Winter Fronts And S60 Stutter Issues

Leroy Pershing
February 2023

Now that winter has arrived, we receive occasional calls about whether or not a winter front should be installed. You sometimes see them on trucks when driving down the highway. It makes people think that they are not doing all they can for their truck. This could not be further from the truth. Ignoring the advice of anyone who recommends one to you would be beneficial. Winter fronts are only necessary in rare cases and are not needed for modern engines. Detroit Diesel specifically states that a winter front should only be used when the outside air temperature is less than -22F AND if the engine is having a hard time maintaining 175F of coolant temperature. For our northern friends this doesn't sound that uncommon, but I seethe when I see winter fronts in warmer states like Pennsylvania. While they may help keep heat in the radiator, they also keep in the charge air cooler! Controlling intake manifold temperature is critical to performance and fuel mileage. To describe how excessive intake temperatures can be harmful allow me to list a few downsides: excessive temperatures can keep the engine fan on which reduces power and fuel mileage, excessive temperatures can increase NOx emissions that increase EGR or DEF consumption, excessive intake temperatures mean the exhaust temperature will also be higher, and in some cases excessive intake temperatures can give false readings to sensors which could lead to check engine lights and less run time! While many of the winter fronts I see do not totally block the grill they are still restrictive and can cause performance issues. Even if you don't experience check engine lights your engine is suffering. It is recommended if you must use a winter front that it must be at least 25% open. If your truck is having difficulty maintaining temperature during the winter than you have an issue with your cooling system.

Have you been experiencing an issue with your DDEC 3 or 4 Series 60 where after a long period of no throttle input your engine will stutter and blow smoke after you begin to accelerate again? We get this call all the time and the fix is simple. I hear people tell me all the time that they have replaced injectors, sensors, wiring harness and some people are even replacing cylinder heads! The issue is in the ECM calibration. For some reason, the calibration calls for an extremely retarded beginning of injection. In some cases, the ECM will not begin to inject fuel until 10 degrees after top dead center. At this point in the cycle there is no hope for this engine to have a 'successful' combustion cycle. You can clearly see and feel that something is not right when you feel the shutter and see the smoking pouring from the exhaust. We have fixed many engines with this issue and the owners are always very skeptical that this will be the fix. After spending years chasing this problem, I would be skeptical too that it is just a calibration issue. Once we adjust the calibration that prevents the ECM from requesting such retarded timing you will never have this issue again. You can go to any one of our remote tuning locations or you can come to our faculty here in Saxonburg Pennsylvania.

Written by: Leroy Pershing, Pittsburgh Power Inc., 3600 S. Noah Drive, Saxonburg, PA, 16056 Phone (724) 360-4080. Email: [email protected]