idle issue...halp

[gramkrakr89]

hmm...

Alternators do have multiple windings, so is it possible that just 1 winding is bad?... perhaps causing low voltage dips at idle recovery?

Swapping for a tested, known good unit sounds like a good idea... he's tried everything else

 

[turbowop]

I did start a thread a couple weeks ago regarding the brake and battery lights coming on really dimly, though the logger showed that the alternator was putting out a full charge. I just got back from a 300 mile round trip over the weekend and other than the stumble coming to stops, the car was great. Even averaged 28mpg.

Now that I'm home, I took the car out to get some food, and those two lights came on really dim again, but the alternator is still fully charging. And the ABS light never came on. Whenever the alternator in 1051 has gone out, all three lights would light up. Maybe I should just pick up a new Bosch alternator. Fawk I hate alternators on these cars. I even have all the goddamn heatshields intact on this car.

Anyway, here is the thread regarding the lights that were coming on: click

 

[toybreaker]

If you suspect an alternator problem, check for A/C ripple.

It will tell the tale if you've got a diode issue.

 

[turbowop]

How would one check for AC ripple? This sounds moar technical than I'm used to. /ubbthreads/images/graemlins/hsugh.gif

 

[toybreaker]

Switch your meter to volts a/c

>Make sure your leads are plugged in correctly on the meter to read a/c

Put the positive lead alligator clip on the alternator output lug

Fire up the motor, and let it stabilise at idle with minimal load (no lights, etc)

Put the other lead on a good ground

Read the a/c voltage displayed

Load up the system with lights/heater fan, etc.

Anything under a half a volt a/c is good to go

Anything over ~about~ a half a volt a/c shows a weak diode, but it's probably going to live for awhile (ish)

Anything significantly over that indicates a more serious problem in the rectifier area of life.

 

[iceman69510]

Mmm, mmm, love some good ripple! /ubbthreads/images/graemlins/grin.gif

I had a 97 Spyder that the battery and brake lights were on dimly. Turned out the alternator was overcharging (15.1V). I had to load it up with everything electrical I could think of to get the light to even have a possibility of going out.

 

[turbowop]

Thanks, I'll give that a whirl after work. /ubbthreads/images/graemlins/smile.gif

I'm also picking up a new (not reman) Bosch alternator on the way home. Even if the alt is okay, it can't hurt to have a spare with these cars anyway. Lifetime warranty with towing and the Bosch on 1051 is doing okay so I feel pretty comfortable with them.

 

[turbowop]

Quoting toybreaker:


Switch your meter to volts a/c

>Make sure your leads are plugged in correctly on the meter to read a/c

Put the positive lead alligator clip on the alternator output lug

Fire up the motor, and let it stabilise at idle with minimal load (no lights, etc)

Put the other lead on a good ground

Read the a/c voltage displayed

Load up the system with lights/heater fan, etc.

Anything under a half a volt a/c is good to go

Anything over ~about~ a half a volt a/c shows a weak diode, but it's probably going to live for awhile (ish)

Anything significantly over that indicates a more serious problem in the rectifier area of life.



So I did this. First reading with no accessories on it was bouncing between 30.8 and 31.4. I'm not sure if that's right. Perhaps the decimal needs to be moved. My DMM only had two available settings. With lights, foggies, rear defrost, stereo, and blower motor on it bounced around a smidge lower. It was kind of hard to read since the numbers weren't very steady. I don't know if that means anything or not...

*edit* Obviously I'm horrible at testing electrical stuff. I think the test came out okay. I'm guessing that decimal needs to be moved in front of the 3. So in both cases I was below a half volt.

 

[turbowop]

Well now we can add new alternator to the list. No more dim battery and brake lights on the dash (so far), but the car still wants to stumble a bit when coming to stops. I even added a ground wire to the alternator housing for good measure when installing the new one.

At this point, I give up. The car isn't dying and it's really just a nuisance to my OCD if anything. The car runs great otherwise. /ubbthreads/images/graemlins/dunno.gif

 

[turbowop]

Tried a different MAF tonight. Same result.

 

[cheekychimp]

Mark,

I had the same problems as you know and it appears I have eventually fixed them. I don't know which of these solved the issue because I did everything together, but you can perhaps check and see if anything might be the culprit.

New Alternator
Heavy gauge charging wire from alternator to battery
New ISC
Grounding Kit
EVO/2G TPS (I needed this because I had no closed idle switch on my throttle body)
New power steering sensor.

The last one is the only thing looking at everything else that you have tested that I can think might be the issue. Does it stumble/die at all stops or ones where you are turning in? If your sensor is shagged like mine was, could the ISC be failing to bring up the revs when the power steering is activated as you turn the wheel. This problem is obviously only going to surface at low speeds when the power steering activates.

I did also swap in another radiator because mine was leaking coolant at the filler neck. I doubt this was the cause of any issue but I did wonder if the other radiator was keeping the engine too cool. I only had the crappy stock coolant temp gauge so I couldn't really tell if this was the cause of anything but I seriously doubt it to be honest.

Paul.

 

[turbowop]

Yeah, I don't think it's the PS sensor. I don't have to be turning the wheel to see the problem.

At this point, I don't care anymore. The car never really stalls, it just stumbles when coming to stops. It otherwise drives great, pulls hard, and gets excellent fuel mileage.

 

[VR_IV_MR]

im sorry this probably won't be much help but my car has the same problem. However, after the drop in rpms, your car seems to bounce the rpms back up high to about 1200 before settling around 800. Mine doesn't do that. My rpms drop as far down as yours do to about 500 when i push clutch in coming to a stop, but then will stay there until i come to an ABSOLUTELY FULL stop, then it will slowly but surely climb up to ~800. It never does the bounce up to 1200 like yours.

My car also has no idle surging issues, only this issue when coming to a stop and dropping into neutral.

"this thing is fucked" as well

lol

 

[VR_IV_MR]

Do your rpms drop at idle from pressing the brake pedal? Mine does.

I'm starting to think its a bad ground. A buddy with a nissan said he had the same problem and added a ground from the motor to the frame and the problem went away.

edit: i dont want to reread everything, did you try the throttle body from the other car or did you just clean the one thats on it now?

 

[turbowop]

Grounds are all there, tested and good. I haven't tried a different throttle body yet, just cleaned up the one that's on there.

 

[cheekychimp]

Mark,

I understand your issue isn't turning related, but would you check that PS sensor? The new one we put in needs adjusting and is throwing a CEL code but I noticed it only does it on deceleration passing below 2000 rpms. As soon as you accelerate the light goes out and the issue goes away . Is that around the rpms that you are seeing issues?

 

[bazeng]

Hi All,

I'm thinking about changing my alternator to fix this idle problem (crap idle when lights are on etc).

Voltage fluctuates between 12.4 - 13.4 volts.

Can anybody point me to the correct Saturn alterntors that you guys use?

I did a search on ebay and got this:
click

Any help appreciated.
I'll provide feedback to let you know if it fixes my problem.

 

[GSTwithPSI]

Hey I know this is a stretch but what about the vehicle speed sensor (AKA reed switch)? You say the car only does it when coming to a stop, but runs perfect otherwise? If you are having the problem with the engine RPM dropping abnormally low after letting off the throttle you may be having problems with the speed sensor or idle switch (

 

[turbowop]

I thought about the VSS and tried a different cluster. I also ruled it out because my cruise control works just fine, which from what I've read, uses that sensor as well. No change.

 

[jepherz]

Also, if the VSS was bad, at idle (clutch in) while cruising should show idle RPM (850ish) rather than cruise idle (1200?).