If the fault codes P2013 and P2004 are current, and not simply old stored codes that haven't been cancelled, then it's most likely the problem is swirl flap related because that's what the codes are telling you. Not sure why you're looking at other possibilities when the car is already doing the job for you via the diagnostics. Cancel the codes and check if they come back when the problem happens again. If they do return then sort out whatever swirl flap problem is causing them.
Thanks for the responses guys. I'll answer Alexie first based upon whats just happened today. Currently maf is unplugged and i drove to work this morning. Very little power, slowly revs to a max of 3k revs. Sounds like limp mode to me. Got in the car to come home and its perfectly revving to the red line, full power available (albeit with the maf unplugged its down a few bhp). I turned the engine off and back on and it had full power about 4 times. Then on the next go, it was back to what I can only describe as limp mode. Tried another 4 or 5 times of on/off, but still limp mode.
I cleared the codes and re-read them when the car was running perfect. I did this a few times to ensure consistency. When it was perfect I got P2004, P2013, P0101 and P0111 (the last 2 are the maf related codes I think). I did the same again when the car was in limp mode and got the same 4 codes! When the maf is connected, the same scenario occurs.
Does the swirl flap failure match the intermitness of the fault? i.e. Initially discussion was about an electrical fault.
No. I've had that swirl bar off for maybe 4 years. Electrical fault was mentioned because how can the car fluctuate from perfect to limp mode and back again.
What have you done with the flaps on 1,2,4? Is the actuator rod removed? Are the pivots knackered, ie admitting air? Are the flaps locked open, eg with glue?
As I said elsewhere, locking the (metal manifold) flaps open, sealing the pivots, and removing the actuator bar so that the motor does nothing except rotate uselessly, shouldn't lead to fault codes, let alone limp mode. At least, according to what I've read elsewhere it doesn't.
If the flaps are not locked but free to rotate and/or leak air into the manifold from worn pivots, all bets are off. Air ingress from leaks will play havoc with MAP. Having flap 3 operating, but the others free to do what they like also sounds like a really bad idea.
Basically, when swirl flaps are closed, one of the 2 inlet valves per cylinder is doing nothing useful. Each inlet valve has its own separate inlet tract. The tracts with the swirl valves are a little smaller in cross section than the tracts without, but a closed flap is that is useful for promoting swirl at low revs, is going to ruin the engine's ability to breathe and achieve high revs.
It's also going to produce MAP readings that the car may well regard as a fault, especially when the actuator motor is telling the ECU that the flaps are open. Air leaking into the manifold will just mess things up further. Add a ton of sooty goo all over the inside of the manifold as icing on the cake.
If you haven't done so already, disconnect the actuator to #3 and fasten all the flaps open, using silicone or similar to fix and seal the pivots - or buy a repair kit and get them working properly. But if the manifold has never been off and cleaned and your car has been breathing EGR and turbo oil mist for 100k or more, it will probably be a right old mess inside, with inlet tracts that are choked with carbon and swirl flaps that more resemble pieces of coal than flaps.
I've owned the car for 9 years and had the egr physically blanked for 6 of those years. My map sensor is never gummed up. About 6 months ago I sealed the top of the flaps, where they leak. I used a putty that hardens like stone, which air sealed them and locked them in the open position. I did all 4 flaps and the car drove much better - previous flat spots disappeared. Whether flap number 3 was still able to be moved, I can't tell - I was focused on sealing the air leaks. I never bothered reading codes after this, as my EGR code came on every time anyway. If the car drove ok, I wasn't concerned about EMLs. So with these P2004, P2013 ....I don't know if they have always been on.
I could disconnect the actuator at flap 3, which no doubt would clear those codes. But i'm surprised that I get limp mode because of it. Those flaps have been spinning around for years before I sealed and locked them. And why would the car suddenly be fine today. When the maf was connected, I was experiencing the same situation -every few on/off's of the engine would either make it perfect or limp mode. Initially a failing maf was a good suggestion, but with the maf unplugged I'm still getting either perfect or limp mode.
I don't know if the swirl flap codes are a red herring. I can't understand the instant switch from perfect engine to limp mode. The first limp mode I had was maybe 2 months ago and then they became more frequent.
Thoughts and ideas are most welcome! thanks again