2004 Ibiza cupra 1.8T Fuel Trims (High Negative) run -8.6%

[ibiza1.8t-cupra]

Hi,
I have done some logs in VCDS and I have Fuel Trims of:

BLOCK 032
idle -0.9%
run -8.6%

This run fuel trim seems high, I have replaced the MAF and it is still a high negative.

Not sure what could be causing this, I believe it is running rich with it being a high negative?

 

[R3k1355]

Not had a previous owner messing around with the injectors has it?

 

[ibiza1.8t-cupra]

Hi,
Thanks, how would I be able to tell if Injectors were wrong?

I'm thinking a boost leak, will have a spray around intercooler hoses with diluted washing up liquid and go for a short drive, if rain ever stops, not sure how else I could find a boost leak?

 

[R3k1355]

Hi,
Thanks, how would I be able to tell if Injectors were wrong?

Check the colour/part number to make sure someone's not just dropped a larger set int

I'm thinking a boost leak, will have a spray around intercooler hoses with diluted washing up liquid and go for a short drive, if rain ever stops, not sure how else I could find a boost leak?

The best way is to pressurise the intake system and listen for a hiss, or drop in pressure. You'll need to make a DIY kit to work with your setup.

This MCM video explains the basics, if you don't have a compressor to hand you can fit a tyre valve and use the same pump you'd do your tyres with.

 

[ibiza1.8t-cupra]

Hi,
Checked the injectors they are all: 06A906031BA
Black colour OEM type.
That looks correct according to:
http://www.oemepc.com/seat

I had a really good look at all the hoses from turbo to intake and found a jubilee clip that looked to be tightening up, but had lost its thread inside, replaced that, it was the top 90 degree hose off the turbo, hidden away under the hoses heat jacket.

Also replaced the big o ring inside one of the metal hoses joint and....

wow got the power back, loads more power now, it absolutely flies... happy to have found this, it must have been leaking for a while,