Welcome to My Channel! Unfortunately 1999 Lotus Esprit developed a misfire in two cylinders and it was quite a process to diagnose and repair.
What started out as a possible ignition system refresh ended up as an ECU repair and a good amount of the weekend lost.
I started out using an inductive timing light to narrow down which cylinders had spark and which didn’t. I then located the terminal assignment on the 88-pin ECU connector for the coil outputs.
Those terminal numbers are: 29, 32, 49, 52. With the engine running I used a multi-meter and determined that 3 of the 4 outputs were generating operating voltage (12.8-13v) while one was 9-10v. That coincided with the two no spark cylinders. I then used a continuity tester to determine which driver in the ECU was responsible for that output. I then swapped the driver with the driver for the other two cylinders on that bank and the result was the same although i was expecting to loose cylinders 1 and 4 and gain 2 and 3. Out of frustration I decided to reflow the solder on all of the major components from the drivers towards the connector, as well as clean the board thoroughly. This proved to be the solution as the car is fixed!
I made this video in the hopes that it’ll help people diagnose these cars as the information on them is limited. Please subscribe as I’ll be posting more repair videos(hopefully nothing new!), and other general automotive propaganda.
Thanks for watching!
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Excellent soldering! I'm happy for you!
I did eventually figure out a lot of the individual parts on the board and what they are for, this is a univeral ECU used on other cars so there are a lot of unused transistors on that heatsink there.
Awsome, glad i'm not the only 1 who got into their 918 ECU to figure out the ignitor issue. YOu might have seen me talk about it and post pics, my ignitor was actually bad,
i replaced with one from a Megasquirt kit. In the end I installed full Megasquirt standalone.
Great work man!! I know this wasn't your problem but careful with the new spark plug wires. Many times they don't click onto the spark plugs. The lead needs to be pushed deeper through the boot so it can reach and snap into the plug. BTW, you do have the high torque ECU right?
Thanks so much for making this. I had a misfire last week on my 2002 after some very high revs. I cleared the code and it hasn't returned – fingers crossed.
Do you use the Windows OBD program written specifically for the Esprit by another hobbyist? If so, I'd appreciate a video going over exactly what all of the screens and categories mean. There are a puzzling amount of options, and I can only guess what half of them even mean.
Thanks again, and you've got a new subscriber now.
good vid – glad you figured it out, man. Enjoy the car – maybe we will cross paths with our Esprits some day.
This inspired me to learn to solder on my F50 ecu and make it run better.
Muito bom ! Quando for ai vou andar nesse carro! abs