The PAT WS6

iTrader: (14)

i have just now noticed that my speedometer is off. I followed some friends when my speedometer said i was goin 30 and they were really going 35 and when mine said 40 they were going 50. I have had my car since june and had noticed that it seems like your going faster than you really are. What could this be from? could the preivous owner had bigger rims on there and got it tuned? Could this be fixed with LS1 Edit?
any help would be great thanks

MattIROC

iTrader: (19)

maybe it has gears? ls1edit can fix it.

2001NBMZ28

I'd go to www.f-body.org/gears/ and cross check your speed against your RPM.

CRAGER

Ok, try this.

1st thing, if you know the car had 18's does that mean you know the guy? Ask him if he had gears on it, also ask him what size tires he had for the 18's. Then click here:

http://www.sccoa.com/faq/tirecalc.html

Check the size vs stock tire sizes (245/50/16 & 275/40/17). He probably kept the same overall tire height, so the speedo difference is probably not from that but maybe from gears like others have stated.

2nd thing you can try. Since you have an M6, get on the highway in 6th and get to 2,000 rpm's. You should be at 87-88mph. If you can have a buddy pace next to you on the cell phone to confirm that would really help.

BTW- Yes LS1Edit can correct this.


Peace,
Craig.

The PAT WS6

iTrader: (14)

no i didnt knw the guy, but i do not think it has gears cus gm replaced my rear end about 2 months ago and when they swap them out im sure they put the stock gears in there

The PAT WS6

iTrader: (14)

i will try the speedometer check tomrw to make sure i have the stock gears in there

wilddawg

find a gps and set the cruise at sixty and give it a chance to register. then you can fix it with ls1 edit

Zymosis

iTrader: (7)

Exactly what I was thinking if he didn't want to do the other things. My dads GPS is suprisingly accurate (More so then I thought it would be when he first got it)

CRAGER

Thats a cool idea and all, but you want to check out a few different speeds as well.


LightEmUpLs1- So whats the word, try anything yet?


Peace,
Craig.

The PAT WS6

iTrader: (14)

i still have not figured out the problem but when i am in sixth gear and going 60mph i am at 1600 rpms, but i am acutally doing 70mph cus my friend was next to me. i need to see what my speed is when i am doing 2000 rpms in 6th. This would be able to tell me if i have or had gears correct? if i cross check it with this link www.f-body.org/gears/

2001NBMZ28

I just played with that calculator a little:

Stock tire height, 1600 RPM in 6th, speedo reading 60 = 4.10's
Stock tire height, 1600 RPM in 6th, actual speed 71 = 3.42's

You said GM just replaced the gears a couple months ago...just guessing but sounds like the car had 4.10's and the speedo changed...then they put stock 3.42's back in it...speedo wasn't changed back. ????? I use that calculator to make sure my speedo is correct after programming for my 2.73 to 3.42 swap and it's spot on.

warpwr

Why not go back to the GM place that did the work and ask them to adjust speedo to the gears they put in? Usually parts and labor are warranteed for 12 mos/12k miles. They should know what ratio they put in there. They probably didn't realize they were changing the ratio at the time.

CRAGER

I agree with 2001NBMZ28, your computer seems to think you have 4.10's.

Now when they changed the gears, was that when you owned it? If so you didn't notice a BIG change in everything, speed, when to shift, not knowing what damn gear you're in?

The dealership will not reset the computer because they put stock gears in and your computer thinks it has aftermarket 4.10's. You might be able to talk them into it, if not they can flash your PCM and you'll be set. Or you can go to someone with LS1Edit and they'll fix you up. Shouldn't charge much just for gear change in the computer.


Peace,
Craig.

The PAT WS6

iTrader: (14)

i know for sure that i did not have 4.10s in before i got the car. cus im sure i would of felt the difference when i got the new rear end. so im thinking the guy who had it before me took the 4.10s out before he sold it with the computer already tuned to be set for 4.10s. not even caring about the tune he threw in the 3.42's and sold the car, does that sound right?
i just now noticed this problem but im sure its been like this since ive owned it (6 months)
but ne ways can ls1edit fix this problem?


thanks for all the help guys

CRAGER

Yes, the guy before you probably had 4.10's, then swapped them out for the stock 3.42's.

Yes, LS1Edit can fix that (as well as many other things like your skip-shift), hell even the P.O.S. Hypertech can as well (speedo).
Or you can have the dealship flash your computer to stock.
But since you have some headers and other bolt-ons, go ahead and get you a custom tune with LS1Edit and pick up some more power.

Peace,
Craig.

The PAT WS6

iTrader: (14)

i aint got no headers yet, but if i take it to the dealership and if they flash it will it undo the egr code that was deleted?

CRAGER

It will not undo anything, everything will be back to stock program.
But if you have an EGR problem then yes the SES light will come back on from an EGR problem.

Do you have an LS6 intake or something, did you removed the EGR?

Just get tuning from LS1Edit, and until then remind yourself the speed you are off.

P.S. When I get off work and get home about 10pm Central time hit me up on AIM if you want to.


Peace,
Craig.

The PAT WS6

iTrader: (14)

yeah when i put my ls6 intake on i removed the EGR and simple quick racing delted my code for it
thanks crager i will hit u up later