Check engine light related to bad vibration and messy idle.

[mclarensmps]

I just changed the alternator on the car last week but didn't get to take it out on too many occasions after that. Car drove perfectly fine the 3-4 times i took it out, but yesterday I had to go down to the store to grab a few groceries and when i started the car up it was totally fine. It was extremely cold, but my car is in underground building parking so the initial startup temperature was around -5 -6 degrees C. After letting the engine warm up for 2 minutes i drove it to the store and it stood out there for about 3-4 minutes with the drive there being 5 minutes (-14 degrees C, coming to -25 with windchill). As soon as I started the car the check engine light went on and i could feel a vibration through the gear shifter as well as from the front end of the car. Also the idling was going up and down slightly and i had to keep the car over 2k revs to keep the vibration minimal and to keep the car from stalling because of the bad idle. I did not take it over 3k RPM because I don't wan to overstress the engine so i drove it b/w 2-3K rpm.

I started up the car today for about 1 minute just to see if the problem was better or worse and the idle was jumping between a few hundred rpm and 1.5k rpm. The car is due for an oil change soon (3 green lights) which i am planning to do in the coming week, however, i think the problem may be more severe than just an oil change. Any suggestions as to what this could be?

The vibration is definately engine related as it is clearly coming from the front end and transmitting (somehow) through to the gearbox. (The gearbox also needs a tranny fluid swap, however, even in neutral and with a fully engaged clutch im feeling motor vibration in the car.

It's getting kinda stressful as I am going to be needing the car for a lot of work very soon and the last thing i need is for something really bad that needs to be fixed in the motor .

Any input will be helpful guys, thanks in advance =)

 

[grc]

it's a 92, have you ever changed any of the vacuum hoses or the intake bellows?

 

[Kirby]

Since it was running fine after the alternator change, they are probably not directly related, other than grc's comment. While changing the alternator, you may have disturbed hoses or unrelated electrical connectors. Check everything around the alternator and the mass air flow meter.

Did you notice a loss of power? I'm guessing yes. Sounds like it might be missing on 1 cylinder. In a 4 cylinder engine, the vibration will be very noticeable when just 1 cylinder drops out. I don't know if the 4 cyl. has 4 coils, or 1 or 2 coil packs. I would check for spark at each plug. A tedious job, but a sure check is to run the car for a minute, then pull all 4 spark plugs. If a cylinder is not firing, the plug will be cold, and wet with gas.

 

[mclarensmps]

cheers guys, the plugs will be the first place i will check today, and take a look at the vacuum hoses as well. My friend has also suggested it may be the coils, so it is a good starting point. I'll keep you guys updated on what happened (it definately does sound like one cylinder is not firing)