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05 Suzuki Forenza transmission problems
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Firepath
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Jan 23, 2015, 7:08 PM
Post #1 of 10
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05 Suzuki Forenza transmission problems
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While I'm driving by a speed radar gun at 40mph, the radar shows that I'm going about 35mph. I used my phone as a speedometer once, my phone said 102mph, when my cars speedometer showed about 110mph.
When I'm going around 30mph and put the pedal to the floor then release it, the RPM's go up, and the car slows down a little bit. I think I need to have my fluid changed, but it has no dipstick.
Would it be worth my time to get these issues fixed? Should I worry about them?
Thank you
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Discretesignals
Ultimate Carjunky
/ Moderator
Jan 23, 2015, 7:38 PM
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Re: 05 Suzuki Forenza transmission problems
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Not sure what your problem actually is. Can't make any sense out of what you typed.
Since we volunteer our time and knowledge, we ask for you to please follow up when a problem is resolved.
(This post was edited by Discretesignals on Jan 23, 2015, 7:39 PM)
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Firepath
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Jan 23, 2015, 7:47 PM
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Re: 05 Suzuki Forenza transmission problems
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I don't really know either. Basically, there is an inaccuracy in the speedometer, and the car might be slipping.
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Discretesignals
Ultimate Carjunky
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Jan 23, 2015, 8:00 PM
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Re: 05 Suzuki Forenza transmission problems
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Do the tire sizes match what is on the tire pressure label that is located on the driver's door jam? Was there any recent work done on the transmission or speedometer?
I really wouldn't consider using your phone as a comparator for determining speedometer accuracy. The radar gun may not be calibrated? Has the radar gun been tested on other vehicles and shown to be accurate?
You could have a shop plug into a scan tool and monitor the vehicle speed sensor data to see if it matches your speedometer reading.
Is this automatic or manual transmission? Automatics usually don't slip when you close the throttle because the torque converter stops multiplying torque. A slipping transmission happens when your accelerating. If it was slipping, the engine would rev, but you wouldn't be accelerating.
110 mph? Hopefully this was on a race track.
Since we volunteer our time and knowledge, we ask for you to please follow up when a problem is resolved.
(This post was edited by Discretesignals on Jan 23, 2015, 8:01 PM)
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Discretesignals
Ultimate Carjunky
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Jan 23, 2015, 8:18 PM
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Re: 05 Suzuki Forenza transmission problems
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Most speedometers have tolerances of some ±10%, mainly due to variations in tire diameter.[citation needed] Sources of error due to tire diameter variations are wear, temperature, pressure, vehicle load, and nominal tire size. Vehicle manufacturers usually calibrate speedometers to read high by an amount equal to the average error, to ensure that their speedometers never indicate a lower speed than the actual speed of the vehicle, to ensure they are not liable for drivers violating speed limits.[citation needed]
http://en.wikipedia.org/wiki/Speedometer
10 % of 40 mph is 4 mph, so your speedo may not be accurate, but it is normal by the manufacture to keep you out of getting speeding tickets due to variances that may affect the changes in the speedometer reading.
Since we volunteer our time and knowledge, we ask for you to please follow up when a problem is resolved.
(This post was edited by Discretesignals on Jan 23, 2015, 8:22 PM)
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Firepath
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Jan 23, 2015, 9:42 PM
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Re: 05 Suzuki Forenza transmission problems
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The tire sizes match the sticker in the door jam. I haven't had the pressure checked lately. There hasn't been any work done on the transmission, that I know of.
After an accident, I was renting a vehicle from enterprise (2014 VW Jetta), and the radar was dead on accurate.
The vehicle is an automatic transmission. The 110, was on a highway.
At 40mph, i've done the math, and it's -12.5℅ slower.
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Discretesignals
Ultimate Carjunky
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Jan 23, 2015, 9:59 PM
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Re: 05 Suzuki Forenza transmission problems
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Really not sure on that one beside comparing speed sensor data to the speedometer to see if there is an inaccuracy. You may need to drive another Forenza the same year as yours to see if the speedometer inaccuracy is the same or not. It may be a characteristic of that vehicle. I am sure that +-10% variance is not set in stone between manufactures.
Since we volunteer our time and knowledge, we ask for you to please follow up when a problem is resolved.
(This post was edited by Discretesignals on Jan 23, 2015, 10:00 PM)
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Firepath
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Jan 23, 2015, 10:20 PM
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Re: 05 Suzuki Forenza transmission problems
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I can say that the odometer is pretty accurate. I ran a mileage check, and used google maps, phones odometer, and the car odometer, they were all about the same. How can someone get the speed sensor data, or check it?
I can't try another Forenza, I don't have access to one. I also don't know very much about cars.
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Discretesignals
Ultimate Carjunky
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Jan 23, 2015, 10:30 PM
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Re: 05 Suzuki Forenza transmission problems
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You'll need a scan tool that can access the engine computer data stream. The OBD2 side of the PCM should have vehicle speed sensor information. I really don't know what you'll need do to correct the speedo if the data is different. The speed information could be adjusted through software in the controller (PCM or IPC) for the speedo or maybe it has something to do mechanically in the speedo itself that the manufacture calibrated into it. It is definetely not something I see very much. Some vehicles had the option in software to change tire sizes to keep the speedo accurate. Not sure if yours is one of those.
You could always bend the needle...LOL. J/K
Since we volunteer our time and knowledge, we ask for you to please follow up when a problem is resolved.
(This post was edited by Discretesignals on Jan 23, 2015, 10:40 PM)
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gsferraro
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Jan 24, 2015, 12:19 PM
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Re: 05 Suzuki Forenza transmission problems
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Not alot of info on this trans, its a ZF4HP16. I looked up the location of the vss, according to shopkey, the location is left rear of engine. Gary
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