TOPIC: 1997 Toyota 4Runner, 3.4L,, US

I did this one a while back and am just now getting it posted on the Forum. I got lucky and didn't have to do any vacuum leak hunting. Actually, I didn't even cap the PCV hose. Before the mod he was getting about 12 mpg city, 14 hwy. Now he's getting 5-6 mpg more in the city, 6-7 on the hwy. That's 40-50% better mileage. It was the first time I got that whistle effect. It only seemed to whistle at low speed though and it wasn't too bad. It's an automatic, and he says it also seems to run smoother now.

I used a medium bit and did cut through one area that I couldn't patch from outside. I had to do it from inside, but it seems to have held up so far. It was a sort of sleeve thing that surrounded the axle and extended out almost to the throttle position sensor.

Hi Jonathan,

Nice job, also good to see the ecu being cooperative.

The whistle effect is a combination result of the throttle plate position and the groove angle. One would not expect to hear it at higher speeds.

I would tend to think that considering the results without the PCV mod that one of two things are going on...

1 - the engine is tight enough that the manifold vacuum is fairly high allowing the groove to do it's job.

2 - It may be possible that the PCV valve is clogged, creating the increased manifold vacuum with the same results.

One other thing you can do is to increase the spark plug gaps by 20%.

Should one want to tamper with success, that is...

Another groove to the better

Karl Fortner
Tacoma, Washington

Hi Karl,

Thanks for the reply. I didn´t know that about the whistle. I definitely need to be on here more often, I learn so much from guys like you.

Good feedback about why it worked without the PCV mod too. I didn´t cap that port because I was only in the states a short while and I did the mod the day I left. I started in the morning, but didn´t finish until dark and then I couldn´t figure out where the PCV line was connecting. Given that timing, I didn´t do anything with the spark plugs either. Again, I got lucky on this one. It´s so nice when that happens. If I call the mileage gain 50% it´s actually the best gain I´ve been able to deliver so far.

Cheers,
Jonathan

Yeah it's really a nice job keep it up.

Thanks Aaron.

Your signature line says "salvage snowmobiles", does that mean you have access to some ungrooved snowmobile engines?