Lee D T

iTrader: (1)

Hi,

My 1995 STI RA failed its emmisions test today by a good amount (dont know exact figure)

I have recently fitted a Walbro fuel pump and a regulator set at 3bar atmospheric 2.5bar connected to the inlet manifold.
I also fitted an ecu chip with the mods taken into account though it was a postal map.(Standard 380cc injectors)

My mates have told me that they can smell petrol in my exhaust gases when I am accelerating hard and some dark smoke(fuel)

What woud be my best options for passing the emmisions test ie could I lower the fuel pressure?
Lower the boost pressure?
Find a standard replacement ecu?

Any help would be appreciated,

Thanks,

Lee.

Scott.T@PolarPerformance

Probably a Lambda fault due to the ECU being under Lambda control during the Emissions test.
The OE ECU manages to run 14.7AFR at cruise/idle even with 440cc injectors and no map adjustments if the Lambda sensor is working.

Lee D T

iTrader: (1)

I had a new chip fitted to the ecu (not one of yours ) which may have had the injector duty changed as I told the programmer I had fitted the fueling mods, could it be that a standard ecu may be a way around the problem?


I've had no running problems so wouldnt the Lambda be okay?

Scott.T@PolarPerformance

If the lambda fails the ECU reverts to using the fuel base map to set the fuelling.
This is probably set well enough to run, but not quite as tight as it would be when running under lambda feedback closed loop control.

The ECU can also apply an offset to the open loop fuelling based on calculations made from the lambda performance.
If the lamda is at fault it could also effect the offset and hence could also be why you think it's overfuelling.

For £30 you could stick a new lambda in and it may well be job done, problem solved. For £30 it's gotta be worth a stab.

If you told the mapper you were putting in 550's then there 'could' be an issue. If it was just a pump and reg then I doubt it is.

car's running 440's instead of 380's idle and cruise perfectly well at 14.7AFR which is what your lambda will try to achieve for the emissions tests.

Your running nigh on standard pressure with the Walbro and FPR, so shouldnt be an issue

Lee D T

iTrader: (1)

Okay,

Thanks Scott,

Any idea which type of Lambda I will need, I've seen a couple, 4 wire, two wire etc.

Scott.T@PolarPerformance

3 wire zirconia M18 thread
OR
4-wire Zirconia m18 thread. The 4th wire is a ground so just take it down to chassis.

Universal 3-wire Zirconia Heated Oxygen Sensor :: Gendan Direct

You can pay a bit more and get a bosch LS02 or LS04 but I would plump for a universal as I have had no issues with them and as I said previous it's worth a try for £30

Lee D T

iTrader: (1)

Thanks,

You are a star