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Discussion Starter #1
Hello, im new but have been reading for a long time and have learned alot on here. I am currently have issues with the exhaust fumes and need a little help with it.

The fumes are so bad that if i drive it for a few miles i can smell them for hours on my clothes. if you stand near it or sometimes while driving its so bad it burns my eyes. Its not so much of a rich fuel smell tho i do think a/f ratio is off and is a little rich. it sometimes runs rough after it warms up for 5 min. and trys to stall. reverse stalls seem to to be worse/more often.

i have checked the o2 sensor. cleaned it no change at all.
checked the MAP and seemed to be ok. I am wondering if this isnt a EGR valve issue. i removed the EGR valve to check it out to see maybe it could be stuck open. well it wasnt stuck open and did move up and down, however it does not seal fully. i can blow air and even see a little light thru it. could this be the prob? Thank you for any help.
 

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Discussion Starter #2
i have not checked for codes yet. i don't have a scanner for obd1. i will check with my local advance auto parts and see if they do.
 

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Discussion Starter #4
awesome i will try it out this afternoon
 

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Discussion Starter #5
well i just checked for codes, didn't find anything.
 

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Do you smog in your area? If so, does it pass?
 

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running lean will burn your eyes

so will burning coolant

does your truck have full exhaust and tailpipe and a converter on it

and are you driving with rear window down?

any oil leaks burning off exhaust under the hood
 

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Where does your exhaust come out? Under the tailgate or out to the side? I know from experience that if you don't duct the exhaust to the side of the body, the exhaust has a tendency to get pulled back into the truck, especially when the rear window is open.

Aside from that, check for the things TrustyRusty mentioned.

One other thought. Try pulling the PCM and opening it up to check for damaged circuitry. With as old as these rigs are, whenever I hear someone say "I think air/fuel is wrong, but can't figure out why" I think it maybe that the fuel control is damaged and your engine is running in a fault mode. The good news is it takes about 10 minutes to pull the PCM and open it up to check for damage. I also drive a 91' and spent months tracking down a lean fuel issue only to find out the PCM had a couple of capacitors that had leaked all over the board and basically prevented it from functioning properly.

The PCM is located inside your firewall on the far drivers side. First, you have to remove the giant wire plug from the engine compartment by removing the retaining screw. Next, remove the side panel to the left of the parking brake inside the cab. That big metal box is the PCM. Remove the retaining bolt and bracket and it should slide right out. Next just open it up and look over the circuitry and if anything looks funky to you, like rust or burnt or otherwise "not right" its probably damaged.

Examples:

 

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Discussion Starter #9
no there is no smog testing down here, so i would have no clue about that.

im running no cat, with ground pounders just past the trans. had tail pipes all the way out the back bumper and it did the same then as well just happened to change it recently

i have not checked the pcm yet but i will as soon as i get home this afternoon. Thanks guys!
 

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Discussion Starter #10
ok i just checked the PCM and there are a few small dark spots on the board and two capacitors have what looks like a bit of corrosion on them. should i replace it or would this even cause a problem?
 

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That is likely your problem. Doesn't take much to cause a circuit board to fail
 

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Discussion Starter #12
anyone know the best place to get a replacement? found a few for around 300$ which seems a bit high to me
 

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Discussion Starter #13
as it turns out i have a 1995's PCM. Does this matter? Does anyone the code for a 1991 5.8 E4OD?
 

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dumping exhaust under truck and no cats will give you a stinky exhaust as you will suck fumes in

the bronco is not like a truck where it has a sealed cab

the only time I don't get fumes in mine is when I have full tail pipes,out one side only
 

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Ford stuck the tailpipe out the side for a reason. They determined that there was an extremely high risk of sucking exhaust back into the vehicle because of how the Bronco is designed and how moving air works. You think they wouldn't have loved to save a couple of pennies by having a straight pipe rather than paying for the bend? That's your problem right there.
 

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ok i just checked the PCM and there are a few small dark spots on the board and two capacitors have what looks like a bit of corrosion on them. should i replace it or would this even cause a problem?
Actually, if you're not afraid of using a soldering iron, you can just replace the capacitors. Most radio shacks still sell minor electronic parts like that. Hopefully, they have the right size. Capacitors are measured by uF (micro Farads) so make sure you get the right size. If RS doesn't have the right size, you can solder two smaller capacitors that add up to the correct uF rating in parallel and it should still work.

If on the other hand, you're not confident in that, I got my rebuilt PCM from Solo Auto Electronics. They did send the wrong PCM the first time, but the customer service was amazingly good. As in, when I called to let them know the wrong PCM was sent, they went ahead and sent the correct one out that day, and let me return both the wrong PCM and my bad one in the same return package so I didn't have to pay extra postage. They also said I could wait till I got the correct PCM before sending them in so I could still drive my Bronco. Like I said, AMAZING customer service. I think I paid $200. The hard part is matching up the transmission/engine combination, which is what they messed up on the first PCM. Look them up on the internet and give them a call. You won't be disappointed. :thumbup

Oh, and vent your tail pipe out the side of the truck. That will keep exhaust from being sucked back into the bronco.
 

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Discussion Starter #17
i understand i will get some exhuast smells with my exhaust setup but these are not normal fumes and, its just not running right.

Steve i tried to post pictures but i cant.I would be happy to email them.

thanks AFBRONCO i will look them up sometime today!
 

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Discussion Starter #18
 

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