I have replace the EGR valve and the O2 sensor on my 94 4runner 3.0 4WD and the check engine light comes on after a short bit of driving an then when the engine is turned off and then on again, the CEL will be cleared and then after a bit of driving, it would come on again. Any thoughts?

 

Not enough information. What code are you getting? What made you replace the EGR and O2 in the first place?

 

i initially had a check engine light on but the diagnostic plug was all messed up and I couldn't get a code pulled so I empirically just changed the O2 sensor thinking that it was the most likely reason. However, I continued to have a check engine light on so I had the diagnostic plug replaced and the code was pulled and it was the EGR valve. So I had that replaced. Now it just come on after a bit of driving and then when I shut off the car, the light gets cleared until the car is driven for a bit again and then comes on. The truck seems to be running smooth, . . . just annoying that the light comes on and you think that the car is going to blow up any minute.

 

Are you still getting the same code?

Mike in AR

 

i am going to check the code, now how do you do it again without the OBD1 machine, I heard you can take a paper clip and jump two terminals?

 

Right. Jumper the Te1 and E1 pins in the Diagnosis port. Turn the ignition to ON. Read the flashes. Two-digit codes will flash the two parts of the number approx. 2/10 of one second apart. Complete codes will be separated by approximately 1/2 second pause. Example: code 2 followed by code 52 would be -- flash flash..................... flash flash flash flash flash .. flash flash.

Here's a link to the diagnosis page:

http://www.off-road.com/toyota/tech/codes/index.html

Mike in AR

 

this same thing happened to me yesterday..... drove home from work ~10 miles.... CEL came on after 2 miles and went off at around 5 miles....... i was so sad when it came on (last time it came on, it was my headgasket about 2 years ago ~$1200).... then it went off, and i am somewhat relieved....

but now i am still wondering if it will come on again.... arrrggg..... and what's causing it

quick question: can i pull codes even if the CEL if off?


JQ
93 v6 4x4 auto

 

yeah you can still pull the codes. Like the guy above said, on the little diag thing, short terminals te1 and e1 with a paperclip or something.

Turn the key until the cel starts blinking...that's your code.

That code will stay in the computer until you either unplug the battery for a while or take out the efi fuse.

 

will the code stay in the memory even thought every time I turn off the engine the CEL turns off?

 

yes.. as he said the light only goes off if you pull the efi fuse or the lose the battery connection for an extended period.

 

Well, I would say you have a sticky EGR vavle, but you replaced that. I think you have a simple vacuum operated EGR. To that end, you need to check the vacuum signal. This should be a "ported" signal, in other words, vacuum only off idle (and possibly at at certain level of vacuum). Or is this valve controlled electronically, I can't remember. Either way, you've got to get a signal to the EGR valve. (Newer vehicles have a completely electric variable computer controlled EGR valve...cool)

Once you know the signal is okay, I would check the passage way that connects the EGR to the intake. Remember the EGR is the "exhaust gas recycler", often the passageway gets clogged. So even though the EGR may be opening, there is no flow of exhaust gasses. Many old timers say to block off the EGR passageway or put a bee-bee in the control line. I personally don't have any issue with EGR as long as it functions correctly if doesn't take away any HP. Anyway, Your passageway may be clogged, or may be breaking loose some carbon chunks that are sticking your valve. I don't think Toyota uses a DPV like Ford, hopefully others will chime in if I'm wrong, and that changes things. Anyway, check these things first and post back. It may be a monitoring problem, but chances are it's something simple.

 

There is a separate vacuum modulator that actuates the EGR on my 92 3.0. I believe the EGR is only designed to operate when the engine is at high vacuum (cruising, not accelerating), so it shouldn't detract from power unless it ( or the vacuum modulator ) is not functioning properly.

Mike in AR

 

I'm having similar issues with my 93, but it is not holding the code after I turn the engine off. Any ideas on how the get the code for what's happening?

 

Check it with the engine running. The CEL flashes when I jumper the pins to set the base timimg, even tho it's a constant, fast-flash denoting 'system OK'.

Mike in AR