TOPIC: 1999 chev 4.3 L vortec

Hi Tracy G
I did the mod in 3 shots. first was the main groove, idle air, pcv, .second was the filter side groove cut with flat side toward the plate, third was the filter side groove cut with round side toward the plate, and the smoothing of the t.b. wall.

Test driving after the third mod ,seems to have quicker response to accelerator, faster speed on the road and more torque on blactop driving in high gear. Also hear more swishing sound when underhood accelerating by hand. I just did this one , so don,t know about mileage but i feel like it will be better.
If you look into the archives you will see some info about the double groove from Serge, the Russian guy, hope i spelled the name right. He got best results with double groove with the round part toward the engine. Sorry I don,t remember where i saw it now , i will look and see if i can find it. It is part of a letter that Ron received from Serge , Ron published it in the forum . I think it is under personal license . (look under personal license program, scroll down it is on first page IMPROVE YOUR GROOVE posted by Ron.) Notice in Sergey photos the turbulance without the smooth wall.

The truck is 4.3L 6cyl. 1999 Chevy S10 4wheel drive

I noticed the best low end grunt with cranckcase vent to atmosphere, like farm tractor

Maybe I leave it alone for now and see if the stubborn little winch will give me some more MPG

Greg P

Yeah Greg I thought about Sergey's double groove soon as I read yours.

That last part was cryptic...IF you feel so inclined might give better description of that "special" mod, and a pic or 2 (remember my Addiction) working w/ Metal...Well Im a Groovin' type O' guy, I don't weld, but I can build Rocket Stoves and Ovens from surplus/scrap metal/cans...think I could qualify...? up to you of course (panting like a puppy...)

Doin' great Greg!

Tracy G

Hi Tracy G...........Maybe i best leave it alone.. ....Greg P

Did another milage check, only about 6.5 gal of gas but just had to see, it is now 20.23 miles per gallon. low grade fuel 87

Hello all, i am here to ask for advice, I have done two of the 4.3L vortec chev enginges, both engines will throw codes P1509 High idle rpm. and P0507 High idle rpm , the service engine lights for both engines come on as you are on the highway and accelerating, getting on it. Such as passing a car or coming down entrance ramp to enter interstate highway.
When the engine is at idle it idles at between 650-750 rpm I never notice any high idle rpms , there must be a sensor some where that does not see what it wants to see. Any suggestions to remedy the problem or should it be ignored and let the service engine light stay on.????......Greg P

put pcv valve back to normal try that first

Dan thanks for the advice, i put pcv back to normal, engine idles about 200 rpm higher , seems to have a little slower response to pedal. Took it for a short drive , got down on it a few times and no codes yet, sometimes it would take a week or two ,for it to throw a code, i will try it like this for a while , hope it don,t effect the mileage. Thanks....................Greg P

Greg you might "adjust" the PCV by partially restricting the man. vacuum source, to find a "setting" such that codes aren't set, but you get some of benefit of the full re-route.

I just did a PCV re-route on a '03 Ford f-150, and took it for a short drive. It does feel like more power w/ re-route and the (multiple) man. sources capped.

I wonder if you drilled the IAC restrict. hole a bit larger, if that could help?

Tracy G

Thanks Tracy G , the weather here is crap, I will try it when weather is fit to be outside.
thanks.............Greg P

Hello TracyG , Weather got fit enough to be outside for short while. I went out to the parts store and got a couple of the 1/8 to 3/8 hose splice and used the smallest hole and spliced my pcv hoses between the manifold and pcv valve, so now it is sucking thru the 1/8 inch hole . That brought my rpm back down and the truck seems to love it. My power is back and pedal reaction time i think is even better than before ( when pcv was pluged.) It feels like motor is super charged , the engine has always had crankcase vent , but i had pluged the pcv and pcv vacume line. I don,t realy understand what has happened with the motor, but it feels like a good thing. Didn,t throw any codes and i drove it hard, but it may take a while , hope it is all fixed now.

And yea, about that double groove, that hound will hunt. I bet your customer will be happy even if he don,t get better milage, and yea keep letting off the pedal before it stops accelerating. its like pulling back on the reins of a horse that just wants to go. Sure wish i had some of those back bits.
....thanks........Greg P

Thank you again Greg! So now that you followed my suggestion, there are 4 basic ways to deal w/ the PCV.

1. Cap it off on both ends (I dont recommend or do this)

2. Do a re-route to the "passive" side to the main air induction duct, often by tee-ing to Breather hose. Cap the manifold vacuum source.

3 Leave the PCV connected to manifold vacuum, but add a restriction to the vac. hose, as you just did.

4. Leave it alone, stock.

I'm glad ya tried #3, it's interesting that it seems to like that better than w/ #1 or #4.

Only nagging concern I have about altering PCV, is this: Stock PCV system pulls lots of oil vapor, combustion byproducts and water vapor OUT of the crankcase sending it back thru the intake. So, though that ultimately cruds-up intake man., valves and combustion chambers,it does get lots of this crap out of the crankcase. Eliminating/reducing manifold vac. this crap can show up in the hoses/lines, which is why I embarked on the air-oil separator stuff to catch/control the crud.
We enhance manifold vac. by altering the PCV system--but we need to be on lookout for the crud showing up! IT has always been in there, just going "down the gullet" into the engine, forcing the engine to be an Incinerator. Some engines will produce more crud than others. My Subaru, being all-aluminum, REALLY produces water condensation in winter.
A thoughtful Gadgetman, looking out for his own or another person's engine's welfare, will remember this. Some have or might be tempted to just let PCV vent in the open, but that's not very good for Environment...PCV was the very first mass-adopted pollution control system, over 50 yrs ago, replacing road draft tubes.

So Greg- well just watch how your Chevy does. Sounds like you have found a real Formula for the 4.3 Vortec. I thought of how you cut the second upstream Groove, I could only imagine a chancy technique w/ regular bit, w/ no backstop. I did step to the plate and get my Certified Level in 2012, so I had the longer shaft back-cut style bit, I'd never used it. Man that thing is Impressive, it cut a very smooth Groove, going in from upstream, holding about 20 deg. up from parallell of throttle bore, using throttle butterfly plate as backstop. It gives a different Groove, does not produce such a pronounced flat wall. Slow going requires patience, but awesome results! And-Ive gone back to using my Panavice to hold the TB in place freeing up both hands. Perhaps you might again explain the technique you used w/ bits you have to get the second Groove...if ya could, you would be a Hero of GadgetmanLand for sure! I'm not sure, but it may be that however you did yours, a second Groove done w/ regular bit may give better results...?? more to think about...

Good on You, Greg!

Tracy G

Tracy G ,, here is method i used to cut the second groove on filter side of plate. I first cut the groove on filter side of plate in usual way, placing flat side of bit against plate and useing the plate as a backstop. The groove is cut , then i take a black marker and make a very fine black line at the edge of the groove that is away from the plate , closest to incoming air. I put this line there as as a guide so as not to cut too far up stream when i recut the groove with flat side of bit facing outward toward filter, you will have to comeinto t.b. from engine side,i tried to recut the groove leaving the black mark in place or maybe taking just a bit of the black mark as you are cutting. i used the choping cuts taking about 1/2 a bit width per chop and sinking the bit down to the shaft, i only used med. speed on the bit very slow and careful and in about 60 min. the groove is finished with flat side faceing outward. When doing the second cut i removed the plate. if you look back at pic filter side groove you can see some of the black mark still in place , could see it better if the photo was enlarged. That is the way i cut the filter side groove with Personal Lisense bits...................Greg P