3.0L runs ROUGH when warm...

[mattinthebox]

I know it's not a true Nissan but it's a Nissan wrapped in Mercury clothing.

I have a 95 mercury villager minivan, 3.0L auto, which has been pretty dependable for all my needs.Today it started doing something strange and I'm at a loss as where to start looking for a solution to this problem.

Here's the scenerio:Engine runs normal when first started (cold), but as it heats to normal operating temperature (about 15 min.) it begins to run VERY VERY rough.

At this point it starts sputtering, coughing and the vehicle becomes inoperable (no power, backfire and will not get past approx. 10-15 mph) and will not run smooth again until engine cools.

At NO point does the CEL come on.

Now that's the part that is getting me, after it cools off it will fire up and run fine till it reaches normal operating temp again.

I's obvious to be temp related but what?If an O2 sensor it would throw a code.If a MAF it would also throw a code.It runs fine when cold so I ruled out timing belt issues.Maybe a crank sensor, would that throw a trouble code? ECU? I dunno

I sure would appreciate any help anyone can give.

Thanks in advance...

[ricebike]

weird that after going into "closed loop" mode, it'll run rough...

did you pull any codes at all, eventhough no CEL is on?

disconnect the o2 sensor to force it into open loop all the time & see if there's no change after operating temp is reached... sure, this is will waste gas mileage...

ps: here's the service manual for your vehicle; suggest you go thru the diagnostic section

http://www.nicoclub.com/FSM/quest/1994-1995_Quest/

download the ec.pdf file on desktop, then open w/ acrobat reader

post up the results GL

many things can go wrong... for example a few posts down w/ another person... he just guessed at his problem...

zer...-hill
Modified by ricebike at 10:30 PM 3/4/2009

[markf1971]

I know it's not a true Nissan but it's a Nissan wrapped in Mercury clothing.

I have a 95 mercury villager minivan, 3.0L auto, which has been pretty dependable for all my needs.Today it started doing something strange and I'm at a loss as where to start looking for a solution to this problem.

Here's the scenerio:Engine runs normal when first started (cold), but as it heats to normal operating temperature (about 15 min.) it begins to run VERY VERY rough.

At this point it starts sputtering, coughing and the vehicle becomes inoperable (no power, backfire and will not get past approx. 10-15 mph) and will not run smooth again until engine cools.

At NO point does the CEL come on.

Now that's the part that is getting me, after it cools off it will fire up and run fine till it reaches normal operating temp again.

I's obvious to be temp related but what?If an O2 sensor it would throw a code.If a MAF it would also throw a code.It runs fine when cold so I ruled out timing belt issues.Maybe a crank sensor, would that throw a trouble code? ECU? I dunno

I sure would appreciate any help anyone can give.

Thanks in advance...

I am having EXACTLY the same problem. I would appreciate any help. Thanks!