Here is the blurb on lump mode from Nistune. Yes, the car will run while in this mode but it does not run well and will not exceed 3000rpm. I have highlighted the section pertaining to the issue where you can see there is indeed a limp mode that will allow the car to run when a catastrophic issue happens.
The symptoms describe the OP's issues exactly, and this is the fix. That's all there is to it.
From:
http://nistune.com/docs/Installation...iagnostics.pdf
Quote:
Processor limp mode
Later model ECU's have an internal processor limp mode also. When the program from the ECU chip
or daughter board is not functioning, an auxiliary processor will inject a set pulse width for each
injection regardless of other sensor inputs and ECU program. When in limp mode, this will be indicated
to the operator through the means of a LED in the ECU
Processor limp mode is entered when a major fault has occurred. Major faults occur with anything to do
with the ECU micro code being unable to run. This can be a result of the various factors where the
processor is unable to execute the code properly. If it occurs after resoldering and resoldering then
there may be an introduced problem causing the ECU to go into processor limp mode.
The processor bus on any ECU consists of 8-16 data lines and 16 address lines plus control lines. If
any of these lines is broken or shorted during the installation process, it will stop data flowing correctly
on the lines and the ECU will not be able to run properly.
Symptoms vary depending on engine (specifics covered in the relevant section for each engine) but
one thing is constant across all engines – Consult communications will NOT be active in limp mode. So
you will not be able to connect to it.
Engine running badly is defined as engine may start but idle will be poor and engine will overfuel badly,
resulting in obvious clouds of partially burnt fuel coming from exhaust. Engine may not run at all if
injectors and/or AFM are non-standard. May lean out when rev exceed 2000rpm
Signs of limp mode on common ECUs:
• Check engine light and/or ECU LED will stay on
• Will not be able to connect to the ECU using consult
• When IGN is turned on fuel pump will only pulse on momentarily rather than running for 3 to 5
seconds.
• Engine will not run correctly. Engine may start but idle will be poor and engine will overfuel badly,
resulting in obvious clouds of partially burnt fuel coming from exhaust. Engine may not run at all if
injectors and/or AFM are non-standard. May lean out when rev exceed 2000rpm
If you’ve performed the NIStune board install yourself and the ECU has gone into limp mode then
please check the following:
• Soldering of 20+20 header. Clean flux from all joints and inspect each joint using an eyeglass
and a good light. In particular look for solder bridges between pins and slugs of solder on the ECU
• Check that tracks have not been cut by pushing too hard on the desoldering gun
• Check that you have moved the necessary jumper(s) for the ECU to use the daughter board
• Check the part number on your board matches your ECU number when possible
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