Low Idle?

[NissanNismoZ]

I'm trying to see if anyone can come up with what i can do to pathy to help the idle..such as, at night with heater blowing on 3, headlights on, radio going, when stopped at a stop sign it idles at 550-600 rpm (in drive) any ideas? it didnt do it since messing with my MAF wiring and trying to run the new wires, which i restored to stock wiring coz it was trying to run at 2RPM (no joke)

Thanks!

[Phantom01Pathfinder]

550-600rpm idle doesn't sound like a bad range for idle. My R50 will idle at 1100rpm when first started up...then slowly gets down to 6-700ish rpm.

 

Are you looking to get the idle higher or???

[Slartibartfast]

It's not surprising that the idle drops with heat, that's just how they roll. Older cars (like my dad's TR4a) need to be given a little more gas until they heat up, or they're more likely to stall. What is a bit surprising is how low yours is going. IIRC there's an idle adjust screw somewhere? The thing on the computer that you mess with to pull codes is marked idle adjust IIRC, might try turning that up a little, see if it does anything. Might have ended up turned too far down while you were fighting the MAF.

 

And does it only do it with radio/lights/etc? That is odd... it's a higher drain on the alternator, which I guess could cause some slowdown, but I've never noticed a difference in how mine runs with stuff on vs off.

[devonianwalk]

That is odd... it's a higher drain on the alternator, which I guess could cause some slowdown, but I've never noticed a difference in how mine runs with stuff on vs off.

 

 

It could be possible that the alternator is having difficulty keeping up with the extra electrical load. I just recently replaced my alternator and have seen significant change in power window speeds. I only replaced it because the bearing was going out on it.

[sewebster]

Check out EF/FC page 20 in the 95 FSM (download in garage section). It shows you all the different sensors that can influence idle, such as power steering, air conditioning, and battery voltage. This is so that when you aren't moving, the computer will increase air flow to keep idle high enough when those systems are under load. Could be one of those circuits is messed up. Or if the adjust screw is turned all the way closed, the AAC valve might be maxing out and even when fully open you don't have enough air going through.

[Kingman]

It should go up by about 200RPM with the heater and stuff on as the AAC raises the idle. Try turning your heater on low and watch to see if your idle jumps up. If it doesn't, that's probably why the alternator is working so hard to keep up with the load at low RPM. What's your voltage to the battery when everything is on?

 

With my fan on high, headlights on, and rear defroster on the idle drops about 150RPM and voltage drops to a little over 12V instead of 14V while idling at 700RPM. Around 1K I get my voltage back. Keep in mind this isn't normal and I'll need to replace the alternator again soon.

 

And you're not supposed to play with the idle screw in the first place...

[NissanNismoZ]

Here are the results..

12.3v/600RPM Everything ON, in drive (heater on full blast, headlights on, defrost on)

12.6v/650RPM Everything ON, in neutral

13.0v/750RPM Everything OFF, in neutral

 

seems like the alty cant keep up with the voltages needed...

BUT as Kingman said, my voltages are fine at 750rpm or higher...

and everything i turned on, made the idle lower and lower..

Edited October 29, 2011 by NissanNismoZ

[Kingman]

and everything i turned on, made the idle lower and lower..

 

Check out EF/FC page 20 in the 95 FSM (download in garage section). It shows you all the different sensors that can influence idle, such as power steering, air conditioning, and battery voltage. This is so that when you aren't moving, the computer will increase air flow to keep idle high enough when those systems are under load

 

Fixing that might keep the alternator charging enough.

[NissanNismoZ]

and i'm also looking in the EC section, i have no EF/FC section..not in any of the ones i can find..?

Nevermind..okay, i found it..it says it uses the VSS for it, as well..and i have a VSS code...?

i just have no idea on where to start for the VSS...

Edited October 29, 2011 by NissanNismoZ

[RJSquirrel]

VSS == vehicle speed sensor. It provides the electrical signal to the speedometer/odometer. It attaches to the transfer case. Any issues with the speedometer/odometer reading properly? The sensors have plastic gears on them that can be replaced. The plastic pieces are known to fail from time-to-time, causing issues even if the sensor itself is still good.

Edited October 31, 2011 by RJSquirrel

[NissanNismoZ]

VSS == vehicle speed sensor. It provides the electrical signal to the speedometer/odometer. It attaches to the transfer case. Any issues with the speedometer/odometer reading properly? The sensors have plastic gears on them that can be replaced. The plastic pieces are known to fail from time-to-time, causing issues even if the sensor itself is still good.

 

hmm..nope actually the speedo is right on with the GPS..havent had any problems so far.. that's why im not sure what it is..

Now the CEL is doing it again to where it wont even go off..