Can you have 2 ECU’s for 1 car

I’m sure everyone knows what I’m getting at, 1 ECU tunes and the other stock for when I need to get work done. Has anyone tried this before?

Hmm as far as I know.... no.... for example, such as 1987-93 ford mustang 5.0 engine, they have all different ecu codes such as A9L, A9P etc. A9L meant for 89-92 (I think?) thats for manual trans. A9P is for 89 and? For auto trans 5.0 but can accept 5 speed swap. Which both 1989 mustang 5.0’s I have are of 2 A9P plus they have slightly aggressive tune by factory for advanced timing bump.... plus advance timing to 15 degree so it means 17-18 degree total and require 93 octane fuel all the way..... therefore they launch much harder that way. I also have spare A9P from 89 Mustang GT that crapped out on me the very day I bought her... almost free car. Long story. She got another ecu and fired right up. That was in 2014.... fast forwarding to Dec 2018, ecu died agin. Got another loaner ecu, she fired up again plus new fuel pump... thanks goes to ethanol fuel! Am going to be non ethanol car for good. She had fuel pumps replace twice in 5 years. Old pump had only 50 miles on it.... normal is 38 psi and result last week was 5 psi.... wow!

As of that situation.... You need to make sure the ecu code are correct for your car as other former vehicle. Thats as far as I know. I allow myself to be corrected.


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Actually, you can. I've got two for my '02, and people swap ECUs between cars frequently. You have to have a tuner delete the immobilizer, however. And both ECUs have to have exactly the same part number. The best approach is to keep the OE ECU stock and buy a second ECU to have the tuner delete the immobilizer and tune. That way you can swap to stock for service/warranty.

Check with a tuner before buying an ECU, however, to make sure they can make this work on your generation car.

Any CJAA ecu will work on any CJAA car, as long as the transmission type is the same.

The caveat is, the immo must be deleted or VIN matched, which any tuner should be able to do.

I have a custom tuned ecu for my 98 and the original stock one in my garage.

Probably easier and cheaper to get a handheld tune loader like flashzilla, q-loader, etc. and flash back to stock if needed. Did you recently get a new tdi?

turbobrick240 said:

Probably easier and cheaper to get a handheld tune loader like flashzilla, q-loader, etc. and flash back to stock if needed. Did you recently get a new tdi?

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EXCEPT, people are paranoid about the dealer detecting multiple re-flashes.

Can’t flash back and fourth there is a counter built in that says how many times the cars been flashed and VW knows how many times your car has been flashed

hymato said:

Can’t flash back and fourth there is a counter built in that says how many times the cars been flashed and VW knows how many times your car has been flashed

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I doubt it would be a problem. They could also tell if the mileage on the cluster doesn't match that on the ecu. I'd rather just enjoy the versatility of the tune loader than try to be super sneaky about hiding mods.

I have a different point of view: If you're willing to tune the car you should be your own warranty. If you don't like that option, don't have it tuned.

So you guys are saying its better to tune and flash the car at once after i delete the dpf/egr parts?

Hence losing warranty..... comparing to stock and get tuned then flash it stock before every dealership visits?


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IndigoBlueWagon said:

I have a different point of view: If you're willing to tune the car you should be your own warranty. If you don't like that option, don't have it tuned.

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I pretty much see it that way too. I also wouldn't buy a car if I thought it was likely going to need warranty repairs.