Randomly runs super lean/ecu limp mode?

[tomlaw]

My 1G runs great 99% of the time. I have a keydiver chip, arm wideband and safc 2 professionally tuned. A couple times while driving, after having gotten on it a bit, it will start running super lean (off the scale) under any kind of throttle and barely idle. This has happened about 3 times in the past month. I usually alleviate the problem by unplugging the ecu and plugging it back up and giving it a couple min. Happened on the e-way one time and I just kept driving (couldn't really accelerate much at all) and the problem went away after 3-4 min.

If the ecu sees too much knock (60-85% throttle in lower gears) does it just go into some kind of a limp mode, this never happened with the stock ecu. Any suggestions?

Also I saw some wierd yellowish gooey liquid stuff mostly on top of the ecu case. What is this? I haven't opened the case yet

 

[eburg2490skillz]

what do you mean by limp mode? does it bog or act as a 2 step setting while driving. does engine temp or rpm effect it? what exhaust do you have. if yu have a catylitic converter, it could be clogged or a bad o2 sensor if you didnt bypass them on the tune. what tuning program are you running on?

 

[ChiTownHussla]

what if the car does 2 step while driving what does that mean? my 2g does that.

 

[DSMTyson]

My 1G runs great 99% of the time. I have a keydiver chip, arm wideband and safc 2 professionally tuned. A couple times while driving, after having gotten on it a bit, it will start running super lean (off the scale) under any kind of throttle and barely idle. This has happened about 3 times in the past month. I usually alleviate the problem by unplugging the ecu and plugging it back up and giving it a couple min. Happened on the e-way one time and I just kept driving (couldn't really accelerate much at all) and the problem went away after 3-4 min.

If the ecu sees too much knock (60-85% throttle in lower gears) does it just go into some kind of a limp mode, this never happened with the stock ecu. Any suggestions?

Also I saw some wierd yellowish gooey liquid stuff mostly on top of the ecu case. What is this? I haven't opened the case yet

Open up your ECU, take a picture and post it on here. So that we can either diagnose it as a problem or rule it out.

what if the car does 2 step while driving what does that mean? my 2g does that.

It most likely means you need to have your ECU repaired, or you have some sort of wiring issue(?)

 

[miliman13]

hey bud your gonna get asked alot of questions that arent going to answer yours so before you entertain everyones theory try swaping out your coil pack and see if that helps a faulty coil pack will cause you to run lean and will make you run a bit weak and it is not a chronic problem but rather a re-occuring one if not then try some thing else i hope it helps. thats what i did,

 

[Dert]

How old is your wideband? My car was randomly goin off the scale lean while driving making the car run like ass
and sometimes even shutting off, mostly after a romp on the gas pedal. After a lot of searching I stumbled across an evo forum where a member had the exact same issues I was having. Turns out, his AEM wideband was going out, he swapped in a new one and issue went away. I swapped mine out and it hasn't done it since. The life of these sensors are short, and become even shorter if used as front o2 location. This may not be the same issue as what you are having, but it's a thought.

 

[eburg2490skillz]

@miliman13 why would you assume something that has many possible components that would affect this problem. lets narrow down problems before he goes out and spends hundreds if not thousands before he fixed the problem. you could be right, but lets narrow down the list

 

[ChiTownHussla]

What all do you guys want to know? Ill post everything u ask. I have no link, stock t25, hard turbo piping, stock sidemount. mostly stock besides 6 AN from tank to filter to rail. Runs lean and has no power unless I baby the throttle. Previous owner installed dual pump setup in tank , wally 190 he said. Thanks

 

[92AWDHX40]

Any pics of the ec would really help.

 

[eburg2490skillz]

my advice would to post a picture of the ecu like said above, check spark tip for abnormal wear (if you still have plugs). if they are white colored and/or burnt then it would prove that you are running lean to cancel out the wideband reading incorrectly. see if your maf sensor is still good and clean. check for fuel related problems like a clogged ingector(s), but i dont think it is fuel related. coil pack shouldnt be the problem because it is occuring a couple times a month

 

[DSMTyson]

Open up your ECU, take a picture and post it on here. So that we can either diagnose it as a problem or rule it out.

Like I said before...

 

[ChiTownHussla]

OK guys. ECU pics coming tomorrow. DSMTYSON you were right , my bad for doubting broseph

 

[miliman13]

hey back again' new CAS fixed up my problem . im not suggesting buying anything but rather work with your local dsm community and see if they can lend u a sensor just to try it out..

 

[eburg2490skillz]

CAS seems to be a huge problem with many different problems occuring. what was wrong with your car miliman? if he can start up his car fine...i would think the CAS would be ok

 

[crand]

im curious as to what fuel pump your running and how its wired, ive hear atleast for wallys under wot for an extended period of time they can give you some issues, i know thats with big injectors, but maybe with a stock pump?

 

[miliman13]

well i just went for the most likely suspect. i happened to have extra green lid CAS . we have all heard the black top is the beeter of the 3 available adjustable CAS but a Cas can be faulty and still work at times. we dont know what exactly causes hes trouble but we know it makes him run lean . it worked with me and it might with him. he has a 1G so perhaps it could solve something . its worth an attempt

but to many parts working togethor to know what went wrong. ignition/timming/fuel ? ' hey bud hows the diagnosis +

 

[eburg2490skillz]

what do you mean by "faulty"?