'87 Colony park turned off during movement!

[JesusGM]

Hello guys!

I would like to tell you my experience past few weeks with my ´87 Colony Park 5.0 EFI.
in 2 different moments, the car suddenly turned off while i´m in movement. I consider this very dangerous since I lost many functions on the car or at least does not work properly (steering, brakes, transmission, etc...). My city in Chile has many hills and I don´t want to be in that situation when I´m in a downhill
After the car turned off, I try to start again and the engine runs again without problem, but with the fear that this occurs again. Today, after this second episode (the first one was about 1 week ago), I park the car, run the engine in parking for a while, and turned off again. start again with the key, and again the same after a few minutes. (no warning lights remained on in the dashboard).
For the record, I have a similar problem when I bought the car 1 1/2 year ago, but it was the Ignition module, apparently. So, 1 year ago I changed: Ignition Module (Motorcraft), Ignition Coil (Motrcraft), Spark Plug and maintenace to all the electric sistem. That time, the car turned off and won´t run again after the engine gets cold again, but now it stop is sudden.
My other problem is that the car stop when i made short movements, when I´m parking for example, could it be related?

Any ideas to begin the investigation of the problem, in the past your wisdom made a correct diagnosis!
Thanks and regards!

[sly]

check the connector to the ignition module on the distributor. If it's loose, it could be losing contact momentarily. I had this issue with the 88 MGM I used to have and solved it by pushing the plug on and wrapping a tie around the clip and module to help mold the plastic of the clip back into shape. After a week, I took the tie off and never had an issue after that.

It could also be a loose connector to the ignition switch that you already replaced. Definitely check that to make sure it's not loose. It could also be the ignition module having heat soak issues (going bad). If this involves high humidity or rainy days, it could be a crack in the ignition coil. If you lose all electrical (all warning lights go out and no power to the radio or lights) then it's probably a ground issue to the battery, body, engine or the positive battery cable. If you only lose engine electrical (no warning lights, but still have the radio and lights) it could be the small black wire at the negative battery terminal is loose. That's the ECM ground. It must be secure. If you lose warning lights and radio, but keep lights, it's probably the ignition switch.

[Mainemantom]

I have the same problem on my 83 Merc. No one has been able to fix it. Many parts thrown at it. Many $$$. I will have to check all of those items myself. I am sure it is something simple. Maybe even a broken wire.
I was thinking maybe a occasional blockage at the fuel pump ?

[JesusGM]

Thanks for the detailed explanation, Sly!.

I will check connections of the coil and ignition module. If I remembered well (I was kind of nervous when this happened), the car seems to "loose power", turned off and the warning lights on dashboad were on, as usual when you turn the key for contact, exterior lights were on, don´t remember about the radio. The strange of all this situation is that the car turn on again inmediately after each episode when I turn the key, when I have problems with the ignition sistem, the car didn´t run again after a while. When you have this problem, your car ran again inmediately too?

About the crack on the ignition coil, certainly we are on winter here, but could this happen even if the coil has 1 year of use?. (please, excuse me if I have some english gramatical fault

[JesusGM]

I have the same problem on my 83 Merc. No one has been able to fix it. Many parts thrown at it. Many $$$. I will have to check all of those items myself. I am sure it is something simple. Maybe even a broken wire.
I was thinking maybe a occasional blockage at the fuel pump ?

Also think about the fuel pump, but the pump and all filters were replaced on mine, unless that the pipes are blocked before. Also, I hear the fuel pump working, even with the car turned off.

[dan]

Try the IAC valve. Clean it. Had that problem with my 90 grand marq, it would suddenly turn off but i could turn it back on and ran fine. Replaced it and had no more issues.

Sent from my LG-LS997 using Tapatalk

[jaywish]

If I understand you correctly it has only shutoff when at idle and using the power steering?

[sly]

Yes... coils can crack after only a year... parts quality isn't all that great any more and old stock parts are more likely to do so. It's not common though.

[gadget73]

Bad relays or relay connections can also be an issue. The sockets on mine were in bad condition when I got it. The insulation on the wires was gone and the wire inside was mostly green fuzz. One of those relays is fuel pump, the other is computer power. Losing either will make the engine shut off. Might be worth checking those out or tapping them to see if it acts up.

[JesusGM]

If I understand you correctly it has only shutoff when at idle and using the power steering?

In part, it was the first symptom, when I park the car in reverse or doing many movements, but lately, the car shutoff when I´m driving and now, at idle.But the engine stops suddenly, without warnings.

About the relay, I change the relay of fuel pump when I change the pump, only for prevention. I will check all your suggestions and try!

[JesusGM]

Try the IAC valve. Clean it. Had that problem with my 90 grand marq, it would suddenly turn off but i could turn it back on and ran fine. Replaced it and had no more issues.

Sent from my LG-LS997 using Tapatalk

Where is located the IAC Valve?
Thanks!

[dan]

Its on top of the throttle body. Its a cylinder shape

Where is located the IAC Valve?
Thanks!

Sent from my LG-LS997 using Tapatalk

[sly]

IAC - Idle air control valve... on the firewall side of the throttle body.

Should look something like this.

[JesusGM]

Is this the IAC valve?. Just noticed that a connector is unplugged!. Maybe is that the problem?
I think that it was done for someone in the past, because looks not so easy to unplug with the engine movement. Could be any reason to leave it unplugged?
Also, the valve needs a manual cleaning or need a clean with some chemical?. Still not remove it to do it well!

[VicCrownVic]

Yes, that's your IAC. That one does not look original so maybe the electrical connector doesn't fit and that's why someone left it unplugged? Or maybe it was just unplugged by accident. Plug it in and let us know what happens.