Weird RB20DET problem.

[TheZeven]

So, last night I swapped turbos on my RB20DET. The original was making weird sounds under boost, and I had another RB20 turbo laying around in good condition. So yeah, swapped it right. No big deal, shouldn't cause a change in -anything-.

Leave my buddy's house last night. Cars runs great. Perfect. Better than before. I turn to my girlfriend and say "Cars running better, eh?" And no more than 1 minute after that the headlights get really dim, as in, I can't see s***, even with high beams. Car dies on the side of the road.

Get it towed to a nearby school with a bunch of lights overhead, a couple friends made there way out.. We look at the car for like .. an hour.

All the IC connections are good. No blown fuses. Wires are all reconnected for MAF (the only thing I disconnected when swapping the turbo).

Car needed a jump to start. Did so. It started. It ran "okay". Let it idle for a few minutes, it died. WTF. Do another look-over, moved the battery ground (re-locate to trunk), jump it again. Same thing.

Could this be a CAS issue? O2 sensor? MAF seems to be good.

Car had been running a bit rich for a while, but was still driveable. I don't know how rich, no wideband. Just while parked and revved it would leave a bit (a lot) of black on the ground.

Any ideas would be greatly appreciated.

For reference, the only engine mods are a FMIC and the new OEM turbo.

Thanks in advance.

[Joe]

check your alternator wiring and output.

[glitched]

check your alternator wiring and output.

Yup, sounds like an alternator issue.

[TheZeven]

Thanks for the input. Car should be home in about 2 hours (have to wait for friend to get home to use his truck for the tow-dolly). How would I go about checking alternator output? Multimeter @ the battery?

[pepegurr]

Also charge your battery fully and then use multimeter to see if your amperage stays put or goes down, if it stays put your alternator may be bad if it drops you can just about guarentee your battery has died on you.

[RustspecS13]

Also charge your battery fully and then use multimeter to see if your -VOLTAGE- stays put or goes down, if it stays put your alternator may be bad if it drops you can just about guarentee your battery has died on you.

Do that, and check the voltage. Or take out your alternator and get it tested at advance auto/auto zone/napa etc etc.

And if that is your problem, don't let the new alt recharge a dead or half dead battery, that can cause it to burn out faster too. You'll still need to recharge the battery fully.

~Alex

[glitched]

you can get a cheap $30 battery charger at like walmart or harborfreight.

parts stores will test alternators for free (either out of the car or if you can get the car there.

[TheZeven]

Pulled alternator and took it to the local Shucks/Kragen/whatever. They told me it wasn't outputting anything. Don't know if that's accurate or not, I'd expect "something" coming from it. Oh well.

Gonna see if I can have it rebuilt locally, otherwise gonna see about ordering from rawbrokerage. Seems to be a good deal.

Thanks for the help guys.

[TheZeven]

Replaced with a 98 Quest alternator. Car stays running now. Not that I expected otherwise, but you guys were right