Where's the dividing line between VEC2 and AEM tunable Viper setups?

[SUN RA KAT]

Where\'s the dividing line between VEC2 and AEM tunable Viper setups?

Where's the dividing line between VEC2 and AEM tunable Viper setups?

I've been told by some of the best names in tuning that the VEC2 can be used successfully to tune almost every modded Viper.

I've also been told that seriously modded Vipers need the AEM and the VEC2 can't handle the mods.

Where's the dividing line? Or even IS there a line?

 

[Joseph Dell]

Re: Where\'s the dividing line between VEC2 and AEM tunable Viper setups?

VEC2 can handle timing, fuel, and the triggering of ONE (sometimes two) other items (water/****, NOS, shift light, etc...).

AEM is an entire computer that can change idle, adjust adaptives, trigger things on or off, run a make-shift traction control, control boost (on a turbo car), and data log incredibly well.

With AEM/Motec/anything-other-than-a-VEC2, you are dealing directly with a computer and its program. With the VEC2, you are dealing with a piggy-back system with very little overall control.

I like to think of the VEC2 as very 2-dimensional... the AEM/[Motec/FAST/insert-replacement-computer-for-car-here] as rather 3 dimensional.

example1: with the AEM, you tell it exactly how many CC's your fuel injectors are. With the VEC2, you tell the VEC2 how to modify the signal such that the fuel signal is modified in terms of what the stock computer thinks is installed.

example2: With the AEM, you adjust the timing map to be exactly what you want. With the VEC2, you adjust the timing map in terms of how the stock map is modified. in the AEM, if I say 21 degrees of timing at 6000rpm at 10psi, then that is what we have. with the VEC2, we say 'modify the stock signal by adding or removing *** amount of timing at *** rpm and *** boost level'. What is the original? no one really knows for sure. but we have guestimates.

example3: AEM can set the idle to be whatever you want. VEC2 you can't. if you want to set the idle with the VEC2, you have to fake-it by mucking with the throttle bodies to let more air in. but the adaptives don't like that and you get idle surge (a common VEC2 problem). [oh yeah: mess w/ the throttle plate screw on the accufab throttle bodies and you void its warranty. ]

Which is better? depends on your needs. AEM makes it possible to do lots of stuff. VEC2 is really easy to do 2-3 things with. For a slightly modified car, the VEC2 is cake. For a highly modified car (where the cam requires a change to idle) or where you need to control lots of stuff like boost control, traction control, etc... then the AEM is a reasonable option.

here are a couple of AEM screen shots for those who have never seen them. note the top bar of options...

AEM dashboard on laptop

One of the AEM tuning screens. note that these are all customizable so you can have whatever you want in the window.

AEM isn't without its issues just like the VEC2 isn't w/o its issues. Neither is perfect. AEM = lots of control. VEC2 = some control. do you _need_ lots of control? Most folks don't. Most cars don't.

just my .02...

JD

 

[newredrt10]

Re: Where\'s the dividing line between VEC2 and AEM tunable Viper setups?

Good description, can I add one more thing. If I under stand the two system the AEM is a direct control system while the Vec2 is a modifier system. This means that the AEM is a faster responding control. The vec2 has to wait for the car's PCM to react to its inputs before some thing happens. In some cases the Vec2 may be playing catchup and not react fast enough for good control of the motor. While the AEM does not have to deal with cars PCM. Is this correct think.

 

[Joseph Dell]

Re: Where\'s the dividing line between VEC2 and AEM tunable Viper setups?

Correct! That is the difference between a piggy-back (or modifier as you call it) and a direct control type.

For all you geeks out there (read: supercharged Vipermad), the AEM is trick because it has a GUI to control everything and it has more parameters than you could ever imagine playing with. It took me over a month to get comfortable with the basics, and over 3 to get really comfortable tuning my own car. After 5 months i felt pretty good about helping out other people.

JD

 

[Schulmann]

Re: Where\'s the dividing line between VEC2 and AEM tunable Viper setups?

Joseph gives a very good description and I am very impressed but ....


Tuning a car is a very time consumming activity. Take for instance the time that racing teams spend to tune their cars. The stock PCM is not perfect but does a very decent job. When you modify an engin PCM can't take into consideration certain parameters (boost&fuel octan) which requires to alter the ignition and fuel pulses.

The VEC2 is a very simple computer to alter two signals: ignition and fuel pulses. Which is enough in 99% of cases.
It has also the ability to manage other devices: W/M injection or NOS.

The VEC2 has the ability to detect boost and so it alters the PCM's signals. The vec2 only works close and above boost. Everything else is managed by the PCM.


It takes time to write a good VEC2 program and it takes a lot more time to write a good AEM program.


AEM is much more complex than the VEC2. It replaces the stock PCM. It has hundreds of tuning parameters. You have to tune your program for even idling. Is this good ? Yes and is very interesting but requires a lot of time. AEM is a great tool but the VEC2 is already enough thrilling for me. I don't want to waste my time to tune for idling and things like that. If I had the money and time I would by a AEM for the fun.

I know a couple of guys with very agressive cam. They run on stock PCM quite well.

Kenny, I know yout long story from the other thread ...
Read a couple of books about tuning.
Here is good and not too complexe to start. I am sure you will love it.


"How to tune and modify Engine Management systems" from Jeff Hartman. Motorbooks workshop edition

It talks about AEM, biggy back (Vec2), chip swapping etc ...

 

[Joseph Dell]

Re: Where\'s the dividing line between VEC2 and AEM tunable Viper setups?

I'm trying not to take over this thread, but you have hit on a personal sweet-spot of mine... Call it the "J" spot. anyway..

The book above is AWESOME. Get it. It will change your life.

Regarding the VEC2 - It does NOT work only above boost... it has parameters that can be set based on vacume/boost OR based on TPS (although most viper people don't know that the 0-5 volts on a viper TPS really run .094-3.94, appx).

While I agree that tuning can be time consuming, i've gone to the dyno to tune cars and we've made over 20 runs in an hour (making changes and little tweaks in between). It all depends on what you are trying to do and how comfortable you are with making changes. It doesn't HAVE to be a time consuming process.

Race teams DO spend tons of time working on their cars tuning. Often, though, this is because they are in classes where all the cars are identical. In the SPEC miata class, it is worth it for people to spend 8 hours tuning 5 more HP out of a car... and that is b/c 5hp is a huge difference when everyone else is X minus 5.

but i digress. I'll keep quiet for a few minutes. Maybe even bath a dog. feel free to PM me tuning type questions or I can send you sample VEC2 or AEM programs to play with. Nice thing about BOTH set-ups is that you can work with them off-line before you push or upload the changes to the computers... me likes that.

AEM isn't as daunting as it sounds, BTW. this is b/c tuners have "basic" programs that have 90% of things already set-up for you. plus, if you take a set-up like mine, modify it slightly (for your injectors, for example) and then push it, your car will probably run pretty good.

peace out!

JD

 

[Mr Hemi Head]

Re: Where\'s the dividing line between VEC2 and AEM tunable Viper setups?

The AEM has no OBDII connector, is that correct? This would be required for vehicle inspection in some states. If your car will throw codes with the stock PCM just swapping for inspection won't work. What is the solution?

Also the AEM for Vipers is expensive compared with other makes, is this due to the connectors or ?

 

[Joseph Dell]

Re: Where\'s the dividing line between VEC2 and AEM tunable Viper setups?

AEM uses the OBDII connector, but not for OBDII. It is NOT OBDII compliant. This is b/c it doesn't speak the OBDII language.

A Mopar Performance ECU, on the other hand, is both OBDII compliant and quite cooperative for emissions.

Hemi-Head points out something important: If you don't have the ability to swap PCMs back and forth for emissions (if emissions are a requirement for you) then the AEM won't work for you. Or it will except for once a year.

JD

 

[SUN RA KAT]

Re: Where\'s the dividing line between VEC2 and AEM tunable Viper setups?

My county used to have emission testing and I suspect it will again.

 

[plumcrazy]

Re: Where\'s the dividing line between VEC2 and AEM tunable Viper setups?

make friends with a local garage and dont worry about emisions...

 

[kwkshift]

Re: Where\'s the dividing line between VEC2 and AEM tunable Viper setups?

make friends with a local garage and dont worry about emisions...

All states aren't like that. For example here in Arizona, emissions testing is done by the State, at their own facilities. They're like ****'s out here. I know that in California they use 3rd party emissions testing which would be great if they did that out here!

 

[Simms]

Re: Where\'s the dividing line between VEC2 and AEM tunable Viper setups?

Not sure about Ohio, but in PA you can emissions exempt your car as long as you stay under 5000 miles a year.

 

[KepRght]

Re: Where\'s the dividing line between VEC2 and AEM tunable Viper setups?

AEM has knock sensors that allow the computer to pull timing out if you start to detonate because of bad gas or extra high heat. the adaptive tune on the fly is hands down the winner in all cases to me.

AEM has a single gauge that allows you to flip through several parameters, like boost, A/F ratio, etc so you have 1 single gauge for 19? things you may want to monitor & for sure all the things you need to monitor.

AEM has traction control if you get stuck in the rain or let the wife drive. you can tune the amount of wheel spin you want with a dial. on/off 1-20%.

AEM allows you to setup special modes. I call it valet mode. Keep the speed below 40mph & revs below 3000rpm. lets say you get the car towed, valet, impounded, forced to let someone drive it, etc. you turn this special key, or hit a hidden button & the car wont go over 40mph or 3000rpm, or what ever you set it to.

Motec has a coil per cylinder ignition option which gives far superior spark. AEM might have this but im not sure.

Vec2 is $1000 AEM is $3000, for the $2000 more you get a ton more flexibility & options with the AEM.

There are more options then this as well. some people don't care about these things, but in my mind if your talking engine management, why play guessing games? do it right. AEM or Motec all the way.

 

[Joseph Dell]

Re: Where\'s the dividing line between VEC2 and AEM tunable Viper setups?

AEM can support knock sensors but doesn't come with any.

AEM traction control *****. I've never seen a knob w/ a dial on an AEM. are you sure it exists? sounds like you are mixing it up w/ a Racelogic.

Never seen the "hidden key" though i've seen two modes of operation w/ an AEM based on a switch.

AEM is 2500 not 3k.

AEM is also not perfect. lots of bugs. it should be set-it-and-forget-it but it isn't.