You are proposing dumping about 50% more fuel into the engine than stock configuration. What are you planning to do to manage this?

 

Truthfully i didn't know the gains would be that significant. Im just looking for a tad bit of power. Im running 35 at the moment and when i go up a hill on the highway i drop about 30 to 40 mph. I know these engines are ment for torque not hp.

 

What gains are you talking about? Adding more fuel won't gain you any power. In fact, you'll lose power by over-fueling by 50% without any way to manage it. Deleting EGR won't gain you any power either.

You may want to start a new thread after doing some reading.

 

Will deleting or blocking the egr, hurt anything? No, at least not in my experience.
It also won't do anything for power.
Look into a truck powermax cam and long tube headers, computer friendly, winning combo back in the day. Just don't expect a powerhouse.
What gear ratio is in your axle/axles? Changing that alone will make a huge difference in your trucks ability to pull a hill.
You also mentioned using a cold air intake, if you look under your air filter housing, you'll notice there's a duct drawing air in through the radiator support, that as cool as the air will ever get, a replacement air filter that has the ability to flow more air may be beneficial but dont expect much.


He mentioned the adjustable fuel pressure regulator, adjusted correctly will allow use of larger injectors, it's been done many times before on the 4.9. if a cam and headers were installed, this could be beneficial if the stock injectors were being pushed too hard but those modifications have been done before without larger injectors.
But your correct, optimal air/fuel is optimal air/fuel, regardless of how it's achieved.

 

Do a search for "silver streak" and gm map sensor. He proposed using a gm map sensor to provide the optimal signal to the computer. I never tried it but the dude knows his stuff so it might be worth exploring.

 

Deleting egr (or at least blocking exhaust gas introduction) provides the same power with a smaller throttle position.

Noticeable? Probably not all by itself on a stock application. It makes for a "crispier" throttle pedal.

The gm map sensor was a trick used by the speed density crowd back in the day (and a select few today) that allowed tuning for boost, as the gm map sensor reads positive pressure as well as vacuum, vs the ford map that reads vac only.

 

Thats under the notion that the conditions are linear, throw in load, say pulling a hill, then the ECM adapts accordingly. Plus egr is inactive under WOT so there's no benefit to egr removal.

Only real benefit I see to keeping the egr, besides emissions tests and legal issues, would be in hopes of squeezing out a little more fuel economy.

But, in the real world, my emissions delete trucks exceed factory economy ratings, so not sure I'm completely convinced.

Gm sensor is still being used in standalone computers, the key is matching what the computer expects to see from the evp, which I've yet to see verified but it's a good avenue to persue.

 

Egr helping mileage is a myth, generated by haywire computer management when egr components malfunction.

There is no benefit of injecting inert gas into the combustion chamber, unless reducing nox emissions is a perceived benefit. The computer will inject fuel according to what you ask of it, if exhaust is present with the air fuel mixture, you will will need a greater pedal position (or rpm in the event of a downshift need) to make the same power as you would if it were just air and fuel.

 

Im just amazed this thread is still going strong like 4 years later!

I do miss that truck, it had frame rot in a place where at the time i was afraid to repair it. I should have re-framed and kept on rocking out.

 

This.

after my 87 was gone, i picked up an 81 F150 with a carbed straight six, and i did my usual routine of tune up and delete out the emissions. the exhaust manifold was cracked, so i swapped to the split manifold setup off of my 87, with dual exhaust, and in doing so, i ended up ditching the EGR off of that truck as well. Maybe it was the freer flowing exhaust, maybe it was the tune up, maybe it was the lack of egr, but the truck picked up a whopping 5 mpg.

obviously, with an 81, there is no computer, its just a single 1 barrel carb. but as this fine gent has been saying, all an EGR does is push a little bit of your exhaust back into the cylinders to try and reburn a little more fuel. there is no power gain, there is no mileage gain, because the EGR air is just being recycled.

to make it a simple theory, what burns better, fresh, undiluted gasoline atomized with fresh air, or gasoline atomized with the exhaust gas from a tailpipe of a running car?

 

They burn exactly the same as long as you keep the oxygen/fuel ratio the same. Exhaust gas isn't some strange "dirty" thing. It's mostly nitrogen, CO2 and some water vapor. Those gasses are basically inert as far as the engine is concerned.

In theory, EGR can increase fuel efficiency. It basically introduces inert gas into the manifold, which effectively decreases the displacement of the engine. This requires a slightly larger throttle opening to maintain the same engine output, which decreases pumping losses and increases efficiency. However, any gains in from reduction in pumping losses are probably negated by the fact that the EGR gas is hot. Some modern engines have EGR coolers.

 

They do not burn the same, you can't maintain the same afr with exhaust going into the intake. If the exhaust is 15:1 going out, and 5-15% of the intake air is exhaust (which it is, depending on throttle and load) that is already a "rich" mixture going in. If 100% of the intake was 15:1 afr exhaust gasses, the AFR wouldn't be 15:1, but that's what it would read coming out if you cranked it. Of course, it wouldn't run.

If we measured air/fuel pre combustion, you could make the case that you could "keep oxygen/fuel ratio the same".

So, an afr with egr isn't really "afr", as it is read in the exhaust...it is (egr + air)/fuel ratio....
Egr was never designed to improve mileage or power.

 

You don't think the calibration engineers that spend thousands of man hours developing the software that runs the engine don't know that?

It's actually really pretty easy. The computer knows how much exhaust gas is flowing into the intake, the calibration engineers know the composition of the exhaust gasses (mostly inert). They can just compensate by reducing the amount of fuel injected by the calculated amount of "inert gas" in the manifold. It gets even easier when you have a mass-air sensor, since once the EGR opens, the mass-air flow rate in the intake will reduce by exactly how much EGR is being administered, and the computer will reduce fueling to match.

Any error in their calculations will be corrected by the oxygen sensor and closed-loop fueling. You can even verify this yourself with a wideband oxygen sensor. When the EGR opens, the overall A/F ratio does not change. The computer knows less "burnable" air is in the manifold and compensates accordingly. It's not rocket science.

EGR on the old carb'd engines is a completely different thing than EGR on modern EFI systems.

 

I'll let you read what you wrote as it implies less fuel would be injected at the injector, throw in low load aka cruise conditions, where a poorer combustion event could be tolerated, aka engine just isn't making much power, as lead head was getting at, could improved mpg in theory. Not implying your right or wrong, just theres another perspective in there.

With that I'll stop, these discussions are worse than talking religion or politics.

 

Yes, I do, to a the furthest extent of their abilities. Thank you for asking...it's part of the point I was making. They compensate for some of the power loss with advanced timing curve in direct relation to the egr opening, but the AFR as it relates to throttle position is effected by the egr cycle...which causes the power loss that they attempt to combat with more timing. Another way to do it is to further increase fuel, giving a lesser (richer) AFR, as read in the exhaust, for the same throttle position. Of course, as you can clearly see (because it is simple), the real AFR remains the same despite the "richer" reading in the exhaust.

Easy, yes. Correct you are? No. The computer doesn't "trim" fuel with egr duty cycle, that's silly.

The egr duty cycle is wildly variable, a duty cycle that is dependent on many different conditions. if it were constant....it'd be much easier to put into laymen terms.

Let's assume its constant for a moment and controllable by the driver with an on-off switch. If cruising down the road requires 50hp at 15% throttle position with AFR of 16:1 to maintain steady speed, then you turn the EGR on. You will experience a loss of power, no longer maintaining speed, if nothing else changes. Lucky for us! There's not only 85% throttle position left, the computer makes adjustments on the fly. You decide you don't want to slow down, and you don't want to turn off the EGR, so you increase throttle position 2-3% and AFR drops to 15:5:1....now you're making the same power and having your EGR too. Sure, the computer can and does make adjustments for these fueling changes automatically, but it results in either more throttle position/air/fuel, or same throttle position/less air/more fuel (or a greater AFR). You can increase fuel without increasing air (it is clear that some people don't recognize that), the computer does it all the time within it's range (~13:1 - 20+:1). You can also increase or maintain a particular AFR, as read in the exhaust, by introducing more exhaust into the intake. I will reiterate that the exhaust in the intake is not "air" or "fuel", but it can be read by the o2 sensor just the same as the exhaust that the mixture coming in is about to yield. it falsely "richens" AFR as read in the exhaust.

The oxygen sensor does very little, if anything, in regard to EAFR (exhaust air fuel ratio). The computer reads AFR in the exhaust going out of the exhaust system, the computer is not making the calculations for a wildly variable "AFR" of the exhaust going into the intake, and at what duty cycle, to make changes like that. It's variable almost on an infinite scale; percentage of duty cycle of exhaust going back in at a constantly varying AFR. Even if it could, it wouldn't be accurate...the introduction of EGR into the combustion chamber changes the "AFR" reading in the exhaust, it makes it less accurate. This is one of the reasons the factory engineers shut down the EGR at WOT, so the 13.5:1 AFR of WOT is actually an AFR 13.5:1, not EAFR.

I have wideband on all of my gassers. It's impossible to see what the AFR is doing as a result of EGR duty cycle, however, in a system as simple as these trucks, one could probe the EVPS and watch AFR accordingly, but, it'd be a waste of time. IF the AFR, as read in the exhaust, stayed the same as EGR duty cycle increased, you'd lose power and slow down. If a sensor existed to measure air/fuel pre-combustion - you'd be correct for a particular period in time with no conditions changing.

let's recap:

-Exhaust reentering the intake has it's own AFR already, but is inert.
-Inert gas injection reduces power
-EFI management is a wonderful thing
-Your right foot (greater throttle position) and the EFI system (more timing, lower AFR) compensate for inert gas injection
-EGR was designed and introduced to reduce specific emission gasses, nothing else