Problems tuning AFR

[timoldfield74]

Scirocco Storm
Vw 1781cc 16v
1.8t inlet manifold and fuel injectors 31lb/hr now changed to 18lb/h
Lotus elise throttle body
Narrow band lambda


I am running a Ms 2.2 extra code 029, I am having difficulty in tuning the ve map it always seems to be reading a rich state no matter what i do to it, i have changed the fuel injectors to much smaller ones and modified the VE table to suit. I am wondering if there is a problem with the lambda probe and it is not working correctly?

The other thing i have just noticed is that with the laptop pluged in but with the engine NOT running, when you press the throttle the air fuel meter in megatune goes up and down at the same rate. Surely this cant be right!! how can the air fuel ratio be changing if there is nothing coming in or out, is there a problem with the ecu itself or could this be something else?

Other than these problems it has been great, even running rich my fuel economy is better than my old k-jet system but it would be nice to get it spot on

Any ideas would be appreciated

Tim

[Bernard Fife]

Tim,

It sounds like you have a hardware problem. A couple of things to check are:

- the TPS and O2 sensor wires are next to each other on the DB37 connector (TPS=pin 22, O2=pin 23), so check the board (under the connector on the solder side) and the connector itself to make sure these are not shorted together (it's easy to have a losse wire strand bridge these accidentally).

- Wash the board in 99% isopropyl alcohol or acetone, if you haven't already.

- Have a good look around R1, R29, D11, C2, R9, C9, and C10 (as well as the D4 spot where you didn't install a diode) to make sure nothing is shorted to adjacent comonents.

Lance.

[timoldfield74]

thanks Lance, i just pluged in the stim and everthing works independantly as it should, so there be short on the wiring harness i hope. You have saved me plently of head scratching in the rain this afternoon

Thanks

Tim

[timoldfield74]

Just to let anyone who is interested know there was a single strand of wire bridging the throttle position sensor and O2 sensor. I carfully seperated the wires and everything now works perfectly

[bluetrepidation]

OOPS! That'll do it every time.

A.J.