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Reccuring Problem, car stalls randomly

Z

zbomb33

New CEG'er
Joined
Dec 23, 2007
Messages
15
Location
West Michigan
Hi everybod, I'm a long time lurker, first time poster. And I've spent my fair share of time searching the old forums and this one to help me fix my problem. I have a 2.5l 96 Contour with 115 grand on the clock that will just randomly stall while going down the road, it doesn't happen often, but since it's my wife's car it really freaks her out when it happens. So far, I've taken all the advice given (replaced the MAF sensor, idle control valve, checked for vacuum leaks, etc) and have not gotten the problem to go away. Are there any other things I should be looking for? I'm stumped on this one, and I need to get it fixed before the snow starts to fly!

Thanks for any insight!
 
How is the engine wiring harness? When was the spark plugs (and sp wires) changed? What about the fuel filter? Check the ignition coil too. The last two times my car randomly stalled was due to (1) moose (2) broken vacuum hose.
 
Fuel filter was changed recently, changed the Moose as well. I am doing spark plugs and wires this weekend. I'll double check the vacuum lines. Thanks for the reply Tony!
 
is there a particular scenario that causes this? Is it ever when you are coming to a stop? letting foot off the gas pedal? Are you just crusing along and the motor cuts out? details my friend!
 
I do not remember the exactly...but it may have something to do with your EGR valve or IAC. Also, my suggestion to you is to do an intake cleaning. I did this on mine when my car was randomly shutting off and it fixed everything.
 
AliasJerk said:
is there a particular scenario that causes this? Is it ever when you are coming to a stop? letting foot off the gas pedal? Are you just crusing along and the motor cuts out? details my friend!
Click to expand...

Good question, it happens mostly when you are letting off the gas. Sometimes it happens when starting from a stop. Never happens when cruising.


BigBEN said:
I do not remember the exactly...but it may have something to do with your EGR valve or IAC. Also, my suggestion to you is to do an intake cleaning. I did this on mine when my car was randomly shutting off and it fixed everything.
Click to expand...

Intake cleaning! That's a great idea. I did the IAC valve already, but the EGR valve is something that needs to be done. Forgot about that one. I'll post findings after my weekend of car maintenance.
 
I may be pulling too strongly from my Taurus SHO days, but could the crank position sensor be the culprit here? In SHO land, it was usually caused by a leaky waterpump, which would dump coolant onto the sensor below and fry it. The specifics will differ here, but if that sensor has somehow failed, it will almost certainly create a stall.
 
LauraSVT said:
I may be pulling too strongly from my Taurus SHO days, but could the crank position sensor be the culprit here? In SHO land, it was usually caused by a leaky waterpump, which would dump coolant onto the sensor below and fry it. The specifics will differ here, but if that sensor has somehow failed, it will almost certainly create a stall.
Click to expand...
You may be on to something here. Someone previously had a bad camshaft sensor which caused the car stall every now and then at stop lights.
 
LauraSVT said:
I may be pulling too strongly from my Taurus SHO days, but could the crank position sensor be the culprit here? In SHO land, it was usually caused by a leaky waterpump, which would dump coolant onto the sensor below and fry it. The specifics will differ here, but if that sensor has somehow failed, it will almost certainly create a stall.
Click to expand...

You may be on to something. Guess what leaked all over the place that I fixed 5 months ago? Yup, a leaky waterpump. I'll have to look into that as well. Thanks for the tip!
 
So I replaced the plugs and wires, and I'm pretty sure they were never replaced at ALL. With 115 grand on the clock, you should have seen the tips of these plugs, almost eaten away! Anyway, the idle and general running of the motor is 100 times better. So I'm going to make a list of the other items that were suggested here if the problems come up again. Thanks for the help, you guys make a new guy feel welcome :)
 
Well, while the car is running much better, it still is threatening to stall. So, onto changing that camshaft sensor. I figure it's a cheap item so i'll start there first.
 
zbomb33 said:
Well, while the car is running much better, it still is threatening to stall. So, onto changing that camshaft sensor. I figure it's a cheap item so i'll start there first.
Click to expand...

Just remember you've got two sensors in there -- the cam position sensor and the crank position sensor.
 
zbomb33 said:
You may be on to something. Guess what leaked all over the place that I fixed 5 months ago? Yup, a leaky waterpump. I'll have to look into that as well. Thanks for the tip!
Click to expand...


except you have a 2.5L V6 ... the water pump is on the opposite side of the engine from the cam and crank sensor ....
 
As mentioned, failure of the sensors may not happen the same way as you'd see in a Taurus SHO. You may have failure due to age or other factors. No matter -- if the sensor or sensors are toast, they're toast, and could well be the reason you're getting a stall. While I can't guarantee it, it's something at least worth checking. If you haven't run engine codes, now would be a great time to do so.
 
Unfortunately, the only engine code's I have right now are for the engine not getting enough fuel. I'll have to run diagnostics again to get the number.
 
Well, I gave up, bringing it to the stealership to tell me what's up. :eek: I'll post here with the findings for future searches on this topic.
 
Dealership says I need a new fuel pump, but they don't know if that will fix it for sure. They say people who have had a stalling issue ended up replacing the fuel pump and it took care of it. Codes show up a PVE error, and the ports are plugged. They could replace that sensor, and clean the ports out for $450, but they don't think that is causing the stall issue. So for $700 I can have the fuel pump and stalk/screen etc replaced. I smell BS. This issue happens 3 times a month. What do you guys think?
 
Okay.. you haven't given a lot of symptoms and I think I can help with this (if its what I suspect).

What are your symptoms?

Does it DIE and you have to restart the car or does it "stumble/stall" momentarily (almost instantly) then regain composure?

If it stumbles/stalls then returns is it accompanied by any of the following:
flickering CEL light (maybe almost too dim/quick to notice)
a flashing PATS light (center dash above radio, V6 models)
tach diving for zero (if equipped) but speedo steady
fuel delivery goes away and then returns when the car recovers
spark is gone, too.

If so.. check the wiring to the TPS.. unplug the TPS and look at the connector pins and the connector itself. I bet your TPS (attached to the throttle body) is torn to hell and the wiring is shorting on bumps or decel/accel (engine flexes, wires touch). That short in the VREF causes many things to quit working including the PCM (thus no fuel, no spark, no go and the PATS flash is a re-test because the PCM just regained power)


is that your problem?
 
Thanks for the info Ray, unfortunately it has never happened while I've been driving the car (wife has been driving it). It completely dies, no recovery at all. I'll ask her to pay attention to the items you listed. Thanks!
 
zbomb33 said:
Dealership says I need a new fuel pump, but they don't know if that will fix it for sure. They say people who have had a stalling issue ended up replacing the fuel pump and it took care of it. Codes show up a PVE error, and the ports are plugged. They could replace that sensor, and clean the ports out for $450, but they don't think that is causing the stall issue. So for $700 I can have the fuel pump and stalk/screen etc replaced. I smell BS. This issue happens 3 times a month. What do you guys think?
Click to expand...

Well, it is possible. But they should have the means to tell you whats going on with it. It should be fuel pressure, current draw, and current ramp. The last one will show a waveform for the pump motor (a pretty cool test) the tech can figure the rpm of the pump and it's state by viewing the waveform. A good pump will have a clean waveform, with 7-8 humps in a 10ms timebase which will mean 5000-6000 rpms.

So I would ask what testing they did, what the psi of the pump is at the fuel rail. And do the have the equipment to do a current ramp.

Down side to your problem is its not happening all the time. Upside is a electric motor doesn't heal its self and then act up gain. psi, current, and current ramp will tell alot about the health of the fuel pump.
 
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