Good F350 fuel economy?

[TheGrimMechanic]

Yeah, I know. Haven't seen anyone here raving about the fuel economy improvements on their full size, gas fueled V-8 pickup. BUT, I think there some things I've discovered that apply to just about any internal combustion powered vehicle that I haven't read much about anywhere on this site.

I bought the F350 about 7 years ago with 126,000 miles on it. Its powered by a venerable 351 Windsor that was factory rated at 245hp. When I first bought it, I got about 10mpg city and 11mpg hwy. It had an intermittent check engine light that was traced back to a faulty O2 sensor and a cracked distributor cap. After changing the oil and doing a tune up (replacing cap, rotor, wires, plugs, PCV valve, etc.), my mileage improved ever so slightly to 10city/12hwy. Not impressive and still disappointed with how bad the mileage was. I would have expected this out of a 460 powered truck but not the 351. The F350 had decent gearing for mileage (3.55:1) but the automatic 4 speed overdrive E4OD tranny isn't known to be very efficient. The F350 is also a 4x4 but its a standard cab and the weight is fairly low for a full size pickup at 5,500lbs. Highway mileage, as expected, really took a dump above 65mph and this is something I can live with. No need to cruise at 75 in my old truck. All of the checks for mechanical faults were checked and nothing appeared to be defective; no exhaust leaks upstream of the O2 sensor, engine compression was good, no vacuum leaks, fuel pressure correct, etc.

One of the first mods I made was to repair a rusted out muffler. When I removed it, I looked at the cat and found that it had been gutted (or melted itself out) and wasn't functional. I replaced the exhaust from ahead of the non-functional cat with home-made 3" system and a Flowmaster muffler. Still not much difference in the fuel mileage. The next mod came about while trying to address a erratic idle problem. Idle speed was unsteady and erratic at times. This was traced back to an EGR valve that had a worn seat inside and wouldn't close completely at times. Decided to do a little experiment and block it off completely rather than replace it. Instantly gained 1mpg city and 2mpg hwy. Hmmmm.....
This got me thinking about why. After the EGR was blocked off, I noticed that I had some slight pinging at part throttle cruise. A good thing as far as fuel economy. I checked the timing and it was spot-on so just for safety's sake, I retarded it 2 degrees. Apparently, the ECM advanced the timing considerably when the EGR is open to make up for the slowed down rate of combustion caused by the diluted air/fuel charge. By blocking off the EGR, I got the free benefit of advanced ignition timing just where I needed it..... During part-throttle cruise.

More experiments.
The next on the list was the Air Injection Pump. The pump was beginning to make some noise and I've had these fail before. The vanes inside blow apart and the pumps seize, burning up the belt and leaving you stranded. So... off to the auto parts store and put on a shorted belt that bypassed the air pump. Holy Cow!!! Mileage jumped another 3mpg on the highway! Again, I needed to understand why and about the only thing I have been able to figure out is that the air pump was doing its job of pumping air into the exhaust and creating an artificially 'lean' state as far as the O2 sensor was concerned. The ECU responded by richening up the mixture. Now I can see a reason for this as far as emissions systems are concerned. In order for the catalyst to function, there has to be some air in the exhaust and some unburned fuel. If there wasn't, the cat wouldn't come up to temperature and it wouldn't do its job of taking excess air and using it to oxidize CO and unburned hydrocarbons in the exhaust. Brilliant engineering, "lets make an already fuel inefficient vehicle even worse so we can make the exhaust cleaner". Just out of curiosity, I checked the exhaust with an exhaust gas analyzer and found the CO was at 1% and hydrocarbons were around 60ppm. The exhaust was still VERY clean yet none of the emissions control devices were functional. If you take into account the fact that the F350 is burning 33% less fuel, then the real numbers of tailpipe emissions are even better that when the vehicle was new! The EPA numbers for fuel economy for my F350 were almost perfectly inline with what I was getting before I changed anything.

Well, to keep a long story short, I have since made a few other mods to the old F350; An MSD 6A ignition, a hotter thermostat, an adjustable fuel pressure regulator, a better quality fan clutch, replaced the crankshaft pulley with a smaller one (to reduce accessory drive speed), and did away with the stock cold air intake. Right now, I'm getting a consistent 14mpg in town and 17+ on the highway if I keep the speed at 65mph. And this is with 224,000 miles on the stock engine! When its due for a rebuild (I'm sure it'll go to 300,000) I'll make some other changes. More compression, regrind the crank to use smaller 351 Cleveland main bearings, low tension oil rings and gapless compression rings, and if it's in the budget a set of TFS twisted wedge heads. I'm pretty confident I can break 20mpg and also pick up another 75-100 hp.

[mcrews]

nice job!

[chillsworld]

Talk to me about blocking the EGR and air pump.. I have 5.0 Mountaineer and I live in a location where we don't have emissions regulations. My truck currently throws an EGR code, so I need to fix it... But I'll be damned if I'm to going spend hundreds of dollars to fix something that hurts my FE?????

~C

[BabyDiesel]

Now that's what's up! Kuddos to you for taking what you have and making it better

Btw, you have increased your FE by nearly 50% Outstanding!

[dirtydave]

Auto or manual?

[TheGrimMechanic]

Originally Posted by chillsworld

Talk to me about blocking the EGR and air pump.. I have 5.0 Mountaineer and I live in a location where we don't have emissions regulations. My truck currently throws an EGR code, so I need to fix it... But I'll be damned if I'm to going spend hundreds of dollars to fix something that hurts my FE?????

~C

On older Fords ('95 and older), a simple block off plate is used in place of the EGR and the tube that goes to the exhaust manifold welded shut or a threaded plug is used to replace the exhaust tube fitting. Newer Fords (like my '97) will require the connector that's on top of the EGR valve have a few resistors spliced in to 'trick' the ECM into thinking the EGR is still in place. Otherwise, you can leave the EGR valve on and the connector plugged in and just block off the tube. On my F350, a quarter fits nicely inside the nut that holds the exhaust tube to the EGR valve and the exhaust manifold. Just removed the tube and filled the open holes inside the tube-nut with a quarter and put the nut back on the exhaust manifold and EGR valve.

On your Mountaineer what P code is showing up?

The Air Injection Pump can be deleted several ways. On my F350, I had to physically remove the pump because a shorter belt wouldn't fit without removing the pump. But removing the pump would change how the belt was routed and the tensioner would no longer work. This required a few other changes. First, I had to use an alternator bracket for a 302. The 302 bracket relocated the belt tensioner to the correct location. Then I had to swap out the alternator for one used on a 460 (so it was clocked correctly). And I still had to make a small bracket to secure the top of the alternator. An easier way is to just stuff short pieces of wood dowel into the rubber hoses that go the exhaust manifolds. Can't say off the top of my head what you would need to do to remove it on your 302. If your accessory drive on your 302 powered Mountaineer is the same as 302 powered Mustangs, there are ready made kits to delete the air pump.

Originally Posted by dirtydave

Auto or manual?

Tranny is a E4OD 4 speed automatic with overdrive and lockup converter. 1997 was the last year Ford used the E4OD. It was replaced in 1998 by the 4R100. all of the differences were internal and the 4R100 would probably help fuel economy a small amount. The biggest difference between the E4OD and the 4R100 are the gear ratios. Most of the 4R100 parts will swap into the E4OD case.

[chillsworld]

Originally Posted by TheGrimMechanic

Newer Fords (like my '97) will require the connector that's on top of the EGR valve have a few resistors spliced in to 'trick' the ECM into thinking the EGR is still in place. Otherwise, you can leave the EGR valve on and the connector plugged in and just block off the tube. On my F350, a quarter fits nicely inside the nut that holds the exhaust tube to the EGR valve and the exhaust manifold. Just removed the tube and filled the open holes inside the tube-nut with a quarter and put the nut back on the exhaust manifold and EGR valve.

On your Mountaineer what P code is showing up?

Mines a 97, and the code is P0401 (insufficient EGR flow). It's got 288k miles on it, and I think its a safe bet that it's clogged with carbon build up... Haven't had time to really look into it yet. If that's the case I know I will see an increase in FE when I clean it out, do you feel that the increase from deletion is better? I've read a lot of back and forth on this subject... Obviously you have the added benefit from deleting the smog pump, decrease in parasitic losses. And you played with your timing, which I'm assuming also aided in FE? The more I read about it, the more confused I get hahaha

The Air Injection Pump can be deleted several ways. On my F350, I had to physically remove the pump because a shorter belt wouldn't fit without removing the pump. But removing the pump would change how the belt was routed and the tensioner would no longer work. This required a few other changes. First, I had to use an alternator bracket for a 302. The 302 bracket relocated the belt tensioner to the correct location. Then I had to swap out the alternator for one used on a 460 (so it was clocked correctly). And I still had to make a small bracket to secure the top of the alternator. An easier way is to just stuff short pieces of wood dowel into the rubber hoses that go the exhaust manifolds. Can't say off the top of my head what you would need to do to remove it on your 302. If your accessory drive on your 302 powered Mountaineer is the same as 302 powered Mustangs, there are ready made kits to delete the air pump.

From what I understand, the 5.0 stang kit doesn't work without fabrication due to mounting points... But that was just a quick search on the explorer forum, didn't have time to read a whole lot about it last night. I'll dig deeper today.

BTW, you're getting the same mpg as I am in a truck that's only 30 less hp and 1500lbs lighter

~C

[TheGrimMechanic]

Originally Posted by chillsworld

Mines a 97, and the code is P0401 (insufficient EGR flow). It's got 288k miles on it, and I think its a safe bet that it's clogged with carbon build up... Haven't had time to really look into it yet. If that's the case I know I will see an increase in FE when I clean it out, do you feel that the increase from deletion is better? I've read a lot of back and forth on this subject... Obviously you have the added benefit from deleting the smog pump, decrease in parasitic losses. And you played with your timing, which I'm assuming also aided in FE? The more I read about it, the more confused I get hahah

No need to be confused. Deleting the EGR and AIS will improve your fuel mileage. On modern vehicles, the use of EGR is because manufacturers did a cost benefit analysis and would rather use a $25 valve to control NOX instead of a $300 3-way catalyst.

AIS was used long before O2 sensors came to be and is the cheap an easy way to meet EPA rules. AIS is another useless technology where accounting prevailed over engineering. Wideband sensor technology has made AIS obsolete for a long time.

The EGR on your vehicle has a sensor on it that detects the position of the valve. I agree with you that coking of the EGR is the most likely culprit, but there is also the possibility that sensor is bad or an issue with the connector or wiring. There is a way to trick the ECM into thinking the EGR is in place and functioning by chopping off the connector and placing some resistors in its place. I know this trick works on OBDI Fords (pre 1996 EEC-IV) and on some later OBDII (EEC-IV only. Not EEC-V). I'll dig up the diagram and post it later. You would still need to make sure flow through the EGR is blocked completely. If it leaks at all during idle, you'll have issues with idle quality, rpm, hard starting, etc.

I've read a lot about EGR theory and all of the arguments for/against it. I've read a bunch of b.s. about theoretical gains in reduced pumping loss, thermodynamic improvements (?), and improved combustion and I'm pretty sure those theories don't mean anything to 99.9% of the vehicles that have an EGR. (BTW, my wife's 1999 Jeep Cherokee w/4.0 didn't have one from the factory). The truth is, EGR is only used for ONE reason: to reduce NOX (oxides of nitrogen) in the exhaust. NOX emissions are very short lived in the atmosphere and eventually are reduced to N2 and free oxygen. The problem with NOX is its decay product is nitric acid. NOX and nitric acid are also caused by lightning strikes. Nitric acid breaks down quickly in the atmosphere also. The main reason NOX is considered a pollutant is in large enough concentrations in the atmosphere it will cause the reddish brown haze you see in areas that have heavy air pollution because of the presence of nitrogen dioxide (wikipedia(dot)org/wiki/Nitrogen_dioxide). NOX is created in an internal combustion by the presence of oxygen and nitrogen together under high pressure and high temperature. The higher the compression ration and the higher the combustion temperature, the higher the NOX content of the exhaust. NOX, as a percentage of the exhaust gas varies depending on a/f ratio and load and ranges from nearly 0 to about 2500ppm (0.0025%) under peak load at 16:1 a/f ratio. You can read about some of the (b.s.) theoretical gains with EGR here: wikipedia(dot)org/wiki/Exhaust_gas_recirculation.

I don't get the logic of using EGR if it's going to cause my fuel consumption to go up. I'm not against emissions controls on my vehicle but if they are so poorly engineered just to satisfy some disconnected political machine, that opinion changes. EGR almost killed the on-road diesel market because of the technical problems of making it work well enough to satisfy the EPA. Sadly, the 'fix' for EGR's horrible reputation for unreliability and reduced performance was the introduction of 'Diesel Exhaust Fluid' and the burden forced on the consumer of having to periodically fill a tank on your new diesel powered vehicle with piss. I could go on and on about some of the stupidity of some of the garbage you are forced to pay for when you but a car (purposely injecting and burning fuel in the exhaust do 'regenerate' diesel PDF's???) but I would be hijacking my own thread.

[chillsworld]

Well I have some immediate expenses to take care of on my truck before I play with things... Need a full rebuild on the IFS . But once I get that done, I think I will delete cats, custom exhaust, smog pump delete, and see how that works. In the mean time, I think I will try to make the EGR work since I don't have the skills or money to correct timing and tune the engine if I remove the EGR. Thanks so much for responding, and again, great job on your FE!

Also, I totally agree with the concept of making a car run more efficient instead of adding things to reduce emissions that would be lowered if you simply didn't burn as much fuel to begin with. I also hate ethanol mixes at the pump because it reduced my mpg, and there by actually causing more pollution and overall fuel usage in my particular truck (as with many others). And don't get me started with diesel regeneration , I used to constantly be late to deliveries due to stopping for regen in my box truck

~C

[TheGrimMechanic]

Originally Posted by chillsworld

Well I have some immediate expenses to take care of on my truck before I play with things... Need a full rebuild on the IFS . But once I get that done, I think I will delete cats, custom exhaust, smog pump delete, and see how that works. In the mean time, I think I will try to make the EGR work since I don't have the skills or money to correct timing and tune the engine if I remove the EGR. Thanks so much for responding, and again, great job on your FE!~C

When you get to the point of doing the air pump delete, pick up an underdrive pulley set. Found mine on ebay for $70 (new!). It's free horsepower and I picked up 1+mpg with this mod alone. Also saves wear and tear on the water pump, alternator, and power steering pump.

As far as deleting the EGR, it's not too complicated. The pinging at part throttle was with 85 octane fuel. A switch to 87 octane cured that until I bumped the timing back. The timing is easy to do. A timing light and a 9/16 socket on a long extension are all you need. Just remember to disconnect the 'SPOUT' (usually located near the master cylinder) connector before you set the timing and replace it when you're done. Lots of resources on youtube on how to set your timing.