tach learn

To experienced remote start installers. When you tach learn should you do it when idle is high at cold start or should you learn tach after idle is steady and at warm engine temperature? Thanks, Mar

I typically let the idle settle down a bit. I normally learn the tach after the car has been sitting in my barely heated garage so it is typically slightly higher than a fully warmed up engine, but not quite as high as an initial ice cold start. So far I've had no return issues (knock on wood) Kenny

Owner / Technician

KKD Garage LLC

Albany, NY 12205

Let it settle down.

The tach threshold is supposed to represent the vehicle running at idle. When you program most remote start systems they will create a small window around the setpoint (setpoint - 20 for example). The high threshold for engine shut down is typically 2 - 4x the idle RPM. If you have a car that starts and high idles at 1200 RPM but then settles down to 1000 RPM let's look at what that will do to the system. At 1200 RPM the remote start will turn the starter off at 1200 - 20 (from above). If the car is warm and it cranks right to 1,000 RPM the remote start won't see the minimum RPM needed and won't shut the starter off until it times out (usually after around 10 seconds). The high threshold will be 1200 x 4 or 4800 RPM. Well within acceptable range. At 1000 RPM the remote start will turn the starter off at 1000 - 20 RPM. This should be acceptable in either a high idle or low idle situation. The high threshold will be 1000 x 4 or 4000 RPM. Again, well within acceptable range for a high RPM shut down. The other thing to keep in mind is that a motor cranks around 350 RPM. It is important that your low idle is considerably above your crank RPM, otherwise the remote start might shut the starter output off too soon.Kevin Pierson

Great replies, thanks. Will come in handy. Mar