That had occurred to me too, but I checked it several times.
NEVER replace parts just for the heck of it, which is what you did, you assumed without doing any diagnostics on the car.
Did you by chance when you replaced the coil did you pull one terminal off the coil, leaving the others on, then put that wire onto the new coil in the same order, and did that one at a time, or did you pull off all the terminals and then hooked up the new coil and put on all the terminals? If you did the last description you might have screwed up the firing order, get online and check to make sure you have the correct firing order to the coil.
The internet is full of things that could have caused that problem, so what you do is you start with the cheapest thing first and work your way up the ladder. But again, you have to learn how to diagnose a car. It could be something as simple as cleaning the EGR valve or the O2 sensor needed to be cleaned. Cleaning the O2 sensor you can kill two birds with one stone, the injectors will get cleaned too.
It could be a vacuum leak, those cars back then had a lot of vacuum tubes running everywhere. Spray a soapy solution onto the each hose connection and watch what happens to the soap, if it gets sucked in you found youāre problem. Or use carb or fuel injection cleaner, the same stuff youāll be using to clean the EGR and the O2, spray that stuff onto the connection of your vacuum hoses one at a time, and if the engine RPMs suddenly go up you found your problem hose. Or, if you can stand it, though I hate cigars so this one is not for me, but you can disconnect a vacuum hose from the brake booster and blow cigar smoke into it and wait to see if any smoke suddenly appears somewhere else. The smoke could come out of the head, if it does then you have a gasket leak.
There could be a problem with the TPS too, but all of this needs to be diagnosed and eliminated starting with the cheapest thing first and work your way up the ladder.
Since you did buy the coil, you could take it back and get another one, but I seriously doubt thatās the problem. Personally Iām leaning towards the firing order getting mixed up when you replaced the coil, but I gave you other thoughts just in case you didnāt, but I find it odd that it happened after you changed the coil and it hasnāt gotten any better which leads me to that possibility over all the others.
Um, your idea of mixing the firing order up on the little 1.0L 3 cylinder while changing out the ignition coil is kinda hard to do with an external coil that is mounted on the firewall (IIRC), it would only be the one ignition coil wire going from the ignition coil only and nothing at the distributor capā¦ You do not have to move ignition wires from the distributor at all to swap out an external ignition coilā¦ You would be changing out the Distributor cap in order to mess up the firing orderā¦
The ignition coil does not have a firing order, that would be the distributorā¦
If you know how to properly diagnose a vehicle, then you do not throw parts at it cheapest 1st hoping they will stick, that is what a proper diag does, is testing to confirm what requires replacingā¦
What? if you are removing the o2 sensor to clean it, what does that have to do with the fuel injectors?? Unless you are just talking about trying something in a bottleā¦
Is this an AI post??
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The engine doesnāt misfire, it surges, and only when warm. This is a 3 cylinder, if (somehow), the OP swapped just 2 plug wires on the distributor (which wouldnāt have to be touched when replacing the coil as @davesmopar mentioned), the engine would misfire badly or probably not run. Thatās not whatās happening here.
I have owned several Metros in the past. Around 1994 some of these were more complicated. A 1992 is easier to work on if you ask me.
One thing with mine that caused surging and bucking was a bad O2 sensor. If you replace it, buy Denso. I went through at least one Bosch and these cars donāt like them. They came with Denso from the factory. You might also look into vacuum leaks. Maybe a line was old and you bumped and cracked it. Maybe just replace all the lines. Buy several feet (it is cheap) and replace the old lines. Just remove a line and cut a new section about the same length. Replace them one at a time to avoid mixing them up.
It could also be the idle air control valve or IAC.
The good news is that these are super simple cars and there is plenty of room to work on them under the hood which surprises most people. I always ran the 1.0 3 cylinders myself.
I had no check engine lights for either the bad IAC or O2 sensor. These are OBDI cars so much more simplistic than today.
1992 is kind of old and the surging used to be a possible symptom of a bad o2 sensor. You may not get a code for that. I know you didnāt touch that.
NAPA used to have a cheaper line of parts called SILVERLINE or what we referred to as series two. Two names for the same thing, I know. The one for your car may be affordable. Whenever I bought a coil that did not work, I would take it back and get the cheaper one and it didnāt fail.
If your coil wire is swollen near either end, replace it. If you hold your hand against the ignition wires and you get shocked, replace all the wires. Look for a cracked distributor cap. Who knows? you might have bumped it with something hard enough to break it. If your coil has a plastic connector pull on it. If it comes out put it on right after you check the condition of the terminals. If the coil is one with an igniter under it and it is bad, your car is totaled because those things are maybe $350.
I wonder if that could be tested on an obd i car like this by simply disconnecting the O2 sensor? Then noting if that changed the surging? That will (or should) turn on the check engine light, but in order that the car still runs after losing the o2 sensor input, the computer probably switches to the cold engine a/f map, which doesnāt us the o2 sensor input.
I have some experience with a fire-wall-located cracked coil, but surging wasnāt the symptom. The symptom for that was the engine would immediately stall if the coil got damp.
This has been several years ago but the Denso O2 sensor was like $20 at Autozone. Even if it isnāt really bad, you will likely get better mileage. Mine was obviously bad enough to trigger driveability issues but NEVER threw a code. I hear cars of this era basically needed a dead sensor to throw a code and that one that was still somewhat working would not.