I'm new to your board but it looks to have some great info.

Now let me get to the problem I'm having. I have an '89 F150 5.8c.i fuel injected w/automatic trans. When I come to a stop or slow for a turn intermitently my engine will die. This also sometimes happens when I start from a stop. This seems to happen more when it's cold however it has happened when hot. I've checked the EGR, the IAC[Idle Air Control valve] (cleaning IAC did improve the idle)vaccum & vaccum lines appear good and the truck runs good at speed and idle is generally fine. When the engine dies I can start it immediately and the truck will run good again. This does not appear to be a fuel probelm, I'm thinking that it my be electronic control in nature because of the problem mainly happening when the engine is slowing down (I thought I had found the problem when cleaning the IAC improved the idle during compression slow down)but it just happened again help....

Thanks,
Mike

 

vaccum leak? I had that on a ford escort (stop laughing) and it turned out to be a little hose that came loose. Nothing fancy

 

Biohazard- Thanks
Yeah,
I thought about vacuum and I've inspected most of the lines that could find. The intermittent part is whats difficult. Slowing for a turn at low speed when cold seems to be when I can reproduce the problem a few times, but after it warms up its random,and when it happens its always when slowing from 25 or more to a stop or to "coast" (5-10mph) around a turn.

Thanks,
mike

 

You mentioned that you cleaned the IAC (Chevy term), but no mention of cleaning the throttle body itself ? You need to clean the throttle plates and the bores with a brush and some solvent....first things first!
Phil

 

Phillip,

Yes, I did a "liquid tune-up" and disassembled and cleaned all of the associated parts.Like I said earlier It seemd to help and I thought that was the problem but I had it die again this am and I performed the cleaning only an couple of days ago. BTW- IAC is "Idle Air Control" and that is a generic term used by many manufacturers including FORD for the device which controls the air mixture into the throttle body intake at idle. The Ford version uses a solinoid to control a normally closed valve. Other manufactures may use a thermal switch or a sensor which detects engine temp.

Thanks,

mike

 

Mike:

My '81 4.9 did this, in damp weather, and sometimes a light mist was worse than a downpour (?). I also had a 250 ci in-line six in my old Granada (Hey, at least it was a 2-door, 4 sp. O/D!) and after obtaining multiple weak coils from my normal "parts house", a.k.a., the boneyard, I've concluded the stock coils have a tendency to go lame.

Take the coil off the block (easy way is to slide it out of the clamp, if possible) and shake it. If you hear the "coil oil" sloshing, that's not good. I think it means some leaked out. Anyway, it shouldn't slosh.

Do the water spray test at night and watch all the spark leaks--you may find you had more problems than you thought, and it's a good party trick, if nothing else.

While the cold temp. thing is different, my sixes would stall when slowing down, and also when taking off, just like yours. Good coils and new wires pretty much cured this. BTW: after trying several aftermarket (but not racing quality) plug wires, I listened to the Ford techs at work and now use only FoMoCo plug wires and caps, and things are definitely improved.

Let us know.

BigSix

 

Bigsix,
Interesting therory, I was having a problem with the coil wire arcing at the coil just before this started happening.I replaced the coil wire and that corrected the arcing. I have never heard of a coil "sloshing", since air would be requireed in the coil and since they are filled when assembled there should be no air inside unless some of the oil leaked out, which I should be able to see. I will give this a check, it has been raining lately and I do notice similar symptoms to what you discribed.

Thanks,
mike

 

Have you tried replacing the air idle control valve. My 94 F150 would idle normal then the idle would start "bouncing"
up and down until it would finally died. I would also die if i was going fast and suddently braked. When I repaced my valve it was close to $50 bucks so it's not a cheap fix but not all that expensive either. Good Luck!

 

There is a procedure for setting the idle screw on the throttle
lever. The car I was working on (Ford SVO Mustang) had an
idle rpm you set with the IAC disconnected. I think it was
500 rpm. The rpm the car was to supposed to idle at was 900rpm.
You can see how the balance of air from the buttefly vs the IAC
is probably important to how much control the computer actually
has on idle speed. I think I would experiment by opening the
throttle butterfly more or less and see how this affects your
problem. Count the number of turns so you can put it back,
unless it's messed up anyway, in which case you might want to
get a factory manual and set it by the book.

 

Thanks for the tips. I tested out the the IAC (10.7 ohms is with in the acceptable range of 7 to 14ohms). After cleaning it the truck did run a bit better and the IAC appears to be functioning properly. I will take a look at the complete system again this weekend.

Thanks again for everyones help,
mike

 

I had the same problem with my 86 F150 302. The oxegyn sensor had to be cleaned out and that solved the problem. Good Luck

C' Ford man

 

Hey just a suggestion, My 1986 F150 efi 5.0L would do the same thing. I replaced the throtle position sensor, located under the throtle body and have ot had the prolem since.

 

I didn't have a chance to check the system out this last weekend , but I did take the truck on a 400 mi. trip ..no problem.

Today I drove the truck today for the first time since the trip and after warming it up for a few minutes it died while waiting at the first signal light I came to after I stoppped and while I was waiting for the light to change. It seemed to run just a "bit rough", hardly noticible, before it died this time. Almost like a fuel pressure problem but this was only for a second or two and then it quit (at this point I'm pretty sensitive to any changes in the idle and this was a minor but noticable change). It started right up and didn't die again. Before this I was also thinking about the throttle position sensor but this latest symptom doesn't really fit that therory.

Thanks for the help please keep the thoughts coming.

mike

 

Mike:

How'd you make out with spraying the ignition wires and coil w/ water, at night, w/ the engine running, to check for spark "leaks"?

Also, was it dry during your 400 mile trip, then wet the next time you drove, when it stalled again? The reason I ask is with the bad wires/weak coil on my '81, it would also start right back up again, just like yours, and for reasons I don't understand, it would not necessarily stall again at the next light, even though the wet weather was the cause of the stalling to begin with. It was kind of like it just wanted to "remind" me it had a spark problem, but didn't want to be too much of a PITA.

Henry built 'em simple, and sometimes the answer's equally simple. Hope this is the case!

 

Bigsix,

I was thinking it may be related to the moisture(it generally happened in the AM and it has been raining or cool with dew in the morning). But the trip I took was up to the Sierra's (I live in the SF bay area). It was raining and snowing through out the weekend and as I said no problem. I still intend to give all of the suggestions here a try once I get a chance to give the system a complete once over. The problem with intermittent problems is the difficulty in reproducing it to identify the symptom and then find the cause. At this point I'm still trying to figure out whats happening before it dies. I figure if I can get to that point I won't be far from solving this mystery.

Thanks again,

mike "I'm learning way to much about the Ford fuel injection system"