sc400 EGR DELETE --still throwing CEL code 71
#1
Driver School Candidate
Thread Starter
Join Date: Jul 2009
Location: FL
Posts: 12
Likes: 0
Received 0 Likes
on
0 Posts
sc400 EGR DELETE --still throwing CEL code 71
After installing S&S headers on the 1995 sc400 an EGR deletion was needed.
bought the kit from the guy at Lextreme and installed it with the resistor that came with it.
Now, I've read all the EGR forums (for sc400s) on this site and they all instruct to install the 10 ohm 1/2 watt resistor in the EGR probe, or egr temp switch.
well I did that, but guess what... she still reads code 71 (egr malfunction)
spent an hour trouble shooting it, clearing the code, starting it, changing the setup of the resistor...... tested the resistor.. appears to be good..
has anyone else had the same problem when doing the EGR delete??
The EGR valve solenoid also has a 6-pin power connector. I currently have it completely disconnected. does this need some kind of resistance also??
im kinda out of guesses at this point but Im gonna try a couple things soon like replacing the resistor....plugging in the egr valve
any advise would help.. thanks
bought the kit from the guy at Lextreme and installed it with the resistor that came with it.
Now, I've read all the EGR forums (for sc400s) on this site and they all instruct to install the 10 ohm 1/2 watt resistor in the EGR probe, or egr temp switch.
well I did that, but guess what... she still reads code 71 (egr malfunction)
spent an hour trouble shooting it, clearing the code, starting it, changing the setup of the resistor...... tested the resistor.. appears to be good..
has anyone else had the same problem when doing the EGR delete??
The EGR valve solenoid also has a 6-pin power connector. I currently have it completely disconnected. does this need some kind of resistance also??
im kinda out of guesses at this point but Im gonna try a couple things soon like replacing the resistor....plugging in the egr valve
any advise would help.. thanks
#2
Pole Position
iTrader: (1)
If I remember correctly, I used a 10 ohm rheostat to get the cel off and it worked on my supra, make sure you connected all your vsv hoses right for the egr. I don't know if you deleted all your vsv's I think there are 2 or 3 of them, also do you have your o2 sensors plugged in and functioning properly?
After installing S&S headers on the 1995 sc400 an EGR deletion was needed.
bought the kit from the guy at Lextreme and installed it with the resistor that came with it.
Now, I've read all the EGR forums (for sc400s) on this site and they all instruct to install the 10 ohm 1/2 watt resistor in the EGR probe, or egr temp switch.
well I did that, but guess what... she still reads code 71 (egr malfunction)
spent an hour trouble shooting it, clearing the code, starting it, changing the setup of the resistor...... tested the resistor.. appears to be good..
has anyone else had the same problem when doing the EGR delete??
The EGR valve solenoid also has a 6-pin power connector. I currently have it completely disconnected. does this need some kind of resistance also??
im kinda out of guesses at this point but Im gonna try a couple things soon like replacing the resistor....plugging in the egr valve
any advise would help.. thanks
bought the kit from the guy at Lextreme and installed it with the resistor that came with it.
Now, I've read all the EGR forums (for sc400s) on this site and they all instruct to install the 10 ohm 1/2 watt resistor in the EGR probe, or egr temp switch.
well I did that, but guess what... she still reads code 71 (egr malfunction)
spent an hour trouble shooting it, clearing the code, starting it, changing the setup of the resistor...... tested the resistor.. appears to be good..
has anyone else had the same problem when doing the EGR delete??
The EGR valve solenoid also has a 6-pin power connector. I currently have it completely disconnected. does this need some kind of resistance also??
im kinda out of guesses at this point but Im gonna try a couple things soon like replacing the resistor....plugging in the egr valve
any advise would help.. thanks
#3
Driver School Candidate
Thread Starter
Join Date: Jul 2009
Location: FL
Posts: 12
Likes: 0
Received 0 Likes
on
0 Posts
Okay... well after plugging the EGR back in... guess what no code...
unplug it and boom.. CEL.
that probe resistor really doesnt do anything at all. with or without the resistor for the egr temp sensor doesnt matter. Its the 6-pin EGR valve that seems to need resistance to clear the code. Ive plugged the EGR back in now but i need to figure out which wires in the 6-pin connects need resistance..
help anyone??
unplug it and boom.. CEL.
that probe resistor really doesnt do anything at all. with or without the resistor for the egr temp sensor doesnt matter. Its the 6-pin EGR valve that seems to need resistance to clear the code. Ive plugged the EGR back in now but i need to figure out which wires in the 6-pin connects need resistance..
help anyone??
#4
Lead Lap
iTrader: (8)
that probe resistor really doesnt do anything at all. with or without the resistor for the egr temp sensor doesnt matter. Its the 6-pin EGR valve that seems to need resistance to clear the code. Ive plugged the EGR back in now but i need to figure out which wires in the 6-pin connects need resistance..
The manual says to disconnect the 6-pin EGR valve connector and run resistance checks across various terminals. However, I have no such connector! It's the first thing I've run across in the manual that just plain doesn't match up. I don't remember what link I downloaded it from and whether that was year-specific... I'm guessing it applies to multiple years and that 6-pin connector is a significant element as far as why the EGR Delete works for some and not others, CEL-wise.
The OP has a '95. Did the EGR system change between '94 and '95 to include that 6-pin connector?
#5
Lead Lap
iTrader: (8)
Here's an unanswered post showing the same no-connector setup as mine, this one on a '92 SC400:
https://www.clublexus.com/forums/per...992-sc400.html
Also, I found an EGR thread saying that the EGR temperature sensor is located on (or connected to?) the EGR pipe. I'll take a look at that in the morning.
https://www.clublexus.com/forums/per...992-sc400.html
Also, I found an EGR thread saying that the EGR temperature sensor is located on (or connected to?) the EGR pipe. I'll take a look at that in the morning.
#8
Lexus Test Driver
iTrader: (3)
I'm pretty sure up to 94 uses a vsv operated EGR valve. In theory the only way the ECU knows the system is working is by reading the temp sensor.
95 and up uses an electronic valve. It uses the temp sensor and a position sensor in the valve motor. If you take the screws out of the motor and plug it in AND put a resistor on the temp sensor, the ECU shouldn't throw EGR codes.
I think in 96 and up, just to be complicated, the ECU reads the temp sensor to make sure that the valve is both opening and closing so it will throw a code regardless. Stuck closed or stuck open codes or maybe excessive / insufficient flow codes.
#9
Lead Lap
iTrader: (8)
Gotcha. Thanks for the additional info. That's the one big thing I wish people would be more careful with here, specifying what model and year they're referring to. You pretty much have to assume people are talking about SC300s unless they specify otherwise, and I've been tripped up several times trying to find something on my car that was stated as applying to all years.
Anyway, I finished up my blanking plates today for the EGR valve and the EGR pipe into the manifold. The latter was a bear to get loose! I ended up rounding off one of the 12mm bolts pretty good, so I need to replace that before tightening it down or I'll never get it off again. I didn't bother trying to remove the bottom half of the EGR pipe, as that sounds pretty much impossible without a lift. I also left the EGR valve in place, since I haven't drained the coolant yet to disconnect those lines and bypass it. The modulator valve and VSV are removed, with the connector to the VSV just sitting there. I capped off the unused vacuum ports.
With all that done, I drove it around this evening, in town and on the highway, and didn't receive the dreaded Code 71. And no knock sensor (pinging) trips. Yippee. It sounds like you're right that the '94 only looks at the temp sensor. I finally figured out yesterday that the temp sensor is the little 2-wire probe up into the bottom of the EGR valve's mount. It sits on one of the valve's bolts. As long as that is left plugged in, the rest of the system appears to be content.
I'll be curious to see if there's any noticeable swing in mpg...
'95+ with the position sensor must be the mysterious 6-pin connector that shows up in the manual and various DIY guides.
Anyway, I finished up my blanking plates today for the EGR valve and the EGR pipe into the manifold. The latter was a bear to get loose! I ended up rounding off one of the 12mm bolts pretty good, so I need to replace that before tightening it down or I'll never get it off again. I didn't bother trying to remove the bottom half of the EGR pipe, as that sounds pretty much impossible without a lift. I also left the EGR valve in place, since I haven't drained the coolant yet to disconnect those lines and bypass it. The modulator valve and VSV are removed, with the connector to the VSV just sitting there. I capped off the unused vacuum ports.
With all that done, I drove it around this evening, in town and on the highway, and didn't receive the dreaded Code 71. And no knock sensor (pinging) trips. Yippee. It sounds like you're right that the '94 only looks at the temp sensor. I finally figured out yesterday that the temp sensor is the little 2-wire probe up into the bottom of the EGR valve's mount. It sits on one of the valve's bolts. As long as that is left plugged in, the rest of the system appears to be content.
I'll be curious to see if there's any noticeable swing in mpg...
'95+ with the position sensor must be the mysterious 6-pin connector that shows up in the manual and various DIY guides.
#10
Lead Lap
iTrader: (8)
I still have some troubleshooting to do with the A/C system. It works fine at speed, but when idling in Drive makes for some pretty rough RPM fluctuations. In Park or Neutral, the RPMs rise enough that it doesn't happen. I'm not sure if it's IAC or compressor (or something else), but that A/C rough patch often coincided with tripping the knock sensor in the past, so I assume it's all somehow connected.
Anyway, the pattern seems to be that the OBDI system only detects the missing EGR when something else comes to its attention. Has anyone else seem similar behavior? I'm not quite sure how to go about diagnosing (and more importantly, overriding) that, being such a sporadic incident.
Unfortunately, Code 71 won't clear on its own after a few minutes like Code 55, so it requires pulling the EFI fuse when it happens. At least it doesn't affect driveability like the knock sensor and its retarded timing, but I hate not checking right away to make sure there's not another code lurking.
#11
Lead Lap
iTrader: (8)
I've gotten the Code 71 three or four times now and did some more research. Apparently, it gets tripped through a variety of conditions that are related to what the temperature sensor detects, but I'm not clear on why that only happens with the EGR system deleted unless doing so changes temperatures at the probe (by eliminating exhaust gases)?
https://www.clublexus.com/forums/per...f-off-diy.html
http://www.3si.org/forum/f1/resistor...h-pics-382054/
So, I went ahead and unplugged my temperature probe and added a 10 ohm 1/2 watt resistor to the harness side of the plug, pushing one leg into each pin housing. We'll see if that permanently disables the Code 71 CEL...
https://www.clublexus.com/forums/per...f-off-diy.html
I had 71 code error . It is set when ECU do not see that EGR is working at some conditions (engine hot light throttle operations)
Mitsubishi thread: the ECUs in these cars look for a single variable: the right temp. sensor voltage at the right time. Here are the conditions:
Coolant temperature above 180 degrees
RPM between 1800-2200
Constant load for 30 seconds.
The ONLY way to get code XX once you've deleted your EGR is to drive like this. If you never drive this low in the revs, or if you don't drive on the highway much, the ECU will never check the temp sensor voltage and you'll NEVER get the check engine light for EGR. This is why people argue about it and insist that their cars are quirky exceptions.
Coolant temperature above 180 degrees
RPM between 1800-2200
Constant load for 30 seconds.
The ONLY way to get code XX once you've deleted your EGR is to drive like this. If you never drive this low in the revs, or if you don't drive on the highway much, the ECU will never check the temp sensor voltage and you'll NEVER get the check engine light for EGR. This is why people argue about it and insist that their cars are quirky exceptions.
#12
Driver School Candidate
Join Date: Sep 2014
Location: Massachusetts
Posts: 3
Likes: 0
Received 0 Likes
on
0 Posts
I've gotten the Code 71 three or four times now and did some more research. Apparently, it gets tripped through a variety of conditions that are related to what the temperature sensor detects, but I'm not clear on why that only happens with the EGR system deleted unless doing so changes temperatures at the probe (by eliminating exhaust gases)?
https://www.clublexus.com/forums/per...f-off-diy.html
http://www.3si.org/forum/f1/resistor...h-pics-382054/
So, I went ahead and unplugged my temperature probe and added a 10 ohm 1/2 watt resistor to the harness side of the plug, pushing one leg into each pin housing. We'll see if that permanently disables the Code 71 CEL...
https://www.clublexus.com/forums/per...f-off-diy.html
http://www.3si.org/forum/f1/resistor...h-pics-382054/
So, I went ahead and unplugged my temperature probe and added a 10 ohm 1/2 watt resistor to the harness side of the plug, pushing one leg into each pin housing. We'll see if that permanently disables the Code 71 CEL...