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Random loss of power


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#1 01OBK

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Posted 04 December 2017 - 07:54 PM

Alright brains trust, I've got a weird and persistent problem that seems to happen on the stock ecu/stock tune.

I get random periods of absolutely no power at all, sometimes they're short 2-5mins periods sometimes as long as 30-40mins of driving, trans doesnt want kick down either, even with my foot on the floor. Also idles rough too, the engine stumbles and shakes like its got a misfire but the exhaust doesn't sound like it does, if that makes sense. Doesn't fluctuate revs at idle, stays around 750rpm just runs rough.

From what I can tell (no boost gauge) I'm still getting a small amount of boost, below 7psi, the gfb BOV doesn't open below 7psi I can hear the primary flutter.

Then randomly as I'm driving along it's almost like a light switch and it's back to normal.

I don't think it's anything to do with the engine side of things cause it doesn't do it on the Zero/Sports ecu only on stock (stock ecu has been modified by Eculabs but used to do it before it was modified)

Any ideas would be greatly appreciated cause I'm completely stumped

#2 patrick27s

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Posted 07 December 2017 - 10:26 AM

I know this might sound obvious but make sure the looms for the ecu are in properly could a shitty electrical connection causing issues,

My car had issues after swapping ecu’s and one of the cables had come loose (well actually I had to solder the cables back together when I removed the zs sequential controller, and the solder joint must have snapped when I swapped ECU’s.

Also I had a similar issue to you after swapping my intake manifold and it turned out to be a loose connection in the manifold loom.

Just something to double check

#3 01OBK

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Posted 07 December 2017 - 03:31 PM

Yeah I've checked all the connections they seems fine.
It's just weird that it only does it on the stock ecu.

#4 01OBK

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Posted 15 January 2018 - 06:56 PM

Just had a thought come into my head on this, could it be anything to do with compression ratio difference between the ej206 and ej208, I did put a second set of refurbished heads on before the engine swap, but never knew if the were off an 206 or 208. They were identical when next to each other apart from some different casting number codes.
If the heads were off a 208 would that be why it runs good on the manual ecu and poor on the auto one?
Would the compression ratio difference be in the heads or pistons?
Cheers

#5 Barbbachello

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Posted 16 January 2018 - 07:43 AM

In the pistons generally



#6 El_Freddo

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Posted 16 January 2018 - 10:07 PM

In the pistons generally

Cams can also influence this to a degree. I've known compression to mainly be piston, combustion chamber design/size and HG thickness.

Being a TT, looked into vac lines or a dodgy solenoid? Or something wrong with the stock ECU?

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#7 01OBK

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Posted 17 January 2018 - 12:22 PM

I don't think it's anything to do with vac lines etc. cause it runs and hits boost perfect on the tuned ecu, could be an issue with something inside the stock Ecu ay but Eculabs didn't mention anything when they modified it.
That's what got me to thinking heads cause of possible combution chamber differences

#8 Barbbachello

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Posted 17 January 2018 - 12:46 PM

I think youll find theyre the same castings. Why change a whole head casting when you can change the pistons and gaskets to get the compression. From a manufacturers point of view



#9 B4liberty

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Posted 23 January 2018 - 04:12 PM

Your car is in limp mode. Your computer is sensing something isn't right and boost is cut in half so not to damage the engine. Happens to mine quite often when the weather is hot and motor has work done to it.
Disconnect the negative terminal on the battery for 10min to reset it. Works for mine hope it helps.

#10 01OBK

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Posted 24 January 2018 - 08:57 PM

Have had the battery disconnected multiple time when swapping ecu's, doesn't seem to make a difference for me unfortunately




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