Bugger...Fault Code P0172

The Oily Bits S2 Specific Topics
1

It’s almost as though my car was earwiggin my conversation with Wayne at Sincs about fitting a smaller supercharger pulley. No sooner do I get off the phone to him and drive home from work do I get the Engine check light come on, I’ve checked the fault code and it’s P0172 which apparently is:

P0172
This code is set when the calculated fuel demand has been decreased to its minimum limit of -17% and the
system still cannot maintain an air/fuel ratio of 14.7:1 under normal driving conditions.
Potential failure modes:
� Fuel Pressure too high
� Leaking fuel injector
� Restriction in the exhaust system or air intake / filter
� Erratic throttle position sensor
Notes:
� The MIL will be illuminated if the fault is present for 2 consecutive trips.

I reckon it could be something to do with the quieter back box Jim supplied me with after my remap at Sinc with the original super loud one. This quieter box could be causing too much back pressure for the map that Sincs have in the ECU currently. Either that or possibly a leaking injector. Anyone else want to throw their pennies worth in?

Lol…could be that it just hates it’s busy black wrap!

2

hhmmmm been reading on the lotustalk and it seems some guys over the pond have had to have their 02 sensors replaced to fix it.

3

Reading the cause of the P0172 code, it would suggest the car is running too rich. Normally a change in back box alone wouldn’t effect the map too much (unlike changing manifolds), but it does sound a possible reason.

I did however go from Jims 24 x 7" GT3 backbox to the 24 x 8" version without adjusting the map with no problems.

4

Check the injectors. I wouldn’t have thought an exhaust would dramatically impact AFR. Besides the ECU is smart enough to adjust which is why all mods to the toyota require an ECU remap.

5

It could well be a lambda sensor. Worth checking.

6

I’m having the pre cat 02 sensor replaced next week so hopefully that will cure it!

7

Mmg in Sutton coldfield changed the 02 sensor and all is well again.

Thanks to those that replied on here I didn’t start taking the engine apart!