Can I tune my auto 420a?

[Dsm_chuy]

Hey guys, i have an AUTOMATIC 420a. Im planning on boosting it with 7 psi. My question is Can I tune my automatic eclipse after turbo install ? Do I need to tune it? How do I tune it?

 

[jesse12345]

Your going to need an fmu and a bigger fuel pump. I usually buy the spa adjustable fmu on ebay and it works really good. You can set base and rising rate. I'd get a wideband at the very least just so you know what your car is doing. I boosted my auto 420a and that transmission did not like it at all, just a heads up.

 

[BLACK'98DSM]

You can't really tune the stock ecu (YOU can't tune it at all. There's a chance you can send it off to be reprogrammed, but that is very inefficient and I am yet to hear of someone doing so).
The best way to tune, and the way I recommend, is using Megasquirt. MS2 or MS3, either will work fine but MS3 has a few tweaks to make it more user friendly in 2023, IMO. With MS3 you have the choice of batchfire/wasted spark or sequential fuel/spark (I partially prefer 3 vs 2 for COP ignition setup). With this you can fully view and adjust every electronic engine parameters.

My thoughts on the transmission: Either 5 speed swap the car or start with a car already 5 speed equipped. The auto is an economy based transmission, and it will not launch or shift very well in a high hp application. There also aren't many aftermarket upgrades available. Enough to reasonably use in a non turbo build, but still always prefer the NV-T350 for these cars. The manual swap is a fairly involved job which is why I threw out the option of starting with a different car, but it can definitely be done.

TECHNICALLY you can run the turbo without tuning as long as you control the fuel delivery. Though I never liked that idea. Yes it will run, but your system is outdated and you're leaving extra power bottled up.

Based on the lack of info I can assume the engine itself is in stock form (at least internally). I'd start with checking it's health/condition. Compression test, leakdown test, does it smoke? Any unusual noises? Leaking from anywhere? Boost a worn engine, it will not last very long.
At a minimum I'd want to install headstuds, MLS head gasket and freshen up everything else. Forged pistons would be great because everytime you hit boost, even a low pressure, the ringlands are at risk.

 

[Dsm_chuy]

@black’98dsm Thank you for the information i am taking notes along the way. So my question has been answered. Yes i can run a turbo kit without a tune but won’t run right unless i do more modifications.

 

[Canadian_CD9A]

@black’98dsm Thank you for the information i am taking notes along the way. So my question has been answered. Yes i can run a turbo kit without a tune but won’t run right unless i do more modifications.

Just to be clear - the issue isn’t that it won’t run right, the issue is that it’s going to destroy your engine very quickly if you don’t do those additional modifications to control fuel. Do not just slap a turbo on your car without addressing fuel and hope for the best, it doesn’t work like that.