FC - Limp mode and boost issues

[johnf]

As you will remember I believe Pete rewired the car.

What numbers are on the stock ecu and is it in the footwell like the FD

[Prof]

As you will remember I believe Pete rewired the car.
 
What numbers are on the stock ecu and is it in the footwell like the FD

N374, N380 - something like that - if it\'s any number combo like that and has 3 yellow connectors then it\'s a stock or chipped ECU so the error codes can be read as above.

[johnf]

Looks like a stock ECU N380

I have an old one from my FD and that has exactly the same numbers.

[johnf]

Had a look at the car yesterday and the first thing we noticed was that the lambda sensor wire wasn\'t connected anywhere.

fitted it as per picture - is that the right connector?

How would you expect it to run without this connected.

Couldn\'t make much sense trying to get error codes so decided to see if this makes any difference first.

Also fitted a boost gauge so I\'ll take it for a run later and see what it\'s doing.

[Prof]

The car will run fine without the stock lambda sensor - it will throw an error code, sometimes 2 - but these are for the lamda and \'feedback\' errors that will be generated by it not being there.
 
Unlike most cars that rely on the O2 to control idle, the FC doesn\'t - it only ever uses the O2 to control the closed loop portion of the map which occurs on cruise and light load.  Anyone who has ever connected one of those LED AFR meters to the stock lambda will know exactly when this occurs - as the led display \'bounces\' back and forth when it\'s working in this mode as the sensor constantly adjusts the ecu to rich and lean alternately - averaging out a near stoich combustion.  This occurs between about 1200 rpm and 3000, but never under WOT conditions or heavy load, and not on idle or warmup either.
 
If you run the car with the lambda disconnected it will use fixed maps that mean it will ruin a tiny bit richer than normal, but the car will be quite driveable.  You will not get any fuel cut or boost cut from no lambda.

[johnf]

Couldn\'t make a lot or sense out of trying to read the fault codes but it hasn\'t dropped into limp mode again.

Fitted a boost gauge, Apexi, that reads in Kpa which I\'m told is a similar scale to Bar.

I get boost cut at a reading of .75ish.

If the stock boost is .55 I am overboosting.

As far as I know the car is pretty stock apart from a cone air filter and I changed the

exhuast back to what I believe to be stock boxes.

So in laymans terms what are the common causes of overboost and should I just look at

fitting a boost controller or try to find out what\'s going on.

Would fitting a boost controller just be a way of getting round an issue I ought to solve?

Also been suggested that I change the oil metering pump as this could be the cause of

both the limp mode and boost issues.

Any thoughts

Thanks

[mick choi]

Hi John try using a fuel cut defender! As this cured my boost cut when I put a straight through exhaust from turbo back & induction kit, as it tricks the ecu that it\'s only boosting to its std boost around 7.5psi when it\'s @ about 11psi with no probs @ all.      Or I have a old style hks fcon ecu £100 posted that came off my fc with harness so it\'s plug n play , all u need to do is get it remapped!

[HaywardRotary]

Over boost is caused by the exhaust being to free flowing over the stock one John.Simple cure is a restriction in exhaust to make it flow like a stock one.
Default will be 99% you need a good used oil metering pump.
The two faults are not connected as boost cut does not cause ecu to go on default.