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Resolved 2G battery/alternator/bad ground issue

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coupe_nasty

10+ Year Contributor
266
16
Oct 15, 2011
Easton, Maryland
Ok, so ive been having an issue with my GSX ever since i got the car dyno tuned about 6 months ago. The night it was tuned, i was driving on the highway and i blew my intercooler pipe off the turbo, which caused the car to buck and shut off obviously.

I fixed the pipe and went to start it and my battery was dead. So i was about to get a jump and then all of the sudden it came back on and the car started and ran fine. Now every few weeks it will out of nowhere just completely die at a stop light. No dash lights, no ignition clicking, just dead.

I get jumped and then have to keep giving it gas, otherwise it will die. Had battery and alternator tested and they tested good. The last time this happened i noticed something very strange, when i was about to jump it i hooked the jumper cables to JUST my battery and nothing else and suddenly the dash lights and fans kicked on. So i was thinking ok, i must have a bad connection at the battery and the jumper cables must have bumped it.

I changed both battery terminals and made super tight connections. Car starts right up and holds 14v. Then i went to drive it and here we go again. RPMs dipped very low when approaching a stop in neutral. When i go to shut the car off, usually the RPM needle drops slowly after being shut off from idle to 0. But now when i shut the car off the needle drops fast and hard, almost like it has a weight hanging on it.

The symptoms made me think i had a bad conection or loose wire but everything seems tight and good. Im at a loss and going crazy about this, any ideas?
 
Solution
I still have the car and yes the issue has been fixed.

It turned out to be a bad OEM alternator from extremepsi. They sent me a new one and i haven't had an issue since.
Just tested my battery with a multimeter and its reading 12.8v when car is off. Reading around 13.8v when car is running. my ground terminal it reading 0 ohms when car is off and .04 ohms when car is running.

Could this be an issue with my ecu? any way to test it? i have dsmlink v3 lite installed
 
Update: So i put a brand new battery, and battery terminals in the car just to be sure that wasnt the problem. Still having issues. The Car will start up and idle fine. Holds voltage fine until i go to drive it. When i drive it, anytime i come to a stop and let off the throttle, the rpms dip very low to where the car almost cuts off. Then after about 10 seconds, it rises back up to a normal rpm and voltage.
 
It does sound like an iac problem. Id unplug it and see what happens on most cars it will idle high but wont stall. I think you can run without it on link anyways. Id probably give it a shot before buying an alternator.
 
I'm sure electrical systems are just fine, the voltage and rpms dropping is obviously normal because the engine is almost shut down.

Pull the pipe off going to the throttle body and inspect, if there is black build up, its time to thoroughly clean the throttle body, especially the small passages. If that is clean or still have issues after cleaning, has anyone played with the biss screw adjustment lately? Is there a black rubber plug still intact on the throttle body?
 
I had a very similar issue on my 1g. It turned out the alternator fuse had cracked at what looked like a point where it was brazed. So it would intermittently make and lose contact causing the battery to go dead from not charging sometimes.
 
Just replaced the alternator with a brand new oem alternator and belt. Still having issues. The rpms are dipping too low every now and then approaching a stop. Im out of ideas. I have replaced battery as well as battery terminals, anternator, belt, checked ground wires, tested isc motor. Only thing left i can think is maybe an ecu problem or issue with my tune.
 
You still havent said anything about the voltage "when the rpms drop". You said the idle output is near 14V. So.... unless you can see on link that the voltage starts to drop off when driving then you need to stop messing with the charging system. Post up a log of idle, warm idle, cruise, and coasting in neutral. It been so long since ive tinkered with link but there should be a coast offset value you can change.
 
Why haven't you checked the TB. Its easy. The charging systems' voltage is going to drop when alt isn't spinning fast enough due to the engine almost shutting down. Its a side effect of the slower moving engine. Quit wasting money on a side effect that's totally duh normal.

Or an issue with your tune in link. But I don't know link so I don't know where in link.
 
Have you checked the battery fuse (80 or 100 amp) under the hood that is bolted in with two 10mm bolts and are they tight? Just making you aware of it and if the bolts holding it in are loose it could explain some of this. Happened to me is why I bring it up. Just MTC. Good luck.
 
Yes when the rpms dip low, the voltage does as well. Till is just about to die, then it catches itself and jumps back to normal. It doesnt happen all the time though. Some days it runs perfect
 
UPDATE: So after the install of the new OEM alternator and battery, everything was fine for a few days. Now something new has happened which im hoping will help determine what the issue might be. I was driving today, came to a red light, all was good, then all the sudden the voltage dropped to about 11.8v and the rpms jumped up to about 1200rpms as if to accommodate the voltage dropping. THEN MY Battery dash light AND Brake dash light came on and stayed on. they have been on ever since and the car wont go above 12 volts. im at a loss here and out of ideas.
 
Do you maybe have something else going on that's draining your charging system or burning out your alternator? I believe one way an alternator gets burned out is charging up a run-down battery, which I did with my previous/ aftermarket alternator several times.
 
UPDATE: Ok so ive been through hell with this thing.

Installed the brand new OEM alternator and it lasted a few days. Sent it back, they said it was bad, and they sent me another new one. Installed heat wrap around my manifold and downpipe in case heat was the issue. Installed the other new alternator today. start the car and holds voltage at 14.4 perfect. Go to back out of the garage and just like before the RPMs dip very low when i let off the throttle and voltage drops to about 11 volts, then corrects itself and jumps back to 14 volts.

Brand new battery (Charged), brand new battery terminals, 2nd brand new OEM alternator, good belt tension, Heat wrapped exhaust, no power steering leaks on alternator, inspected fuses, inspected ECU for corrosion or burn marks, tested ISC motor, checked grounds, I'm truly at a loss and out of ideas.

I'm afraid to drive the car and either get stranded again or burn up another alternator.
 
Pretend you have no idea the voltage is dropping once the RPM's dip.

Then start a new thread explaining every drive-ability symptom, such as the RPM's dropping when you let off the pedal. One exception to the new thread: don't mention anything electrical.
 
UPDATE: Ok so ive been through hell with this thing.

Installed the brand new OEM alternator and it lasted a few days. Sent it back, they said it was bad, and they sent me another new one. Installed heat wrap around my manifold and downpipe in case heat was the issue. Installed the other new alternator today. start the car and holds voltage at 14.4 perfect. Go to back out of the garage and just like before the RPMs dip very low when i let off the throttle and voltage drops to about 11 volts, then corrects itself and jumps back to 14 volts.

Brand new battery (Charged), brand new battery terminals, 2nd brand new OEM alternator, good belt tension, Heat wrapped exhaust, no power steering leaks on alternator, inspected fuses, inspected ECU for corrosion or burn marks, tested ISC motor, checked grounds, I'm truly at a loss and out of ideas.

I'm afraid to drive the car and either get stranded again or burn up another alternator.

Did this ever get resolved?
 
I was going to suggiest low timing at idle causing the rpm to drop at a stop,
Or the idle set too low.

It's funny this thread was bumped i had charging system issues myself, found a few holes in the alternator power cable sheething, and also ive had a bad alt plug for years. Bad alts kill batteries and bad batteries kill alts. I'm curious if he found the fix or sold the car off LOL.
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