New Alternator, now tach reads 0 RPM at idle-idles better!
markymayhem
Band Wagon
OK, weird one here...
1991 RT4WD, auto, 129k miles
Just had a new alternator put in, the brushes finally gave out on the original nippondenso.
side note: I put in a random rebuilt, which I looked up the brand and it had the least # of bad reviews compared to the other ~$100 rebuilts avaliable.
I'm keeping the denso and rebuilding it in case I have any issues with the rebuilt in there now. I figure if it goes out, I'll put in the rebuilt denso and sell the warranty swap. Or if it turns out to be good, a rebuilt denso is worth enough to cover the whole cost of the replacement. Which I had done, because although I chipped all the rust off and unbolted the lower bolt, and both upper bolts, I couldn't quite get the damn thing out of the engine bay, and didn't want to mess with the brake cylinder, as old as it is... They pulled the drivers side axle, BTW.
Anyway... For the last few months on the old alternator, I would occasionally get a ROUGH idle, like it vibrates the tapes on the dash to the point of distraction and I had to wedge napkins in the glovebox door to quiet the rattle. In addition, maybe 10 times total in the last 6 months I've owned the car, I would start it, and it would start wonderfully, as usual. The RPM would go to 1000 or so [cold] or it's normal warm spot, what 650 or so? but then just drop to 0 and the car dies. It starts up right away, however, but does the same thing. The only 'fix' is to rev the engine a bit, and get in gear and moving ASAP. The issue is gone by the end of the block, almost.
so I have the new alternator, and the idle is much smoother. When it gets 'rough' it's barely enough to rattle the tapes a bit, but you can't see them dancing as you could before
The first day the new alternator was in, the tach read a steady 650 or so RPM at idle [it read much lower sometimes before at idle, when it was idling very rough, barely enough to register] and it was very smooth.
Now, a week in or so, the idle isn't quite as smooth, but still better than before. However, the tach reads 0 RPM at idle now, but seems to work otherwise as normal, and the shifts seem to happen at about the same place on the tach as they used to, or maybe a bit higher [on the guage], but cruise the RPM is pretty much exactly what is always has been, 2800-2900 or so
It's almost like the tach now reads 500RPM lower at idle and 500RPM higher when accelerating...
Another thing, before the alternator was replaced, and after it got cold here, I noticed a weird thing on the tach when starting up early in the morning, the car started right up, and was not racing or dropping RPM, just running a nice high idle. However, the tach was bouncing all over from 0 to 1000 or so. That happened several times, before I got the new alternator.
And that's that...
however...another electrical issue comes to mind, which I will create a new thread for when it warms up next year, and which will mention briefly here.
When it's HOT out, sometime the car cranks and won't start. When it won't start, pressing the brake in park does not cause the neutral safety switch in the shift console to click. However, I do not thing it is the neutral safety. To get it to start, I switch the key from II to III or I to III repreatedly and both watch the idiot lights and listen for a click behind the drivers side upper air vent. when the check engine light goes out after a sec when going from I to III and I hear a click from behind the air vents, I know that when I step on the brake I will hear the click from the neutral safety switch in the shift console and the car will start if I crank it. After tracking down all the sounds etc. I have saved much cranking on the starter!
And in printing info from alldata I find reference to some sort of switch or relay located right where I am hearing the click behind the vent. I don't have the printout handy, but the only reference at all was one small illustration with a caption and picture, nothing in the text at all, and I couldn't find the part by the name given at any of the local parts stores. As it cooled off, no more problem...
Thanks for all your help!
-m
1991 RT4WD, auto, 129k miles
Just had a new alternator put in, the brushes finally gave out on the original nippondenso.
side note: I put in a random rebuilt, which I looked up the brand and it had the least # of bad reviews compared to the other ~$100 rebuilts avaliable.
I'm keeping the denso and rebuilding it in case I have any issues with the rebuilt in there now. I figure if it goes out, I'll put in the rebuilt denso and sell the warranty swap. Or if it turns out to be good, a rebuilt denso is worth enough to cover the whole cost of the replacement. Which I had done, because although I chipped all the rust off and unbolted the lower bolt, and both upper bolts, I couldn't quite get the damn thing out of the engine bay, and didn't want to mess with the brake cylinder, as old as it is... They pulled the drivers side axle, BTW.
Anyway... For the last few months on the old alternator, I would occasionally get a ROUGH idle, like it vibrates the tapes on the dash to the point of distraction and I had to wedge napkins in the glovebox door to quiet the rattle. In addition, maybe 10 times total in the last 6 months I've owned the car, I would start it, and it would start wonderfully, as usual. The RPM would go to 1000 or so [cold] or it's normal warm spot, what 650 or so? but then just drop to 0 and the car dies. It starts up right away, however, but does the same thing. The only 'fix' is to rev the engine a bit, and get in gear and moving ASAP. The issue is gone by the end of the block, almost.
so I have the new alternator, and the idle is much smoother. When it gets 'rough' it's barely enough to rattle the tapes a bit, but you can't see them dancing as you could before
The first day the new alternator was in, the tach read a steady 650 or so RPM at idle [it read much lower sometimes before at idle, when it was idling very rough, barely enough to register] and it was very smooth.
Now, a week in or so, the idle isn't quite as smooth, but still better than before. However, the tach reads 0 RPM at idle now, but seems to work otherwise as normal, and the shifts seem to happen at about the same place on the tach as they used to, or maybe a bit higher [on the guage], but cruise the RPM is pretty much exactly what is always has been, 2800-2900 or so
It's almost like the tach now reads 500RPM lower at idle and 500RPM higher when accelerating...
Another thing, before the alternator was replaced, and after it got cold here, I noticed a weird thing on the tach when starting up early in the morning, the car started right up, and was not racing or dropping RPM, just running a nice high idle. However, the tach was bouncing all over from 0 to 1000 or so. That happened several times, before I got the new alternator.
And that's that...
however...another electrical issue comes to mind, which I will create a new thread for when it warms up next year, and which will mention briefly here.
When it's HOT out, sometime the car cranks and won't start. When it won't start, pressing the brake in park does not cause the neutral safety switch in the shift console to click. However, I do not thing it is the neutral safety. To get it to start, I switch the key from II to III or I to III repreatedly and both watch the idiot lights and listen for a click behind the drivers side upper air vent. when the check engine light goes out after a sec when going from I to III and I hear a click from behind the air vents, I know that when I step on the brake I will hear the click from the neutral safety switch in the shift console and the car will start if I crank it. After tracking down all the sounds etc. I have saved much cranking on the starter!
And in printing info from alldata I find reference to some sort of switch or relay located right where I am hearing the click behind the vent. I don't have the printout handy, but the only reference at all was one small illustration with a caption and picture, nothing in the text at all, and I couldn't find the part by the name given at any of the local parts stores. As it cooled off, no more problem...
Thanks for all your help!
-m
Comments
mine does this too. i think it is the distributor but not confirmed. I think it is because there is oil in the cap (busted seals) and my theory is that the oil is blocking the contacts of the cap/rotor until it's revved which pushes the oil out of the way. I will confirm when distributor replacement fixes the issue. Until then it's just theory. Since there's oil in the dizzy I need to replace it anyway whether that's the problem with the idle or not. If replacing the dizzy doesn't work I'm going to check fuel filters and fuel pump and then if that is not the issue then I will rebuild my carb.
I hope any of this information can help you.