Fuel Trims STILL Negative (with datalog)

[Aoslo]

What number are you actually getting though?

42 right now, winter i get at the lowest 37 - talking -20 MN weather

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[gtman]

On an Si? Well... the mystery continues.

I barely get low 30's in winter in the Mid-Atlantic.

 

[Aoslo]

On an Si? Well... the mystery continues.

I barely get low 30's in winter in the Mid-Atlantic.

Right! My car is goofy!

 

[Aoslo]

Here’s pictures of my old spark plug I changed 2 weeks ago. I don’t know if it’s of any relevance but I thought I’d drop it in here.

 

[arpypat]

Do you have an aftermarket intake?

 

[Aoslo]

Do you have an aftermarket intake?

I do not

 

[Jason Baker]

Ironically, I was in this same boat about a year ago. Same type of setup except I was running E the whole time.
After researching and digging, my last ditch was to replace the injectors.
Well…. The motor blew a week later with the stock injectors. I worked on fixing the LTFT for 6 months before it went kablooy!

Not saying that’s the case for you or that this would be imminent but…. I would find the issue sooner than later. I can’t rule out the injectors as the culprit.

Anyways, with My new motor, with all nice and new injectors, on the stock calibration, the new motor is running perfect fuel trims.
It cost me like $10,000 but, my trims are good again. .

 

[Aoslo]

Ironically, I was in this same boat about a year ago. Same type of setup except I was running E the whole time.
After researching and digging, my last ditch was to replace the injectors.
Well…. The motor blew a week later with the stock injectors. I worked on fixing the LTFT for 6 months before it went kablooy!

Not saying that’s the case for you or that this would be imminent but…. I would find the issue sooner than later. I can’t rule out the injectors as the culprit.

Anyways, with My new motor, with all nice and new injectors, on the stock calibration, the new motor is running perfect fuel trims.
It cost me like $10,000 but, my trims are good again. .

yikes, did you find out it was injectors for you then?

 

[Jason Baker]

yikes, did you find out it was injectors for you then?

Well without any actual proof left, I took the injectors that were in it on detonation and had them checked. The cylinder that popped had an injector that was slightly clogged but still worked. Guy told me that he doubted that would pop a cylinder but…..
Anyways without actual data or proof to share, I cannot comment on “what” the issue was. I suppose I ruled out low pressure fuel pump, high pressure fuel pump and all lines in between since they are currently the same ones and it’s working better than before. So….. I may deduce that the injectors had something to do with it.
We may never know.

 

[Jason Baker]

Well without any actual proof left, I took the injectors that were in it on detonation and had them checked. The cylinder that popped had an injector that was slightly clogged but still worked. Guy told me that he doubted that would pop a cylinder but…..
Anyways without actual data or proof to share, I cannot comment on “what” the issue was. I suppose I ruled out low pressure fuel pump, high pressure fuel pump and all lines in between since they are currently the same ones and it’s working better than before. So….. I may deduce that the injectors had something to do with it.
We may never know.

New injectors are $400. And if you wanted to climb on top of the motor, you might be able to get them out but it’s gonna suck!
Best to pull the motor out unfortunately.

 

[Aoslo]

New injectors are $400. And if you wanted to climb on top of the motor, you might be able to get them out but it’s gonna suck!
Best to pull the motor out unfortunately.

I’ll see if o2 sensors change anything, I have access to a lift and plan on doing my clutch so I’ll do injectors then.

 

[Jason Baker]

I’ll see if o2 sensors change anything, I have access to a lift and plan on doing my clutch so I’ll do injectors then.

Lifts are huge!
Although a lift won’t help to do the injectors. Well…. Not too much help I guess.
It can totally be the 02 sensors as well.
Keep up the fight brother! You’ll get there.

 

[Aoslo]

Got an update, I replaced the O2 sensors and it didn’t change anything. Do I go for a custom tune or change the injectors? I’d hate to keep blowing money into the wind.

 

[Aoslo]

UPDATE:

I finally got to replacing my fuel injectors. That was problem, just physically looking at the lm they all were covered in carbon. Idles better now and fuel trims are very close to 0. One of these days I have a friend who has a bore scope and will give you guys info on how the valves look at 100k miles on these si’s.

 

[alxgravel]

UPDATE:

I finally got to replacing my fuel injectors. That was problem, just physically looking at the lm they all were covered in carbon. Idles better now and fuel trims are very close to 0. One of these days I have a friend who has a bore scope and will give you guys info on how the valves look at 100k miles on these si’s.

Mine was out at 89k kilo so 100k miles for sure one was not working well. Great that was ur problem so the car is running good against !

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