2010 Sequoia - ECU problems?

Hello,

I have a 2010 Sequoia Limited 5.7 v8. When I bought it at about 35,000 miles, I got the TRD cold air intake installed. It initially got high 15's for mpg with mostly city driving and it would sometimes dip into the low 12's in winter in 4x4.

My truck is now at 160,000 miles. I have never serviced the air filter explicitly but routinely had it taken to the local Toyota dealership for all routine service, oil changes, etc.

Currently my truck is doing three suspicious things.

1. My gas mileage is low 12's in summer. I reset the mpg about a month ago and did about half of the driving on the highway, half city and it has not broken 13 mpg.
2. Every now and then, maybe 3 or 4 times now, when I turn it on, the 4LO light start flashing for a bit then eventually stops. It takes a few minutes before it stops.
3. The accelerator feels sluggish at times either like its not getting enough air or its not pumping in enough gas. Then something happens and it kind of takes off a bit. It is not always very responsive to the gas pedal and it doesn't always feel like its getting full power, gas or air.

Today I opened up the air intake and the filter had maybe 1/6th of it that was fairly clogged, the rest seemed pretty clean. I tried to clean it a bit, but didn't have the right tools, but that didn't seem to make a lot of difference.

So I am wondering if my ECU might be going bad or if this is more likely an airflow problem. Over the years when I accelerate hard with it I get a sulfur smell coming from the engine. I read up on that in the past and it seemed like some have that, some don't but I never found any conclusive reason to it.

I have never had any check engine lights, but not sure if you would get a check engine light with a bad ECU. I have read off and on that the stock ECU is not optimal but I never did anything about it, but if my ECU is going bad, maybe I should get a new one or get it reflashed???

Any ideas how I can try to figure out what the root cause is and the best way to fix it?

Thank you,
Kevin

 

Is your truck a flex fuel?

 

Yes it is a flex fuel.

I also found this thread about the 4LO, might be related. I do have an after market viper alarm and I have aftermarket HID headlights installed. I do have my Satellite radio not start sometimes. Maybe part of my problem is I am drawing too much power at start, Could that either be messing up the ECU or maybe that has damaged the ECU or the fuel pump ECU?

https://www.toyotanation.com/threads/4lo-flashing.1599522/

 

Get a reading if your ethanol content. If over 10% it’s stuck in flex fuel mode.