This week I started experiencing a slow start and when started a rough idle and then a very harsh hesitation causing a very rich combustion when ignited.

I went through the usual steps of Cleaning the IAC and cleaning the MAF. The rough Idle went away and the hesitation did also... until the engine got warm.


Low and behold the outside of my house started smelling like sulphur (rotten eggs). My catalytic converter was fouled causing reduced exhaust flow and stalling/hesitation of my X. So if you still have idling and hesitation problems give your catalytic converter a look, it may be the source of your problems.

--Supa

I have been told that Cats are only good for 80-100K? Thanks for the heads up, mine has been similar just not as bad as yours...It's stinky though and the exhaust is really hot at the tailpipe.
Thanks
KJMac

well after replacing my cat converters (and the rest of the exhaust) ive yet to see improvement on this problems

well after replacing my cat converters (and the rest of the exhaust) ive yet to see improvement on this problems

are you getting any codes?

How do you tell if a cat is bad? Besides replacing it and then the problem going away.

If the outside of your house smelled like rotten eggs from your cat it doesn't mean that the cat is plugged or bad...it means that it is working overtime because your car is running to rich. UNLESS THE CAT IS PLUGGED IT HAS NO AFFECT ON HOW YOUR ENGINE RUNS.

I have a 1991 4.0L V6 and having problems with the starting of the car and harsh idle. I rebuilt the tranny with a new torque converter. The flywheel had two small cracks which I drilled at the end. Also the end of the crank shaft bushing is a little damaged. Now when I start the car I hear a loud clanking noise coming from the starter/ bell houseing area. plz help

Replace your mas sensor. I just did one at my shop ona 94. It is common for explorers.

The way to see if your cat is plugged is by using a back pressure gauge by taking out one of your O2 sensors.

This can be tricky tho if your cat is broken becasue when going over bumps it might move in a way that it blocks the exhaust or doesnt....but by hitting it with your hand you should hear somthing rattle inside letting you know its broken or the mesh is out of place and will crack the inside of the cat sooner or later

Edit: But it could always be your muffler tho, hard to say....thats where the infrared scanner comes out or touching the pipe until you find a cool spot

I have been told that Cats are only good for 80-100K

Simply not true.

I have seen cats go well over 200k.

I have been told that Cats are only good for 80-100K? Thanks for the heads up, mine has been similar just not as bad as yours...It's stinky though and the exhaust is really hot at the tailpipe.
Thanks
KJMac

I have the original cat on my 1993 Bronco w/233,000 miles.

Ended up needing a new MAF. go figure.

I know this doesn't really apply to rough idle or hesitation but your DPFE hoses need to be checked periodically too. One hose is a "control" and the other takes live data. If one of those hoses sucks in on itself it will throw reading way off. Readings that effect how rich or lean the fuel mixture is. Many believe that the MAF and TPS sensors control it, but they only control injector pulse, not how much fuel fires during that pulse. Just keep that in mind.

Try this thread for a verified rough idle solution. Maybe you are having the same problem too.

http://www.explorerforum.com/forums/showthread.php?t=217062

I unplugged MAF to see if it was causing my rough idle and hesitation and it did not improve. Is this a sure fire way to exclude the MAF? I hope that is all it is. I have cleaned IAC, new fuel filter, air filter, checked ECT sensor, changed plugs , lubed EGR and truck still runs very poorly. Feels like misfire. (4) plugs on driver side ( bank 2?) were fouled...Also getting po172 (too rich bank 1) Possibly the Injectors?

o ok well my 98 explorer sounds to be having the same problems. i replaced the plugs and wires, checked the coil and it was ok, checked the mass air with a new one and didn't make a difference. i replaced both front oxygen sensors as well and still nothing changed, it randomly dies at idle and what is the dpfe? thanks.

dpfe is a sensor that takes readings off of two little rubber tubes that come out of the driver's side exhaust manifold. One hose is a control which has a constant reading. The other hose senses exhaust backpressure near the heads and adjusts fuel amount to change it to an ideal reading. I replaced both of mine because they were sucking in on theirselves (giving a bad reading). After replacing mine it ran better, and I'm getting around 23 mpg

My rough idle , misfire and heavy bucking was due to a torn signal wire on one upstream o2 sensor. I replaced both sensors and voila! Runs like new. Turns out i gave it a hell of a tune up anyway. Thanks for the help.

anyopne tell me how to make my exploder do a doughnut??? the tracktion control has ben unplugged from the module and the front tires still spinn its posssed????

o ok thanks guys, i think i am gonna try replacing that sensor today. if that doesn't work then i am gonna try the computer, my friend had a v6 mustang that was just dumping fuel out an injector and it was just a bad computer, i can't think of much else that it could be, already tried the mass air, 02's ect. i can even hear the car pop when i accelerate with the windows down, we also tested the fuel pressure reg. to make sure it was sucking vacuum and holding which it did. ahhh just too frustrating, even my friends dad who has been a mech. his whole life is puzzled.

replaced the sensor but no luck there either, i just give up.

When you heard it pop did it do it under light or heavy acceleration?

My Explorer has just started "popping" at low acceleration. The CEL was on for a short while, misfire on C7, but it has since turned off. I checked my wires and they all seem fine. I thought it might just be bad gas, I had just filled up the night before it started happening. But now I'm not so sure, I used up half the tank and refilled and added water remover to it yet it's still popping at low acceleration. What else could this be? The idle is rough, but it's always been pretty rough.

Thanks

If you say it's been running bad for a while I have a possible solution. I'm not saying this is the answer but it's worth it to check. The more an engine runs poorly, the more crap goes through the exhaust. Instead of getting a complete burn you get chunks of left over combustion material. This can clog the catalytic converter causing excessive backpressure in the engine. The popping noise you have *may* be the engine trying to backfire due to extreme backpressure. Get a guage that screws in place of the o2 sensor before the converter and run the truck. Even hit the gas a little as if you were accelerating. Once again, I'm not saying this is the answer, but I've seen it happen many times on many cars. It won't set a code because the o2 that monitors the converter only sees that it's burning what's getting through. It doesn't sense backpressure, or lack there of.

So, any updates?

So, any updates?

What gauge would I need to get? I couldn't really find anything besides a air/fuel mixture gauge.

I tried swapping the coil packs out with known good ones, but that didn't help. Tomorrow I'm going to try and swap the MAF out and check the gap on the spark plugs.

It's called a backpressure tester gauge. You remove the oxygen sensor from the exhaust, and install the gauge into the fitting in the exhaust as if it were an oxygen sensor. If I find one on here I'll show you.

Here (http://www.sjdiscounttools.com/otc7215.html) is an example of a gauge.

well took it to ford today to get it looked at and they said one bank is running rich one running lean and they determined that the timing chains slipped and that the timing on the car is off so its making it run poorly, they said something like 4 chains doesn't make much sense to me...solution

what about hard to start? like u turn the key and sometimes it takes 2-3 tries..i heard u dont mess with gas pedal with fuel injection but sometimes u have to tap it a little bit to fire up..idle is strong and runs great besides that, any opinions?? 01 X 4x4 4.0 sohc..110,000 miles

You say this is common?
What is the syntoms? My doesn't like to idle after a storm...it will run but until warmed up sometimes I can rev it enough to make it stop..any thoughts?
MAF?