So I just noticed by putting my Garmin on my windshield that my speedo is about 10miles off. Meaning that it is reading 10mph faster than I am actually going. Says 60mph actually going 50mph, etc. So at about (80mph on the dash, 70mph in reality - My RPMs are 3300rpms)

Is the gearing of the needle different in an automatic car? I recently swapped from LS auto to LS manual but I retained the auto cluster for now. I know I got a B series OBD2 speed sensor for the tranny, but I just dont know if there are different ones.

Is there a quick fix for this problem?

 

If it is consistently off by 10 MPH, you just pull the needle and put it back on in the correct position.

Did it recently, to match my GPS.. ; ' )

 

^ This is your best bet and quickest fix.

I recommend getting a friend to help you, because it's not too safe going down the road at 60 mph, or any speed for that matter really, and watching a gps, then trying to put the needle on.

 

That's such a ghetto fix though lol

 

Tire size being used? It does make a difference...

 

^^ I think it s 205/40R16

 

Well, there's the problem.

You have a smaller diameter tire than stock. This will cause the speedometer to read high, and the odometer to record more miles than actually driven.

Also, the stock speedometer isn't perfectly accurate, so expect some differences between it and an external measurement.

 

Im sorry, I was mistaken. I am actually running a 215/45R16 tire. I just ran it through the tire calculator and the stock size 195/60R14 on my LS is 23.21" rolling diameter compared to the current 215/45R16 23.61" rolling diameter.

That meant the extra 3/8" of diameter should slow the speedometer just a tad, not speed it up a consistent 10mph.

 

Could pull the speedo gear and have a look at the teeth

 

these teg clusters are horribly off but i think if its 10% off from the actual...its in specification <---stupid

my teg reads 70mph while my gps reads 67. i have 195/55/15 tires too.
the GPS is dead on...its always accurate with the radars placed on the sidewalks and everywhere else.

 

Thanks for the input guys. I won't loose too much sleep over this knowing that I am a constant 10mph faster on the speedo. It seems that this inaccuracy is somewhat common. Hopefully I will be upgrading to a GSR tranny somewhere down the line, so I'll reinspect the speedo gear at that time.

 

Nice. You actually understands tire sizing, unlike most people.

Yes, 205/45-16 and 215/45-16 are both "close enough" to not worry about the change in diameter.

10% off sounds about right (sadly). Think about this, if it reads low you would be tempted to sue Honda for a speeding ticket. If it reads high, you have no way to blame Honda.

Also, tires change diameter from wear and different tires come in slightly different sizes, even when marked as the same size. So, the manufacturers will usually have the speedometer read a bit higher than the largest tire in the "correct size", when new, to keep that safety margin. As the tire wears, the inaccuracy will increase.

 

^^^ I have been in the tuning game over a decade and been on here for quite some time as a lurker I know the tire variance dilemma too... like from my personal experience, Toyo's run small buy BFG's run a little bigger. at least in the size tires i purchased in the past.

 

I myself have a similar problem. I have a 2000 automatic integra. I converted it to manual with a b20z and a type r lsd tranny. Car revs fine with auto ecu obd2.However I converted it to obd1 with an obd2b to obd1 harness alongside a 1995 obd1 p75 manual ecu. And now the car wont rev pass 5500. It hits 5500 but then just goes down and picks up again. The problem only persists while with in obd1?

How do I fix this?

Thanking you in advance

 

^^I do not have any issues revving or with my swap. My only concern is the incorrect Speedometer output. Perhaps someone with better OBD2 to OBD1 experience will be better suited to assist you.

 

Should be a code stored. Pull it and find out why it's limiting rpm