ivan
27-04-07, 01:42 PM
Changing Rev Limiter on a 4EFE
(4EFTE and 5EFE/5EFHE computers would apply aswell)
WARNING There is a chance this mod could damage your engine, do so at YOUR OWN RISK
So how would one go about raising the 4EFE limiter? We know the standard rev limiter on a 4EFE is at a low 6200RPM however the sister engine, the 4EFTE is much higher at 7200RPM.
To change the limiter is actually very easy, it will cost a maximum of about $10 and take about 1 hour including the time to remove/reinstall the ECU and perform a test run around the block.
What you need to do is replace one of the components on the ECU circuit board with a component of a different value.
To complete this DIY you will need the following:
Philipshead screwdriver
Soldering iron
Small needle nose pliers
12.960MHz oscilating crystal (Can be ordered from www.futurlec.com.au (http://www.futurlec.com.au/)) (the MHz would be different if you were to apply a different RPM cutout)Method:
Remove your ECU from the vehicle. It will be located under the dash, either behind the glove-box or under the stereo in the centre of the dash. You will be required to remove plastic covers to get to it. Take your ECU. It should look like this:
257
Remove the covers from both sides (they are held on with a screw in each corner)
Locate the crystal as that is what you will be replacing. It is circled in the photo below:
256
CAREFULLY remove the existing crystal using your soldering iron on the back side of the board (on the join where it is soldered) and your pliers to pull the crystal out the front side at the same time.
Note: Don’t leave the iron on for too long, as it would be possible to overheat the chip next to it. Go from leg to leg of the crystal a little at a time to get it out easily. With a little patience it will come out in no time.
Again, CAREFULLY using your soldering iron and pliers, solder the new 12.960MHz crystal in place of the removed crystal (they do not have polarity so it does not matter which way you put it on). Hold the leg of the crystal with the pliers, and push down into the hole while applying the soldering iron, both from the top side of the circuit board.
Once you are done trim off any excess crystal leg that is sticking out the bottom of the board, and make sure the top of the crystal does not get crushed by the top plate.
Replace the ECU covers, put the ECU into the car, and you are ready to test it.The results we received were:
6900RPM free revving without hitting the limiter
In gear the engine valve bounces at around about 6700-6800RPM
With the wideband metre the AFR's were fine at around 13:1. It appears the ECU is mapped higher than the factory rev limit so it should be safe.
In a couple of months a review will be added to the bottom of this article to explain exactly how it went (drivability wise)
On the standard 4EFE peak power is roughly just under 6000 rpm (free flowing air-box and filter), so the extra revs are not very helpful at this stage. If you plan on installing extractors, 4EFTE inlet manifold, porting the head and upgrading the valve springs, I believe you could make good use with the extra RPM.Remember that it is your responsibility and if you decide to do this modification, you have to bear the consequences if something is to go wrong down the track.
Regards,
Ivan
Note: This article may have been copied from another website and revised to better suit the Starlet community. If you are the owner of the original article and would like us to remove it, please contact me via email with the subject "Remove Article" and i will remove it from this website as soon as possible.
(4EFTE and 5EFE/5EFHE computers would apply aswell)
WARNING There is a chance this mod could damage your engine, do so at YOUR OWN RISK
So how would one go about raising the 4EFE limiter? We know the standard rev limiter on a 4EFE is at a low 6200RPM however the sister engine, the 4EFTE is much higher at 7200RPM.
To change the limiter is actually very easy, it will cost a maximum of about $10 and take about 1 hour including the time to remove/reinstall the ECU and perform a test run around the block.
What you need to do is replace one of the components on the ECU circuit board with a component of a different value.
To complete this DIY you will need the following:
Philipshead screwdriver
Soldering iron
Small needle nose pliers
12.960MHz oscilating crystal (Can be ordered from www.futurlec.com.au (http://www.futurlec.com.au/)) (the MHz would be different if you were to apply a different RPM cutout)Method:
Remove your ECU from the vehicle. It will be located under the dash, either behind the glove-box or under the stereo in the centre of the dash. You will be required to remove plastic covers to get to it. Take your ECU. It should look like this:
257
Remove the covers from both sides (they are held on with a screw in each corner)
Locate the crystal as that is what you will be replacing. It is circled in the photo below:
256
CAREFULLY remove the existing crystal using your soldering iron on the back side of the board (on the join where it is soldered) and your pliers to pull the crystal out the front side at the same time.
Note: Don’t leave the iron on for too long, as it would be possible to overheat the chip next to it. Go from leg to leg of the crystal a little at a time to get it out easily. With a little patience it will come out in no time.
Again, CAREFULLY using your soldering iron and pliers, solder the new 12.960MHz crystal in place of the removed crystal (they do not have polarity so it does not matter which way you put it on). Hold the leg of the crystal with the pliers, and push down into the hole while applying the soldering iron, both from the top side of the circuit board.
Once you are done trim off any excess crystal leg that is sticking out the bottom of the board, and make sure the top of the crystal does not get crushed by the top plate.
Replace the ECU covers, put the ECU into the car, and you are ready to test it.The results we received were:
6900RPM free revving without hitting the limiter
In gear the engine valve bounces at around about 6700-6800RPM
With the wideband metre the AFR's were fine at around 13:1. It appears the ECU is mapped higher than the factory rev limit so it should be safe.
In a couple of months a review will be added to the bottom of this article to explain exactly how it went (drivability wise)
On the standard 4EFE peak power is roughly just under 6000 rpm (free flowing air-box and filter), so the extra revs are not very helpful at this stage. If you plan on installing extractors, 4EFTE inlet manifold, porting the head and upgrading the valve springs, I believe you could make good use with the extra RPM.Remember that it is your responsibility and if you decide to do this modification, you have to bear the consequences if something is to go wrong down the track.
Regards,
Ivan
Note: This article may have been copied from another website and revised to better suit the Starlet community. If you are the owner of the original article and would like us to remove it, please contact me via email with the subject "Remove Article" and i will remove it from this website as soon as possible.