90V6RedHotLuminaEuro Posted September 4, 2011 Report Share Posted September 4, 2011 I recently purchased this car... been catching up on repairs and maintenance... Next... The Speedometer is off by approximately +15 MPH (ie. 55 mph reads approx. 70 mph). What are your thoughts? Quote Link to comment Share on other sites More sharing options...
urbex Posted September 4, 2011 Report Share Posted September 4, 2011 I would guess a bad speed sensor. That' just a guess though. Quote Link to comment Share on other sites More sharing options...
Twenty Posted September 5, 2011 Report Share Posted September 5, 2011 Is it on the original wheels and tires or an aftermarket set? It could be that the tires are simply the wrong size. Quote Link to comment Share on other sites More sharing options...
slick Posted September 5, 2011 Report Share Posted September 5, 2011 15 mph difference is pretty large. If the tires were the incorrect size, it would be VERY noticeable. Hook it up to a OBD 1 scanner, drive around, and see what the scanner says that your mph is. You could have a failing sensor. Or your cluster could be off. Quote Link to comment Share on other sites More sharing options...
90V6RedHotLuminaEuro Posted September 5, 2011 Author Report Share Posted September 5, 2011 Is it on the original wheels and tires or an aftermarket set? It could be that the tires are simply the wrong size. I checked the tires... they're correct... Thanks for the response... those are some nice rides you got there! ...that '67 brings back memories of my old pal from Brooklyn... Sal Geraci... had one of those... white on white on white... Quote Link to comment Share on other sites More sharing options...
90V6RedHotLuminaEuro Posted September 5, 2011 Author Report Share Posted September 5, 2011 15 mph difference is pretty large. If the tires were the incorrect size, it would be VERY noticeable. Hook it up to a OBD 1 scanner, drive around, and see what the scanner says that your mph is. You could have a failing sensor. Or your cluster could be off. Thanks for the response. My girl helped me check the speed first by driving along with me and using the cell phones... and then I hooked it up to her GPS which gives a speed indication... I'm not sure what you mean by my "Cluster" being off. Quote Link to comment Share on other sites More sharing options...
urbex Posted September 5, 2011 Report Share Posted September 5, 2011 The actual speedometer in the car can be off. If you plug in an OBD scanner it will read the speed. If it doesn't match what the speedometer says you might have a cluster going bad. This is the case in my Lumina, but it's only 1-2mph so it doesn't bother me. Quote Link to comment Share on other sites More sharing options...
90V6RedHotLuminaEuro Posted September 5, 2011 Author Report Share Posted September 5, 2011 The actual speedometer in the car can be off. If you plug in an OBD scanner it will read the speed. If it doesn't match what the speedometer says you might have a cluster going bad. This is the case in my Lumina, but it's only 1-2mph so it doesn't bother me. I get it! ...the sensor could be working properly and sending out the correct signal... but the actual speedometer might not be interpreting properly... but with the scanner I'll be able to read what the sensor is out putting, compare it to what the speedometer is showing, and determine who the culprit is. So now the trick is going to be getting my hands on a scanner to use, free of charge, so I can run the tests. Maybe AutoZone or Advance has a loaner tool scanner available. Thanks much for the helpful info. Quote Link to comment Share on other sites More sharing options...
urbex Posted September 5, 2011 Report Share Posted September 5, 2011 I get it! ...the sensor could be working properly and sending out the correct signal... but the actual speedometer might not be interpreting properly... but with the scanner I'll be able to read what the sensor is out putting, compare it to what the speedometer is showing, and determine who the culprit is. So now the trick is going to be getting my hands on a scanner to use, free of charge, so I can run the tests. Maybe AutoZone or Advance has a loaner tool scanner available. Thanks much for the helpful info. Exactly. But you'll still want to match the speed that the scanner shows to a GPS or something so you know if THAT speed showing is accurate. Quote Link to comment Share on other sites More sharing options...
Hairdo12 Posted September 5, 2011 Report Share Posted September 5, 2011 If a scanner is hard to source... Accelerate grandpa style to the so called 70 mph according to your speedometer. Then when you're in 4th gear and your torque convertors locks up. It should happen at around 48 to 52 mph at low engine load. 1750 rpms in 4th gear and tq con locked is about 50 mph. Given you have the rally cluster with a tach... Otherwise you can go by the sound of the motor. Quote Link to comment Share on other sites More sharing options...
LuminaPower92 Posted September 5, 2011 Report Share Posted September 5, 2011 Just throwing it out there. Should you ever have a problem with you VSS, your odometer, speedometer, and tranny wont shift correctly. Usually a bad wheel speed sensor will throw a code. At least it did on my 92. Quote Link to comment Share on other sites More sharing options...
Hairdo12 Posted September 5, 2011 Report Share Posted September 5, 2011 90 lumina would be a non E trans. My speed sensor went out and I still had all four gears, however no tq con lock up. Quote Link to comment Share on other sites More sharing options...
LuminaPower92 Posted September 5, 2011 Report Share Posted September 5, 2011 90 lumina would be a non E trans. My speed sensor went out and I still had all four gears, however no tq con lock up. My 92 Euro is a 4t60. I occasionally had 4th gear and no speedo and odometer. Was nice for keeping the miles down. Quote Link to comment Share on other sites More sharing options...
Breakdown Posted September 7, 2011 Report Share Posted September 7, 2011 Is it on the original wheels and tires or an aftermarket set? It could be that the tires are simply the wrong size. When you say wrong size, we're talking running 17" rims only versus 15's with proper sidewall tires to account for that difference. As Slick stated you'd have to be driving something that would have the car practically on it's belly. Quote Link to comment Share on other sites More sharing options...
virtuetovice Posted September 7, 2011 Report Share Posted September 7, 2011 Could be the same situation I had when I replaced my trans with a used unit, I've been told the reluctor wheel in my trans could be different. Are you absolutely sure the transmission is original? Quote Link to comment Share on other sites More sharing options...
90V6RedHotLuminaEuro Posted September 7, 2011 Author Report Share Posted September 7, 2011 Could be the same situation I had when I replaced my trans with a used unit, I've been told the reluctor wheel in my trans could be different. Are you absolutely sure the transmission is original? Thanks for the response. That's a Good Question. How can I tell if the Tranny and/or Engine are the original factory installed units? Quote Link to comment Share on other sites More sharing options...
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