I have a 1999 Chev Surburban, 5.7 liter Vortec. I eliminated the EGR valve and put in the grooved throttle body on November 15th, 2018, along with a complete tune up. We have put a little over 4000 miles and have seen only about a 10% increase in fuel mileage. i was hoping and expecting a 25% or so improvement, so i am looking for some ideas from anyone out there having any experience with this engine.
Hi Clark -
please describe what was done during the tune up.
how many miles are on this 'burb?
You don't mention anything about modifying the PCV system when you installed your TB; EGR and PCV systems are 2 different things.
One thing I'm certain of on these trucks is that the power system/grounding need some attention - if your sensors are getting funky readings, the computer won't adjust correctly to their inputs. this also has implications for ignition, by extension: if the power doesn't flow easily, you won't get proper spark/fuel burn in the cylinders, right?
You are absolutely right, I eliminated the PCV not the EGR.
The Burb has a little less than 120,000 miles on it. the tune up consisted of plugs, gapped at 60/1000,s, cap, rotor, wires, timing sensor, and of course the grooved throttle body.
This is a mexican built vehicle, so it has no catalytic converters,
We are seeing better performance and seems to burn the fuel more efficiently, but since we live in Mexico, where the fuel is still over $4 per gallon we were really looking for some better fuel economy, at least more than 10%.
First off - you will want to reverse your PCV removal; the engine needs the water and unburned fuel vapour recycled into the intake. Our version of modifying the PCV system (that Ron seems lately to be-evaluating to an extent on a similar vehicle in another post) moves them from an active vacuum line to a passive/variable system as described in the manual supplied with your throttle body. believe me, you'll see some results from that in itself, but be prepared to do some fabrication to increase the size of the tunnel those vapours travel through to ease their passage, if possible. (I roughly doubled mine from 5/16" to 3/4" and it made a bigger difference than I thought)
Next, please consider that we've changed the dynamics of how air moves through your engine by implementing the groove; this may necessitate changing some other things (like when the spark fires) to obtain optimum efficiency and the biggest gains in mileage. This is especially true when you've opened up the gap in your spark plugs (it takes longer for the spark to jump the bigger gap, right? Nanoseconds longer perhaps, but if they're not firing at the right time, you're going to get an incomplete burn and not as much power).
Now, I didn't believe it until I tried it, but TracyG made an argument here that good ignition is a fundamental aspect to tuning a vehicle, and since I've gotten positive results using it, I've become a preacher in that church as well. Not all spark plug wires are created equally: most wires have a resistance to them that increases the longer those wires are, and even wires of the same length can have different resistance between them due to materials and manufacturing. That resistance slows the ignition energy from getting to your spark gap, and reduces the potential size/strength of the spark itself, regardless of the gap. Go shopping at a parts store with a multimeter capable of measuring Ohms of resistance if you don't believe me, and pick 3 different brands of cables for the same vehicle, then measure the longest cable of each. I'll bet you that there is at LEAST s 3kohm differnce between/range across them, if not more, and You'll obviously want to pick the set with the lowest resistance to be on your vehicle. If you want to take that to the extreme, order a set of wires from Granitelli in Caifornia - their Zero ohm MPGPlus wires truly ARE zero ohm, or close enough to it that they are still miles ahead of the rest. If you try this and it brings you mileage results as it did me, AND you get bitten by the ignition bug, you could also look for aftermarket ignition coils with lower primary resistance - that charges a coil faster, and can also make for a more consistent spark across a range of operational variables.
Final thought for now- the tune up, did it include an air filter replacement? A clean filter flows more air to make bigger groove waveforms...just sayin...
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IMHO, since Ron CREATED the website- and since he was the vehicle the Creator chose to use to bring this all to life...
I move that Ron's Karma count/symbol be the Infinity symbol, ya know that thing that looks like two raindrops meeting at their tips. Without Ron, there would be no Karma here, no Gadgetman Groove. And this discussion would not be.
Thanks for the reference re: Ignition, Greg. Ignition is integral to the trinity of engine operation. fuel, spark, compression. Based upon what is commercially available for us mere mortals to buy--your Ignition CAN'T be too good! Going the extra mile w/ Ignition really does pay dividends. It was gratifying to read your words here, Greg.
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