'94 Code 71, EGR Bypass and redneck technique.. (1 Viewer)

[Ebag333]

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

It doesn't dump it directly into the cylinder, but where it dumps it is closest to the #6 cylinder which means most of the recirculated exhaust goes there.

How does the EGR really function?

The EGR system is designed to reduce fuel usage and reduce emissions.

It reduces fuel usage by essentially replacing some of the fuel/air mix with exhaust. It is only supposed to operate at cruising speeds, not idle or WOT, so you should never notice it.

It reduces emissions by adding exhaust gases which have very little material to burn, so the temperatures drop. Lower temperatures mean less NOX. Also by recycling the exhaust, it will help burn anything that didn't get burnt the first time around.

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

It's pretty obvious that it's an afterthought. The positioning of the main engine harness to the EGR tube shows that!

The engine was designed and built to be run without the EGR. Plenty of people have had their vehicles pass emissions without functioning EGR's (it wouldn't even be active unless you were on a 4 wheel drive dyno). The CEL rarely pops up even when it's completely disabled.

Disabling it really doesn't have much (if any) effect, and IMHO the bonuses to disabling it are worth it.

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

So get rid of it.

 

[kidglove13]

Thanks!

I know there is know solid evidence that the EGR is behind HG failure at #6 but one would think that the exhaust gases being dumped there would increase temps at #6 and therefor cause adverse effects somewhere down the line.

I know that there has been heated discussion about this but it just seems to coincidental.

Will it effect the fuel curve when removed

 

[Ebag333]

I know there is know solid evidence that the EGR is behind HG failure at #6 but one would think that the exhaust gases being dumped there would increase temps at #6 and therefor cause adverse effects somewhere down the line.

There's a lot of debate whether pre-heated exhaust would increase or decrease the temps in the cylinder. On one hand, it's already hot. Obviously increasing intake temps means your engine runs warmer (you run warmer in Arizona in the summer than Alaska in winter). On the other hand, there's less burnable material in there, so less heat will be generated.

One person (can't remember who offhand, Bear80 maybe?) suggested that due to the cylinder running cooler it can cause something called "head gasket creep". I haven't researched that, so can't attest to it.

I know that there has been heated discussion about this but it just seems to coincidental.

Too many coincidences for me.

• Non-EGR spec trucks (seem to) have fewer HG issues than EGR spec trucks.
• Cylinder 6 is the cylinder that gets most of the EGR.
• Cylinder 6 is the cylinder that the EGR fails on.

Will it effect the fuel curve when removed

In theory your fuel milage will drop, especially for the highway miles. In reality, I haven't seen any difference and many people have reported no difference. For as many people who have reported an increase (usually only 1 or 2 MPG) there have been a equal(ish) number reporting an equal(ish) change in the opposite direction.

Personally, I don't think it makes enough difference to really be noticable one way or the other, and even in my daily commute about 90% of my commute is on the freeway, where I should be heavily effected by the EGR system.

 

[kidglove13]

Thanks

 

[Land Speeder]

I've done this setup to my '94 after the headgasket blew a few months ago and fixed that... i had a CEL as well, but have not since I bypassed the EGR by looping back the tubes and adding a 1K ohm resister to the clip that clips into the wiring harness...

 

[kidglove13]

Is the resistor really needed?

 

[Land Speeder]

Is the resistor really needed?

In my case.. yes, and the resistor is what tells the ECU that the EGR system that's it's clear and functioning... at least that's how I understand it... re-routing the hoses was done after i did the resistor and my light went off...

 

[Railroader]

Is the resistor really needed?

About 500 miles in, with just the wire jumper, I'm saying no resistor necessary....

 

[Land Speeder]

About 500 miles in, with just the wire jumper, I'm saying no resistor necessary....

ahh, i see what your saying now... as long as it's jumped...

 

[Rickus]

It seems like I do not have the temp switch on my Cruiser is this possible???? I've got a '93 1FZFE VX LTD and the intake manifold does look different than the one in the picture........The Cruiser does have exhaust gas temp sensors on the exhaust though.

 

[Ebag333]

It seems like I do not have the temp switch on my Cruiser is this possible???? I've got a '93 1FZFE VX LTD and the intake manifold does look different than the one in the picture........The Cruiser does have exhaust gas temp sensors on the exhaust though.

Your '93 should look the same as Railroader's.

You are probably thinking of the PAIR system when you are talking about the exhaust gas temp sensors on the exhaust. That's an entirely different emissions system, and one that I would personally eliminate if I owned a truck with it. The EGR system does not have an exhaust gas temp sensor on the exhaust.

Pictures of what you are talking about would help immensely.

 

[Land Speeder]

I would have to assume you do not have the EGR system that the US cruisers have...

 

[tblume]

It seems like I do not have the temp switch on my Cruiser is this possible???? I've got a '93 1FZFE VX LTD and the intake manifold does look different than the one in the picture........The Cruiser does have exhaust gas temp sensors on the exhaust though.

definitely possible; my '93 has a production month of feb, and sparked this thread by Ebag: https://forum.ih8mud.com/80-series-tech/308200-disable-egr-system-mostly-toyota-way.html

first post there has a link to my post as well, has pictures to do the "stare and compare" with your intake, my temp probe end of the harness has a factory jumper- no resistor or sensor at all.

HTH

oh yeah, official welcome to newb's >

 

[tucker74]

Excellent thread ... I've had my CEL go on and off for a couple of years due to code 71. Every time I'm about to break down and buy a new EGR/VSV it seems to go out. This last time it has stayed on for a couple of weeks, found this thread and spent 3 minutes looping my vacuum hoses and jumping the plug. If the CEL stays off I'll go ahead and order the OEM jumper -



Tucker

 

[Ebag333]

If the CEL stays off I'll go ahead and order the OEM jumper -

If you can find it.

If you can't, I have one that I got for the rig. Since the jumper method does not work for OBD-II trucks, I have no need of it now.

 

[stlcruiser]

Greetings:

12/94 Build date with OBD 1. Tried jumping with no resistor and CEL came back on at second highway trip. Added resister and CEL has been off for multiple trips and 700 miles thus far.



Steve
94' 215,000

 

[hawaiicruz]

Greetings:

12/94 Build date with OBD 1. Tried jumping with no resistor and CEL came back on at second highway trip. Added resister and CEL has been off for multiple trips and 700 miles thus far.

Thanks for the heads up. I jumped mine without the resistor, and still have the CEL, even though the EGR is disabled. I'll have to try the resistor

 

[chansdaman]

Let me get this straight

What if I re-route the vacuum, hook the resister to the connector (head side, not the harness, thanks AGAIN Eric), and reset the ECU when EGR pipe is hot. Does that mean I will also have hot gas going into the plenum ALL THE TIME? In other words, do I have to ensure that the EGR is disabled before initializing the entire procedure?

 

[Land Speeder]

What if I re-route the vacuum, hook the resister to the connector going to the head (thanks Land Speeder), and reset the ECU when EGR pipe is hot. Does that mean I will also have hot gas going into the plenum ALL THE TIME? In other words, do I have to ensure that the EGR is disabled before initializing the entire procedure?

whoa! Cut the clip side that is on the head side, and solder the resistor on it and reclip it back into the wiring harness side... It doesn't get "jumpered" on the head side, but on the harness side.

OK I know what I mean, but even when I read it it can get confusing... can someone else rephrase it for me? It needs to be looped back into the harness, not the head.

 

[dudedude]

got toyota part 82824-35020 to complete my egr bypass on my 1994 FZJ80.
it is as easy as looping the vacuum hose and installing the correct toyota plug, reseting the ecu and no more CEL for over 50 miles and going strong!!!


the toyota part is available at toyotapartzone.com
and is described as CONNECTOR, WIRING HA
[T100 | 1994 | VCK20L-TRMREK | 199208-199408 | 3VZE | STD | MTM | RCB | HLF | CND | VCK20]

It doesn't sound like the right part but it is. 15.56 plus 9.00 shipping is a little pricy for a piece of plastic
but it clips right in and there is no need to worry about duct tape or any other "redneck" fix.

next up is to find a really well engineered (read "not JBweld") solution to blocking off the EGR assembly and removing it all together.