Desmog 92 FJ80 HUGE MPG increase. (1 Viewer)

[JollyGreen]

I just put BB's into the vac lines on all the EGR stuff and put the air pump bypass belt on it to test an idle problem I was having and my 80 idles 10 times better now. I obviously have a vacuum leak somewhere. I will find it and plan on putting the smog stuff back.

The unexpected side effect was I went from 10.8 MPG on my first 2 tanks to 15.3 MPG verified on 2 tanks just from doing this alone!

I didn't notice much of a power change but there is a huge increase in torque.

All of the egr vacuum lines over on the drivers side of the motor, I put BB's in the line to block it off and put a shorter belt than normally goes to the smog pump so it bypassed the smog pump "by not having a belt on it. Gates TR22525 replacement belt.

 

[NKP Garage]

Are you sure your right foot is acting the same as it was before the change?

 

[JollyGreen]

Sort of, the truck is accelerating at the same rate, the extra torque is probably making a difference.

 

[NKP Garage]

If your truck was running rich before due to vacuum leak issues, that may explain the added power and gain in fuel economy.

 

[Bisonthecruiser]

Can you elaborate? I'm confused on what steps you actually did.

I just put BB's into the vac lines on all the EGR stuff and put the air pump bypass belt on it to test an idle problem I was having and my 80 idles 10 times better now. I obviously have a vacuum leak somewhere. I will find it and plan on putting the smog stuff back.

The unexpected side effect was I went from 10.8 MPG on my first 2 tanks to 15.3 MPG verified on 2 tanks just from doing this alone!

I didn't notice much of a power change but there is a huge increase in torque.

 

[ThePookieBear]

X2!! I am interested. I'm sure my vacuum stuff is messed up too. I want in on this action.

 

[JollyGreen]

look up....

 

[onewhippedpuppy]

The desomg on my '91 currently consists of the EGR disconnected from vacuum and exhaust, the air pump removed, and all of the vacuum stuff on the fender removed. The difference is night and day, it's like a different engine. I have no illusion of more power (it is a 3FE after all) but it is dramatically smoother and much more willing to rev. I hope in the next few weeks to have an EGR block plate fabbed and gut the cats. For anyone in a non-smog state this is a no-brainer, and is 100% reversible.

 

[N20ntegra24]

DO you have a Part number for the belt you used. I have been wanting to bypass my air pump since I got my 80.

 

[JollyGreen]

Gates TR22525 belt

 

[ThePookieBear]

Nice. Subscribed. Thanks guys.

 

[spdwaver]

I have some work to do! Thanks for the info., looks like I may attempt to duplicate this, then post up the MPG results and see if it matches yours.

 

[ThePookieBear]

OneWhippedPuppy- Do you have a thread detailing all this, maybe also with pics by chance?

 

[onewhippedpuppy]

OneWhippedPuppy- Do you have a thread detailing all this, maybe also with pics by chance?

This is the guide I followed:

http://www.ih8mud.com/tech/pdf/3FE-Desmog_Guide.pdf

Seriously, once I started it was incredibly straightforward. You can effectively disable the EGR by unhooking the vacuum and exhaust pipe. I also left the air injection manifold in place and simply capped the input pipe. Note that you want to make sure the vacuum line is still connected to your fuel pressure regulator, see here:

http://www.ih8mud.com/tech/pdf/3FE-Desmog_Guide.pdf

 

[slow91fj90]

Hello my question is, I recently got the code 71 EGR check engine light. When disabling the EGR using any of the methods above, will it clear that code? Or you guys that have done this mod, is your truck throwing a code now?

Thanks

 

[Slowleak]

Is there something similar to this for FZJ80s also?.....cause my MPG along with probably 99% of all the other owners gas mileage SUCKS!

 

[MoJ]

A 50% increase in MPG from block vac lines and bypassing the smog pump? As much as I hope you're right, I think you're confusing causation and correlation.

 

[retrofive]

Is there something similar to this for FZJ80s also?.....cause my MPG along with probably 99% of all the other owners gas mileage SUCKS!

There is. Ebag333 has his thread on how to disable the system.

 

[caldentey]

Anybody else get some MPG increase from doing this?

 

[onewhippedpuppy]

Checking my MPG is depressing. I just know that the truck runs much smoother. Though double the MPG seems excessive. Maybe the EGR was totally shot?

There's no code from disabling the EGR on an FJ80. On the FZJ80 there's some form of temperature sensor that has to be disabled, I believe by adding a resistor to the connector. Search, there's many threads on the topic.