rudboy

Hi,

I've got a 95wrx with a sti red top engine fitted.

My MOT ran has ran out and everything is fine for a new one, all but one slight issue with the emmisions,
They are sky high, co-2.5% and hydrocarbons-300+

I have a very competant mechanic on the job but we seem to be stuck between a rock and a hard place,
When the car is cold the readings are lower than stated above but as soon as the temp is above 1/4 of the guage the readings rise steadily.
We have changed Cat, maf (x3), coolant temp sensor, lamda sensors (x3),ECU,Map sensor, Plugs
None of these has made any difference at all. we are getting seriously pissed off with this as we just cant think of anything that hasnt been checked or changed.
Any help/advice greatly appreciated.

Thanks in advance,

Rudboy.

Jolly Green Monster

iTrader: (4)

You say sti engine in wrx, do you have sti injectors on wrx ecu?

Jolly Green Monster

iTrader: (4)

Also what is lambda reading?

rudboy

Hi mate,

MY mechys gas tester doesn't read lambda but on the volt meter it reads 2.5v where it should be reading 0.6v?? (does this make sense to you? just recived this info through text message).

Also The ecu that the car is running is to the best of our knowledge an STI one it was certainly removed from the same car as the engine, which im lead to believe has sti injectors.

Jolly Green Monster

iTrader: (4)

Mot measures 3things lambda, co and hydrocarbon

If lambda is high the other two will be too

Lambda should be around 1 where 0.9 is richer and 1.1 leaner.

That voltage is wrong

The rookie

iTrader: (1)

A CO reading of 2.5% equates to a Lambda reading of about 0.92 (Lambda one is 0.67% CO) so its running rich, nothing to do with the catalyst.

MOT tester to be a pedant measures 4 gasses (that is why it's called a 4 gas analyser!) , CO, HC, CO2 and O2 from which is calculates Lambda, Lambda itself cannot be measured directly.

I agree with JGM, that voltage is wrong, most it should read is 1V, if for some reason it is running too rich the feedback accnot correct past a certain amount, either the fuel pressure is too high (has the vac hose fallen of the regulator) or the injectors are wrong as Simon intimated would be the mostl likely things.

As you have found, throwing bits at it without proper diagnosis can be an expensive waste of time, get it to someone who can run the right checks I think.

Simon

Jolly Green Monster

iTrader: (4)

Yes fair point rookie i meant the 3 that have to pass etc

Simon

rudboy

Simon,

Thankfully we have'nt spent any money on these parts that we have changed/tried, as i have a few mates with scoobys and they allowed me to try certain parts off of there motors. the others have either been mine from my old engine or from my mechys. all parts were known to work prior to changing and worked back on original cars.

The fuel pressure rails pressure was checked and was found to be 3bar, (this was the figure i was given on here a while back in a different thread.)

the injectors are correct as far as i know from asking details about these a few months ago in a different thread, this problem has been ongoing for 3 months now,

is the lamda reading wrong because the sensor is goosed or because its over fuelling? you can actually smell the fuel when its running. also how would the emmisions rise with the engine temp?

Cheers.

f4la k

iTrader: (1)

Make sure your using correct fuel for ecu setup. You should try takin it a blast and getting the cat really warm and take a readin after that. The cat needs to be really warmed up..