Stalling problem at idle return

[JoesSHO]

Gotta help me out here, V8 gurus- I don't know these V8's yet! Here is the situation with the new ride...

Car drives great. Starts fine, runs fine. Not as fast as my '95 MTX but a much tighter ride. However, here is the first issue...

When you are coming to a stop and the car is returning to idle, it has a habit of stalling out. Not all the time, but a fair amount of the time, maybe 1/2 of the time?

Here is the weird part- when it stalls, if you try to start the car back up from the key on (run) position where it was when it stalled, it will not start back up. However, if you turn the key off, then start the car normally, it fires up like nothing is wrong.

One time when I was driving it, I made the "Michigan u-turn" on Lapeer Rd., and it didn't quite stall, but it was blowing black smoke out the exhaust, like it was dumping fuel or something, then it petered out and acted just like described above. Only time it did that, I think because I was getting back into the gas just before it stalled. Coasted to a stop, turned key off, started up again like nothing happened.

Usually, it just loses it and shuts off around idle. When I got there to pick the car up, started it up no problem, no smoke at all- it ran, idled for about 30-45 seconds, then just quit. Get in, turn key off, then start, all is well in SHO land.

I thought that it was an electrical issue, possibly with the rear bank wire harness, from reading around, but haven't pulled anything apart yet, since I just got it home tonight. I thought electrical because of the key must be turned off to cut power before restarting thing...

Anyone run into this before? I'll keep searching, I just wanted to get it on the board...

Thanx!

 

[wuzzzer]

Alpine green? Is it a repaint?

 

[JoesSHO]

oops! I'm such a noob. See other paint post question!

 

[SHOZ123]

One way to see if it is the IAC is when it's stalled and the key is still on try opening the throttle with the gas pedal while cranking.

 

[Ian Macoomb]

I had similar issues just before my first coil went bad. It hasn't happened again in over 4 years.

 

[1QuickCoupe]

Holy crap!!! That is the same thing that is happening to my car. I have replaced the fuel pump, and filter, fuel pressure regulator, TPS, IAC, cam and crank position sensor, set the throttle gap, and cleaned the MAFS. The guys on here suggested that I replace the MAFS. The "happenings" only happened about half as much after I cleaned the MAFS, so I am on the look out for one for a decent price. It doesn't throw any codes, so that is not even an option in my case. Mine also will not start unless you cycle power Good luck!

 

[Mr. SHO]

If you did all that crap and didn't find the problem, you may need to do what I did... clean and WD every connection you can find under the hood, and triple check all the ground points. It's amazing the crud you'll find in some of those connections, and there's usually at least one loose ground connection.

 

[JoesSHO]

I am currently waiting for the previous owner to let me know which coils he had replaced last year, and I am going to order two more, (two were replaced) I will replace the back bank, and go from there...

Oh- that and I'm waiting for it to drop back below 100 degrees in my garage...!

 

[SuperHO]

Lemme know when you plan on doing that. I'd love to come and help you yank that intake.

Of course, beer will have to be involved. And you might as well change your plugs while you're at it.

 

[JoesSHO]

plugs changed 3,200 miles ago when he had the two coils replaced... I'll buy beer- as soon as it's under 100 degrees... Well, I'll buy beer before that, but they won't be consumed in the garage until then...

 

[Mr Anonymous]

Start with the fuel filter and check fuel pressure. Still could be a coil, but inability to fire right back up suggests a fuel flow issue.

 

[Want.to.be]

i had the same problem and the dealer replaced #8 coil. A few weeks later the car is doing it again.

I am taking her in for another check and see.

jpc

 

[JoesSHO]

I have a fuel filter and will replace that as soon as it is warmer in my ovn than it is in my garage... It's bad when you walk outside from the kitchen and your glasses fog up and you can't see. It seems to b a bit humid...

I think coils and fuel filter will solve it... I'll post updates...

 

[SHOZ123]

I would have an occasional stall when dropping to idle. Here is what i did to fix.

Check out the throttle plate and the thottle stop. It should be open just a bit so it does not completley close and bind.

With the throttle closed turn the throttle stop screw in until there is .05" or 2mm clearance. The turn in one half turn. Clear the PCM memeory and drive away.

 

[JoesSHO]

I'll have to check that out too... Need to go over the car, being that it's been here for 4 days and I haven't laid a finger on it yet.

 

[Muck]

Random stalling

My vehicle (97 SHO) doing exactly, or almost exactly the same thing also. Funny about the cycling of the ignition, I discovered that right away, and figured it had to be the electrical spike created, or, the act of "clearing" the temporary pcm memory, 'cuz then it fires right back up, like you said. Try to start it from the run position, and it acts as 'tho the rev limiter is kicking in at 1,300 rpm, it chugs and blows black smoke, etc. I also have replaced: MAF, Tps switch, plugs. I noticed one new coil in the back bank, cyl. #2 Fuel pressure check out at about 35 - 40. So, I'm somewhat stuck. I've only had it for 6 days, my last SHO was a 1994. Chuck

 

[JoesSHO]

Mine was cured with new rear coils, so I suspect one (or more) were bad...

 

[Muck]

Coils

Of course, now my question is this: Since this coil is not exclusive to the SHO, why is there no aftermarket coils for this application, for say 40 - 50 bucks a coil, which is plenty?:laugh_ti:

 

[SHOZ123]

But the coil is exclusive to the SHO due to its physical shape. The other Fords that use COP don't have the valley in the valve cover where the coils nest. So they all have the mounting tabs at the bottom of the coil body vs the top like the SHO and have a lot longer boot.