Ok guys I am a little confused.

I have a set of 680cc PTE injectors fitted to my car.

They are set as follows:

Injector Scaling 650cc

Injector Battery Voltage Latency Compensation

MS

3.312
2.184
1.416
0.960
0.696
0.480
0.360

Now last week my 02 sensor needed to be replaced, due to me swapping the turbo elbow over, and cross threading my sensor when they replaced it under recall a couple of years ago.

I fitted my spare sensor but this was dead

So as a temp measure I used the LC-1 to simulate the nb signal

This worked ok, but was a little slow when coming off WOT back to cruise and caused a few engine cutouts at junctions.

Anyway I made some logs with the LC-1 simulating the nb and my fuel trims were all 0.1 for low med and high.

I have now replaced the 02 sensor with a brand new one from

Just been out to log the car, and my fuel trims are now 10.9 - 12.9

Anyone have any idea's why the sudden jump ?

 

If the trims are up by 10%, then the ECU is adding fuel. This means that either your LC-1 is out of calibration (reading leaner than actual), or the NB sensor is defective.

 

Since fitting the new sesnor I have obviously disconnected the LC-1 from simulating the nb signal now.

So the LC-1 shouldn't effect anything to do with the fuel trims should it ?

Or do you mean that my LC-1 might have been reading leaner than it was, hence the fuel trims were down to 0.1% ?

I seem to recall that last logs on the old sensor the logs were showing around 12% on some of the fuel trims.

So how do I get them back to 0.1% ?

Increse the injector scaling or change the timing ?

 

Correct, now that the LC-1 is disconnected from the front O2 input, it has no further effect on trims. I just mean that relative to the NB sensor, your LC-1 is reading lean. If both trims are reading ~+10%, then decrease in injector size scaling value by 10%, i.e., try 585.

 

Will give it a try tomorrow then.

Thanks for the info

 

what about some sort of exhaust leak? pressumably the NB went into the dump pipe whereas the LC1 is in the front/down pipe

hrmm actually - if exhaust was leaking out then AFR would NOT change, if air was leaking in then the LC1 would be reading leaner thus the ECU would be adding fuel..

which is not the case..

so yeah - what MrFred said

 

Thanks tephra.

There was no exhaust leak, as I left the dead sensor in the hole to stop that happening

lol