replacing on a 1992 Lotus Esprit SE
by Lotus Esprit World
This guide will show you how to remove and replace a throttle position sensor on a Steven's Esprit. The sensor does as it's called. It gives the ECU the throttle position. You put your foot down and open the throttle and this sensor tells the ECU. This signal is one of the most important inputs used by the ECU for fuel control and for many of the ECM controlled outputs.
We had a cold start problem, were the Esprit wouldn't hold a constant idle from cold, often stalling without a little help from the right foot. We plugged in freescan to see what the problem was and noticed the throttle position was jumping about when we were nowhere near the pedal. This was giving the ECU the wrong information, which was causing the idle problem.
The TPS is a very critical sensor for the ECU and is it's not working properly it can cause all sorts of running problems. We replaced ours and our cold start problems disappeared. It's easy to change and something anyone can do with the right tools. A TPS is around £35 from any Lotus Dealer. Christopher Neil supplied ours with a few days.
This job is not difficult and should take under an hour to complete.
You will need the following parts:
New throttle sensor
You will need the following tools:
FreeScan Cable and software
Nice new shiny throttle sensor! These parts aren't serviceable, so it's a new part. The sensor is located on the rear of the engine and can be seen and reached easily. Just two screws hold it in place and a connection to the ECU.
You'll need a small screwdriver to remove the screws, both in head size and length. Remove the connector first, then you can remove the screws. You can pull the sensor off and remove it from the car.
The old and new sensors! Not much difference. Replace the sensor in the reverse of how you removed it. Takes only minutes. Once it's back in place and connected up to the ECU, you can connect up FreeScan to your car to check it's working properly.
Start the programme chatting to the ECU with the ignition on, but the engine not running. The Engine Data tab will take you to the blue screen with data from the ECU on. There you'll find a Throttle Pos, with hopefully a 0 next to it. Place you foot on the accelerator pedal and what the figure increase. It should be 95+ when you have your foot flat to the floor.
The only adjustment is to slightly rotate the TPS in the oversize screw holes. It's important to take your FreeScan readings by operating the throttle pedal, check that you have minimal free play in the throttle cable and the throttles do fully close.
You can also check it with the Sensor Diagnostics tab. Here check the typically output voltage is 0.5 volt with closed throttle and a typical output voltage of 4.5 volts with wide open throttle.
FreeScan USB Package
For all Injected 4-cylinder Esprits
This package contains the FreeScan software, high quality ALDL cable and 36 page FreeScan Manual. FreeScan can hook you up via your laptop to read the coding from your ECU. Perfect for troubleshooting and also includes free diagnosing of your log files and future updates. Read more here
This is a very easy part to fit and if it's not working properly you'll see a big difference with the new part fitted. The ECU is very sensitive to the throttle position and if it's not giving a correct reading it will give you all sorts of problems. Setting up the sensor to give the correct readings is dependant on each car. LEW's Esprit didn't need any setting up, so it was two screws and replace. Hook up FreeScan to check the throttle position and we'd finished. If your Esprit is like ours, then this is one of the easiest things to do on your Esprit.
This mod was performed by LEW on their 1992 Esprit SE.
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