EGR help
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EGR help
I need some advice. Tomorrow I'm leaving on a drive from Iowa to Utah. 1300 miles one way. The EGR system is basically non operable. The diverter valve works fine and isn't stuck or anything but the vacuum solenoid is busted and so the valve never opens. The check engine light comes on after the engine warms up. I was wondering if spending about forty dollars on a new one would give me enough of a boost in MPG for the trip to be worth it. I'll be driving back too so a 2600 mile round trip. I get 12 to 14 MPG right now. Thanks for the help
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Joined: Sep 2008
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From: DeKalb, Ill.
If I were you I would spend the money for the valve.
I did some quick math, with 14 mpg at $2 a gallon, you'll spend $371.
At 15 mpg, you'll spend $347 in gas.
Turns out the valve cost you more than you saved in gas with my numbers.
Here's the kicker.
The egr system slows down the burn time of your fuel mixture.
Considering this, your timing curve is set up to burn fuel at a slower rate.
Without that exhaust gas in the fuel mix, your fuel mix could be igniting too fast.
Maybe you get way better mileage with a good egr and save a bunch of dough.
I dunno. I would think twice about a long trip with something like this out of wack.
Murph.
I did some quick math, with 14 mpg at $2 a gallon, you'll spend $371.
At 15 mpg, you'll spend $347 in gas.
Turns out the valve cost you more than you saved in gas with my numbers.
Here's the kicker.
The egr system slows down the burn time of your fuel mixture.
Considering this, your timing curve is set up to burn fuel at a slower rate.
Without that exhaust gas in the fuel mix, your fuel mix could be igniting too fast.
Maybe you get way better mileage with a good egr and save a bunch of dough.
I dunno. I would think twice about a long trip with something like this out of wack.
Murph.
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Elder User
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You're right. I was thinking earlier about leaving the EGR as is and taking the DUI dizzy out the the 1985 F-250 w/300 and putting it in the bronco. Just to 'force' the timing to be a certain thing rather than computer controlled. But I thought otherwise and think I'm just going to put the danged money into a new vacuum solenoid. It's only forty bucks and I'm 95% sure that's what's at fault. And 2600 miles is a long way to drive with faulty EGR when I know I could just fix it with a trip to an ATM. Thanks Murph 
BTW. I was reading that the reason EGR helps with gas mileage is because it bleeds off some of the engine vacuum as it draws in exhaust and therefore reduces pumping loss. Less vacuum pulling against the piston on the intake stroke, yada yada. That sounds a little hokey to me. I'm more apt to believe it's because the combustion temps are lower and timing can be advanced more. On an EFI truck anyway, where the ECU does it for you. Whatever the reason. I'll fix the EGR tomorrow.
BTW. I was reading that the reason EGR helps with gas mileage is because it bleeds off some of the engine vacuum as it draws in exhaust and therefore reduces pumping loss. Less vacuum pulling against the piston on the intake stroke, yada yada. That sounds a little hokey to me. I'm more apt to believe it's because the combustion temps are lower and timing can be advanced more. On an EFI truck anyway, where the ECU does it for you. Whatever the reason. I'll fix the EGR tomorrow.
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Joined: Sep 2008
Posts: 563
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From: DeKalb, Ill.
Let me know what you have been reading.
I have been fighting an ignition ping for over a month now.
I'm about bald from all of the head scratching I've been doing.
I've made every timing adjustment I can make, but nothing cures the ping.
I'm not going to give up on the problem, but lately I am stuck in my tracks.
Any of your egr knowledge might help me out.
I'm suspicious of two things:
1) Ford was experimenting with emissions in "75, and I have a "guinea pig" truck.
2) The PO removed the egr system and didn't adjust anything else.
Either way, I'm at my whit's end. I need to learn more about this egr system.
If there is an easy way for you forward some literature to me, I'd be thankful.
Have fun on the trip,
Murph.
I have been fighting an ignition ping for over a month now.
I'm about bald from all of the head scratching I've been doing.
I've made every timing adjustment I can make, but nothing cures the ping.
I'm not going to give up on the problem, but lately I am stuck in my tracks.
Any of your egr knowledge might help me out.
I'm suspicious of two things:
1) Ford was experimenting with emissions in "75, and I have a "guinea pig" truck.
2) The PO removed the egr system and didn't adjust anything else.
Either way, I'm at my whit's end. I need to learn more about this egr system.
If there is an easy way for you forward some literature to me, I'd be thankful.
Have fun on the trip,
Murph.
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Elder User
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I don't know where I could really point you. Most of what I read is sourced off the net and then piecing together with my noggin' what makes sense to me. If your truck was a 'guinea pig' year then it might be that your carb is jetted down to compensate for the diluted air the engine was designed for. Now that your intake air is no longer diluted you may be running lean enough to get detonation with a stock timing curve. You could easily tell if you were wealthy enough to buy a wideband oxygen sensor. Try putting a larger fuel jet in your carb. I have a 1v feedback carb lying around from that F-250. I could take the main jet out and send it to you if you want it. I don't need the carb anymore.
