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| NLGHIA5.0 |
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I've been noticing lately that my NL has been upshifting at full throttle with power mode on at around 4600 rpm. My previous ED Ghia shifted at bang on 5000 rpm and my EL XR8 at 5500.
This obviously seems too low, so I was wondering if other Fairlanes were the same. Thought it may be a Fairlane thing? The tyres on the car are now 225/50/16's when the factory fitment was 215/60/16. I know the speedo reads too high by 7-8 kph at 100, so I thought this may also make the tacho inaccurate too? If I hold it in first it revs out cleanly past 6000. Any ideas? |
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| XR9UTE |
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Shift speed will be effected by your taller tyres.
Taller tyres won't effect your tacho. |
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| NLGHIA5.0 |
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{USERNAME} wrote: Shift speed will be effected by your taller tyres. Taller tyres won't effect your tacho. The tyres are lower profile now, not taller. How will that effect shift speed, faster or slower? I've got a shift kit anyway but curious to know. |
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| XR9UTE |
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Sorry, yes if your speedo reads higher than it actually is(because of your low profile tyres) it will shift earlier.
If you want to change the shift speed you could use one of those pulse adjuster kits you can get from Jaycar. That way you can split off the speed signal where it goes to the TCU and adjust it to where you want it. |
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| Nigel |
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Would that not be tach related rather than wheel speed??
Interesting. I have an EL Fairmont - and I have an XR8 TCM sitting in the shed. Mine will spin out to 5k on Petrol Nigel |
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| XR9UTE |
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No Nige, It's a function of Driveshaft speed vs TPS.
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| Nigel |
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That seems counter-intuitive to me!. but that also makes sense - I would have thought the more reliable/important information was input shaft speed and output shaft speed, with TPS. Actually thats both isnt it.
Good to know |
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| XR9UTE |
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Well, the combination of input shaft speed(engine rpm) vs output shaft speed(VSS) is used for trans diagnostics, like converter lockup speed. Because of that VSS is most important for shift points. The trans could be slipping it's head off and if it looked at RPM for shift points only it would fry itself in no time because it wouldn't know it.
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| NLGHIA5.0 |
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{USERNAME} wrote: Sorry, yes if your speedo reads higher than it actually is(because of your low profile tyres) it will shift earlier. If you want to change the shift speed you could use one of those pulse adjuster kits you can get from Jaycar. That way you can split off the speed signal where it goes to the TCU and adjust it to where you want it. Thanks for that. Makes sense why it shifts so early then. I'm putting some 18's on soon which will be a little taller so should bring the defecit back a little bit so i'll see what its like after that. Will 3.7 gears effect it as well, cause i'll be doing that soon. |
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| v8cortina |
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Posts: 39 Joined: 10th Jun 2011 |
hi, i dont have a nf fairlane but i do have the v8 from one in my cortina
 it shifts up about 4600 WOT 17" wheels not sure of tyre profile, but the speedo is 7km/h out so what would i do to get it back upto the original shft speed and a proper reading on the speedo?
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| XR9UTE |
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Change the speed sensor gear or use one of the pulse adjusters I mentioned.
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| v8cortina |
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Posts: 39 Joined: 10th Jun 2011 |
what would i be looking at to change the speed senser gear? what would i change it to? and also did the nf fairlane have a power/eco button? if it did im looking to hook it back up, cruisin' at 3400rpm seems a bit high for 110..
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| 66 coupe |
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{USERNAME} wrote: I've been noticing lately that my NL has been upshifting at full throttle with power mode on at around 4600 rpm. My previous ED Ghia shifted at bang on 5000 rpm and my EL XR8 at 5500. This obviously seems too low, so I was wondering if other Fairlanes were the same. Thought it may be a Fairlane thing? The tyres on the car are now 225/50/16's when the factory fitment was 215/60/16. I know the speedo reads too high by 7-8 kph at 100, so I thought this may also make the tacho inaccurate too? If I hold it in first it revs out cleanly past 6000. Any ideas? before trying any of the above, get someone to sit in the car and put their foot flat on the accelerator (with engine NOT running) and ensue the throttlebody is opening all the way. It may not be, which will cause it to shift early as the TCM never see's full load. |
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| NLGHIA5.0 |
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{USERNAME} wrote: {USERNAME} wrote: I've been noticing lately that my NL has been upshifting at full throttle with power mode on at around 4600 rpm. My previous ED Ghia shifted at bang on 5000 rpm and my EL XR8 at 5500. This obviously seems too low, so I was wondering if other Fairlanes were the same. Thought it may be a Fairlane thing? The tyres on the car are now 225/50/16's when the factory fitment was 215/60/16. I know the speedo reads too high by 7-8 kph at 100, so I thought this may also make the tacho inaccurate too? If I hold it in first it revs out cleanly past 6000. Any ideas? before trying any of the above, get someone to sit in the car and put their foot flat on the accelerator (with engine NOT running) and ensue the throttlebody is opening all the way. It may not be, which will cause it to shift early as the TCM never see's full load. I've already done that, the thought did cross my mind but it opened all the way. I definately think its the smaller tyres. If i put lower diff gears in would this alter the speedo and shift points like the smaller tyres have, or bring it closer to where it should be? |
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| 66 coupe |
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As long as you have not changed the speedo cog, tyre size has nothing to do with shift points.
the shift points are a function of tailshaft speed vs throttle position. even if you took the wheels off, it will still shift at the same speed on the speedo thats programmed into the TCM. As pete suggested, the shift points can be scaled with a speedo corrector if required. Have you tried resetting the TCM and performed a throttle calibration? |
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