Fred99LS1

I just got my HPP III in the mail today that I bought from this site. I programmed my car with the following customized settings;
HPP engine tuning
non-rfg gas
rev limiter: 6400 rpms
tire height for the P255/16/50's I entered as 26.25"
180 thermostat
top speed limiter bumped out of the way to 255
rear gear axle to 4.10

My speedometer still only reads 9 mph when doing 15 mph proved by a radar the police here on base have set up. Cruising at 25 mph on my speedometer has got me doing probably close to 35-40.... I bought this car from a kid who told me he thought the Moser 12 Bolt had 4.10 gears. Maybe I have 4.56 gears but when I jacked the rear of the car off the ground and turned the drive shaft 1 revolution the tire went around 4 times & about 5 inches past the verticle chalk mark I put on the tire. What could be causing this????

Also on another note I entered non-RFG gas. Afterwards I drove to the local gas station & the pump didn't say RFG on it anywhere but it did say 10% ethanol. So should I have entered RFG gas or non-rfg gas?

Thanks for the help. I want an accurate speedo damn it!
Fred

Camaroholic

iTrader: (1)

What kind of tires are you running? Are they really that much bigger than stock (that's about .6" overall height - still shouldn't account for being off that much tho).

Before you did the HPP, how far was the speedo off?

-Andrew

Fred99LS1

The tires are BFG drag radials P255/16/50's, according to Summit the O.D. is 26.1.

The speedo seemed to be off by about the same difference as before I'd say. I think the previous owner might of had a HPP or some sort of tuning on it when I bought it. I think he wanted the speedometer to read lower to keep the mileage lower. (I think) What about the gas too?

Fred99LS1

I placed a chalk line on the tire & pavement then pushed the car so the tire went one revolution, put another chalk line on the pavement and measured between the two chalk lines. I came up with 80"s. I divided by 3.1416 & got 25.46 for a tire height. This was the way to measure tire height that the HPP manual prescribed. So I programmed the car for 25.50 tire height & went from 9 mph indicated at 15 mph(By radar) to 8 mph from the original 26.2 programmed setting. I reprogrammed the car for 30" tall tires & the speedo read 10 mph when the radar here on base read 15 mph.

The other thing I noticed is that the HPP manual says I should be able to calibrate for 4.56 gears, but the HPP only goes to 4.10... I wonder if the 4.56 option is only for the A4 cars?

Could it be possible that the vehicle has a speed sensor that is faulty? For what it's worth the cruise control doesn't work either & the fuses are all good.

Also if anyone knows whether the gas that is 10% ethanol is considered RFG fuel or not?

Joker79

ok, i found some info about the fuel. the only page i found that put them together was http://www.arkenol.com/art_002.html, and from that i'd say yes it is considered RFG fuel.

here's some other pages with ethanol fuel facts...
http://www.michigan.gov/mda/0%2C1607...75--%2C00.html
http://www.agriculture.state.ia.us/ethanolfacts.html

Fred99LS1

TTT, any ideas.

Camaroholic

iTrader: (1)

Sure sounds like the previous owner might have programmed it for different gears...

Can you try larger - much larger - tire size? Like 40"? I know, sounds funny, but I've had to do it on custom LT1 programming when dealing with nonstandard VSS signals.

Weird that the HPP won't let you do 4.56's. I know the stock computer can take it.

Fred99LS1

Andrew,

I know you know what your doing as you programmed the computer for my 94 Z28. Should I call Hypertech & see why the 4.56 gear option is not available? BTW, the biggest available tire height option on the HPP is 30". I'd have to go to 50" to make the speedo read accurate.

Even if the previous owner programmed the car for a different gear ratio, shouldn't I be able to change the setting with the HPP? Thanks, Fred

Fred99LS1

I corrected my mph.. I had to enter 2.73 gears & 30" tall tires via the HPP. Now by radar I'm doing 15 mph when my speedo says 15 mph. Odd but reality!
Oh well, atleast my speedo is accurate now, Fred