Stalling Continued, Please Read - AGAIN

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Chris Kulbaba

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Well I thought I had my stalling issue figured out, but I had it act up again the other day a couple times.



I want to explain again exactly what happened, to see if anyone here has another idea for me to discover... I really want to fix this problem, badly.



I can drive my ST around town for abour an hour or so, then all of a sudden when I come to a stop light, the speed needle slowly drops on its way to zero. When the speed gets down to about 20km/h the RPM needle will slowly go down to pretty much stalling, it doesnt stall immediately. It will sit at this terrible idle speed where the engine seems to be working pretty hard to keep running. Once I realize its happening (usually when I see the RPMS drop under 400 or so) I put it in neutral. It idles properly, I rev the engine a couple times to be sure, and put it back into drive, and Im on my way. Sometimes after the first stall I can drive around for 10-20 mins, wihtout any problems while stopping or taking slow corners. And sometimes it happens at the next slow turn or stop. One thing to mention is. If I *DONT* rev the negine a couple times before putting it back into drive, it stall immediately. I pretty much HAVE to rev it a couple times over 3000rpm to get it to drive after almost stalling out.





I have done the following things to try to solve this mystery.



Cleaned Air Filter

Cleaned MAF Sensor

Cleaned Intake, Manually and with Seafoam Cleaner

Cleaned IAC (2x now)

Disconnected Battery for 4hrs (I just left it off and did some other stuff for a while)

I had it into a tranny shop that says everything looks 100%, no metal shavings or otherwise in the pan.

I Held my finger over the brake booster line as suggested by ToddZ, it idled fine.

I changed the PCV Valve

I changed the EGR Valve

I changed the entire vacuum line from under the throttlebody to the PCV valve

I changed the Fuel Filter

I wiggled my Computer Connection under the hood

I made sure all pulleys, etc are still moving, and not bogging down the engine from what I can tell.



I want to get pretty much every mod ToddZ sells for the ST, but I cant do that until I solve this issue, please give me any ideas on what I can/should do.











 
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Maybe Replace the IAC not just clean it... THE motor could be bad in it ... .... I posted on Adams thread, but you did what I posted....



Unless the reverse idle kick system is malfunction, but that is computer related..



try checking the TPS voltage, or raising the idle screw 1/4 turn.... It sould like the truck doesn't know it is being put in reverse...



I wounder if you tilt the steering wheel a little if the column wires are not getting a good connection to the computer to tell it the truck is in reverse and to raise the idle..



Todd Z

 
Mine isnt an issue in reverse. Its ONLY when I come to a stop by braking after an hour or so of driving... thats what mystifyign me. If it was a constant problem, I think it would be easier to identify.



What changes after the engine is quite hot? I dont understand it at all.



 
XST. my neighbor just had some problems w/ his dodge truck. carried it to the shop and they switched out 2 sensors and that still didnt fix it. come to find out the problem was a stopped up cat. convertor . I dont know but maybe just a suggestion. And in the beginning he thought he had transmission problems. And the shop thought it was his idle air sensor but it was the cat. converter.
 
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Throwing this out there... On my 65 t-bird I had a stalling problem at low rpms. After I checked virtually everything I found a filter in the gas tank that was clogged to high hell. REplaced it and TADA. The pump would pull gas thru at higher rpms but not lower rpms. not sure if the trac has a gas tank filter but i would assume it would. maybe u just have alot of crap floating in that tank.
 
The egr valve take the exhaust and burns it in the engine during highway cruising to reduce emissions, lower exhaust temps and promote better MPG....



The egr could be stuck open or the switch telling it to open could be leaking and allowing vacuum to the valve at idle..



once the engine is warm the 02 sensors and temp sensor are of importance...



I wounder if it is the temp sensor or the 02's.... and the computer is not throwing a CEL thinking all is fine...



Todd Z
 
Could the trans shop be wrong and the torque converter is locking up. Maybe when you put it in nuetral and rev it, it is unlocking. From your explaination, sounds like something is luging the motor down,as if a clutch that doesnt disingage...
 
I had a 1995 2 door Explorer do the exact same thing, in 1996. It would die in reverse, in gear, at stop lights; just a random. I left it at the dealer for a week and finally they duplicated it but didn't really know what the problem was. I meet with senior Ford Tech Repiar guy didn't know much about it either.



They almost stripped the car down replacing almost everything and it turned out to be casting sand from the radiator was clogging causing the stall.



First thing is I would check the coolent bottle. If theirs sandish like material around the top of the weep hole, have it change. The sand is causing the stall. Even though I'd never get a check engine light or engine temp was normal, it would still stall because of the sand in the radiator.



Just a suggestion.



Big Al
 
The problem sounds heat related.



There was a thread on here not to long ago with someone having issues that were heat related. A rubber hose was collapsing and causing idle problems or something. When it was cold, the hose was firm and fine. Once hot, it would become sort of elastic and collapse on itself. Not sure if it was a vaccuum hose or something...........might check into it.
 
Yes that was me ;)



I thought it was my answer, but it wasnt :(



Yeah I was almost positive about the lockup solenoid not unlocking the torque convertor or whatever...



Its pretty much the only thing that MAKES SENSE. But why would it only lock up after being warmed up.



I am so confused.



When I complained about the squeeling noise under the truck to the people that fixed the tranny, they said the noise was coming from around the CAT, and it was almost like a whistle, not a squeel... The whistle/squeel only started after my tranny rebuild.



Shesh, I just dont know what to do, lol. I dont want to take it anywhere, cause its a lot cheaper for me to fart around than thave them fart around fixing stuff.



Is my only hope to leave it at the dealer? I guess if I could snafu a tech after it starts doing it and get him in there we can go for a drive. The problem is no one wants to ride around town for an hour and then it not happen, so they seem to just give it back.



The transmission place said that if the torque converter or lockup solenoid wasnt disengaing or whatever it would stall IMMEDIATELY, not just sit at a really low idle speed.



Thanks for all the opinions so far, keep em coming. I want to get to the bottom of this mess... I love my ST, but she is really pi!@#$ing my off righ now. hahaha.



 
I am still lost as to why my ST is acting up. Im actually having thoughts about getting rid of it... which is a pain in the arse, with all ive done to this thing...



Anyways...



One more thing that I can add to the information as to what happens when it stalls out on me.



When I leave it, it does stall, just takes a couple seconds.



ALSO, When I use a XCal tune it still stalls, actually more often and sooner that without.



This give anyone any ideas?
 
XST,

As Todd said, it may be the control for the EGR rather than the EGR. The EGR (Exhaust Gas Recycling) injects a small amount of exhaust gas into the intake to reduce emission and reduce combustion temperatures.



The EGR should be closed at idle since even a small amount of exhaust gas will upset the precise idel mixture and will cause the engine to run rough and stall. When operating properly, the EGR only iject exhast gas into the intake mixture only when the egine is operating above idle and at full operating temperature. Since the EGR is controled by vacuum and temperature controls, it sounds as if one of the controls is failing once the engine gets to operating temperature and not shutting off the EGR at idle.



It is not the EGR valve since it starts and runs fine until it warms up. If the EGR were sticking, it would be stuck open all the time and whould cause the engine to stall immediately....and you said you replaced it.



You should examine and test all the EGR controls and temperature sensors, as well as all the connections and vacuum lines associated with the EGR.



You best investment would be in a good repair manual for the Sport Trac/Explorer for model years that have the same 4.0 SOHC V6 engine



...Rich
 
Have you tried doing any datalogging with the Xcal2? Maybe you can see something in there that will shed some light on the subject :)
 

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