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| mr_rx7_ |
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Age: 38 Posts: 347 Joined: 10th Jan 2005 Ride: 2002 Mustang Cobra Location: Broadmeadows (Melb. North) |
I'm going from 3.08 to either 3.9 or 4.11 diff soon... and I was wondering if there's a cheap way to change the shift points on an auto ECU via a Chip/Edit?
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| Steady ED |
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The shiftpoints will be fine if you don't change the speedo sender gear, ie. if your speedo stays reading wrong.
_________________ ED XR8 Sprint - S-Trim, V500, 249rwkw |
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| mr_rx7_ |
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Age: 38 Posts: 347 Joined: 10th Jan 2005 Ride: 2002 Mustang Cobra Location: Broadmeadows (Melb. North) |
Dodgy as haha. I mostly do city n suburb driving so don't want to get booked by having an incorrect speedo.
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| Steady ED |
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Well theres no speedo sender gear for 3.9s/4.11s anyway
You'll have to use a jaycar speedo corrector or similar. There was talking of possibly needing two if you want shiftpoints right, depending on whether the speedo signal is split, or whether the ECU or dash gets the signal first. Can't remember what worked.
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| mr_rx7_ |
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Age: 38 Posts: 347 Joined: 10th Jan 2005 Ride: 2002 Mustang Cobra Location: Broadmeadows (Melb. North) |
Yeah my mates going to put in the Jaycar corrector for me...
You just gave me a thought... Maybe put one Jaycar corrector between the sender unit and the speedo to correct the speedo by say X%...and then put another one between the ECU and speedo/sender/watever it gets it's input from and correct the signal by -X%... think it could work?
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| Steady ED |
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Yeah thats what I meant, not sure if you need too however.
I've got a mate that ran 3.7s in an auto with a jaycar speedo corrector, thats who we discussed using two with, I think he only ended up needing one however, so I'll check with him tomorrow. I have a feeling it sends the signal to the ECU first, then the dash gets its signal from there, so you'd have to modify the signal after the ECU.
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| mr_rx7_ |
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Age: 38 Posts: 347 Joined: 10th Jan 2005 Ride: 2002 Mustang Cobra Location: Broadmeadows (Melb. North) |
Thanks for that mate. Let me know what he tells ya.
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| TerroristGHIA |
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I did this when i went from 3.45 to 3.9. I fitted an XD transducer to the box, which gave the correct speedo reading, then i put the Jaycar corrector on the box ECU. I got my corrector from shiftkits.com.au, and they pre built it for me including instructions on how to install it. Mind you this was for a V8
Brett
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| Molloy |
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Steady ED wrote: The shiftpoints will be fine if you don't change the speedo sender gear, ie. if your speedo stays reading wrong. so if u change the speedo gear so it reads correctly that will stuff up your shift points?
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| mr_rx7_ |
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Age: 38 Posts: 347 Joined: 10th Jan 2005 Ride: 2002 Mustang Cobra Location: Broadmeadows (Melb. North) |
No Molloy, ur shift points don't change. They are set at different km/h... not RPM.
Say a 3.08 ECU shifts at 87km/h...on a 3.08 diff that would be say 4000rpm but on a 3.9 diff it would be alot higher, so if u plant down the accelerator, you will hit the rev limiter you reach 87km/h thus the ECU won't shift unless you back off. But if you don't change the speedo gear, the ECU will think your at 87km/h and shift up when really ur doing 70km/h so you won't rev out to the limiter before the ECU changes. Hope that makes sence...
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| Steady ED |
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Molloy wrote: Steady ED wrote: The shiftpoints will be fine if you don't change the speedo sender gear, ie. if your speedo stays reading wrong. so if u change the speedo gear so it reads correctly that will stuff up your shift points?Yes, unless you also have an auto ECU that matches the diff ratio. eg. 3.45 Diff, grey sender gear, XR6 ECU.
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| mr_rx7_ |
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Age: 38 Posts: 347 Joined: 10th Jan 2005 Ride: 2002 Mustang Cobra Location: Broadmeadows (Melb. North) |
So did anyone work it out? Steady ED, did your friend shed any light??
Brett, would it be very different from V8 to i6 do you think?
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| Steady ED |
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mr_rx7_ wrote: Brett, would it be very different from V8 to i6 do you think?
Yeah, V8s get a seperate trans controller, as opposed to integrated trans control in the 6s. From what I've been told, the speedo signal goes to the ECU first, so without looking at wiring diagrams, I'm assuming theres a speedo signal fed to the dash from the ECU, you need to tap into it there.
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| mr_rx7_ |
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Age: 38 Posts: 347 Joined: 10th Jan 2005 Ride: 2002 Mustang Cobra Location: Broadmeadows (Melb. North) |
Ok, what about the Police Cluster? That has the speedo calibrator. So assuming the ECU still receives the uncalibrated signal from the sender, and then the cluster corrects the signal it receives from the ECU, my ECU should still shift normally but my speedo should be correct?
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| Steady ED |
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mr_rx7_ wrote: Ok, what about the Police Cluster? That has the speedo calibrator. So assuming the ECU still receives the uncalibrated signal from the sender, and then the cluster corrects the signal it receives from the ECU, my ECU should still shift normally but my speedo should be correct?
Yes, but I dunno how much adjustment they have. May not be enough for 4.11s
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