Voltage Regulator cause of idle issue's?

[And_44]

Howdy,

Ok, been searching and reading but these Alternators have varied symptoms and problems.

I'll start off with what it has been doing. My idle when I start the car cold it is low 650-1k rpms. Never higher no sign of surge or hunting and will stay running until it heats up. When it's hot it starts but after the initial crank about 50% of time it just idles down and dies. I have to keep the gas slightly depressed for a min and it will idle. When I'm driving the car and depress the clutch from a high rpm the rpms fall and a majority of time the car dies, the only way I can get it to stay running is to keep it in gear and let the rpms fall down to idle speed as I slow down. When ever the rpms drop to idle range I've noticed that when it dips to the low point my lights dim and car stumble if it stays running the idle goes to normal and lights go back, and if it dies the lights return to normal.

Now for what's been done. The alternator itself is about 5months old from Autozone 75amp. I know they are crap. I've been hunting down other culprits. Replaced a leaky BISS o-ring, new throttle gaskets, adjusted TPS, swapped old ICS which tested fine and the current one tested same, I just rebuilt a 2nd ECU tonight and will be swapping it tomorrow, ECU in there now has 4-5years on current rebuild. Wires and plugs have about 6k on them, and plugs are cleaned and gap checked every 3k. Battery has 11months on it and it's new. Fuel filter has 6k on it. Injector gaskets have 6k on them. Injectors are used but have about 95k on them (car has 162k). I've swapped out the CAS. Adjusted and keep rechecking timing. Adjusted Idle. All the electronics mentioned above have tested within limits.

I'm guess, I'm hoping that by bouncing this off fellow DSM'ers you guys can give me a new insight on what to look for or verify my current hypothesis that my alternator could be a cause of these issue.

My last alternator was the original 20 year old one and I was dealing with a nasty misfire(s) car would fire on 2 cylinder's. 4 and 3. The thing wasn't putting out enough voltage to fire the other 2 plugs. And when the rpms went up to 2.5k or above it would start running "normal". When I swapped the wires on the coil the voltage followed the post on coil. The coil happened to be the one that was nearest to the posts on back of coil where power was applied. And knowing that electricity follows the shortest path to ground realized that not enough juice was being pushed through.

Well thank you in advance for any insight or help. And thanks for reading.

 

[1badpurple]

If your lights are dimming while slowing down I would go ahead and replace the alternator. Mine had issues with dying with a failing alternator as well.

 

[AlaskanDsm]

When was the last time that you replaced your battery?

 

[DSM1G90]

I'd say that your problem isn't ALT related, but more in the TB area.

If you're getting 13.8+ at the battery when the vehicle is running, leave the ALT condition alone (true about Autozone though .... and I feel sorry for people being stuck having to use them ...) for it's doing the job required.

could be the FIAV getting stupid on you why you don't have high RPM's at cold then it settles down to a nice 750rpm when fully warm.

Did you do the ISC alignment trick with grounding the two required areas before setting the BISS?

..some areas that I can think of ... good luck- DSM

 

[And_44]

AlaskanDSM-Battery is 11months new bought it new.

DSM1G90-Haven't tested the voltage yet. Will do this weekend though. And did some thinking and Alternator was bought from O'reillies/Schucks. Thought about the FIAV but not to sure about it as the problem still occurs more often when it's warm. And it happened with both throttle bodies I have swapped in. Yes, I grounded the ISC according to spec. Besides paying for someone to do a complete rebuild on my Throttle body I've pretty much done it myself, and starting to think it's not my problem.

I've finished replacing the caps on my extra ECU and will be swapping that in either this weekend or Tuesday next week.

 

[DSM1G90]

I was also going to say goofy temp sensor, but while your doing the caps on that ECU, check for any open ground traces on that ECU's momboard for they love to mess with sensors to make things not run in the closed loop situation.

..another area to peek into .. - DSM

 

[And_44]

Well, since I've adjusted the TPS it's been idling and running ALOT better. When it's cold it still wants to die when idle is pushed in from a high rpm. Will be doing another leak test to make sure, it seems similar to when I first got car and the BOV was vented. Just the low idle seems weird.

Might be having a Stock 90 EPROM ECU on the way by weeks end so will try the other ECU I just replaced caps on this Tuesday. And will have that EPROM to try for a 3rd.....

I'll keep ya'll updated as I love threads that do that;D

P.S. I rechecked my 2nd ECU and traces look great just the resistors at R112-R115 (4 total) for my injectors look like they've over heated in past the board is a tad brownish, and the resistors are whitish/greyish in center. Look online for replacements but not having much luck. But I've been working and tired. Think they might of got messed with before I replaced the previous injectors, I had one with a ~ Ohm and other where just as old but tested fine. Probally strained them.....

2nd P.S. Reread it all and well I'll be looking at the close position of my throttle plate. Maybe it's not closing all the way and with the higher vacuum with engine braking my be sealing it...... Not sure I'll find out with the leak test I'll be doing in next few days.

 

[BLueBeast]

You sound very knowledgable, but like others have stated & I have experienced the Autozone, checkers, etc, alternators suck! I don't know why they are allowed to sell such a sub-par part. You either fork out the money for a good one (i.e. OEM Mitsu), or NAPA or Carquest sell better aftermarket ALT's. Personally I forked out the money & bought a beastly 165amp "Load Boss" you can google them. I am hoping its the last ALT. I will ever have to buy. I also got a really good Optima battery & I would send my ECU off to ECMLINK.com & made sure professionals went over it & got it fixed right.

Another option if your in a bind is to get the Canadian spec. Alternator from Autozone/checkers, etc.....as they are always required to have daytime running lights & they are 90amp vs. 75amp U.S. spec Alt's.

Good luck man, keep us posted.

 

[And_44]

3rd time is a charm. Got the new Galaxy and been using that for my web browsing. Keeps malfuntioning.

But swapped the ecus and the problems with the low idle at cold and it stalling from high rpms went away. But this ecu with the damaged resistors for the injectors was showing an ugly face. At slight throttle got kinda bumpy injectors where actin up.

So will be replacing capacitors on this one ecu with good resistors and will be looking more for replacment resistors for the other.

Good news is that I won the auction for the eprom ecu for 81 shipped and will being getting that withing the next 2 weeks. That will be sent off to get looking at by a professional and most likely also getting dsmlink v3 with tax return.

Anyone know of anywhere to get replacement resistors/capacitors beside ebay? The resistors I'm looking for are for locations r112 thru r115 (4 total) these are for the injectors located near the ics black bars and green blocks on the ecu.

I'll keep this thread updated with my progress. Thanks for reading and for any input you fellow dsm'ers can give.

 

[DSM1G90]

..maybe digikey might have your resistors? How about a Google search on the items needed?

good luck-DSM

 

[And_44]

Google searched and unsure;( I'll be bring one of the resistors from a fried ECU into a radio shack or Fry's in next few days and just them there. Digikey had some but I couldn't tell or be really sure if they'd do the trick. RESISTOR 27 OHM 1W CARB COMP - OA270KE