Hi all
I have the engine management light coming on occasionally and I wondered if anyone can suggest what the problem could be?
Using ProTune accessing Diagnostic Trouble Codes I am having a Fault P0170 and P0173 which is ‘Adaptive Max Limit ‘on both Front and Rear cylinders
It seems that the ECM controls these values and I can’t find any detail of what might be causing these issues.
Any thoughts?

Probably as a result of drilling out the exhaust baffles the ECU adaptive fuel map is hitting its limit and throwing the fault codes.

The answer is an unlocked ECU - try Garage56 or Krazy Horse.

Agreed. Your engine is trying to compensate the fuel ratio and timing to deal with engine operating conditions. So either you have some mods that are allowing the engine to breath better (and hence use more fuel), or if your engine is all standard then it's related to a fault such as an intake or exhaust leak. I believe it can also be related to running a standard engine up to the fuel cutoff point (i.e. red line), though I have no direct experience there.

Drilling out stock exhaust/no air filter would not result in these error codes. Check intake seals for leaks, and headers for exhaust leaks, also, check your fuel pressure

What are you doing just before the engine management light comes on as it is occasional? I agree with KankeL a baffelectomy and air filter would not cause the error codes.

Mine did not throw codes until I overfilled the gas tank. And finally it threw the Max Limit code with the new cams.

I chased P0173 ‘Rear Adaptive Max Limit ‘ for the better part of a year on my car. First, those are frustrating codes. The order of areas I would check are: 1) Fuel pressure measured at the schrader valve at the manifold. 2) Air leaks at the intake manifold where it meets the cylinders. 3) Exhaust leaks at the exhaust manifold. 4) C02 Sensors.

If you are getting both codes I have a hard time believing both intake manifold gaskets went south at the same time - unless you recently installed a new air filter.... As I understand those codes...... somehow either 10% more or less fuel or 10% more or less air is being found (or requested and not found) by your ECM. If that makes sense. Search P0170 and P0173 - there are a few threads on this issue.

I have a G56 Exhaust on my car and installing (or making) a free-flowing exhaust alone, or even with an aftermarket free flowing air filter, will not cause those codes.

In chasing P0173 I replaced one not so great fuel pump that would not hold fuel pressure, switched the C02 sensors in the exhaust to see if that changed the code (it did not), replaced both intake manifold gaskets, and finally installed Emil's Fuel System Upgrade kit. No more code with Emil's system. Cannot say enough good things about Emil and his system that delivers fuel to both fuel rails at the same time the way S&S designed the fuel system to operate. And a real fuel filter BEFORE the injectors and an actual fuel pressure regulator with a gauge and ability to adjust fuel pressure is a bonus.

Good luck. Search the codes themselves on here for more info.

Thanks for the info

The fault is on permanently on the Rear Cylinder now and the idling is hunting at around 1800 revs until the car is stationary when it drops down again.

Fitted a new fuel pump a while back so I’ll rule that out for now.

Baffles out and new air cleaner fitted about a1000 miles ago and no faults until now.

I’ll start with the intake seals first and go from there I guess

Sticking idle can be due to a bad idle module or a higher than usual fuel pressure.

https://www.ebay.com/itm/333898484626

I had problems with fast idling which slowed when you stop, like you describe: it turned out the bottom bolt on the throttle body had sheared and air was leaking in.

See this post