Fuel Trim FSI AWA

Paul Waterfall

Registered User
Looking for some help regarding fuel trim log I have. Most of the log is engine idling, when I pulled the dipstick the values went positive, but in general always negative. I know at idle it should fluctuate 2 or 3 %, also misfire on cylinder 3. The coil and plug are good, I`ve checked wiring to coil 3 and all good.
 

Darran

Registered User
It will go positive when you pull dipstick, that's right, check the PCV valve on a T piece under inlet manifold !

Is idle ruff when cold then smooths out?

What's the lambda reading on idle (short term) MVB 032 and MVB 033.

Trim is controlled by Lambda and MAF ,maybe worth disconnecting MAF and then rereading trim.
 
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Paul Waterfall

Registered User
Hi Darren thanks for the reply, it does feel a little rough when cold and in general drives ok for a few miles, I can always feel what you may call a soft misfire most of the time, but the car seem to pull well enough then starts to misfires badly on pot 3 usually about 2000 rpm and judders bad. Im I right in saying the PCV valve is built in the valve cover on the AWA engine. Not sure if I could attach a log but I`ve added a pic for you to see, the log is engine at idle, the log is much longer and I pulled the dipstick and MVB 033 went to 21.1% . Also you can see the misfire log on pot 3 which increased to 34. I`ll disconnect the MAF tomorrow evening and reread the blocks.



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Thanks Paul
 

Darran

Registered User
Yes pcv is big plastic affair on top right of rocker cover, do you have vcds , would be much easier to read than MS exel.

2000rpm is just about where boost starts to climb, have you checked the n75 valve and all connected vacuum pipes inc the one to the dump valve.

Normally anything passed 3% indicates a leak.
 
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Paul Waterfall

Registered User
The FSI I have is non turbo. I have VCDS, but the log is saved as excel.

Am i right in saying MVB 32 reading 4.8% would be running lean as in to much unmetered air.
 
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