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Discussion Starter #1
I received help earlier with this problem, and I have finally found the soulution after testing many other things. Bronco was backfiring like crazy and RPM's were jumping all over the place, especially at 2000 RPM's. I bought a Hayes and tested the ignigition, checked the plug wires, firing order etc, everything checked out ok.

I then unpluged the 90 degree angle hose that conects to the top of the EGR valve, and that solved all the problems. Bronco does not backfire anymore, and idles fine. My only question now, is will I create additional problems by just leaving that unpluged.

Again thanks for all your help.
 

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Lick my balls
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I believe that is part of your emissions and by diverting exhaust gas into the combustion chamber it allows the engine to run cooler and thus saving your valves from getting burnt. Follow that vacuum line to a relay and test it to see if it is faulty.
 

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Rest in Peace Friend...
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You probably have a defective EGR. If they stick open due to carbon build up and will cause a rough running engine. It's function is to reduce NOx in your emissions. It does that by reducing the cumbustion chamber temp. An engine will run just fine without it but you probablly will have problems with emissions testing. I've run without mine hooked up for years. 93 and older only get a visual check here.

Good luck,

:thumbup
 

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Discussion Starter #4
There are no emissions test here in Kansas so that is no problem. I do have a lot of exhaust fumes in the cab area of the truck. Could this be adding to the problem. I do know that I have several other small exhaust leaks that I am in the process of fixing, but will this, EGR Valve, also have to be fixed to reslove that problem totally, or can I just leave it unpluged?
 

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Rest in Peace Friend...
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Leave it unplugged, just plug off the vacuum line. Work your way back to the PCV that it comes from and put a vacuum cap where the hose connects. It has nothing to do with exhust leaks. You are probably sucking exhaust in thru seals that are not working properly like on the tail gate. If you leave the rear window open, most Broncos suck in exhaust. If you have leaks in your exhaust system it can come in any place you have a hole. You better get that fixed, I know a guy that almost died from carbon monoxide poisening because of exhaust leaks and holes. Holes are OK, leaks aren't :).
 

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Satyr of the Midwest
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EGR reduces nitrogen oxides (NOx), not hydrocarbon emissions. NOx's form when air is compressed and burned at high temperature. EGR serves to reduce peak combustion temperature, thus prolonging engine life and reducing the need for higher octane gasoline. Doesn't help much when the engine won't run right with it, though. :(
 

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SigEpBlue said:
EGR reduces nitrogen oxides (NOx), not hydrocarbon emissions. NOx's form when air is compressed and burned at high temperature. EGR serves to reduce peak combustion temperature, thus prolonging engine life and reducing the need for higher octane gasoline. Doesn't help much when the engine won't run right with it, though. :(
Right, serves me right to answer when I'm tired. I don't buy the engine life or the octane part of that. The device was only added for the NOx problem. Octane requirement is directly tied to compression ratio and prevention of predetonation. The NOx problem is tied to combustion temperatures. Two seperate situations that can occur at completely different times. The temperatures we are talking about are in the 1000s of degrees and reducing that a small amount based on numerous engine conditions. The way it does that is to introduce gases that are already the product of combustion which reduces the amount of available combustable gas in the cylinder when ignition takes place.

:thumbup
 

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Lick my balls
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:thumbup cool, I was right. I can't believe I remember that from highschool.
 

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Discussion Starter #9
Well you guys successfully took that conversation over my head :). I guess it is still ok just to leave it unpluged and cap the vaccum line. This is not an everyday driver. It is driven maybe 2000 miles a year. I always use the premium gas if that makes any different.
 

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hawkfan1020 said:
Well you guys successfully took that conversation over my head :). I guess it is still ok just to leave it unpluged and cap the vaccum line. This is not an everyday driver. It is driven maybe 2000 miles a year. I always use the premium gas if that makes any different.
Sorry, but yes you can leave it off just plug the vacuum line either at the EGR or back at the other end of it. The octane BS is not true, the engine is designed to run on regular ( 87 ) octane, EGR or not. You are wasting your money putting in premium. Premium is for moderately high compression street engines.
 

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The Anti Yam!
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Seabronc said:
You probably have a defective EGR. If they stick open due to carbon build up and will cause a rough running engine.
If it was stuck open it still wouldnt close with the vacume line off of it.

Either the EVR has failed in the open position or someone has routed continuouse manifold vaccume to the EGR.

Disconecting the EGR from vacume will couse an EVP code to be stored in the computer. This code however will not couse the Check Engine light to come on.
 

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Gacknar said:
If it was stuck open it still wouldnt close with the vacume line off of it.

Either the EVR has failed in the open position or someone has routed continuouse manifold vaccume to the EGR.

Disconecting the EGR from vacume will couse an EVP code to be stored in the computer. This code however will not couse the Check Engine light to come on.

You are right that if it is stuck open something would have to be done, but us old carbed engines don't have that stuff like EVPs, check engine lights, and codes :wowcb: . Apparently it isn't stuck open because removing the vacuum line fixes the problem, don't know why I suggested it might be open in the first place. The old PCV control for EGRs is a little problematic and depending on the calibration has numerous possible control devices and configurations.

:thumbup
 

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Satyr of the Midwest
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My mention of a need for higher octane is related to the overall cooling effect of EGR, not a direct correlation, i.e. EGR != 110 octane ;) As far as engine life, it's also related to overall temperature; oils break down, sludges form, etc., from higher operating temperatures. I'm not trying to claim that you're going to get another 100k miles out of an engine with EGR versus one without, but IMHO, every little bit counts. I'm having to remind myself we're talking about carbureted engines here, not EFI's. :duh
 

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SigEpBlue said:
My mention of a need for higher octane is related to the overall cooling effect of EGR, not a direct correlation, i.e. EGR != 110 octane ;) As far as engine life, it's also related to overall temperature; oils break down, sludges form, etc., from higher operating temperatures. I'm not trying to claim that you're going to get another 100k miles out of an engine with EGR versus one without, but IMHO, every little bit counts. I'm having to remind myself we're talking about carbureted engines here, not EFI's. :duh
I think you are mixing apples with oranges ;) . The EGR doesn't have any effect on the overall cooling of the engine. The overall temperature is controlled by the cooling system and that is what effects the oil, down in the range of 200 degrees. The EGR is influencing the combustion gas temperature some place in the range of 2500 degrees.

Where did you come up with EGR = 110 octane? :scratchhe

;)
 

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The Anti Yam!
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Seabronc said:
but us old carbed engines don't have that stuff like EVPs, check engine lights, and codes :wowcb:
Whait......This is a carbed engine?

See, I missed that part. Seabronc>:twak <Gacknar


Seabronc said:
Where did you come up with EGR = 110 octane? :scratchhe
I think what he is alluding to is that the inert EGR can reduce pinging by making the Fuel/Air charge harder to ignite, just like (harder to ignite) higher octane gas will .
 

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Satyr of the Midwest
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Correct. Thanks, Gack!

BTW, the symbol != means 'NOT EQUAL', or at least that's what's implied. I hardly ever make a typo. :brownbag

If ya don't think changing air/fuel ratios will affect temperature of an engine, just talk to an airplane pilot about how they control the engine temperature. Better yet, think about what happens when you lean out on nitrous oxide on a drag racing engine. I'm not trying to 'fan flames' just tryin' to put my point of view out there. :toothless
 

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Not sure if this appeared in these posts, but the cooling effect of EGR is caused by oxygen displacement. Exhaust gas will not burn nor support combustion, so the effect is that the engine draws less air and fuel. Combustion pressures drop, and NOX drops as a result.

Now the nasty part. Many Ford engines from the late 70's and early 80's will self destruct without the EGR connected. The culprit is preignition and detonation due to the lack of the cooling effect of the EGR. If your engine does not ping with the EGR disconnected, you're probably OK. If it does ping, you need to fix the EGR, or retard the timing so far that performance and mileage suffer. The only true fix I've found is to replace the camshaft (the factory cam profiles dramatically increase peak cylinder pressures.) Virtually any aftermarket cam will work, and you can bump compression significantly with the correct grind, even without EGR.
 

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Rest in Peace Friend...
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SigEpBlue said:
Correct. Thanks, Gack!

BTW, the symbol != means 'NOT EQUAL', or at least that's what's implied. I hardly ever make a typo. :brownbag

If ya don't think changing air/fuel ratios will affect temperature of an engine, just talk to an airplane pilot about how they control the engine temperature. Better yet, think about what happens when you lean out on nitrous oxide on a drag racing engine. I'm not trying to 'fan flames' just tryin' to put my point of view out there. :toothless
Believe me, I'm not trying to put you down. Read the quote at the bottom of my signature on communication which applies to everyone who attempts to convey a thought, guess I should have keept that in mind when reading your post also :Doh0715. The worst medium of all is a written chat or forum entry where the visual and vocal clues are left out. Some might call this an argument :argue but I call it a discussion :beer . I have found it intellectually interesting, because you challenged my understanding of the EGRs porpose and how it works. I have had to go back and research the subject to see if I think I understand what the experts say on the subject. If that changes my perception of the EGR, I'll be back to eat CROW :deal .


Larston said:
Now the nasty part. Many Ford engines from the late 70's and early 80's will self destruct without the EGR connected.
I believe that is because they were higher compression than the 80+ engines and reducing compression ofcourse reduces the posibility of detonation/ping. I still maintain, that aside from the environmental issues, an EGR is a unnecessary device that robs power from the engine. The last time I looked, I didn't see one on a dragster ;) .

:thumbup
 

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Rest in Peace Friend...
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HUH, what quote? Oh well, sometimes it shows up and other times it don't

Here it is;

Communication: I know you think you know what I said, but what you need to know is I didn't say what I ment.
 
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