Electrical problems - please help

[Rogo]

I am the new owner of an '86 MarkVII with 113,000 miles. I am not sure if its an LSC or not, I dont know much about the model. The problem I'm having is this; If I leave the battery connected overnight something drains it, and I am unable to start it up. The previous owner also told me that the car would occasionaly shut off while driving, but I have not had that problem yet. I'm wondering how big of a problem it is, if its a simple wiring problem, and how much I should expect to pay if I take into the shop. The car is going to drive me across the country come this next Monday (the 28th) and I want to make sure its in good condition. Any help would be greatly apreciated!

[Rogo]

by the way, its a brand new battery.

[Lscman]

Battery drain could be countless things. A DC clamp-on ammeter will trace the current through the harness to the source. An alternative is to systematically begin disconnecting plugs and pulling fuses until the current goes away. this would need to be done with an ammeter in series with the battery terminal and wire. Either way works. I am assuming you verified the batteries capacity to hold a charge. Most large auto parts stores will do this for free.

[Charlie]

Battery drain could indeed be a number of things. The first thing you could do is to remove you under hood and trunk light because they often get stuck on. Over nite is fast those lights are not that big of a draw but, it is a easy one to check.Your alternator if bad could also be causing a draw even when the engine is not running. Any compent shop should be able to check this out in a couple minutes. The other thing you may want to check out is the igniton switch. These cars had falty ignition switches the could cause all sorts of wierd problems. A new one is less than 20 bucks. Even if that is not the cause of this problem you may want to change it anyway because they have been known to start a car on fire even when it is shut of. I kinda feel that you should check this out. It could be your problem and you are getting close to haveing a fire. Remember I am just another car owner like you I am no expert.

[franco]

I agree with Charlie. Start with the simple things first, always. Sometimes it's as simple as a bulb.
Also, have that alternator checked out asap. I feel that this may be the problem, but if not at least you've ruled it out.

[Rogo]

So I went and got the moter checked out by a good shop, and the guy said the regulator wsa drawing on the battery. The thing had scum oozing out of it. So i slapped a new one in there and everything seems to be hunky-dorey.
But I had another question if anyone might have an answer. This is my first MarkVII, and I noticed that the idle seems to be pretty irregular upon startup. After about two or three minutes it evens out and idles pretty low. I was wondering if there was something that regulated it that way on purpose, or if this engine is just old enough to be a little cold or something.
I dont think its a big deal, I just want to get as familiar with my new honey as possible. Thanks for all the help, guys.

[woodybjr]

The idle irregularity you are speaking of is quite common on these cars with the EEC-IV computer controlled engine. I recently purchased an '88 LSC. The man I bought it from has replaced everything that has possibly went wrong with the car. He advised me upon purchase that the car would "hunt idle" for 15-20 seconds at the initial start up of the day, he "claims" the software that was used back in the day of these cars was somewhat crude and did have some imperfections. I have done alot of searching and have really found no solution to the problem yet, and I suspect I never will. If every sensor and valve has been replaced and it still does it, I am assuming its a little gremlin that will stay with these cars. Enjoy your RIDE...Woody

[pro-five-oh]

Woody, there is no reason for that hunt. Is your Idle-Air Control valve (the cylinder mounted on the throttle body spacer) new? If not, clean the old one.

[woodybjr]

Yes - the IAB is new -- took it off and checked it out. All parts are moving free. The EGR is new, has new O2 sensors, ACT sensor, ECT sensor. Mine stalls on the first start when the engine is cold. Second start, I get the "hunting idle" for 15-20 seconds. After this, the idle is stable and the car runs good. I have also noticed that if I try to take off on a cold engine I get some hesitation. Do you think its a bad IAB still? I have my suspicions but really dont know where else to look. Have no check engine codes either. Woody

[pro-five-oh]

Woody,

I am surprised that your car is doing this, and there is a cure for it.

There is a sensor called the "EGR Vent" that bleeds off vacuum off the EGR. If the filter for the EGR vent is clogged, the cold idle will suffer. It is a cylinderical shape thing located on the passenger side fender near the strut tower. There is a cap which you remove and then pull the foam filter out and clean it will soap and water. The car won't run without that cap on...try it!

Secondly, have you checked for vacuum leaks? I had a very small one from the intake that killed my cold-idle and eventually hurt my gas mileage. After I found it and replaced the hose, the car idled like new.

[ October 25, 2001: Message edited by: pro-five-oh ]

[woodybjr]

Well I just got finished with cleaning the filter on the EGR Vent Sensor -- man was it dirty. Had to wash it 4 times w/soap to get all the dirt out. Its pretty safe to say it was clogged. I wont know for sure if it worked till in the morning after the car sits all night. I will post a follow up tomorrow to let you know how it went. Thanks for the help!!

Woody

[woodybjr]

The filter cleaning did the trick. No more wondering idle on cold engine start up and no more stalling on a cold crank. I did bump up the idle a little bit (it seemed a little low while in gear). No "gremlins" right now.

Thanks for all the help pro-five-oh!!

Woody

[Lscman]

"Double starts" are common on Ford products. They had recalls on several non-5.0L vehicles to install secondary in-line fuel pumps (Tempo etc). Check fuel pressure, man. There is a fuel check valve that prevents loss of pressure when parked. There is also a unique fuel pump circuit that precharges on key turn before the start position is reached. This circuit could be bad. Install a gauge and monitor injector rail pressure on startup. If it momentarily sags below 30 PSI, fuel pressure is the culprit. Also, it could be a control wiring problem. Don't assume that all CPU outputs and end devices are working just because you changed the control gizmo at the end of the wire. Wiring grounds and opens are common on 10+ year old vehicles. The idle air valve on the throttle body is augmented by a mechanical screw limiter on the throttle body linkage, just like a 60's carb. This reduces overshoot and hunting. You should disconnect the wire to the idle bypass valve and set the screw for 700 RPM or so when hot. Sometimes this will correct stalling on startup.

[ October 30, 2001: Message edited by: Lscman ]

[pro-five-oh]

I had a feeling that the EGR Vent was the problem! :D

If the old foam thing is really beat up after washing it, get another one from a 1986-up Ford car in a junkyard.

[WILLIAM SHIREY]

Is there an EGR vent filter on an '85 Mark as well? I'm having idle problems and just wondering if this was something else I could check. Thanks. :mad:

[pro-five-oh]

William, yes you should have the same thing. I don't know where, but I'd guess its in the same place.

[Michael VII LSC/SE]

:D :D Pulled kthe cap and cleaned the foam. Didn't appear too dirty jbut athe results were as promised. I waited till we had a few cooler mornings before I responded. The searching for idle is gone. :D :D But the idle goes to 1800, 2000 down to 1250 up and finally after 10 or so seconds goes to 750 and holds. does this sound normal? I don't like those early high rpms on a cold engine. :confused: