99 Ford Escort stalling when slowing down

[Kaido]

My brother has a 5-speed 1999 Ford Escort coupe with 150k miles on it. Lately, whenever it slows down (like coming off a highway), it will stall usually at under 10mph - complete loss of power (engine, steering, brakes). It will restart right away, but it's annoying when sitting in traffic and dangerous when turning into a parking space and it just dies and you have to yank the wheel to not crash. I don't know the maintenance history on it, so I don't know if it needs new plugs or sensors or what.

Anything in particular to have the mechanic look for when he takes it in?

Edit: He said it usually does it when slowing down at an angle, usually off an off-ramp from the highway.

 

[Bartman39]

Sounds like the IAC (Idle Air Control) is bad or close to it...? (possibly just dirty...?)

 

[phucheneh]

Sounds like the IAC (Idle Air Control) is bad or close to it...? (possibly just dirty...?)

This, or just the throttle in general. Even on cars without electronic throttle, a really filthy one can be responsible for a temporary drop in idle speed after coming down from higher RPM's. Especially while hot.

There may also be an idle adjustment on that car. It really shouldn't ever need to be touched, though, assuming someone hasn't already messed with it. TPS may also be adjustable. If the voltage it's returning to the ECM is higher than what it expects at idle, the ECM may not properly operate the IAC to meter air at idle. I would think any of this stuff would cause a more constant problem, though, not just a stumble as the revs drop to idle speed.

If the issue is indeed related to clutching in, I would wonder why he's saying it does it on off-ramps or that it's going to be make him crash in a parking lot. I would have to offer 'stop pushing the clutch in on off-ramps' and 'stop driving like an ass is parking lots.'

 

[XavierMace]

My old Eclipse did this on occasion. Replacing the mass airflow sensor took care of it.

 

[phucheneh]

If it's the MAF, unplugging it should force the ECM to 'guess' at the amount of air coming into the engine using other sensor data. Depending on what inputs it has, it could be a very rough guess, but it will probably err on the side of not dying if that is indeed the issue. Usually, though, if the MAF is bad enough to cause stalling, it will happen at idle in neutral, too.

Modern wire-type MAF's don't usually cause that, though. Just fuel trim codes from inaccurate reads. Or no reading, which would throw a MAF signal code. The old flapper-door MAF's could cause dying or a no-start, though.

Anything's possible. But I'd be looking at throttle-related stuff first. Again: assuming the complaint being described is what I think it is. Sometimes people's descriptions and how I interpret them don't exactly match up with what's going on...

 

[Kaido]

If the issue is indeed related to clutching in, I would wonder why he's saying it does it on off-ramps or that it's going to be make him crash in a parking lot. I would have to offer 'stop pushing the clutch in on off-ramps' and 'stop driving like a jerk in parking lots.'

I've driven it - it loses power either way, with the clutch up or down. It happens more often when the car is slowing down on a downward slope, and especially when doing a full stop, like at a stoplight or stop sign.

It always restarts right away, no hassles with that. I was thinking maybe it's an overheating problem, because it usually only happens after driving for a little while, like on the highway, but it always starts right back up again & runs fine.

 

[phucheneh]

I'm confused as to how it can die with the clutch engaged (clutch pedal up). The engine does not need any management while under decel; the front wheels will keep it spinning. If it dies, that would imply a clutch problem, which I would think you would already have noticed when accelerating.

I'm still thinking it's linked to the engine being unloaded and dropping to idle. Which says 'throttle-related' to me. I'd backprobe the connector for the TPS and doublecheck that it has the proper voltage at idle. I don't know the spec on that particular engine, but .6-.7v is probably about right. If it's .9-1v or more, it's probably too high.

Also make sure you don't have any vacuum leaks, and give the throttle a cleaning. Not a whole lot of work and I think you'll find the issue to be mostly if not entirely resolved.

Oh, also: a simple way to check the IAC is to unplug it at idle. If the idle speed doesn't change, there's your problem.

 

[BUTCH1]

I'd look for vacuum leaks, check the fuel pump pressure in addition to the IAC as already mentioned, is it setting any codes?, buy one of those $20 Ebay ELM scanners and link it to your phone or tablet with "Torque" can get a lot of info on what's happeneing as it's running..

 

[alpineranger]

Cars stalling when coming to a stop from cruising at speed is almost always an issue with the EGR system where the EGR valve gets stuck open. Fortunately they are usually fairly easy to clean. Unplugging the connector on the EGR solenoid is usually the easiest way to verify that this is the problem.

 

[Kaido]

Cars stalling when coming to a stop from cruising at speed is almost always an issue with the EGR system where the EGR valve gets stuck open. Fortunately they are usually fairly easy to clean. Unplugging the connector on the EGR solenoid is usually the easiest way to verify that this is the problem.

I'll check it out, thanks.

He wants to get something more reliable, so I may pick it up as a project car from him.

 

[Kaido]

Picked it up today, looks like it's my new project car! 150k miles on the clock.

Kicked off the work today at a local shop. New speed sensor & got the odometer, speedometer, and dash light fixed. Plus a new outer tie rod end & an alignment. Rear tire has a slow leak & all are overdue to replacement. Shop wanted $250 for new spark plugs, but Autozone had the OEM Motocraft plugs & wires for $45, so I'll do those tomorrow. Needs a fuel system cleanout too. Had an oil change late last month so I'm good there.

I have a few projects in mind for her. She'll be my commuter car, primarily for work, for the next several months. Radio is first up on the list since it only has a tape player. Crutchfield didn't have a dash kit, but I found one on Amazon for $35. There are some nice digital media receivers (no CD player, just Bluetooth & AUX) for like $99, which will be fine for streaming audio & calls from my phone. So the tentative list:

* Fix stalling issue & anything else that needs attention (tires etc.)
* Stereo system (been meaning to build an Autotuba sub)
* Dashcam DVR & blind-spot camera system project idea
* Paintjob using liquid vinyl (more details later)

It will be really fun having a 5-speed again, the sucker is basically a little go-kart. I think it still averages around 30 MPG. On the hot list is fixing the stalling issue & getting some new tires on it, after that it's all fun stuff.