Hi,

This is for a 1987 GT 2.8L

I have been chasing an idle issue and recently got Paul Romskys ALDL kit. The car runs okay in normal mode with a slight stumble, especially when warm and shifting into gear. I plan to replace the Vacuum lines

When the car is in ALDL mode, it is difficult to start driving and experiences bad idle issues and stalling.
When the car is in "Factory Mode" all issues seem to go away and idle is flawless.
I'd imagine that the ECU is ignoring some sensors and not trying to chase a vacuum leak, or ignoring a failing sensor?

Can someone please provide more info on factory mode?

It will be hard to do, in ALDL mode the ECM will lock the timing to base timing, I'm surprised it's even drivable. It's diagnostics mode meaning the vehicle is running on base variables and ment to have the engine run at idle so that the readings can be compared to factory ' base' settings.

[This message has been edited by jelly2m8 (edited 09-06-2025).]