2002 Mercury Mountaineer - Engine dies/stalls

[lincolnshibuya]

My wife complained that her truck stalled twice last week while she was driving. While driving at slow speed (25-40+mph) the engine dies and all the lights go off. Weird thing is it will start right away again as if nothing happened. No codes and no rough idle. I'm suspecting at first it could be a fuel related issue but the fuel filter was replaced 50k miles ago and there's no sign of hard starting. Cleaned the MAF, throttle body and replaced the air filter and drove it myself today to replicate the issue. Nothing so far, I was wondering if somebody has similar issues. Note that I have no rough idle (IAC,vacuum leaks) or hard starting (fuel filter/pump) issues. Was wondering if it's something electrical that gets loose sometimes.

 

[Number4]

Sounds like an electrical issue. [MENTION=134770]BigRondo[/MENTION] has an 02 and some experience here. He should post in a few.

 

[lincolnshibuya]

Well, been driving it around for 4 days racking up 200 miles and can't replicate the problem. Wife still won't trust it so she's driving my hybrid, good way to save on gas money on her side while I pay for gas weekly now. Can't believe how much my wife is spending every week on gas for this truck. I've told her that if you bring this to a shop or a dealer, better kiss that diagnostic fee goodbye because it will never get fixed when the problem can't be replicated (just a bit of grumble telling her to learn how to drive correctly)

 

[lincolnshibuya]

Solved! new IAC

After doing an overhaul of my rack and pinion and front suspension lately. I noticed that when coasting downhill (foot not on the gas) the rpm will go up and down. Decided to clean up the IAC and it was worst after that, it stalled everytime I start it. I was able to run it by just keeping the throttle open and it pretty much described what my wife experienced when it stalled. Ordered a new Motorcraft IAC since aftermarket ones are reported to not work properly. Runs fine and idles smoothly now.

 

[SyberTiger]

After doing an overhaul of my rack and pinion and front suspension lately. I noticed that when coasting downhill (foot not on the gas) the rpm will go up and down. Decided to clean up the IAC and it was worst after that, it stalled everytime I start it. I was able to run it by just keeping the throttle open and it pretty much described what my wife experienced when it stalled. Ordered a new Motorcraft IAC since aftermarket ones are reported to not work properly. Runs fine and idles smoothly now.

I get that the Motorcraft IAC fixed your problem but I'm trying to understand why "all the lights go off" when this problem happens. Sounds unrelated and perhaps you have an electrical problem somewhere.

 

[lincolnshibuya]

I just didn't state it properly, what I mean by "lights go off" is that all the warning lights (service engine soon, abs, battery, low oil pressure..etc) lit when the engine stalled. It stalls at coasting and when doing a slow turn to park.

 

[SyberTiger]

I just didn't state it properly, what I mean by "lights go off" is that all the warning lights (service engine soon, abs, battery, low oil pressure..etc) lit when the engine stalled. It stalls at coasting and when doing a slow turn to park.

But you have it fixed now...Right? Everything is cool now?

 

[lincolnshibuya]

it's definitely driving better now, new IAC, new shocks, rack and pinion and wheel alignment.

there's definitely some todo list on this truck:
* have to replace all COPs. (3 out of 8 are new now, all Accel)
* rear whine, can't say if it's the bearing (seems both) or the differential.

 

[Limited02]

it's definitely driving better now, new IAC, new shocks, rack and pinion and wheel alignment.

there's definitely some todo list on this truck:
* have to replace all COPs. (3 out of 8 are new now, all Accel)
* rear whine, can't say if it's the bearing (seems both) or the differential.

Does the hum go away when you let off the gas while cruising? If so, it's the rear diff. If not, it's either wheel bearings or tires.

 

[lincolnshibuya]

the guys at tiresplus test drove it after the alignment and they confirmed that it wasn't the tires and the differential. They said it's the wheel bearings and when I asked which one? "both" and gives me a $1200 estimate to do it..

I think the truck is just too loud to notice the hum of the differential when I let go off the gas. I can't really tell the difference, what I noticed is that making a turn left of right makes the same noise.. so tiresplus might be right it could be both. I've removed both of the knuckle last summer to check the bearing and I don't feel any roughness on both (I did change the coaxial ball joint on the rear passenger side since it's shot) so that made me think it's the differential. I also replaced the seal on the rear passenger side with the new design since it was leaking too.

Hopefully I could replace both sooner (and later found out that it's the diff too) if I have some extra time and weather permits (crazy rain and cold weather in KC, Go Royals!).