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I had seen in many places about the possible power gain by adjusting the spring tension to richen or lean out the mixture. Mine an 1986 Runner 22 re 5spd with 269,000+ miles. Depends on where you look there are different oppinions on wheather to do or not and also on which direction to go with it. Hell i flipped a coin and went with counter clockwise ( to loosen the tension) . Most seem to at least agree on one thing and that is the number of teeth to go and that is 6. Some said had to adjust again. I in great thought and with the way my luck goes i went with 4 . Just to be on the safe side. With the possibility of engine damage. Have to say it made an all around improvement. The quickness of response when pushing the pedal. Has quite a bit more acceleration than before. Running 31-10.50-15s and have added several pounds with tube front bumper and winch, side rock guards, extra battery and so on. Would have to say it is like gained a gear as far as hill pulling. Im new to the Yota life and am learning from you good people. In my searches it is god to read and see what works and what dont so just wanted to put my two cents in and say that although may not work for all vehicles . For me at this time it is an improvement. Maybe could have gone further and gotten more improvement but why push my luck. Thanks. Evan.
Thanks for your post. I may try the same experiment. I have lots of experience with carbs and fuel enrichment so I’m not worried about making changes.
If you haven’t done so yet, disabling your egr valve will increase responsiveness also. You can plug one vac line between the two components with a BB. Easily reversible if you need to pass smog and costs nothing.
Both the AFM adjustment and EGR disable were printed in an old TRD white paper in the late ‘80s/early ‘90s…I paid about $20 for it at the time. Wish there were more tuning tips but i believe that was all you got for the money.
only that it improved responsiveness, iirc. But that’s about the same as any other engine. Egr is a big vac leak when operating.
Not the same as a vacuum leak by any means.
A vacuum leak introduces fully oxygenated air into the air/fuel mixture, leaning that mixture commensurate with the size of the leak.
Vacuum leaks often raise the peak combustion temperature in one, or all cylinders, depending where the leak is located.
An operating EGR merely dilutes the air/fuel mixture with mostly inert gases, effectively richening the mixture and Lowering peak combustion temps.
Both a vacuum leak and an EGR might affect performance and power, but if the EGR is working as designed, it should only supply recycled exhaust gases at fairly high vacuum/ moderate RPM cruising speed conditions, while a vacuum leak is constant.
A vacuum leak introduces fully oxygenated air into the air/fuel mixture, leaning that mixture commensurate with the size of the leak.
Vacuum leaks often raise the peak combustion temperature in one, or all cylinders, depending where the leak is located.
An operating EGR merely dilutes the air/fuel mixture with mostly inert gases, effectively richening the mixture and Lowering peak combustion temps.
Both a vacuum leak and an EGR might affect performance and power, but if the EGR is working as designed, it should only supply recycled exhaust gases at fairly high vacuum/ moderate RPM cruising speed conditions, while a vacuum leak is constant.
so your argument is that it’s not fully oxygenated air or constant.
That’s all well and good. Do you think the performance of the engine with correctly operating EGR would feel any different if it was drawing from “fully oxygenated air” instead of exhaust gas? I don’t. The point is increased responsiveness under certain conditions. For all intents and purposes, it’s a timed internal vac leak. Jam it open and tell me what happens to the way the engine runs.
Have you tried tuning the AFM based on the O2 sensor voltage with the truck in open loop? What did the "TRD White Paper" say was the criteria for a correct adjustment?
Jul 20, 2021 | 07:32 PM
