Round Delphi or square Mitsubishi ignition coils

Hi Anthony,

Thanks for the question. For those that say this doesn't matter unfortunately they are incorrect. There is a difference and it is flex fuel vehicles vs non. Most people will not have an issue if they never run E85 in their flex fuel vehicles. However, if you have a "Z" VIN then you need these coils in the event you run E85.

Also, the best way to find out which one you need to use is to look at the one that is currently in the vehicle. Reason being, many people have changed the engine in these vehicles and did not think about making sure they are replacing the engine with the same engine that was in it. Both will work so you could have a Z VIN and not have a flex fuel engine anymore.

I have included the stamping number for each so you can find out what is in your vehicle and whether it is correct for your VIN. However, Z VINs require the square coils.

The other main issue I have when people say, "both work, don't worry about it, " is because if both work then there would not be a difference. Automotive suppliers do not make duplicate parts in two styles with two different part numbers just because they feel like it. This is bad business and they don't do it. There is a reason and even if both work on regular fuel, the engine was tuned and PCM calibrated to work with what the engineers designed it for. Altering that may not cause an immediate issue but I am always in the camp of, the engineers knew what they were doing in situations like this. Improvements on parts/design can be made but this is not one of those cases. They intended for one coil to go in one style engine and the other to go in the other, so if it were my vehicle I would go with what they suggested.

Again, you could put the round in it and see if you have issues but if you want to stick with what GM called for, you need the square.

Thanks