Idle and electrical issues after sitting for 2 months.

[CtrlAltDestroy]

My car, 99 GST Spyder, sat in place for about 2 months while I sourced and installed a new turbo. I got everything bolted back together and that part of it works fine.

I started the car a couple of time for short periods to help with troubleshooting. I started the car up after I finished repairs and it started without issue. As it idled the battery light was on. The radio was going in and out, as in it had power then didn't then did, etc. I took it for a drive and the car died after about 2 blocks. The battery was dead.

I pulled the battery, took it home, charged it for 1.5 hours, put the battery back in, and drove it home. The next day I took the battery to Autozone (where I bought it last September). They charged it and tested it. They said that it's fine.

I took it home and back it back in the car. I took it for a test drive. The battery light was on constantly. Until I gunned the engine and revved it up to around 5k rpm. The battery light went out and stayed out. Until it died from an idle issue (more on that in a sec). I started it back up, battery light was on, and went out again after another 5K-ish rev.

It started raining during this so I drove the car back home. During it the radio started going in and out again. Tomorrow after work I'll test the alternator output voltage. What else should I look for? Seems like it's would only be the alternator or battery.

Now, for the idle. Before the car went down for repairs it would occasionally stumble at a stop light. The RPMs would dip, stumble a little, then go back to normal idle. Now, after the repairs, it'll idle fine when in park. But when it's in drive and reverse the RPMs will dip low at a stop and die roughly 50% of the time. What should I look for, adjust, or fix for this?

Thanks.

 

[1davho]

Definitely sounds like an alternator and low volatage can cause all sorts of issues. After you fix the voltage issue, if you still have idle problems, check for boost leaks and then look into the isc.

 

[CtrlAltDestroy]

Alternator was putting out 11.7 volts. I took the old one out and get a new (manufactured) one from Advance. Went to put the new one in, looked at it, and realized that it's the wrong one. So I took it back, got the right one, but now it's too dark. I'll put the new one in tomorrow.

Would you mind pointing me to a guide on checking for boost leaks? I'll look into that tomorrow after the new alternator is installed.

 

[Gomes]

Could also be a bad ground. Mine sat for the winter and come summer I had one head light because the ground for the lights on the passenger side got corroded. If the alternator is not the case that is.

2G Turbo DSM Boost Leaks -How to test and fix

 

[rezalas]

First, it seems like you definitely have an alternator issue which could be causing any number of electrical issues. The idling problem could be an O2 sensor oddly enough. After I replaced my upstream sensor the idling issue completely cleared up for me. Are you getting a check engine light at all?

 

[DSM1G90]

Yep, bad alternator was the culprit for your charging problems.

 

[CtrlAltDestroy]

The alternator was giving 11.7 volts. I changed the alternator and now the charging system is a-ok.

I took it for a test drive and after about 10 minutes the CEL came on. I took it to Autozone and had the computer read. It showed a code P0125, insufficient coolant temp. After researching it on here I saw that it's most likely related to a bad front O2 sensor. I changed the O2 sensor, lifted the battery cable to clear the code, and took it for a test drive. After a 25ish minute drive no CEL came up. Since then I've put another 50ish miles on it and no CEL.

I took it for emissions, it passed, and I renewed the registration. Woot.

The idle is better. After the new O2 sensor it was stuff rough but after a few miles it got better. It's fairly steady now at about 750rpm. Occasionally it'll dip down to about 500 and then go back up. It doesn't stall anymore.

 

[DGrigg05]

Voltage regulator is bad inside the alternator. Get a new one. or have it rebuilt.