Over the weekend I changed my exhaust from standard to flowed OEM headers. Wide throat down pipe & sports cat, straight though 2.5" centre section and Miltek back box.

Seemed OK but I get a fuel cut off at high load high revs - as if the fuel pump or injectors are duff.

I also got some error codes , 13 Crank position sensor 31 Throttle position sensor and 53 fuel pump / circuit.

Car is a 97 UK turbo 99K miles

Anyone got any ideas. Seems odd the crank sensor can log a fault but you can still start the engine - which I can.

Any help much appreciated.
Clint

 

do an ecu reset and then see what codes then appear.. the codes could be previous faults etc..

sounds like it is now over boosting hence the fuel cut due to too much boost.

do you have a boost gauge or knock link?

Simon

 

Neither Knock link or boost gauge I'm afraid.

Didn't think I'd be getting into over boost territory as there is still 1 cat on the system.

Will go and do a reset now in lunch break.

Thanks
Clint

 

just a downpipe change can be enough to cause overboost.. depends on the car.

 

Reset done, no more fault codes, but problem has not gone away, not sure I expected it to with a reset though.

Hard acceleration gives a cut out, then after a breif pause we are off again. If I am more gentle with my right foot, acceleration is not interupted.

More fingers pointing at overboost ? What are the options, just a remap ?




I did also find another 'issue' when changing the exhaust. The left and right side exhaust ports are very different colours - something tell tail about the fuel injectors / fuel pump / ECU ?

A can or worms, this hooby I tell you.

Thanks for the help.
Clint

 

wouldn't have expected the problem to go away either, only the error codes and the current error code if any recorded obvious.

the different colour ports could be a number of problems.. reduced fuel pressure - failing fuel pump, faulty fuel pressure regulator. Faulty injectors.. unlikely two on the same bank but possible.

I would run an earth wire from negative battery to the block.. the handful of error codes would point towards a ground problem..

difficult to know what to suggest with regard to the uneven exhaust ports.. if you change something, you won't know if it has worked or not with out removing the manifold again.

What are the plugs like? do the plugs show the same story?

Simon

 

I had thought the 2 lighter coloured plugs (I changed them about 400 miles ago) were from different sides of the engine, but now think I must have mixed that up.

Do my symptoms sound like overboost or could they equally be a fuel supply problem. Considering the age of the car and milage MY97 99K miles it would seem quite possible the fuel supply system is worn / dirty in places, perhaps causing the exhaust issue and cut out ?

Regarding the side to side difference, what is there common to 1 side against the other, the only thing I can think of is fuel pipe route, but I doubt if this could cause such a drop in pressue to give the results here but thats only gut feel.

I understand normal injectors are good for 300 - 300bhp - I'm no going near that so standard will be fine I think, can you only get these from Subaru ?

 

the plugs tips don't look too different.. ie. they were running similar mixture most of the time / just before removal.

the cut out sounds like over boost.. especially the fact that you can stop it by using part throttle.

Get a boost gauge to check.

I would recheck the plugs.. does the car smoke at all? possible it might be oil leaking on that head through the valve stem seals rather than running rich?

The fuel system is common supply and fuel pressure reg.. but the supply is to the passenger side and fuel pressure regulated and returned to the tank on the drivers side.. if the pump is not flowing enough then it will cause uneven fuel delivery when the pressure drops belove the 3bar the fuel pressure reg is regulating it to.

standard injectors are fine for the changes you have done so far.

you can get them cleaned.

Simon

 

So I'll get a new fuel pump and new fuel pressure regulator, aiming at tackling 1 problem. Is there any benfit getting the higher performance pump or not for my mods ?

Cleaning the fuel injectors - do you take them out, or use a chemical addative in the petrol for cleaning?


Boost gauge to check for overboost. Ideas of where to buy ?

Potentially - needs re-map then everything checked and safe £


Many thanks for your help

 

I am not sure I would rush out and get a new fuel pump and reg.. I would try and establish if they are the problem first..
check the plugs again..

Yes take them out and send them away to be cleaned.. I would NOT put any cleaning addictive in..

Simon