Electrical issues, Help please.

[LiquidX]

Car was driving fine (just got it back yesterday from engine rebuild) until I was on my way to store. What happened is my idle was set at 1100rpm but it would sometimes go up to 1500-2000 when at idle. Also the rpm would drop a bit when the clutch is pushed in as well. I was a little unsure of the higher idle at the time until everything else started to happen.

My rpm in neutral was going up to 2800, holding and then dropping back down after a few seconds. My radio was turning on and off, my AC started to decide when it wanted to blow cold air or just have the fan on (AC switch was pressed in and still lit up). At the stop light my tach dropped to 0rpm and when I put the turn signal on, the tach needle bounced a couple hundred rpm in sync with the turn signal. My stock boost gauge needle was at the half way point as well at idle. SRS light turned on too.

At Autozone (where I was heading to already) I did my business and went to turn the car on only for it to attempt to crank over. Tried a few more times and it wasn't moving at all. With the key to the Acc position the boost gauge was at half way still and the temp gauge was 3/4 the way up (slowly coming down).

Battery wouldn't read so I got a jump and the employee stated there is a problem as the car should have started up right away instead of hesitating. Both the battery and alternator are new (napa battery, autozone alt).

Drive home everything was fine except the idle going a bit higher than 1100 and dropping back down. Temp stayed where it should and radio was working fine. The voltage for the battery when I was home ended up being 11.3

I'm stumped on why all of those were affect at the same time. I called mechanic and I am to drop the car off tomorrow for them to look into it. Any advice now would help out.

That should cover the bulk of it.

Thanks
Scott

 

[1995gsx20g]

i know it looks like a lot to deal with but you have to start simple. with a DVOM check battery voltage and resistance, it may be shorted. if it is shorted, start the car then unhook the battery and your issues should disappear.

by design ecu operation/powertrain should not be affected until under 9.5 volts.

 

[rarest_90_DsM]

you can also look for shorts in your electrical system, by unhooking the negative terminal of your battery and hooking up a test light to the negative battery terminal, then touching different parts of the chassis with the probe. If you have a short the test light will light up if not then no light. You could use a volt meter to but it would have to be set up for amps instead of volts.

 

[LiquidX]

i know it looks like a lot to deal with but you have to start simple. with a DVOM check battery voltage and resistance, it may be shorted. if it is shorted, start the car then unhook the battery and your issues should disappear.

by design ecu operation/powertrain should not be affected until under 9.5 volts.

I was attempting to test the battery but foolish me turned the dial to the wrong setting and I blew a fuse in my multimeter .

Just for clarification since you mentioned 9.5 being the key, before I parked I had issues but my volt read out was unknown. The 11.3 was after I got home from driving 20min after being jump started. I'm wondering if it was low enough that everything became affected for that reason?

Being late already, it seems that I'll be having the garage diagnose the issue for what is going on as it seems to be a drain somewhere as well.

you can also look for shorts in your electrical system, by unhooking the negative terminal of your battery and hooking up a test light to the negative battery terminal, then touching different parts of the chassis with the probe. If you have a short the test light will light up if not then no light. You could use a volt meter to but it would have to be set up for amps instead of volts.

If I had a test light I would have been doing that but unfortunately I do not have one



I am leaning towards a bad IAC still however. I'll get that tested and the other thing that comes to mind would be the idle switch maybe. I have Link v3 sitting at home so if some other issues arise I'll have to put that in to fix. I just don't want to potentially send a voltage surge to the chip and fry the other ecu IF that is possible.

 

[LunarEclips]

The voltage regulators in those Autozone altenators go bad all the time and cause problems with alot of the syntoms you're producing. Someone here on the forums was complaining about one last week if i remember correctly. I'd start there....

BTW, its better to use OEM parts than buy cheap aftermarket parts from AZ for this exact reason. Especially when it deals with electrical.

 

[1995gsx20g]

BTW, its better to use OEM parts than buy cheap aftermarket parts from AZ for this exact reason. Especially when it deals with electrical.

i agree with you 100% except when it comes to alternators.. personally i think its just our location with heat and 99% of alternator rebuilder's not testing 100% of the alternators components, like the 12.3v circuit.

 

[tjbiker031]

Get rid of that alternator from autozone. You were on the right track with parts until the AZ alternator. Get a Napa alternator and start from there. That way you'll know u have good parts to pin-point where the issue is. I had a AZ alternator (not knowing any better) and im on at least my 4th one in at the most 9 months.

 

[LunarEclips]

i agree with you 100% except when it comes to alternators.. personally i think its just our location with heat and 99% of alternator rebuilder's not testing 100% of the alternators components, like the 12.3v circuit.

This is the exact reason why buying cheap aftermarket parts is a problem. When you make parts as a manufacturer for cheap, your ideal motive is to move bulk product fast to make money and because of this there is very little care put into the product. How would you feel about installing a cheap altenator in your car and it malfunctioning due to a simple faulty regulator. And because of this faulty regulator it spiked way pass 13-14.4v resulting in a fried ECU and all sorts of other good expensive electrical components. Its a worst case scenario but very well could happen, all because youd like to save 200$.

 

[EclipticalGS]

Do you by any chance have an open dump??

Edit: Nvm, read your mods, Either way, Ive had Autozone Alts. go bad within months.

 

[LiquidX]

Alright to respond to everyone that chimed in (thank you) the alternator was bought only 2 days ago and not even used for a full 24 hours yet. Is there a way to check to see if the voltage regulator is bad? Also what's the difference between Napa and AZ alternators? All I know is mine is 75A and costed about $120

I have a recirculated o2 housing by the way and did find out that I have a bad coolant cap as fluid is by passing the cap just by squeezing on a cold upper rad hose. So maybe my temp sensor was right on that aspect if there was a massive air bubble in the system since the over flow bottle was empty when I checked that out.

If I hear anything tomorrow I'll update with that information and if anyone else responds I'll put in for that as well.

 

[romeen]

The two things that I would check first are:

1) ECU. Pull the cover off and have a look inside. Look for burnt tracings or any other signs of damage.

2) Power Transistor. A bad PT can cause weird, random electrical havoc (I don't understand why). It's also where your tach gets it's rpm signal from.

Also look for loose ground connections/damaged ground wires. Some wiring may have been damaged when the motor was reinstalled.

 

[Killian]

Ugh AZ alternators....enough said.

 

[LiquidX]

I'll go and look into those parts that are mentioned. Where exactly is the power transistor located at?

 

[XiKeiyaZI]

Beneath the coil pack!

;D It's a flat long piece that is connected to the harness and your Coils.

Usually a black plug mounted on a brass-colored plate.

 

[1995gsx20g]

This is the exact reason why buying cheap aftermarket parts is a problem. When you make parts as a manufacturer for cheap, your ideal motive is to move bulk product fast to make money and because of this there is very little care put into the product. How would you feel about installing a cheap altenator in your car and it malfunctioning due to a simple faulty regulator. And because of this faulty regulator it spiked way pass 13-14.4v resulting in a fried ECU and all sorts of other good expensive electrical components. Its a worst case scenario but very well could happen, all because youd like to save 200$.

i don't want to thread jack and there are plenty of threads on this already but i understand where you are coming from with the cheap manufactures but putting that aside. I believe all alternators, every brand even mitsu are cursed from the start because of design location.

You can believe what you want i have no problem with that but when it comes to alternators that's how i feel.

i put alternators in the same group as our drivelines, it just happens, because it was not designed to handle the conditions we put them in.

 

[LiquidX]

Alright, I managed to locate te power transistor (I think) to clarify it would be a black box with the gold/brass colored bracket and would say "Mitsubishi Power TR Unit" and some numbers underneith it. If that is it, and to my understanding, it needs to be grounded out. There is a bolt hole in the bracket that went though another bolt hole on the coil pack and would line up with my Evo3 IM. There was NO bolt going through there.

Could that be a big source of problems? I did put a new bolt in and still need to take it to the shop.

No fuses are blown and the wiring on the underside of the engine bay fuse box look ok as well.

 

[romeen]

Yes, that's the correct one Scott and you are correct about it needing to be grounded. The back side of it (as I'm sure you noticed) is metal. I would take a pic of where mine was bolted to after my 6 bolt/1G IM swap but the head is off at the moment. As long as it's secure using just one bolt to secure it is fine.

 

[XiKeiyaZI]

Aside from the fact that the middle wire going to the TR unit is a ground... yeah, it might help.

 

[EclipticalGS]

My Power Transistor was hanging for a while with no ill effects, but I re attatched it for heat transfer.

 

[romeen]

Aside from the fact that the middle wire going to the TR unit is a ground... yeah, it might help.

My Power Transistor was hanging for a while with no ill effects, but I re attatched it for heat transfer.

So the metal backing on the unit is not for grounding but rather heat transfer? I didn't know that.

 

[EclipticalGS]

Yeah that little thing gets hot, I was trying to unclip my injector and got a decent burn across my hand.

 

[ramsack]

So the metal backing on the unit is not for grounding but rather heat transfer? I didn't know that.

correct.

when i put a new fully rebuilt alternator in my mr2 it was putting out like 18v at first and the lights flickered. this only lasted a few minutes. it could just have acted stupid because it was a new alternator and the brushes may not have been worn into the commutators fully. i hope for your sake or anyone else who's gonna be personally looking into it that if there is a problem, that it isn't something wiring in the harness. nightmare.

 

[1995gsx20g]

my intake manifold gets pretty hot considering the coolant passages that flow threw the throttle body.

personally i wanna assume that it is mounted like that to prevent vibrations, but i don't really know, ive just been argumentative lately..

 

[ramsack]

i can't imagine there being any heat transfer from the power transistor bracket INTO the head. if anything the head will add to the heat of the transistor. and also consider how little surface area of the bracket meets the head. it would be ideal to be able to relocate it and put an aluminium heat sink on it. that bastard would probably last forever, then.

EDIT: it's annoying you can't even type pr011y in. who cares about text lingo as long as it's not like r u and other really lazy short words. pr011y is going to be a real word soon.

 

[LiquidX]

Well I took the car to the garage and on start up it was a little hesitant but turned over. No ill effects on the 20 min drive but I no longer have any CEL which I should since the rear o2 is not connected. Idle was between 900-1200rpm and I think I'm still going to get a newer IAC as well.

The garage did call me and said that so far they haven't found anything but they are going to put new terminals on for the battery post as both the negative and positive are looser than they should be. He is also going to put a new ground on as well. I'm still convinced there is a drain somewhere and I did mention that to him as well.

All I know for sure is once I get it back I'll do another drain test to be sure everything is fine and put in my new ECU with ECMLink v3 so I can check some voltage readings.