im reading around and a lot of people don't recommend the unichip...why, im curious cuz i got one, now im worried

The unichip doesn't really suck, it does what it is suppose to do, it is the fact that the stock ECU is so damn amazing.

What happens is the Unichip has a set of maps (fuel, timing, boost) that change the values coming out of the stock ECU and go into the engine (think of just changing the value by some set value everyone time). The problem is the stock ECU is always adjusting the values of the car. So the stock ECU will see that the car is running leaner then expected because the Unichip told it to run leaner, the stock ECU will start adding fuel. So in the end the car will feel like crap becasue the the stock ECU is trying to fix some unexpected values.

This is why you need to reset the ECU pretty regaruly to have this unichip actually work correctly as this is the point at which the unichip was tuned.

Here is an example

No UNICHIP:
Stock ECU has a value of 10 it is looking for so it sends out the value 10 to the engine for fueling. The engine is running pretty hard and it si cool outside so it is running lean (in comparison to what the stock ECU is looking for) and returns the value 9. So it adjust by sending the value 11 to richen things up a little bit.

With UNICHIP:
Stock ECU has a value of 10 it is looking for so it sends out the value 10 to the engine for fueling. The UNICHIP intercepts the value and changes it to 6 (lowers it 4) to make the car run stronger at leaner conditions so the car returns a value of say 5 because it si cold outside and the car is running hard. The Stock ECU sees this and sends a value of 13 to adjust for the big difference, but now the UNICHIP sees 13 and lowers the value to 8. of course this gets back to the ECU and then has to raise it again to 15, but the unichip lowers it to 11. Then the ECU sees it to rich and lowers it. Neverending cycle for fuel and timing...

That is why it does not work well. The UTEC is pretty similiar to this setup, but allows you to reprogram it and change maps on your own.

Standalone engine management on the other hand does nto face these challenges, but other challenges. Then there is reprogramming the stock ECU, the best option I think so far.

excellent!!, i had to read that a couple of times to fully grasp it...but thanx!

!?!?!?! my hopes have been smashed, i was gettin a utec

1) Didn’t know what one was tuning on top of.
--Couldn’t account for spikes or dips in underlying ignition timing or fuel delivery
2) Didn’t have the resolution commensurate of the underlying maps
--Had to make compromise in one map cell in favor of another
3) No control of open/closed loop transitions
--Partial throttle knock correction/de-tuning
--Unexpected long-term fuel corrections
--Hesitations/EGT problems
4) Poor crank angle signal replication
--Induced misfire CEL
--Induced erratic knock correction activity
--Engine roughness/hard starting
5) Not enough software/hardware flexibility for different tuning approaches
6) No control of stock knock control system
7) No influence over stock closed-loop boost control system
--Eliminated all factory boost compensations and safety margin management
8) No user-programmability to account for car-to-car variance

Cheers,
shiv

Originally posted by Vishnu
1) Didn’t know what one was tuning on top of.
--Couldn’t account for spikes or dips in underlying ignition timing or fuel delivery
2) Didn’t have the resolution commensurate of the underlying maps
--Had to make compromise in one map cell in favor of another
3) No control of open/closed loop transitions
--Partial throttle knock correction/de-tuning
--Unexpected long-term fuel corrections
--Hesitations/EGT problems
4) Poor crank angle signal replication
--Induced misfire CEL
--Induced erratic knock correction activity
--Engine roughness/hard starting
5) Not enough software/hardware flexibility for different tuning approaches
6) No control of stock knock control system
7) No influence over stock closed-loop boost control system
--Eliminated all factory boost compensations and safety margin management
8) No user-programmability to account for car-to-car variance

Cheers,
shiv

Interesting insights. I have one installed in my car. Seems to trigger off CEL during cold starts every morning. OBD Codes P0301, 302, 303 and 304 Misfire. First I suspected is it because of my heat range 7 spark plugs. But there were other WRXs with Unichips installed that does not face this problem. My search for resolution came to nought.

Right now, I have lost my faith in Piggy Backs. I wonder of Autronic or Motec has come up with a plug and play.

You get what you pay for.

Originally posted by Imprezer
You get what you pay for.

Oh I didn't pay. Will be installing the Motec M800 soon.
Installed the Unichip temporarily as I need the fuelling to be right as I am running a large turbo. And also, Autronic and Motec do not have anything to replace this OBDII ECU.

Originally posted by krillz
!?!?!?! my hopes have been smashed, i was gettin a utec

The UTEC does not suffer from the same problems as the unichip
the utec runs the injectors and coils it's self at the points that you program it aslo has very good boost control
look at wrxhackers.com for more answers

Autotronic has a pnp board out right now but they are hand build units and do not control acvs witch may or may not matter to you look for EFI-guy's posts ad I think he is a distributior for them or somthing

__________________
Robert

The 2002 models which is imported to states does not have AVCS.
Only the 250PS GD-NBR JDM and the 2002 265PS and 2000 280PS GDB STi have AVCS. For 2003, the GDA and GDB will have AVCS as standard.

yeah I know that the USDM wrx does not have acvs

I have a ver 7 drive train on the way thought so that matters to me

Strader Performance Engineering has MY2002 Autronic PnP boards available for 1,599.00

Check out www.dynospeed.com

-Ben

Originally posted by bamfwrx
yeah I know that the USDM wrx does not have acvs

I have a ver 7 drive train on the way thought so that matters to me

Whats the final drive? 4.111 or 4.444? AVCS does not affect your transmission. No worries.

I don't really know what the final drive is I guess that it will be 4.111.
I meant the hole drivetrain not just trans. I will need an aftermarket ecu that can support acvs after I do a few mods that will render the Ver 8 ECU not quite compatable. Althought I do plan on driving it as it comes for a while just to see what kind of performace they get std over there.

Originally posted by bamfwrx
I don't really know what the final drive is I guess that it will be 4.111.
I meant the hole drivetrain not just trans. I will need an aftermarket ecu that can support acvs after I do a few mods that will render the Ver 8 ECU not quite compatable. Althought I do plan on driving it as it comes for a while just to see what kind of performace they get std over there.

Well, if you can get the whole wiring loom, that should not be an issue to support AVCS. We have done a Ver 4 WRX conversion to bugeye STi AVCS engine. Works fine!

Originally posted by Vishnu
1) Didn’t know what one was tuning on top of.
--Couldn’t account for spikes or dips in underlying ignition timing or fuel delivery
2) Didn’t have the resolution commensurate of the underlying maps
--Had to make compromise in one map cell in favor of another
3) No control of open/closed loop transitions
--Partial throttle knock correction/de-tuning
--Unexpected long-term fuel corrections
--Hesitations/EGT problems
4) Poor crank angle signal replication
--Induced misfire CEL
--Induced erratic knock correction activity
--Engine roughness/hard starting
5) Not enough software/hardware flexibility for different tuning approaches
6) No control of stock knock control system
7) No influence over stock closed-loop boost control system
--Eliminated all factory boost compensations and safety margin management
8) No user-programmability to account for car-to-car variance

Cheers,
shiv

Shiv,

So what effect does the EMI adapter have on the items you mentioned above?

good question... will the EMI help any/most/all of these issues?

i have a unichip ready to install with a VF-30 when i get injectors. but now it seems that all i am reading about is how the unichip SUCKS! i dont ever remember reading about it being so bad before i got one :-( or is this because the ecutek is sooooo much better? im sure this is the case.

i dont know what to do with this chip, i will be finished with the power mods once put in the VF. at least i have a P&P harness.

The EMI Adapter eliminates one (albeit the biggest, IMHO) problem associated with standard Unichip applications. It controls open/closed loop fuel control transitions which greatly improves partial throttle/full boost performance. Gets ride of the majority of hesitations that have bothered people for some time. One reason why there is so much "Unichip sucks" (it doesn't really) talk is because there have been other options. The one I'm most familiar with is the reflash which has yet to show any downsides as far as drivability is concerned. It's also capable of support substantially more power than the Unichip.

Best Regards
shiv

Originally posted by Vishnu
<snip..>
The one I'm most familiar with is the reflash which has yet to show any downsides as far as drivability is concerned. It's also capable of support substantially more power than the Unichip.For a street-driven WRX, is there any reason to run a stand-alone engine management system (ala TEC-III, etc.) or is the re-mapped factory ECU a better choice in most circumstances? I'm asking the question from the viewpoint of someone who might be running a turbo upgrade, big injectors, big intercooler, and turbo back exhaust, but doesn't plan on doing any fine-tuning, instead relying on either an off-the-shelf map or a dyno tune. Does one system offer better performance than the other in this (street-driven) situation?

I see also that Vishnu Performance now offers the XEDE control system that can store more than one tuning map. I take it that it is now possible to revert from say a Stage 0 setting back to the factory map for reasons such as dealer servicing, emissions testing, etc., or to a race gas map for track days. Is the map switching in the XEDE accomplished through a manual switch or software via laptop?

__________________
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ww
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