Nasty smell/fumes - not fuel, oil or trans fluid - maybe catalytic convtr

10

Asked by Mar 05, 2010 at 07:42 PM about the 1994 Ford Explorer 4 Dr XLT SUV

Question type: Car Customization

94 Expl 4dr 2WD xlt - 115k miles
After the car has been running for a while, 20-30 mins, especially in traffic there is a very unpleasant smell coming from under the car either emgine compartment or more likely underneath it is not fuel, oil or trans fluid but smells like something is very hot - I suspect the catalytic converter.
1. Is this a likely answer? I do not believe the cat conv has ever been replaced.
2. I would really like to run a straight pipe & remove the cat conv altogether as I do not think it inproves emmissions - certainly not as it is. I try to keep the engine well maintained but am now taking this task quite seriously as I am not in a psoition to replace the car & need it for work.
Thanks, Nick

6 Answers

45

the converter is probably going, but the cause is most likely you O2 sensor, or sensors. A vehicle that runs too rich can foul out and plug up the cat. when your done driving look under your vehicle and see how bad heat is radiating offa your cat, or cats. If its bad and you can see it plain as day from the rest of your exhaust, you should get rid of the cat. A straight pipe will work, but may lose some mileage, fords tend to like a little back pressure. New cats can be spendy, especially direct fit units. So if money is an issue, add a straight pipe. I also really suggest changing your O2sensor, or sensors regardless at that mileage, it is past its intended service life. Hope this helps.

45

the converter is probably going, but the cause is most likely you O2 sensor, or sensors. A vehicle that runs too rich can foul out and plug up the cat. when your done driving look under your vehicle and see how bad heat is radiating offa your cat, or cats. If its bad and you can see it plain as day from the rest of your exhaust, you should get rid of the cat. A straight pipe will work, but may lose some mileage, fords tend to like a little back pressure. New cats can be spendy, especially direct fit units. So if money is an issue, add a straight pipe. I also really suggest changing your O2sensor, or sensors regardless at that mileage, it is past its intended service life. Hope this helps. And also, catalytic converters with their elements intact are worth money because of the platinum in them, bring it to a scrap yard that accepts them to collect some cash.

60

with all the issues u post on here with this vehicle I would highly suggest u see a reputable repair facility for a paid or free diagnostic? and a over all inspection so they can prioritize ur needed repairs and let u know if the vehicle merits any work or if the engine/trans r on their last leg? save money by NOT doin repairs that someone thinks MIGHT help....and no removing the cat is not a good idea over all but if its restricted it may help w power and economy by removing it but be advised cats go bad by something else bein bad causing it to fail...they were designed to be a lifetime part and my own vehicles have never had 1 replaced do to needed repairs bein done

10

It has been making the horrible smell for a long time but until I did not use the car much but now I need to. Recently the "Check Engine" light came on & the daignostic code showed a) EGR valve which could be the valve or the sensor and b) the carbon filter from the fuel tank. Could the EGR valave have caused the cat to go bad? Thanks for your prompt response.

1 out of 1 people think this is helpful.
10

The car drives quite nicely but unfortuantely has been neglected. I am able to do the work & would rather deal with the devil I know than buy someone else's problem on wheels. If I run a pipe instead instead of the cat should I use one 1/2" smaller in diameter to provide some back pressure? Taking the old one to a scrap yard that will buy it is a great idea. I hate to send stuff to the dump. Thanks for responding, much appreciated.

A slather of Cosmolene was put there during export. No one bothered to remove it.

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