DLS

i just finished installing my ZT-2 and took the first drive with the car after my head rebuild.
what should AFR be at idle on a 944 turbo?
I think mine is a bit lean at idle ~ 17-18
I will test more soon, ZT-2 is fun

rberry951

Does your car have a regional coding plug and impedance adapter? Do you know if it uses an O2 sensor? AFR at idle with a car using a stock O2 sensor should be 14.7. Also, where do you have the wide band sensor mounted?

Russell

DLS

hm not sure if i have the regional plug but i do have a O2 sensor
my sensor is mounted just before my catalyst.
i have some sort of guruchip and 3 bars FPR.

rberry951

On the wiring harness just before the DME/KLR connectors there is one or two white plugs. One is the regional coding plug, the other is the impedance adapter. They are used to select the different maps inside the chip. If either one of these plugs (and it depends on the model year) has a jumper plug or a resistor plug then you're using a map that does not use the O2 sensor input.

Your wide band sensor sounds like it's in the right place. Check for those plugs I mentioned, and also check your FQS position. I *think* the guru chips use the FQS for injector size scaling, but am not 100% certain they all do because I know there were many different versions. He may not have used them that way on all. The stock FQS behavior is to modify fuel in positions 0-3 by 0%,+3%,-3%,+6%. And the 4-7 positions being the same fuel modification with a -2.77 degree timing retard. Check that the FQS switch is fully counter-clockwise (or anti-clockwise as you say) to position zero unless you have bigger injectors and have been told to do otherwise by guru.

If you have no RCP/IA plugs used, and you're in FQS zero position I would check the idle stabilizer valve and also check the idle adjustment screw on the top of the throttle body, there's a procedure for adjustment on clarks-garage.

Regards,
Russell

DLS

i don´t think i have seen any jumper in the plug.
i shall check the fqs switch

anybody with guruchip that can tell me their afr on idle?

sweanders

What MY is your car? If it's a "kat-car" according to Bilprovningen lambda should be as close to 1 as possible. If it's and 86-88 MY it doesn't matter.

Jake951

I had Guru chips in the past and they idled at 14.7 AFR.

Tom M'Guinn

The closed loop O2 system should keep it near 14.7:1. If your car is idling at 17 or 18, something's not right there. Sure the Zt2 is installed correctly? What happens to the a/f ratio when you drive around? If it looks ok, then your O2 sensor may need replacement.

sweanders

Try unplugging the factory O2-sensor (if you have have one on the car) and see what happens. If nothing happens the sensor is dead.

944's without cat usually does not have a factory O2-sensor.

DLS

my car is a 1990

Went through my zt-2 log today and it seems like the first 5-6min the afr is around 12.5 and then it jumps to 17-18, must be the coldstart program in the beginning, right?

I shall look into this more

sweanders

Does it change when you unplug the O2-sensor? It is one of the easiest cables to reach in the engine compartment.

DLS

i haven´t had the chance to test that yet Anders
but i will test it.

sweanders

It you don't get any changes when disconnecting the lambda-sensor it is probably dead. If you get a change I'd look for an exhaust leak before the Zeitronix O2-sensor.

xsboost90

mine is always 14.7 as soon as zeitronix sensor warms up.

DLS

i have tested to disconnect the o2 sensor and when i disconnect it the AFR jumps to 13.6 from 17.5
do my 02 sensor sound ok?