A.Wilson013

On the freeway I can cruise at 60 mph with my narrowband AF Gauge "dittering" lean to rich as per normal for 100 miles. If for some reason I need to speed up or slow down for a bit, and then I go back to 60 and cruise again, it will show me running all the way at rich.

After I run all the way at rich for a period of time, say 20 miles to the nearest gas station, and I exit the freeway my 4runner will lean out a LOT and have zero throttle response. It even died on two occasions (after the tuner added 5% fuel at 0% throttle to try and fix the problem). The gauge will show all the way lean, and the 4runner will sputter when throttle is applied for a couple seconds, then back to normal.

This does NOT happen EVERY time I drive, but it does happen probably 50% or more of the time.

It does not often throw a code, but has a couple times thrown a P0171 [System Too Lean (Bank 1)] when it will be showing 100% rich on the AF Gauge, climbing a steep incline.

ANY HELP IS GREATLY APPRECIATED.


I am running:
2nd Gen TRD Supercharger
TRD Exhaust
315cc Supra Injectors
Split Second ESC1
APEXi SAFC
Split Second ARM1
Dyno Tuned

vital22re

iTrader: (2)

I really think that it's the short term fuel trim. Give gadget a shout at Urd. Maybe he has an idea.

A.Wilson013

I keep forgetting to send him the e-mail. I typed it up about a week ago. Thanks for the reminder =)

Oh, and I don't mean to disregard what you've been saying at all by posting this, just wanted to see if anyone else has the same problem, or any new ideas.

bmcnutt

I had a similar issue & spent hundreds of dollars, new exhaust,new O2 sensor new plugs, new wires, dealer diagnosics 4 hours, changed MAF sensor, tried different computer, all one at a time with no avail. A small trouble shooting shop took it for a drive and said it was the crank sensor, I did not want to buy one so I got a used one to try and bingo, a 2 minute drive and he knew this, I wish that I went there first.

Texas_Ace

Crank sensor? Would not have guessed that but i have a similar problem just under different circumstances. 2 or 3 times a year it will act like you are describing, bog bad and misfire/sputter and even die.

Didn't have my wideband hooked up till till it happened a few days ago and noticed it was running lean, till then i was thinking something to do with spark.

To date i have not figured it out, it usually goes away by the next day so i don't worry about it, i can still drive the truck when it happens, just got to give it more gas.

What did your truck dyno BTW?

vital22re

iTrader: (2)

wasn't it 214 at the rear? Alex has since pulled the cheap flashy apexi stuff and gone with urd components to control the air fuel and we are throwing in a real a/f gauge thats on its own 02

TheNuge

My '99, 4runner, sr5, 4.3 has same sort of problems.
I replaced plugs, wires, coils, map, cat con, added second cat con, 02 sensors, and throttle position sensor,...it ran better but still chugged, spit, backfired, and stalled....
I changed the coolant temp sensor and I thought that I had it ... but a day later it started again.....
I don't know what to do....
Its suckin back gas and running leaner all the time.

TheNuge

When it runs good it's great ... but I have to warm it up and baby it til it decides to run good.
maybee I'll try the crank sensor

Texas_Ace

You have checked the fuel pump/Fuel filter I am sure?

TheNuge

yes changed filter and checked pump
I also took it to Toyota and they had no answers except keep replacing stuff until problem is solved

Texas_Ace

Throwing parts at a problem rarely fixed it. Luckily up to now you have replaced basic tune up items so you are none the worse for wear.

Sadly don't have much of a suggestion for you either except possibly a bad ECU or wiring.