Forester XT and WRX Recall - LSPI?

[bluesubie]

Leakdown test results should be given in percentages.
https://mobiloil.com/en/article/car-maintenance/car-maintenance-archive/how-to-do-a-leakdown-test

I wonder if the reflash will improve the nasty fuel dilution seen in these engines? Probably not by much given the nature of the beast.

 

[Virtus_Probi]

Originally Posted By: bluesubie
Leakdown test results should be given in percentages.
https://mobiloil.com/en/article/car-maintenance/car-maintenance-archive/how-to-do-a-leakdown-test

I wonder if the reflash will improve the nasty fuel dilution seen in these engines? Probably not by much given the nature of the beast.


I called the dealer and found that they used a Snap-On leakdown tester, and the output dial for it gives a percentage output, not an absolute pressure (the Harbor Freight tool that some dealers have used is similar). The face of the output dial has green/yellow/red zones for low/medium/high leakdown, which wouldn't make sense if absolute pressure was displayed since the input pressure has to be factored in.

So, we concluded that the tech wrote down PSI instead of % by mistake. I am relieved!

 

[onemig]

Hello everyone!

I would like to share my observations as our FXT had its ECU reflashed also.

The vehicle now feels responsive in stop and go driving, requiring minimal throttle input to get moving at a desired pace. Before the reflash, I would have to give it more throttle to get moving to a desired pace and by the time the car responds, there is then too much acceleration than what I want at the given situation. In short, throttle modulation in downtown rush hour traffic has been greatly improved.

At WOT, The car initially felt slow. The ECU probably needed time to adjust as it now also responds better than before. Pre ECU reflash, while in itelligent mode, at WOT, the car most of the time would not raise the rpm enough to provide what I felt is the most optimal RPM range for the most acceleration (around 4,500-5,500 rpm). I almost always had to manually downshift for it to raise the rpm.

 

[onemig]

Just realized, I wrote most optimal..... Lol

 

[gathermewool]

Originally Posted By: dgunay
I've been tuning my cars for a very long time (current car has more than 20 different maps including variable timing for each 10 degrees), and I am 100% sure that properly adjusted fuel trims (means less than +-3% for me) helps to smoothen the ride and throttle response. The more it is properly adjusted, the less primary 02 + ECU have to manipulate the a/f ratio in order to reach stoichiometric efficiency (14.7) in the closed loop.

I am not saying they only changed the fuel trims, but it's the #1 factor that smoothens the ride when it's in the closed loop.
Originally Posted By: dgunay
I forgot to add (no edit)

......and the less ECU manipulates the a/f ratio based on primary o2 readings (which means closer to 0), the smoother ride you get. So our aim is to prevent fuel trim spikes in order to get the best results when tuning a car(especially if it's daily driven).

So what I am trying to say is, adjusting fuel trims are not that "simple" as you mentioned. Even though ECU compensates the fuel trims, it isn't properly adjusted and there will be fuel trim spikes. Fuel trim spikes make your car run [censored].

If you search google, you'd find tons of rough idle/acceleration problems due to unadjusted fuel trims.


I think we're on the same page, just using different terminology. It sounds like you're saying that you tune your fuel mapping, not your fuel trim. In my experience, fuel trims ARE what the ECM adds or subtracts based on O2 sensor (primary only or mostly primary and some secondary.)

In other words, the MAF scaling and ECM fuel tables constitute the base fueling, with compensation provided by the fuel trim, which is 100% dynamic and NOT able to be tuned.

 

[dgunay]

Secondary o2 sensor has nothing to do with the fuel trims or overall performance. It is just there for emissions. You cannot adjust the fuel trims directly. You can only tune your fuel map(s), so that you'd get better fuel trims.

By the way, my car comes with both MAF and MAP sensors (runs with MAF because of maintenance minder and emissions), and if you consider an aftermarket tune in the future, I'd highly recommend switching to the MAP tune in order to get it done more precisely. My MAF sensor is still there, I used to use it as an IAT sensor.

You may want to read this. Great article demonstrates the difference between MAF and MAP aftermarket tune.

http://www.8thcivic.com/forums/7284772-post1.html

 

[gathermewool]

Originally Posted By: dgunay
Secondary o2 sensor has nothing to do with the fuel trims or overall performance. It is just there for emissions. You cannot adjust the fuel trims directly. You can only tune your fuel map(s), so that you'd get better fuel trims.

By the way, my car comes with both MAF and MAP sensors (runs with MAF because of maintenance minder and emissions), and if you consider an aftermarket tune in the future, I'd highly recommend switching to the MAP tune in order to get it done more precisely. My MAF sensor is still there, I used to use it as an IAT sensor.

You may want to read this. Great article demonstrates the difference between MAF and MAP aftermarket tune.

http://www.8thcivic.com/forums/7284772-post1.html


In my old STI, the secondary O2 sensor had an input to fuel trim. It didn't function as only a CAT performance sensor.