it has happened to me twice in the month of owning and like 1000 miles of driving. and it clears with pulling the battery and plugging it back in, the first time it happened I wasnt able to pull the CELs with a paperclip but normally I have 2 CELs for upstream drivers side and downstream passenger side O2 sensors.

I dont even know where to begin on this,

 

Well help us find a pattern. Any similarities between the two times it entered limp mode? Were you revving the motor high at the time, were you at a stop and it fell on its face when you hit the gas? This car can enter limp mode for a number of different reasons, we won't be much help unless you can give us some more clues. Also it's possible the O2 sensors could be doing it.

 

My experience with limp home mode is from knock sensor trips. I wouldn't take the thread off topic with that info except for the fact that it turned out to be the ECU's corroded inputs right where the KS and O2 sensors enter, so either one was equally close to losing signal at any given time. If water pools in the ECU or the lower capacitor starts leaking, those inputs may be in jeopardy.

 

T2d2 is on point, if you ever find the light on and you cannot pull the code thats usually a sign to check the ecu for the blown capacitors. also probably unrelated but change your o2 sensors lol, especially the upstream ones.

 

well the car was sitting without any windows for a month or so and it had rained a bit (california)


so you think the O2 sensors could be bad regardless of the condition of the ECU? I need to figure out my next step, visually checking the ECU? I assume its near the passenger side footwell

also both times I was stopped in a parking spot.

 

When you pull back the carpet in the passenger footwell, you'll see a black plastic shroud that covers the ECU. However, I don't think a visual inspection will do you any good. I looked mine over carefully and thought the capacitors were all intact, and that I was doing preventative maintenance in having them replaced. The circuit board specialist who did the repairs thought likewise until getting the lower capacitor (that I couldn't even see under the metal brace) out of there to reveal the damage. Fortunately, I had ordered two of each and had a spare of the right rating.

Basically, if you don't know that your ECU's capacitors have been repaired, go ahead and get that done and hope it solves the problem. If you don't do it now, you're going to need to soon, anyway. Even the last year of the SCs capacitors have reached the end of their shelf life.

 

how much was the repair? I cant just buy a used one or one from a junkyard? is this a known issue?

 

you might want to fix it first and then check if the o2 codes are still there, they could be coming up from a bad ecu or you could have bad o2's both are possible to be honest I don't know the history of your car etc..

its a known issue that happens pretty randomly, but the one thing that accelerates it is water on the passenger floorboard which will happen if you have the window down or even worn out window/door seals on the passenger side. the toyota test is to take a hair dryer to the outside of the ecu to warm it up and see if the problem occurs. usually it does;t happen until things get a little warm inside the ecu then it goes weird. if the ecu is really shot then it will do it all the time.

check out the awesome toyota diagram special haridryer Service tool

 

If you buy one from a junk yard, it'll probably need the capacitors replaced, as well. They're only good for ~14 years according to the expert, so anyone who hasn't replaced them yet is living on borrowed time. I'm now of the opinion that it should be right up there with oil change, transmission oil, plugs and wires, fuel filter, etc., on the list of things a SC owner should automatically do when purchasing one of these cars.

Ali, that's an awesome schematic! I hadn't seen that one.

 

yea but how much to replace the capacitors?

also I should note this is a 400, if the mention of two banks of O2 sensors didnt give it away lol

 

There are services that charge ~$100-150 to do it. I spent $120 on a local guy who knows circuit boards like nobody's business, but had never worked on ECUs before. He felt bad charging me that much, but it was more than reasonable given the amount of work he ended up doing to de-solder and re-solder all 120 pins in that tiny space, clean up the damage to the board and attach new traces in place of the corroded ones, inspect things for any further damage, etc.

 

Ok I wanted to update this thread.

it happened TWICE yesterday WHILE driving.

and its not what I had initially stated, the car has NO POWER and wont rev, in gear it doesnt really rev past 1.5, and it barely goes.

in neutral or park it revs but wants to die, and it revs slowly and I have to pump the throttle oddly to get it to go up more. I have a video I can post but I should prolly make a clearer one when I can.

all of this comes clear when I remove the battery for a couple seconds...

not sure if this is called limp mode or not.

 

Yea its as if the car only has 1% throttle, and the overdrive button doesnt seem to affect the car either.




question would an ECU from a 95 work in my 92?

 

alright I replaced the drivers upstream, but not the downstream because rock auto decided to send me the wrong part in the right box.


this time when it went into limp mode it was bucking and flashing a CEL at me, forcing me to pull over, when this stuff happens I am on my way to work on 680, not a time for troubleshooting.


how did this make it worse...?

 

What was the CEL this time?