Replaced dead battery, now its running like SH*T!

[sonick]

So my '90 Grand Prix STE ran out of juice a few days ago, and we had the battery replaced with a new Interstate one.

 

Ever since then, the car has been running REALLY poorly.

 

First off, the engine sounds HARSH, with vibrations and a harsh rumble.

Secondly, when idling, the tach, oil pressure guage, and the voltmeter will jump up and down, the Tach occasionally plummeting down to ~600rpm.

Also to note, a mechanic friend of mine told me the engine was running lean due to the smell coming from the exhaust.

 

Last night the engine stalled on me about half a dozen times in the ~45 mins i was driving around town running some errands. I found that when I turned on the AC last night, the car would immediately die on me.

 

Today I drove around, it was not as bad, it cut off twice right after I started the engine and shifted into Reverse.

 

My Dad says something similar happened the last time he replaced the battery, and that the engine computer had been 'reset', and it would settle down after a bit. He had it quicky checked out, the mechanic said he adjusted the idle, and cleaned out some valve that controls the idle, but to no avail, it stalled right when I backed out of the garage.

 

Anybody have any input on what the problem could be?

 

So sad, just 4 days ago it was running (somewhat) smoothly, now its just painful hearing the engine struggling.

[Supreme Cutlass]

It's called an idle-relearn, and you should do it after changing the battery. There's a full writep in the FAQ section.

 

1. Reset ECM by pulling ECM fuse (underhood) for a few seconds.

2. With A/C turned off, start car and immediately put it in Drive with your foot on the brake.

3. If the car does not start initially, keep trying WITHOUT putting your foot on the accelerator.

4. Let the car idle in gear for at least 5 and no more than 7 minutes.

5. Shut off the car for 10 seconds.

6. Start engine, place in drive and let idle for 5 minutes.

7. Shut off engine.

8. Idle is learned.

 

Following that word for word helped me, and it'll probably help you.

[cutty]

you can try the idle relearn like mentioned above, but sounds to me like the alternator is on its way out.

[Robby1870]

you can try the idle relearn like mentioned above, but sounds to me like the alternator is on its way out.

 

I agree.

[sonick]

Thanks for the tips. I tried the idle relearn procedure. It seems like its ilding more steady now, but the engine itself still feels like its running a bit rough. I'll see how it is next time I go on a drive.

 

However, the ECM fuse for my 3.1 was not underhood (it said 3.8 ECM, and there was no fuse in that position). I found the fuse labeled ECM in the glove box fusebox, pulled that, and put it back in after a few seconds.

[pitzel]

If the voltage is bouncing around, it sounds like your voltage regulator (built into your alternator) is on its way out. I had that happen to my new alternator as well (the Iceberg Alternator, from Alternatorparts.com). Ended up swapping the regulator out of my old alternator (with the failling diodes) into the new alternator to correct the problem.

 

Diode failures manifest themselves as flickering displays, and bearing failures manifest themselves as noise. I would definitely look towards the alternator though as the root of the problems.

[SigEpCutlass]

If the voltage is bouncing around, it sounds like your voltage regulator (built into your alternator) is on its way out. I had that happen to my new alternator as well (the Iceberg Alternator, from Alternatorparts.com). Ended up swapping the regulator out of my old alternator (with the failling diodes) into the new alternator to correct the problem.

 

Had the same thing happen to my alt. I'd suggest you replace it before you get stranded somewhere.

[jeremy]

<----another person who thinks that it is the alternator going bad...at least they are an easy fix on the 3.1

[sonick]

Okay, so the idle has settled down for the most part. It starts up fine, and when I apply gas it sounds okay, but after 5 minutes and I get to a stop-light and let it idle, it starts idling harsh again, with the Voltmeter jumping up and down. After a few more minutes of driving, if i let it idle the oil pressure starts jumping up and down as well, along with a small variations in the RPM's.

 

Perhaps the new battery is exposing a weak/dying alternator that the old weak battery did not? Does that make sense?

[cutty]

well if the alternator is on its last leg, or dead already then it can be completely be running on the battery to power everything. and if you dont change the alt soon, it will just drain the new battery.

[kuntzie]

battery could be slightly loose aswell, happenned to my first TGP, the + wasnt alll the way tightened and it would stall out occasionally, but your alternator, if its old you most likely need to replace it

[GIANT MOTH]

I find this hard to believe that the alternator would cause your engine to run rough like it is. I could be wrong but when my alternators die and it runs on the battery it doesnt cause rough idleing from my experience. It makes your dash dim and your windows slow. Stuff like that. If my dash goes crazy my battery is dead. Get a battery charger. If my battery can't hold a charge the alternator is shot.

 

If it's not your alternator. The problem is your EGR valve. Remove it and clean it. You should step ahead and take it all apart and clean it. Get new gaskets. Clean your plenum. There also is the EGR tube to clean as well.

[DiscoStudd]

Tighten both battery cables (make sure the surfaces are clean,) check the ground wire to the engine block, and tighten down the nut on the Auxillary Positive Terminal (located on the driver's side under-hood fusebox.) Check the condition of the battery cables themselves, and check the condition of the lone positive cable running from the starter to the alternator (the one that's bolted to the "lug" on the alternator.) Might as well check the connection at the starter as well...