HI PSI Member 1,586 Member For: 18y 10m 23d Gender: Male Location: Central Queensland Posted 18/03/19 11:58 PM Share Posted 18/03/19 11:58 PM I had a similar issue, which turned out to be a damaged fuel reg diaphragm. Fuel was leaking through while under vacuum (Idle) and entering the plenum through the vacuum line. Link to comment https://www.fordxr6turbo.com/forum/topic/94669-negative-fuel-trims-at-idle/page/2/#findComment-1678856 Share on other sites More sharing options...
Puffwagon Puff Gold Donating Members 16,282 Member For: 10y 2m 18d Gender: Male Location: South Australia Posted 19/03/19 12:13 AM Share Posted 19/03/19 12:13 AM I think it's worth pointing out that the title of the thread is incorrect. The car isn't actually rich at idle, it's pulling fuel out via the trims and it's only 10%, not over 20/pegged. In the original post op says that the afr fluctuates between 0.96 and 1.04 at idle. A busted reg would mean that it goes lean under boost, as there is no increase in fuel pressure. It'll still be interesting to see the whole picture once El Andrew goes over it all. Link to comment https://www.fordxr6turbo.com/forum/topic/94669-negative-fuel-trims-at-idle/page/2/#findComment-1678857 Share on other sites More sharing options...
El Andrew Gold Donating Members 2,036 Member For: 9y 11m 25d Gender: Male Location: Canberra ACT Posted 19/03/19 03:55 AM Author Share Posted 19/03/19 03:55 AM On 19/03/2019 at 12:13 AM, Puffwagon said: I think it's worth pointing out that the title of the thread is incorrect. The car isn't actually rich at idle, it's pulling fuel out via the trims and it's only 10%, not over 20/pegged. In the original post op says that the afr fluctuates between 0.96 and 1.04 at idle. A busted reg would mean that it goes lean under boost, as there is no increase in fuel pressure. It'll still be interesting to see the whole picture once El Andrew goes over it all.It is a good point. Keith/Rab if you can be bothered, negative fuel trims at idle word be a better description for the title.What pisses me off is than I/mechanic/Toyota can't find the positive LTFT cause in the Kluger!! I think I should just average the trims of both cars and be happy. Link to comment https://www.fordxr6turbo.com/forum/topic/94669-negative-fuel-trims-at-idle/page/2/#findComment-1678956 Share on other sites More sharing options...
k31th less WHY; more WOT Site Developer 29,410 Member For: 17y 7d Gender: Male Location: Melbourne Posted 19/03/19 03:57 AM Share Posted 19/03/19 03:57 AM topic title changed 1 Link to comment https://www.fordxr6turbo.com/forum/topic/94669-negative-fuel-trims-at-idle/page/2/#findComment-1678957 Share on other sites More sharing options...
Puffwagon Puff Gold Donating Members 16,282 Member For: 10y 2m 18d Gender: Male Location: South Australia Posted 19/03/19 04:01 AM Share Posted 19/03/19 04:01 AM Vacuum leak for + trims? Link to comment https://www.fordxr6turbo.com/forum/topic/94669-negative-fuel-trims-at-idle/page/2/#findComment-1678958 Share on other sites More sharing options...
El Andrew Gold Donating Members 2,036 Member For: 9y 11m 25d Gender: Male Location: Canberra ACT Posted 19/03/19 04:17 AM Author Share Posted 19/03/19 04:17 AM On 19/03/2019 at 3:57 AM, k31th said: topic title changed Thanks - will be more useful now if someone else has the same issue. Thanks for removing our friend's post too!@Puffwagon yeah tried that - smoke test says no. Lean fault codes on both banks, electrics tested, upstream O2 sensors changed, vac lines replaced. The intank fuel filter is due for replacement (which requires seat removal) so planning to check the fuel system out fully then. Is a dead head setup so reg is in the tank as well. Link to comment https://www.fordxr6turbo.com/forum/topic/94669-negative-fuel-trims-at-idle/page/2/#findComment-1678968 Share on other sites More sharing options...
Puffwagon Puff Gold Donating Members 16,282 Member For: 10y 2m 18d Gender: Male Location: South Australia Posted 19/03/19 04:50 AM Share Posted 19/03/19 04:50 AM On 19/03/2019 at 4:17 AM, El Andrew said: The intank fuel filter is due for replacement (which requires seat removal) so planning to check the fuel system out fully then. Is a dead head setup so reg is in the tank as well. Expand That's where I'd be looking. On 19/03/2019 at 3:55 AM, El Andrew said: I think I should just average the trims of both cars and be happy. Expand There is every chance that this will fix the issue! Link to comment https://www.fordxr6turbo.com/forum/topic/94669-negative-fuel-trims-at-idle/page/2/#findComment-1678997 Share on other sites More sharing options...
El Andrew Gold Donating Members 2,036 Member For: 9y 11m 25d Gender: Male Location: Canberra ACT Posted 29/03/19 02:06 AM Author Share Posted 29/03/19 02:06 AM Well, I'm going to cautiously call this one fixed. Fuel pressure tested fine on Tuesday, but the mechanic did a very thorough check over the car and a bunch of electrical testing.Found the downstream O2 sensor voltage was all over the shop. He reckons that most modern cars do use the downstream one to either a) correlate with the upstream sensor and adjust if there are variations and b) make adjustments to keep the cat operating conditions correct. He suggested replacing the sensor.Checked afterwards and the second O2 sensor is still active in the custom tune that was in the car when I bought it. Given the aftermarket cat probably fluffs the readings I've just switched it off as most people seem to do anyway.Fuel trims have been almost perfect ever since. Obviously fluctuates a bit as you drive but settles down close to zero at steady cruise and idle. Also I'd noticed that when stationary the car would sometimes just catch a near stall, or would actually stall when moving from N to D. That has gone now.Also the mechanic had a HiAce with a turbo 1JZ. 1 Link to comment https://www.fordxr6turbo.com/forum/topic/94669-negative-fuel-trims-at-idle/page/2/#findComment-1680200 Share on other sites More sharing options...
k31th less WHY; more WOT Site Developer 29,410 Member For: 17y 7d Gender: Male Location: Melbourne Posted 29/03/19 02:17 AM Share Posted 29/03/19 02:17 AM haha well done... figured there was a good reason most tuners turn off the downstream sensor pics of hiace with 1jz-t? Link to comment https://www.fordxr6turbo.com/forum/topic/94669-negative-fuel-trims-at-idle/page/2/#findComment-1680204 Share on other sites More sharing options...
El Andrew Gold Donating Members 2,036 Member For: 9y 11m 25d Gender: Male Location: Canberra ACT Posted 29/03/19 02:20 AM Author Share Posted 29/03/19 02:20 AM Sorry no pics!Yeah I assumed the switch off was always to prevent a CEL due to cat behaving differently. I didn't think the sensor actually played an active role in engine management. Doing some reading though suggests I was believing a common myth.Proof is in the pudding though I guess as it definitely made a difference! Link to comment https://www.fordxr6turbo.com/forum/topic/94669-negative-fuel-trims-at-idle/page/2/#findComment-1680207 Share on other sites More sharing options...
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