filled, so it's not like I'm out of gas. The fuel pressure regulator was leaking a bit late last year and was replaced, so that's fine. I checked the system for vacuum leaks and didn't find anything. The alternator is always putting out ~13-14 volts, even in drive when the car isn't moving. I got no check engine lights, the TPS is showing as 0% when my foot's off the gas. Whatever the problem is, it's nothing that is readily apparent. I considered the fuel pump as being weak, but the car runs totally fine on startup and only gives sass when being put into gear. And putting the system under load like driving at high speeds for a long time doesn't seem to bother the pump at all.

So I'm out of ideas at this point. Someone with a similar problem needed a new MAP sensor, so it's something I'll have to try. But I also don't have the time/money to just throw parts at this issue. So if anyone has some good ideas, I'm open to suggestions

 

Sounds like it's only doing this when the motor is still not up to full temperature?

 

It does it any any point after startup. Even if the vehicle has been recently driven and has only had a few minutes to sit.

I’ve been keeping a scanner on it the last couple days to monitor live sensor data in an attempt to look for a pattern. Last time it acted up the ECU was reporting a temperature around 90 degrees Celsius

 

If the ECU is getting the wrong readings, it's going to cause issues.90 C is 194 F right in range.