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Rough Idle


New Member
March 26, 2002
Reaction score
City, State
Logan, Utah
Year, Model & Trim Level
'94 Sport
My '94 Explorer Sport has been running rough for a while. I have cleaned the MAF sensor, replaced the plugs and wires, replaced the throttle control sensor, the idle control sensor, and I have run lots of cleaner through the fuel system. It is getting better gas mileage than I have seen in years. I checked the codes and it said that both sides of the engine are running lean. That would explain the gas mileage! It runs rough and every so often it backfires up into the intake. It doesn't change when you disconnect the spark plug wire to each cylinder. It smells of sufur, but the there is no back pressure that would indicate a problem with the catalytic converter. Any ideas?

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Disconnect the MAF sensor, if it runs smooth then your problem is with one of the sensors like IAC, MAF, O2, TPS or ECT

Thanks for the suggestion. I did try that and it still ran rough. I think I will try the fuel filter next. I took it on a pretty rough road last weekend and now it is running pretty good, but definately not great. Maybe some gunk in the filter sloshed to one side. I'll let you know how it goes.

After replacing the fuel filter and replacing the coil, I finally got it solved. Turns out there were microscopic holes in the air intake between the throttle body and MAF sensor. The technician pumped smoke into the hose and it leaked like a seive. Replaced the hose and it runs great.

I was wrong. It ran great for 2 weeks, and now we are back to the rough idle. I guess we are down to the fuel pump, fuel pressure regulator, or possibly an electrical problem. Any guesses?

Mine runs rough I was also told fuel pressure regulator , I say go for that first.

my idles a idles funny. i think its the 02 sensors in ur case.

It smells of sufur, but the there is no back pressure that would indicate a problem with the catalytic converter. Any ideas?
Doesn't that sulfur smell indicate that the engine is running rich (meaning a lot of excess HC burning in the cat). If the codes say lean, but the engine's running rich, that suggests to me a fault in the O2 sensors/circuits.

Have you checked for other indications of whether the engine is running lean/rich?

Bad throttle responce

hello my 94 has been running rought and spitting and backfiring thru the aircleaner and won't take fuel at times. and then it will just stall. shut it off and sit for and while and some times that works.

I've replaced the fuel filter,tps and the maf sensor and no change I think I need to drop the tank and replace and clean the tank.
Any ideas i'm new to fords but love this truck!!!

History----Truck sat for two years but ran great when first brought then ran thru large water puddle and a hidh rate of speed and since then have had this problem....


My 97 had those codes and a similar rough running issue. I too went threw MAP. AIC valve etc. My rough running was most noticeable when the ambient temperature was cold. It run reasonable well when hot. It came down to the Manifold Orings not quite sealing untill the block temperature came up a bit. Found the leak by spraying a can of engine start around the manifold when it was cold. Took both upper and lower portions off manifold off and sealed them. Fixed 100 %. I know yours is an earlier year but this may help.

In the end it was a bad computer. I guess the lack of the CEL should have pointed me in that direction. I sent 2 new computers back, the third worked.