Hi all,
I am hoping some of you more experienced EFI Live tuners can help save a noob a lot of wasted time and effort. My 15 year old son and I are really enjoying learning EFI Live, but we are not getting anywhere after many, many days of reading and experimenting - I am hoping for some pointers to help me head in the right direction.
The car:
Recently purchased Caterham 7, built in 2014, with a crate LS2 and Tremec TR6060 6-speed. Engine is standard, except the whole intake has been swapped 180 degrees so the throttle body and air-filter are at the scuttle end of the engine bay for packaging reasons. No air-box, air filter is a K&N cone on a 90 degree elbow. Factory MAF. Car is running bespoke exhaust with two Merc SL500 cats, and one pre-cat NB02 per bank.
Car is running an E67 PCM, with an additional bespoke, non-branded box which I think interprets CAN from the ECU and sends cluster data to the HM Dash dashboard.
I have two PCMs that came with the car:
ECU1) Well used E67, with a bespoke LS2 map. Previous owner tells me the car was tuned lean to get it through initial registration emissions compliance.
ECU2) New, crate E67 ECU with stock LS3 map.
The problem:
When the car is run on the used E67/LS2 PCM, it has a huge stumble at 3,300rpm. Try and accelerate from around 3,200, and the engine bogs horribly and the car decellerates. Accelerate hard from well below 3,200, and the engine sails through the stumble and pulls to the redline.
When the car is run on the new E67/LS3 PCM, it fuels and runs perfectly. It seems to make 100bhp more (butt-dyno) everywhere in the rev range, but the dash does not display tach or engine coolant temp (ECT).
What I have tried so far:
1) Ideal plan as the car runs superbly on the LS3 tune - get the LS3 PCM correctly outputting Tach/ECT to the dash. I have done a line by line comparison between LS2 and LS3 tune files, and I cannot find any way of adding the tach/ECT into the LS3 map. The Calibrations : Tacho : Parameters section of the tune files are radically different between the two tune files.
2) Plan B, I copied all of the LS3 tune parameters (including all the detail VE and spark tables) manually onto the LS2 tune. The huge stumble at 3,300 is still there.
I am starting to think that there are some changes at a more basic level than the tune file, that allow the Tach/ECT output and are possibly affecting fuelling also. I have read there is a possibility to create custom OS, but I am not really understanding how to tell if I have a custom OS, and if so, how I view/edit it.
Can anyone offer any tips on where you would go next? Persevere with the LS2 PCM/tune? Stick to the great running LS3 PCM/tune, and maybe try and get the Tach/ECT outputting through a custom OS?
Just in case it helps, I attach:
- The current LS2 tune file, with all the LS3 VE/Spark etc parameters copied across. This drives OK (not as well as the stock LS3 PCM) but has the huge stumble at 3,300rpm
- A V8 datalog run which shows the 3,300 stumble, where the engine goes very lean - NB02 voltages down to 10mV on both banks. You will see from frame 199 that even light acceleration causes the fuelling to go very lean, the injector duty does not increase, and the RPM actually drops.
I would really appreciate any tips or suggestions for where to go next.
Many thanks,
Martin.