Noob looking for some pointers - not making any tune progress.

[Martin_30]

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.

[joecar]

Hi Martin,

Try this:

are both ECM's running the same OS id #...?

If yes, then read the tune from the old ECM and full flash it into the new ECM.

~ posted by phone ~

[joecar]

I'll look thru your log when I get home later tonite.

~ posted by phone ~

[Martin_30]

Appreciate any help/pointers you can offer Joe, thanks. The two ECMs are running different OS id# - I tried copying between them but the software does not allow that of course.

LS2 PCM is OS 19211212
LS3 PCM is OS 12638778

Martin.

[Happy Jim]

Martin,

That's an idiotic engine for that car......Well done sir

I've not looked at the tune yet (viewing on iPad currently), but your description sounds like PE is fine (hard acceleration thru the bog) but normal isn't (so fueling/VE related rather than anything desperately wrong).

Jim

[Martin_30]

Thanks Jim, the engine does dominate the experience somewhat

I also feel pretty confident that there is nothing major here, the fact that it fuels perfectly on an LS3 tune gives me comfort. I am just a little puzzled why copying all the fuel/VE/spark from LS3 to LS2 PCMs does not solve the stumble.

Learning lots here, but so many blind alleys to go down.

Martin.


Sent from my iPhone using Tapatalk

[Martin_30]

I have been looking at the datalog trace of the stumble area itself. I have cropped it down to the 2.5s around the stumble, and I am even more confused now.

As you see from the image, when I press the throttle to gently accelerate from 3,300rpm, the TPS rises (expected), the MAP rises (expected) but the NBO2 sensors both plummet to 0mV and the injector duration does not change at 8%. Really puzzled how the car can run quite nicely at 3,200rpm, but another 100rpm means fully lean even though the injectors are still injecting fuel at 8% duty.

Very strange. Does this mean anything to anyone?

If I put the second E67 PCM in with the stock LS3 map, it runs perfectly at this (and all other) rev ranges. I have copied all the settings/VE/spark settings across to the LS2 map PCM, so I really cannot understand why one PCM/tune behaves so differently to the other.

Martin.

[joecar]

Hmmm... the PCM itself may have a problem.

~ posted by phone ~

[Martin_30]

Hmmm... the PCM itself may have a problem.

~ posted by phone ~

Interesting. The previous owner of the car also suggested a faulty PCM - I treated that with a pinch of salt as in my mind, an ECU either works or it does not, no semi-failing state.

I have a second, brand new PCM to use but I have one big problem:
- The possibly faulty LS2 PCM outputs Tacho and ECT to the Dash, but my new LS3 PCM does not. I have gone through the LS2 tune line by line, and really cannot see where the relevant parameters are - I have tried copying them to the LS3 PCM but cannot get the Tacho/ECT to output to Dash.

Has anyone heard of Tacho/ECT outputs being configured in the OS rather than the tune?

Would anyone be kind enough to take a look at my LS2 Tune file (post 1) and see if they can find where Tacho/ECT outputs are specified?

Martin.


Sent from my iPhone using Tapatalk

[statesman]

So far you've only copied over the fuel/VE/spark tables. You need to copy over every single table in the entire tune file.... including the diagnostic tables.

Yes, it is very time consuming... but if you still get the stumble after copying everything over then you'll know it's some difference in the OS part of the tune file causing the problem, which is not fixable with EFILive.