The system itself is not that bad, but it is the actual tuning software and support that is lacking. I tuned Kyle Busch's Camaro for Detroit Speed and it was a SC'd LS engine. It took a while but actually got it pretty good.

So can it be done? Yes. It it worth the time and effort to do it? Debateable for sure. But even before it can be tuned there are a few things to find out.

Do you have the cable and USB security key? Is it already set up for a 2 bar MAP sensor for forced induction? Is it set up and wired in for wide band oxygen sensor(s)? If the answer is no to all of these, then the cost to upgrade to this point plus tuning time may well exceed the cost of going to a GM factory ECU package or any of the aftermarket kits.

Hope this helps.

Mike Norris

thanks Mike. See you this week. :thumbsup:

No usb,it has a 2 bar map,no o2s. Ive had cars with big stuff,fast and this mefi has thrown me for a loop. Thanks for the input,the consensus seems to be to throw the mefi out and go with oem .

Probably a wise choice to ditch the MEFI 4. As others have said, it wont cause your engine to just spontaneously combust when you turn it over, however if there is no one in your area who knows their way around the system, that you would trust to tune the car, then it seems like a no brainer to switch it out. I know most people roll their eyes and groan when they hear I have a MEFI computer.

Matt

The MEFI is an OEM system, and is far more capable than even modern retail aftermarket systems, with the exception of the new Holley Dominator.

Mike Norris and I were able to get the a MEFI system to work really well. We worked with the folks who used the MEFI-Burn setup, and were able to get the car to start quickly, idle nicely, get good mileage, and have good power. In value terms, they are hard to beat. You just need to find someone who can handle them, and you need to the cable and USB key to unlock them (what Mike said).

Being as my system doesn't use a wideband/o2 do you feel it's a good set up on a supercharged set up? I have no problem using the mefi as long as I can have it running right. I can drive the car down to California or anywhere on the west coast but then the car won't be tuned for the altitude and temps back home. It's either that or do it locally but spend 700+ for the USB and unlock. That's why I was debating throwing a fast at it that will retain my drive by cable tb and not require a maf,or run oem ECM and running a maf and drive by wire set up.

Paul there's a lot of Burger joints en route from here south to Cali. ;)

I like the wide band systems like Fast, Accel, etc. that allow wide open throttle closed loop for forced induction setups. Just gives a little motre safety factor in that the correction is still on at WOT and it will try to add fuel if you're lean or subtract if you're lean. Plus you can limit how much it adjusts either way.

With that said, the non wideband systems like the factory ECM's work fine with forced induction, with the proper tune. I am not a fan of the MEFI 4, I would never run that system in anything I owned. Just doesn't have the features and easy tuneability of most the other systems. Does it even run a two or three bar MAP?

I don't know about 2 or 3 bar MAPs, but the MEFI 4b and 5 are big advances over previous MEFI systems, and even those have more capability than aftermarket systems. It's just that tuning software is lacking for them in a non-proprietary offering. If you have a MEFI, it's connected and you have a running car, and you've got the cable and USB dongle, I'd keep it. They can be connected to wideband or narrow-band O2 sensors, either one or two. They can be run closed loop at WOT. It's just that the tuner/end user has to do the integration to get it all working. If you are buying something new, I'd get something more user friendly.

I'm not sure if its a 2/3 bar, I'd assume it would have to be 2 bar for turn key to use it on a supercharged set up? And no I dont have the cable/dongle. Now you guys have me thinking,if they made a mistake and put a 1 bar map what would be a symptom ? It feels like its hitting a rev limiter when it gets Into load around 2000rpm