Hangwire

Whoaaaaaa nelly do not bring a 4.6L 2V with stock internals and valvesprings past 6,000 RPMS, never. It literally does you no good performance wise unless you want to stay in a certain gear when crossing the 1/4th line.

littlehogg311

Yeeeeah lol... I didnt mean to. And I damn sure havent done it since. It was the day I got it.

cliffyk

Make a note of the rpm and speed in 4th at 60mph or so, then use my "whiz-bang, pretty close but don't sue me, rear axle gear guesstimator to calculate what rear-end gear the PCM thinks is installed.

I f you have an auto use 3rd gear and make sure the converter is locked up (steady cruising).

If the car actually has 3.27s, but the tune thinks you have 3.73s or 4.10s, then the speedometer would read slower than you are actually traveling.

littlehogg311

I do have 3.27s. And the speed does show way less than Im traveling.

cliffyk

I do not doubt that--and this almost certainly means that the tune has been set to indicate that higher ratio gears are installed. If you do as I described above you will be able to determine what ratio the tune believes is installed.

There are two issues here, what gears are actually installed and what gears the PCM thinks are installed.

Roughly, based on what you described in your first posting, it sounds as though the tune is set up for 4.10s.

With 3.27 gears the engine would be turning around 2400 rpm at 90mph in 5th gear, however if the PCM thinks that 4.10 gears are installed it will tell the speedometer to display about 70mph at a 2400 rpm.

littlehogg311

That sounds about right. I do know it shows 70 at 90 and Im sure thats about the rpm it runs. So Im assuming that 4.10s were once installed.

cliffyk

That's what I am thinking--are there any signs that the rear end has been recently opened up? Or, maybe the previous owner swapped out the rear-end (to a new car or a friend) when he traded the car?

Does the rear axle show any signs of having been in and out?

Another issue is that we don't know what tune is in the car at this point. It may be an OEM tune that was modified just for the gear change, or it could be a full custom tune. The only way to tell it to pull it and compare it side-by-side with an OEM tune.

A tuning shop should be willing to do this for a minimal fee, and fix the gear ratio setting while they are "in" there...

cliffyk

This sort of reinforces that it may be a custom tune. The OEM rev-limiter kicks in at 6050 RPM, and although the in-dash tach is not a precision instrument there's no way it's off by that much...

littlehogg311

You can tell some one got in the rear end... also looks like maybe a complete swap could have been done a while back. I can tell some, but not all, bolts to take the rear end out, have been turned.

I thought the rev limiter kicked in somewhere around 6000... not 6800.