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Title: 1.8T APX fuel trims not changing Post by: Ptyrell on August 05, 2013, 08:56:06 PM Hi Guys,
I installed a 4bar FPR and wanted to check the fuel trims for the increase in fuel and after driving around a few times for over 30min they are staying at 0.0 0.0. I reflashed stock ECU and the problem remains :( What could cause this? I have no DTC showing Title: Re: 1.8T APX fuel trims not changing Post by: vagenwerk on August 06, 2013, 01:15:02 AM check short term fuel trims , does it change on idle or when you ride ?
Title: Re: 1.8T APX fuel trims not changing Post by: Ptyrell on August 06, 2013, 02:28:14 AM check short term fuel trims , does it change on idle or when you ride ? I did a short log at idle with the variables I could find related to fuel trim. Nothing seems to change. Any others I should log? http://www.filedropper.com/fueltrim20130806124554 Title: Re: 1.8T APX fuel trims not changing Post by: QuattroEd on August 06, 2013, 11:01:03 AM Is the engine getting to temperature? until operating temp is achieved, long term trims will not be calculated/stored.
Title: Re: 1.8T APX fuel trims not changing Post by: Ptyrell on August 06, 2013, 06:29:35 PM Is the engine getting to temperature? until operating temp is achieved, long term trims will not be calculated/stored. Thanks for the reply QuattroED. I did look at the coolant temp when I had the car idling with VCDS connected. It was going up from 54c to 65c before I shut it off. What is the temp needed to start trimming fuel? I saw no change in idle trims either Title: Re: 1.8T APX fuel trims not changing Post by: QuattroEd on August 06, 2013, 08:12:20 PM I dont know the exact temp, but it is over 65 C for sure.
The CTS has 2 functions, one for the dash and one for the ECU input. If thermo is stuck open (happens with age) then operating temp will only be achieved with start stop driving/ idle. As soon as the car moves forward the radiator receives cooling and can lower engine temp so as not to attain operating temp. 90C. devise some tests to rule out CTS, Stuck thermostat or water pump in that order. Title: Re: 1.8T APX fuel trims not changing Post by: Ptyrell on August 06, 2013, 08:40:05 PM I dont know the exact temp, but it is over 65 C for sure. The CTS has 2 functions, one for the dash and one for the ECU input. If thermo is stuck open (happens with age) then operating temp will only be achieved with start stop driving/ idle. As soon as the car moves forward the radiator receives cooling and can lower engine temp so as not to attain operating temp. 90C. devise some tests to rule out CTS, Stuck thermostat or water pump in that order. I will log coolant temp to make sure it hits 90C via ME7Logger or VCDS Title: Re: 1.8T APX fuel trims not changing Post by: Ptyrell on August 06, 2013, 10:24:51 PM At idle it will go to 96C and trigger fan to keep under that. So temp seem ok
Title: Re: 1.8T APX fuel trims not changing Post by: Ptyrell on August 07, 2013, 01:07:50 AM Reflashed an earlier stock revision of my ECU file and trims are working again now.
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