Strange Electrical Issue with my 1986

[Michaelman]

I own a 1986 Mercury Cougar and I know it's not a Thunderbird (I really wanted the Thunderbird but this one was dirt cheap) but the cars are the same in almost every aspect other than the body style. It is a 2.3L turbo with a 5-speed. The car is a joy to drive, but recently I have had an issue that has rendered it undriveable. One day I was driving it and I noticed some slight surging even while in gear. I came to a stop and the car was bouncing between idle and 0 rpm like crazy, like some kind of crazy misfire, as if only 2 spark plugs are firing at a time or something. I turned the car off and towed it home. Now I'll start it and for a second it will idle high and then it will start doing the misfire again. I was told it might be a ground problem and my ground battery caliper was pretty filthy so I replaced it and still have the same problem. The belt looked a bit loose so I tightened it, only to see if it would change the issue because maybe the alternator was slipping, but it still ran exactly the same. It seems to get even worse when I try to turn on any lights or accessories like AC so I'm more inclined to believe it is an electrical problem. Has anybody had this problem or have any suggestions? I'd really appreciate any help at all. Thanks.

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[Dlluinstra]

How old is the battery..check positive connection also. ECU connectios, ground, distributor loose, condition. Frayed wires. Intermittent grounding.
Just places to check.

 

[OneAmongOthers]

Pull the codes. There must be a way to get the codes. Start with the codes and see which ones come up. It's sounds like something with your fuel injectors or possibly something with the ignition system itself. If all else fails take it to a shop and have them perform some diagnostics on it. You need to find the EXACT problem so you don't just start throwing parts in some vain attempt it may fix your issue. If you are not sure or not mechanically inclined DO NOT attempt to fix this as you could possibly do more damage than good. Also I recommend you do a little research on this youself as most of the 80's era Tbirds and cougars are not really popular vehicles so you would be hard pressed to find help with them.,

 

[40birds]

Not sure if this is against a forum rule but there is a site devoted to these Fox body birds and cougars, I used the site a lot when I was playing with mid 80s birds/cougar. I had a 86 xr7 also, stupidly fast car actually. I’m sure there may be some insight on there. There is also a site devoted to the four eyed fox bodies that might offer some insight. Not saying it is your issue but I had a 87 that did similar to what you describe. Tried numerous things and found it by accident. I had the hood up and hadn’t turned all my garage lights on yet and had my son start the car, it was then I saw a spark, my battery cable although it looked good was coming apart inside the cable end(it was the original) and as the car would flex while driving turning etc it would put enough twist on the cable to act up. Good luck with it and hopefully it’s something just as simple. If you can’t find those sites message me and I’ll let you know