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Thread: Harrop conversion.............nothing is ever easy

  1. #1

    Harrop conversion.............nothing is ever easy

    So I purchased a TVR (Harrop) blower for my AA2. The install wasn't too bad. Changing the oil filter is more of a pain HA! Swapped the injectors out for some 60# (the injectors in there were unknown--turned out to be the 507 cc stage 1/2 GM injectors). The sector 111 ecu didnt have a vin #, but after taking it to the GM dealership and multiple guesses able to load a factory 2006 cobalt ss vin into it. Then loaded the HP tuners software, adjusted the fuel trims. Now it will start, and can rev; however if you go above 3k rpm it goes into a limp mode--just found out that it is because the crank sensor isn't communicating with the ECU because has to sense the e-brake is on for first time revved above 3k and our e-brake isn't wired into the ecu.

    Why, oh why isn't anything truly a plug and play

  2. #2
    Neutron
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    That's some wacky tune if it needs to sense the e-bake. None of us who did any tuning needed to do that. I dont even remember seeing any option for that in HPtuners though Darth did all my tuning. There are a couple of things that will trigger limp mode that we had to turn off though.

    If you have the HPtuners file of your tune you could probably post it here. There are several people with HPtuners who have tuned their Atom's who could look at it. No reason to go though all the pain that they did when learning to tune the car.

  3. #3
    Proton DarthChicken's Avatar
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    On your HPTuners, go into the engine section, then Cuttoff/DFCO. There is a button that says "P/N vs. ECT". Right now, I bet it says 3000rpm or something similar on the 2d chart. Change that to whatever you want to, and you're done.

  4. #4
    Quote Originally Posted by DarthChicken View Post
    On your HPTuners, go into the engine section, then Cuttoff/DFCO. There is a button that says "P/N vs. ECT". Right now, I bet it says 3000rpm or something similar on the 2d chart. Change that to whatever you want to, and you're done.
    Unfortunately PN vs ect is set at 6500..........

  5. #5
    Proton Terry Kennedy's Avatar
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    Quote Originally Posted by beckertb View Post
    The sector 111 ecu didnt have a vin #, but after taking it to the GM dealership and multiple guesses able to load a factory 2006 cobalt ss vin into it. Then loaded the HP tuners software, adjusted the fuel trims. Now it will start, and can rev; however if you go above 3k rpm it goes into a limp mode--just found out that it is because the crank sensor isn't communicating with the ECU because has to sense the e-brake is on for first time revved above 3k and our e-brake isn't wired into the ecu.
    Can you clarify what you mean by "Sector 111 ECU"? As far as I know, nobody has been able to make HP Tuners work with the Brammo ECUs that came on the Atoms. Some people assert that the ECUs are "locked", while I feel that it's just too small a market for HP Tuners do the work to locate the tables, particularly since there are a number of Brammo ECU variants.

    Most people who get into ECU tuning on Atoms start with a stock Cobalt SS ECU, turn off the stuff that makes it shut down right away, and tune from there. The idea is to get an ECU (preferably used, as new ones are very expensive) with the specific "Calibration Number" for a Cobalt SS. That should be on the label on the back. I don't know the number offhand, but I can check later if necessary.

    In any event, if you have a used ECU with that calibration number, it should already have an appropriate VIN loaded. If you purchased a brand new ECU, it would need to be coded at the dealer.

    Most of the ECU inputs and outputs are pretty simple when considered individually. There are 3 possibilities for the way a signal gets into the ECU, and I don't know which one the parking brake uses:

    1) Direct input (switch contacts) into a dedicated pin on the ECU
    2) Connected to the Cobalt instrument cluster when then signals the ECU via the CAN bus
    3) Connected to the BCM which then signals the ECU via the BCM / PCM link

    The first is easy to fake. The second two are a lot harder. If this is truly a one-time requirement, find a cooperative Cobalt owner and have then put the ECU in their car, set the parking brake, and rev to 3500. The ECU doesn't know if there's a Harrop or a hEaton on the car, other than what's tuned via HPTuners, etc.

  6. #6
    Neutrino Norm's Avatar
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    Vince Geglia with Trifecta can open the stock Atom ECU and set it so you can use HP Tuners. He told me that it had something to do with the serial number not being recognized by HP Tuners. Since that is a competing product, my guess is he won't though. Nothing against Vince, but, I want to do my own tuning, so, I have a Cobalt ECU and HP Tuners. Vince did have one very cool feature not offered by HPT and that is the dual tune, I had a meth tune and a ordinary tune on the same ECU flippable by a switch.

  7. #7

    tunes

    When I purchased the car, it had recently had the smaller pulley, injector swap and ecu from sector 111. I spoke with them at Sector 111 and the tuning there was done by Seccant. My car came with an ecu in a box and a set of injectors in a box that were from the original build (mine was #20, originally with sc and 300hp config).

    So, I ordered the Harrop and 60# injectors and wiring harness. Swap went relatively straight forward.

    I took the injector out of the car and looked up online to reference it because when talking to sector 111, they didn't know what injector size it was. It is a stage 1/2 injector rated at 507 cc at 3.8 bar fuel pressure. Calculating that 60# injectors should be 630 cc, we thought the fuel trims are going to be about 20% rich.

    Sooooooooooooooo.

    Hooked up HP tuners. Was able to download the file currently in the car. A couple of members on hp tuners had offered to help with a base tune.

    I looked at the tune someone had sent me--there were some significant differences; however just wanted to see what it would do. On my original tune, the car would start and idle. Didn't try anything more than that. When I began to try to change the tune in the ECU it asked for a vin#. Clearly the atom's vin # is not what it wanted. Sector 111 didn't have any idea what vin # had been used. To shorten this part of the story, I was finally able to find someone at a gm dealership with the tech2 software to flash it back to stock settings. They used a vin for a 2006 cobalt ss. Flashed back the ecu in the car to those settings. Tried to start the car and it would start but wouldn't idle. DIdn't think it was a big deal. Went back to the shop, hooked up HP tuners and installed the base map from the car. Took a little fuel out of it, then a little more. So, it currently has about 20% less than what it had from the tune it had with the 507 cc injectors. It will start and you can rev it to 3200 RPM. If you rev higher than that, it drops a cylinder. Doesn't matter if revving at 5% throttle or 50% throttle. Have been told that there is a synchronization between the crank position sensor and ecu that needs to occur but that according to the gm manual, the car has to be in neutral with the parking brake set at idle for 3 minutes or something; however with the parking brake set in the atom, it doesn't register in the ecu. got the pin outs for what wire needs to be grounded to make the ecu think the parking brake is on. Hope that is my answer.

    I'll see if I can post the 2 tunes.........the 1 is the tune that i pulled out of the car, the second is the one that the hp tuner guru sent me for 60# injectors.

    Hope not to have to take all this out and go back to where I was!!!!!

    ben

  8. #8

    finally

    <iframe width="560" height="315" src="http://www.youtube.com/embed/IyUKxXBftkw" frameborder="0" allowfullscreen></iframe>

    So this was the second pull.


    After 8 pulls and some fine tuning, ended up with a conservative tune 269 hp 6500 rpm, iat's good. Going to the track this weekend. AFR flat at 12.5:1

    I'll let you know how it goes


    ben

  9. #9
    Neutrino MadMaxAtom's Avatar
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    On track,keep an eye on your exhaust gas temperatures. IAT's and a/f won't tell you everything. Ask me how I know.
    The power of an Atom is a terrible thing to waste! Atom owner/operator since 2007. The more you chase perfection,the faster it becomes. John Force for President! (I asked him once in person...he laughed)

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