Reprogrammed chips or piggyback computer systems???

[flash{sbt}]

I am looking for a way to reprogram my chip so the cam switchover happens sooner. As all GT owners know it is very hard to keep the 2ZZ engine in it's powerband. If anybody knows of a system please help. I would perfer to have a piggback system, instead of reprogramming my chip. The apex-i systems look good, but I have not seen one for the Matrix/Vibe 2ZZ engine. Any detailed help would be great.

[mu_ohio]

The computer doesn't directly control the switchover. If you remember, the cam responds due to the change in oil pressure.

[d_m_kolb]

quote:The computer doesn't directly control the switchover. If you remember, the cam responds due to the change in oil pressure.The change in oil pressure is due to a signal the ECM sends a the device that changes the cam profile.If you can understand and correctly hook (wire) up a piggy back computer and have a way to tune it (normally done on a dyno) then a piggy back would be the way to go. You have more personal control over timing and your fuel curve. I personally wish I had more knowledge about piggy back computers like S-AFC but I don't.If you don't understand a piggy back or lack knowledge as I do then having your stock ECM reprogramed is the way to go.Here is some info I pulled off another forum I visit a lot.Red postedquote:On all piggyback devices (S-AFC, Greddy E-Manage, SMT-5, etc), the computer will only learn around them if you try to modify fuel delivery during NORMAL driving.the differentiation here is OBD2 in closed loop versus open loop operation.When you're just dinking around the city or cruising down the highway at low throttle, the onboard computer is running in OBD2 closed loop mode. This means that the computer is following the generally-accepted rules to supply fuel: based on incoming air mass, coolant temp, air temp, RPM's, etc. But in closed loop mode, it is ALSO watching the O2 sensors.When in closed loop mode, it uses the O2 sensor readings to make slight adjustments to the fuel delivery, because at light load the car can run much leaner without damage -- thus sucking less fuel and emitting less carbon monoxide/dioxide.This is where the car ''learns''.But when your foot is on the floor, the computer switches to OBD2 open loop mode. This mode is only used under heavy load, and it doesn't even TRY to learn. It instead just goes something along these lines: FUEL DUMP! It just throws fuel at the problem, because overly rich will not cause damage like overly lean would.The piggy-back computers should only modify fuel when your foot is on the floor; ie open loop mode. This way, the computer only works on the information it's being fed and doesn't attempt to learn around it.On an S-AFC, this is why you always leave the Lo throttle maps alone (if you're running stock injectors) and only modify the Hi throttle maps. You also must adjust the throttle points so that Lo is around 75% or higher and Hi is around 90% or higher... This is to ensure that fuel changes are only made when the computer is in open loop mode.If you're running bigger injectors, the story changes quite a bit.I found this site. It explains quite a bit about S-AFC'shttp://www.roadraceengineering.com/newafc.htmRandom postedquote:What you can and can't control with one varies depending on what piggyback you buy. What it does also varies depending on what Piggyback you buy.Going with the example you gave, the S-AFC.The S-AFC intercepts the MAF signal before going to the ECU, then alters the MAF signal up or down 50%, then sends the signal to the ECU as "modified". This "fools" the ECU into adding more or less fuel. It's limitations are based off air flow readings and fuel injectors. At idle, your MAF should read between 0.198 and 0.400, if you cut the reading 50%, it can trigger a CEL. On the other side of the scale, the MAX allowable MAF reading by the ECU is 21.9 If you hit 22, it will trigger a CEL and go into "limp" mode. If you adjust the air flow up to high at high RPM...you can trigger the "MAF out of range" error. I have YET to hear of anyone having either of these problems, but they are a theoretical concern.

[d_m_kolb]

Here's a small list of piggy back computers and ways to contact the manufacturer.S-AFC Apex-i (www.apexi-usa.com) (fuel)ITC Apex-i (www.apexi-usa.com) (ignition timing)Rev-Speed Meter Apex-i (www.apexi-usa.com) (Speedo, tacho, and estimated HP/torque figures)