my 92 3vze CEL won't go away. code 21 so i replaced o2 sensor with the correct denso but CEL still comes on after closed loop then it cuts my fuel down and i get half power. is it running rich or lean? is it a MAF thing. I've tried to find out how to clean it but hit dead ends on the forums. funny thing is the CEL went away for two weeks when i went on a trip and blew my head gasket. i used a gasket sealant additive which worked and i also had a broken VSV on the intake at the time but the CEL went away after driving 300 kms home then came back and removed the battery and replaced VSV and the CEL came back! it had been running great. The CEL doesn't come on at all if i just restart it then drive along highway at 100 but if i take my foot off then it will come on. any ideas? How do i fix a rich condition?
code 21 won't go quietly
- Thread starter john690
- Start date
Register to hide this ad
so today i did the FSM o2 sensor test : DLC1 connected to my multimeter, connected VF1 TE1 and E1 and no voltage movement. the other terminals showed a fluctuation in volts so I'm sure I'm doing it right. The FSM says if there is zero fluctuation then replace ECM after replacing sensor. the sensor is new and the engine runs fine other than when the CEL is on and even then linage is not too bad, 350 to a tank in the city just terrible power. should i replace the ECM or is it just bad wiring from sensor to terminal. the wires are old and the plastic cover is melted in places from exhaust pipe. a wire at the plug even came out but i stuffed it back in. how do i check if the wires are gone?
KidVermicious
New member
You hit a dead end on finding out how to clean the MAF because you don't have a MAF. You have an AFM, which is a different animal entirely. Here's how to test it.
I'd fix that harness before replacing the ECM. If you've got melted insultation and wires pulling out of plugs, who knows what else is wrong in there? I'd splice in entirely new wire where it gets near the exhaust and then insulate it well, and then I'd depin the connectors on both sides and reterminate them. Clean the connectors well while you're at it. I can almost guarantee that the one wire that came out isn't terminating well, and if it's gone the rest are probably in poor shape as well.
If you do decide to replace the ECM, see if you can buy one from a yard that'll give you your money back if it doesn't work or doesn't fix the problem.
I'd fix that harness before replacing the ECM. If you've got melted insultation and wires pulling out of plugs, who knows what else is wrong in there? I'd splice in entirely new wire where it gets near the exhaust and then insulate it well, and then I'd depin the connectors on both sides and reterminate them. Clean the connectors well while you're at it. I can almost guarantee that the one wire that came out isn't terminating well, and if it's gone the rest are probably in poor shape as well.
If you do decide to replace the ECM, see if you can buy one from a yard that'll give you your money back if it doesn't work or doesn't fix the problem.
flyinhawaiian01
New member
I doubt its the ecm. Get the wiring straightened out first, if there's a bad connection ANYWHERE, its a bad connection and that's going to keep the system from running correctly.
Furthermore, although the Denso o2 sensor may be brand new, it may not work properly, even if its an oem replacement. I have a brand-spanking new Denso sitting right here in my shop, put it on my truck and couldn't pass smog. Drove me crazy until I tried another one (I'm now running an NTK o2 sensor), it passed with flying colors!
I dunno if Denso has been having defective parts lately or what, but when I swap out a brand new o2 sensor with another brand new o2 sensor from another manufacturer, and the emissions numbers change from way out of spec to incredibly clean and way low numbers, that tells me there's a problem with Denso's parts!
Re-run your tests after fixing the wiring, then go from there before replacing more parts.
Furthermore, although the Denso o2 sensor may be brand new, it may not work properly, even if its an oem replacement. I have a brand-spanking new Denso sitting right here in my shop, put it on my truck and couldn't pass smog. Drove me crazy until I tried another one (I'm now running an NTK o2 sensor), it passed with flying colors!
I dunno if Denso has been having defective parts lately or what, but when I swap out a brand new o2 sensor with another brand new o2 sensor from another manufacturer, and the emissions numbers change from way out of spec to incredibly clean and way low numbers, that tells me there's a problem with Denso's parts!
Re-run your tests after fixing the wiring, then go from there before replacing more parts.
alright iill splice in new wiring with the battery off and EFI fuse out then go for a drive. I also read that a PCV problem can cause a rich condition. I unplugged the o2 sensor and the same thing happened so i guess its not reading too rich and cutting fuel its just reading nothing and cutting fuel. why not give me more fuel. id be alright with that.
fixed the wires at the connectors but there id no voltage or resistance at the ends even when engine running. i have finally got a 92 3vze schematic but it says there are 6 o2 sensor terminals but i only have 1 sensor and 4 wires at the harness, i will check for voltage at these terminals on the ECM tomorrow but not sure if the pic is right. does any one have the right schematic of the 3vze 02 4wf a/t for sure. if the ECM has voltage at these terminals then it must be a short in the harness or maybe some problem like PCV that i haven't thought of. this is the schematic i have. the plugs are right shape but not 100% about pins.
http://www.toyota-4runner.org/attachment.php?attachmentid=163546&stc=1&d=1435844176
http://www.toyota-4runner.org/attachment.php?attachmentid=163546&stc=1&d=1435844176
flyinhawaiian01
New member
same thing here as with my post on the other thread about code 21.
I'd try using something a bit easier to identify the wires, such as this one:
http://ww2.justanswer.com/uploads/skyvisions/2012-08-14_202523_93_knk.jpg
I dunno if this is the same ecu as yours, but search for the "pinout" for the ecu, it might make it easier to ID the wire at the ecu so you can test the o2 sensor directly at the ecu.
I'd try using something a bit easier to identify the wires, such as this one:
http://ww2.justanswer.com/uploads/skyvisions/2012-08-14_202523_93_knk.jpg
I dunno if this is the same ecu as yours, but search for the "pinout" for the ecu, it might make it easier to ID the wire at the ecu so you can test the o2 sensor directly at the ecu.
yeah i saw that page too but it looked to be a 22RE ECM. I tested the pins according to the page I found at B6 B10 A22 AND C10 with ig sw on 2 but not running. only B6 had volts. I could only check B plug when running cos it won't run with A or C unplugged but both B6 and B10 had volts when running. should I change my ECM?
went for a drive with different sensor plug configs cos i forgot which order they went in after re terminating. the CEL came on straight away with the first two configs then blew EFI fuse on the 3rd so harness is def working at least on some wires. I got 3 new codes on the drive as well strangely (22 41 and 24) looking at changing ECM now.
giro
New member
Truthfully, I don't know that I've ever used my electrical wiring diagram book before. Mine's for the 92 version, and is says US/Canada.
It's partly the same, and partly different. For one, your diagram shows 2 O2 sensors, and mine (also a 3vz-e) only has one...and only 1 in the diagram.
But the Main O2 sensor in that diagram looks right for the colors of wires and the ports.
I'm only really seeing 4 ports there, with 2 into the ECU
My book shows that the shielded junction of that black wire out of the O2 sensor is made just to the left of the relay/fuse box under the hood (when at the bumper looking at the engine)...the one just behind the battery.
After that junction, it looks like it goes into pin 4 of C1, a block that my book shows should be dark grey and should have a total of 7 wires into it, instead of the 11 shown in your diagram. Ahhh, there's the 6 wires going to the ECU you were talking about. Yep, mine only shows 4 going to the ECU, so if that's what you have you should be fine. Violet-white at 8 going to 15(B) (AKA T), Y-G at pin 13 going to 8(B) (AKA VF), a black at pin 18 going to another splice that goes to the tachometer and the igniter pin block, and then the black wire from the O2 sensor into the splice, at pin 4.
BTW, a note for the Oxygen sensor signal system says:
"The oxygen density in the exhaust emissions is detected and input as a control signal to terminal OX of the ECU. To maintain stable detection performance by the oxygen sensor, a heater is used for warming the sensor. The heater is also controlled by the ECU(HT)"
Ahhh, this is what I read on the next page (page 60). "The oxygen sensor heater control system turns the heater to on when the intake air volume is low (temp of exhaust emissions low), and warms up the oxygen sensor to improve detection performance of the sensor. The ECU evaluates the signals from each sensor (input signals (1-1, 4, 8, 9, 11)), then sends output to terminal HT and controls the heater."
(looks like 1-1 is the water temp signal system, 4 is the RPM signal system, 8 is the battery signal system, 9 is the intake air volume signal system, and 11 is the STA signal system. Offhand, it seems like the water temp and intake air volume are what matter most there...the others should just be that your engine is running, and you'd probably get other errors if those sensors or connections were amok).
Basically, I think with you jumping from a cold start to 100 (km/h?) and staying there is fine, then basically once the engine warms up and the ECU starts using the sensors to control the engine, then it's happy since the engine is hot and moving.
I bet something isn't working right when the O2 heater should run, so whether that's that it's not connected right or the wiring is not sound, or that the O2 heater just isn't working
It's partly the same, and partly different. For one, your diagram shows 2 O2 sensors, and mine (also a 3vz-e) only has one...and only 1 in the diagram.
But the Main O2 sensor in that diagram looks right for the colors of wires and the ports.
I'm only really seeing 4 ports there, with 2 into the ECU
My book shows that the shielded junction of that black wire out of the O2 sensor is made just to the left of the relay/fuse box under the hood (when at the bumper looking at the engine)...the one just behind the battery.
After that junction, it looks like it goes into pin 4 of C1, a block that my book shows should be dark grey and should have a total of 7 wires into it, instead of the 11 shown in your diagram. Ahhh, there's the 6 wires going to the ECU you were talking about. Yep, mine only shows 4 going to the ECU, so if that's what you have you should be fine. Violet-white at 8 going to 15(B) (AKA T), Y-G at pin 13 going to 8(B) (AKA VF), a black at pin 18 going to another splice that goes to the tachometer and the igniter pin block, and then the black wire from the O2 sensor into the splice, at pin 4.
BTW, a note for the Oxygen sensor signal system says:
"The oxygen density in the exhaust emissions is detected and input as a control signal to terminal OX of the ECU. To maintain stable detection performance by the oxygen sensor, a heater is used for warming the sensor. The heater is also controlled by the ECU(HT)"
Ahhh, this is what I read on the next page (page 60). "The oxygen sensor heater control system turns the heater to on when the intake air volume is low (temp of exhaust emissions low), and warms up the oxygen sensor to improve detection performance of the sensor. The ECU evaluates the signals from each sensor (input signals (1-1, 4, 8, 9, 11)), then sends output to terminal HT and controls the heater."
(looks like 1-1 is the water temp signal system, 4 is the RPM signal system, 8 is the battery signal system, 9 is the intake air volume signal system, and 11 is the STA signal system. Offhand, it seems like the water temp and intake air volume are what matter most there...the others should just be that your engine is running, and you'd probably get other errors if those sensors or connections were amok).
Basically, I think with you jumping from a cold start to 100 (km/h?) and staying there is fine, then basically once the engine warms up and the ECU starts using the sensors to control the engine, then it's happy since the engine is hot and moving.
I bet something isn't working right when the O2 heater should run, so whether that's that it's not connected right or the wiring is not sound, or that the O2 heater just isn't working
Thanks for looking into it. So according to your diagram I'm checking the wrong ECM pins? I am waiting on an answer from just answer i have given them my VIN so I can be sure. It seems my harness is getting voltage at least in part cos i blow my EFI fuse if i change the config of the harness terminals going into the plug that connects to the sensor. (I took the plug apart to re terminate pins). Im not sure what resistance i should be getting so i need some exact info before i buy a new ECM. also i don't know if i have checked for shorts in the harness properly cos i have only recently researched this process.
