Does reflashing the engine computer chip harm the engine?
Define “reflashing.”
If a dealer does a factory-authorized reprogramming of the chip to correct a known problem, there should be no problem.
If someone modifies a chip to “improve” performance I’d say the chances of damage are pretty good.
I don’t think there is one clear answer, what engine are you trying to “chip”? How radical a performance change are you looking for? Lot’s of folks chip engines for moderate performance increases without significant issues, you may need to keep the old chip around for emissions testing and resale.
you may need to keep the old chip around for emissions testing and resale.
Since the OP referred to “reflashing”, it is safe to assume that we’re talking about a controller that has integral Flash memory not a discrete, socketed device like an EPROM from “back in the day”.
mcparadise covered the broader question well. The OP should clarify what exactly they are trying to do and on what vehicle to get a more precise answer to the question.
If the dealer is reprograming the EEPROM, there will probably be no effect. If you are have the EEPROM reprogramed by a nonOEM vendor or doing it yourself, the outcome will probably be less than optimal. After all the manufacturer spent a lot of time and money developing the program and mappings to give your engine a driveable personality. If you are shooting for more performance, you will probably will have driveability or emission problems i.e. high Nox, HC, CO, overheated cat, etc. If you have installed power adders (cam change, high flow heads, intake manifold, larger injectors, supercharger, turbocharger, headers, NOS, etc.) you will need to reprogram. The manufacturer/dealer will not be able to help you. Hopefully, you can find a hacker who has developed the new fuel and ignition advance maps or interceptor hardware to make your configuration work. In a nut shell, bad reprograming can burn down an engine, especially when power adders are involved.
Let us know more about what you want to do and how this project comes out
Since the OP referred to “reflashing”, it is safe to assume that we’re talking about a controller that has integral Flash memory not a discrete, socketed device like an EPROM from “back in the day”.
You’re probably right, it would help to know what engine we’re talking about.
I disagree it depends on programmer and vendor and the original design criteria behind the programming.
The case where you see appreciable jumps or changes are in turbo motors like the VW 1.8T or Subaru WRX 2.0L with little affect on the motor.