Drivetrain Calibrate My Speedo

j966er · Feb 28, 2015

I hope someone can help . I picked up a 1997 procharged 4.6 a few days ago an the Speedo is off . The place I got it from said it has 4 10 gears . now I have talked with a few different people at American muscle one said Speedo gear the other said Speedo recalibration tool . Which way should I go ? Also do I need a handheld tuner for the car if I go get it dyno tuned ? It is running rich

COramprat · Mar 3, 2015

Dyno tune to get the fuel condition right. I know it is more expensive but that is the best way to go. You can get a 4 position chip for different tunes or a handheld with the dyno tune loaded into it. The speedo gear is a temporary fix. I had one that tore up in a year so I'd get a speed calibrator. I don't think you can fix the speedometer with a tuner like the newer cars since I believe it is a manual speedometer.

wmburns · Mar 4, 2015

The correct Speedometer fix depends upon the model year. The 1996-1998 MY uses a VSS sensor. The output of the VSS sensor goes to BOTH the PCM and the cluster.

The 1999+ model year uses an OSS sensor. The output of the OSS sensor goes straight to the PCM. The PCM then "tells" the cluster what to display.

Why does this make a difference? Because a PCM re-calibration hand held tuner will only fix the PCM speed. The cluster speed will still be wrong. Therefore for the 98 and older Mustangs, use the VSS gear or an external SpeedCal unit.

The dirty little secrete the sellers of low gears don't tell you is the plastic gears for the VSS sensor don't always hold up because the teeth don't mess well.

For the 99+ model year, use an external SpeedCal or PCM custom tune. For the external Speedcal make sure it's compatible with an OSS style sensor.

j966er · Mar 6, 2015

Thanks for the info guys .I'm real happy with the car I think I got a good deal on it . I paid 7500 and she's only got 54000 miles on her with the procharger bbk long tube headers, bbk 78mm throttle body,plasma booster,msd coil packs & wires . The place I got it from (rpm motors in west palm beach fl) said it has 410 gears,forged bottom end,built heads and a stage 3 clutch. Don't know if what they said is true because they did not have no proof of that stuff. I do know that the boost gage reads 8lbs at 5000 rpm . I have only taken it to about 5500 rpm in 3rd gear an was stuck back in the seat. I'm not gonna get on it to hard intill I get it on a dyno. Fingers crossed for over 500 hp. what do you guys think ? Also I could not talk myself in to selling my six banger . She's not fast but she looks real good . Now my wife has named them beauty and the beast .

Mineral4.6 · Mar 17, 2015

My speedo is off as well with my 3:73 gears. And my car is an 01 so there isn't a speedo gear to replace it's all in the computer. I'm going to pick up a hand held tuner which allows to adjust speedo for gears. Worth the money I think since I've been also having issues with my car not being tuned an all the parts on it.

restomod66 · Mar 19, 2015

Get that thing Dyno tuned like yesterday for peace of mind b/c you wouldn't want to do any harm to the engine. I noticed it's a 97 so don't be too crushed if you return from the Dyno with a sheet in hand that reads ~350rwhp or possibly less. 500hp requires a lot more work than people seem to think, and most Supercharged/Bolt-on New Edge GT's (99-04) Dyno in the 360-420rwhp range from what I've seen. All things being equal you can expect less from a NPI 4.6 in your 97.

j966er · Mar 19, 2015

restomod66 said:
Get that thing Dyno tuned like yesterday for peace of mind b/c you wouldn't want to do any harm to the engine. I noticed it's a 97 so don't be too crushed if you return from the Dyno with a sheet in hand that reads ~350rwhp or possibly less. 500hp requires a lot more work than people seem to think, and most Supercharged/Bolt-on New Edge GT's (99-04) Dyno in the 360-420rwhp range from what I've seen. All things being equal you can expect less from a NPI 4.6 in your 97.

Well thanks for breaking my heart that one hurt ha ha ha . What ever it ends up being I will just have to happy with it . Thanks for the info the more I know the better off I am . I did race a friend that has a 2005 c6 vett he claims it has 425hp an I busted his a$$ . So my fingers are still crossed but have a more realistic number in my head now that I've gotten some info from guys like you that know more about these cars then I do. Thanks again and I will post a dyno sheet as soon as I get it to the shop. For now I'm still driving my sixer everyday.

Drivetrain Calibrate My Speedo

j966er

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COramprat

...I can take it. I think.

wmburns

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Mineral4.6

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restomod66

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Drivetrain Calibrate My Speedo

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