'94 Code 71, EGR Bypass and redneck technique.. (2 Viewers)

[Railroader]

So, after nearly going blind reading EGR posts, and the fact that my truck runs SO GOOD, I've got no interest in going any further than I have to to try and get rid of the CEL...

From what I can gather, I can render the EGR inoperative by doing this...

This seems to have worked, since after a trip to town, with a little 10 mile highway jaunt, the EGR pipe is cool. Truck runs perfectly, no noticeable change. I like the idea of no hot exhaust gas running back thru my motor, and maybe saving the HG by #6 would be a big bonus...

The light came back on, and I remembered someone's "Redneck Fix" that involved jumping the temp sensor plug, so I've done this...

Next step is Radio Shack for the resistor, I guess, if that trick works on the '94. But I've read so much of this stuff, on so many trucks, that I'm looking for some feedback telling me that I'm on the right track here...

Thanks again guys, I'm off to try it out...

 

[BP22]

My 91 was throwing the Code 71 after I "de-smogged" it.
https://forum.ih8mud.com/80-series-tech/315482-1991-3f-e-de-smog-performed-2.html#post4852874

I did the Redneck fix 3 1/2 weeks and about 600 miles ago and no more CEL.
https://forum.ih8mud.com/80-series-tech/308200-disable-egr-system-mostly-toyota-way.html

I'm still a noob but this "fix" has seemed to work for me.

 

[Ebag333]

That's how a local 'MUD member is setup, except he has the actual OEM toyota part that does the same thing.

He's been running that way for years, no CEL.

 

[Railroader]

Well, so far, so good. After about 50 miles, on the road, and in town, no more CEL...It was popping about every ten miles, so I've done SOMETHING....

Thanks, EBag, I was hoping you'd chime in.

Guess I'll go tape it up...

 

[alaskacruiser]

That should work, but there is no point in shorting the temp sensor side of the plug- only the ECU side needs to be shorted.

 

[Railroader]

That should work, but there is no point in shorting the temp sensor side of the plug- only the ECU side needs to be shorted.

I don't understand what you mean, A-Cruiser...

The plug that's got the jumper IS the ECU side...The non-jumped one is hanging outta the temp sensor.

If I'm missing something, pray do elaborate!

 

[CaptainKirk]

Railroader - can you save me the same thing you have already been through reading posts so I don't go blind too? Can you tell me the resister part number from the Shack so I can buy it too once you have identified it and installed it? I am weak at best with electronics and electrical work and could use the direction. Regards, Kirk

 

[Railroader]

Railroader - can you save me the same thing you have already been through reading posts so I don't go blind too? Can you tell me the resister part number from the Shack so I can buy it too once you have identified it and installed it? I am weak at best with electronics and electrical work and could use the direction. Regards, Kirk

I ain't messin' with no resistor unless the light comes back on...And so far it has not. Maybe I'm done with it.

The resistor is pictured in a recent post, but whose post it was escapes me......

 

[tblume]

That's how a local 'MUD member is setup, except he has the actual OEM toyota part that does the same thing.

He's been running that way for years, no CEL.

that's me, and the truck has been running that way since birth...

 

[kup99]

I did the redneck fix, and have had 2 P0402 come back to bite me... one after about 220 miles, and the next one after about 110 miles.. ... I hve not blocked anything off to the egr yet.. that's tomorrows task... I'll keep you posted!!

 

[kup99]

I keep getting the 402 code. seems to stay off for about 100 miles or so, but then it keeps coming back on me!! I haven't stopped the flow with the BB's yet, but would that really matter since the sensor is not connected? I'll also double check my wire/clip piece!

 

[alaskacruiser]

I don't understand what you mean, A-Cruiser...

The plug that's got the jumper IS the ECU side...The non-jumped one is hanging outta the temp sensor.

If I'm missing something, pray do elaborate!

Railroader- sorry I missed this post. In your pic, I see 2 connectors. One has a wire jumper in it. The other has what looks like a black hairpin in it. Can you explain what is going on here? I figured one connector was the temp sensor and the other was the ECU connector?

 

[Railroader]

Railroader- sorry I missed this post. In your pic, I see 2 connectors. One has a wire jumper in it. The other has what looks like a black hairpin in it. Can you explain what is going on here? I figured one connector was the temp sensor and the other was the ECU connector?

Allright, let's see if we can get this right, so a not to confuse anyone...

Just to clarify everything, my LC is a '94, and an OBD1...

In the "jumper photo", what looks like the hairpin in the top half of the connector is actually the stock Toyota wiring harness that goes up into the temp sensor. It's just disconnected and hanging...

The bottom half of the plug, with the jumper, goes to the ECU wiring harness, toward the firewall.

I think I've read somewhere here that on later trucks, the connector was the same, but was reversed for some reason...

Now, on to the results...

In a week of driving daily, and a 200 mile fishing road trip, I'm not getting a CEL anymore. The engine bay is running a good bit cooler, and it may be just me, but my LC seems to be a little more "happy" with the EGR gone. I believe it has a little more "oomph" when you step on the gas at highway speed.

My mileage didn't change, I'm still at about 14.5 on the road, and 11.5 in town.

Overall I'm happy with this modification, so far...

 

[Ebag333]

Now, on to the results...

In a week of driving daily, and a 200 mile fishing road trip, I'm not getting a CEL anymore. The engine bay is running a good bit cooler, and it may be just me, but my LC seems to be a little more "happy" with the EGR gone. I believe it has a little more "oomph" when you step on the gas at highway speed.

My mileage didn't change, I'm still at about 14.5 on the road, and 11.5 in town.

Overall I'm happy with this modification, so far...

Engine bay temps and "oomph" shouldn't have been affected. The EGR is only supposed to operate at cruising speed, where you would feel no difference in oomph and engine bay temps wouldn't really be affected.

If you've noticed an actual differerence (as opposed to a I-want-to-see-a-difference difference ) in temps and the butt dyno, then that would suggest that your EGR was failed open, meaning that you were always getting exhaust gas into the engine. That would reduce power and increase temps. It'd also be a quick way to toast your engine wiring harness (which you should check, by the way).

 

[Railroader]

...that would suggest that your EGR was failed open, meaning that you were always getting exhaust gas into the engine...

I probably have an Overactive Butt Dyno...

But if the EGR was failed open, then wouldn't I STILL be getting exhaust back thru the engine, even with the vac now cut off???

Still learning, here...

 

[Ebag333]

You may, but removing the vacuum lines to the throttle body may help keep it from opening as much.

Drive it around for a bit (on the freeway would be ideal) and then check to see if the EGR pipe is hot. If the EGR is staying closed, the pipe should be warm to the touch. If you leave skin, then it's open.

(And no joke about the leaving skin part, it gets extremely hot if it's open so be careful.)

 

[Railroader]

...Drive it around for a bit (on the freeway would be ideal) and then check to see if the EGR pipe is hot. If the EGR is staying closed, the pipe should be warm to the touch. If you leave skin, then it's open....)

I performed this test back when I was "going blind reading EGR posts". It WAS getting hot, leading me to think it was still working, but out of whack enough to pop a 71 code. Since I've bypassed the vac lines, I KNOW that it's no longer working. The pipe now stays cool enough to touch, even on a 200 mile trip...

Since I read that this engine doesn't "need" the EGR, I decided to leave it bypassed. This can only be a GOOD thing both for the wiring harness, and for the good ol' heater hose that I replaced the PHH and metal tube with...

Seeing as how I have no emissions inspection to deal with, I'm considering removing and plugging up the whole mess.

Sure as Hadeez ain't buying new EGR stuff...

 

[kidglove13]

Just to clarify and not seem dense.
I have 94 1fz as well.

Where is the EGR Pipe that gets hot?

Is this resally that easy?

Just loop out the 2 lines from the EGR and link the sensor connector with a wire link?
Do I need a resistor?

On the front left of the motor there is to be what looks like a pump of some kind that ties back into the air intake and has 2 hard pipes tied into the exhaust.

What is this?

 

[Ebag333]

Where is the EGR Pipe that gets hot?

Directly behind the motor. It comes from the lower drivers side up into the upper passengers side. If you look at the EGR modulator, you can find it.

Is this resally that easy?

For OBD-I, it seems to be.

Just loop out the 2 lines from the EGR and link the sensor connector with a wire link?

Yup.

Do I need a resistor?

Several OBD-I trucks are running without one and no issues.

On the front left of the motor there is to be what looks like a pump of some kind that ties back into the air intake and has 2 hard pipes tied into the exhaust.

What is this?

Would need a pic to be sure, but that sounds like you might be looking at the AC compressor and the PAIR lines. PAIR is completely seperate from the AC system, though the location makes them look like they might be connected.

Removing the PAIR system is another modification that can be done, there's several threads on it.

 

[kidglove13]

thanks ebag!

Yeah I did a search and found out about the pair system.

So the EGR is dumping hot exhaust back into #6 cylinder?

How does the EGR really function?

So the EGR's on the OBD I motors was really an after thought and are designed to run with out them?

Sorry for the questions, I am used to working old muscle cars that do not have all of this crap on them.