Steeda pulley set installed, having idle rpm problems

[FIREBALL]

Not wanting a debate or comments about whether under-drive pulley sets are worth it.

After installing Steeda pulleysl Im having an Idle problems-----when I start it up cold it settles down to regular idle around 750-800 rpm but if I turn the AC on the Idle goes down instead of up like normal and will fluctuate. When I shut the AC off the idle rpm s goes up to over 1050. If I shut the car off and then restart it the idle is normal unless I turn the AC back on. My voltage at idle is around 13. 7 and drops to 13. 4 with AC on. Started doing this right after pulley install so Im associating this with alternator speed but voltage seems to be where it should be?---------So whats going on do I need an even smaller alternator pulley or a higher output alternator?

 

[01yellercobra]

Did you bump anything while swapping the pullies? The pullies shouldn't affect idle. My son had under drive pullies on his 98 and the idle never acted up like that. I wonder if it's a coincidence type thing?

 

[Twisted2]

Did you unplug your IAC valve, by chance?

Edit: Even if you didn't, I'd test that first.
As far as the alternator pulley, it may be that way so as NOT to underdrive the charging system. I think I remember mine being the same way (before I took the underdrive pulleys off).

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[FIREBALL]

I misspoke in my first post the Steeda alternator pulley is smaller than the factory.

When I disconnect the IAC the car wont even idle at all. Its pretty weird that when I turn on the AC the idle lowers instead of raising. Even though voltage looks good Im thinking the possibility of not enough amps with the under drived alternator.

 

[Twisted2]

I misspoke in my first post the Steeda alternator pulley is smaller than the factory.

That's how I interpreted what you said before. Maybe we can talk this out, as I could be wrong in my understanding of pullies.

To me, it seems like the smaller crank pulley, by itself, would try to overdrive everything. After that, the giant water pump pulley, for instance, would underdrive the water pump, whereas the tiny alternator pulley would (again) overdrive the alternator.

In other words, it seems like the pullies are sized to selectively underdrive certain accessories, but not the alternator. Is that your understanding as well?

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[Twisted2]

Maybe my understanding is incorrect, as it seems strange to me. It seems like the smaller crank pulley would provide less leverage to turn the accessories that aren't underdriven. Meaning, the whole serpentine belt would be turning faster, but the engine would be working harder to turn the belt at the crank pulley, and at the alternator--but then less hard, to turn the giant water pump pulley. Haha. The net result is confusing. Hopefully someone else will chime in and straighten that out.

Edit: I'm wondering that in the context of imagining the load the AC compressor imposes, and how different sized pulleys might affect that, and thus, your idle (at least, when you first turn the AC on or off). Just thinking out loud.

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[DSG2003Mach1]

ya thats weird, that should be plenty of voltage. Ive had my Mach idle just fine with ac on and ~12.5 volts due to a failing alternator

 

[Twisted2]

ya thats weird, that should be plenty of voltage. Ive had my Mach idle just fine with ac on and ~12.5 volts due to a failing alternator

Agreed. It doesn't seem like a voltage issue to me.

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[CobraSam]

Did you disconnect the battery while doing the install? Could this be the ECM just re learning it’s idle?? If so, allow the car to idle for 10 min or so then allow it to idle with a load (lights, ac) for 5-10. Then go out and drive it around a bit.

 

[FIREBALL]

To me, it seems like the smaller crank pulley, by itself, would try to overdrive everything. After that, the giant water pump pulley, for instance, would underdrive the water pump, whereas the tiny alternator pulley would (again) overdrive the alternator.

The small (Steeda) crank pulley underdrives all accesories. While the Steeda alternator pulley is smaller than factory it is still turning slower than stock because of the small crank pulley.

Voltage is good but are there enough amps? or is it a coincidence that the IAC or MAF or TCM went out right after installing pullies?

I disconnected battery twice and let the ECU relearn----but no improvement with that.

 

[CobraSam]

The small (Steeda) crank pulley underdrives all accesories. While the Steeda alternator pulley is smaller than factory it is still turning slower than stock because of the small crank pulley.

Voltage is good but are there enough amps? or is it a coincidence that the IAC or MAF or TCM went out right after installing pullies?

I disconnected battery twice and let the ECU relearn----but no improvement with that.

How long did you have the battery connected to the car and have the cur idling or driving?
What I’m suggesting is that you should let it idle and drive it for some time to let the vehicle learn again. How long this exactly takes I can’t 100% say. These symptoms are how my car acted when I first started after it sat for a bit, semi-dissembled. It smoothed out and was good to go

 

[01yellercobra]

Maybe my understanding is incorrect, as it seems strange to me. It seems like the smaller crank pulley would provide less leverage to turn the accessories that aren't underdriven. Meaning, the whole serpentine belt would be turning faster, but the engine would be working harder to turn the belt at the crank pulley, and at the alternator--but then less hard, to turn the giant water pump pulley. Haha. The net result is confusing. Hopefully someone else will chime in and straighten that out.

Edit: I'm wondering that in the context of imagining the load the AC compressor imposes, and how different sized pulleys might affect that, and thus, your idle (at least, when you first turn the AC on or off). Just thinking out loud.

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You're backwards. A smaller crank pulley drives everything slower. The smaller alternator pulley would be to keep the pulley ratios close to ideal.

That's why blower guys go to bigger crank pullies. The larger crank pulley spins the blower faster provided the blower pulley is kept the same size.

 

[Twisted2]

Ah. Thanks for the explanation, fellas. I knew I wasn't quite getting it. The logic reverses, for the drive pulley. I can picture it now. Sorry for derailing.

That's a good point, about the ECU relearning after the battery is reconnected. This is just something I recently noticed, regarding how long that can take. When I had my Diablo chip in, it would take several trips for the car to run normally, after reconnecting the battery. With the stock tune, it seems to sort itself out much more quickly--within a trip or two. Anyhow, that's a good advice, to wait and see if it straightens itself out.

You're backwards. A smaller crank pulley drives everything slower. The smaller alternator pulley would be to keep the pulley ratios close to ideal.

That's why blower guys go to bigger crank pullies. The larger crank pulley spins the blower faster provided the blower pulley is kept the same size.

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[FIREBALL]

How long did you have the battery connected to the car and have the cur idling or driving?
What I’m suggesting is that you should let it idle and drive it for some time to let the vehicle learn again. How long this exactly takes I can’t 100% say. These symptoms are how my car acted when I first started after it sat for a bit, semi-dissembled. It smoothed out and was good to go

I disconected the battery twice and let it idle without load until it got to operating temperature and let it idle for another 5 minutes and then let it idle with AC on for another 10 minutes and then went out and drove it------no changes and still the same thing.

 

[Twisted2]

I think it can take quite a bit longer than that, even at it's quickest. I used to go through a procedure, but now I always just drive the car normally, and seem to get the same result. I'd try to put some real miles on it, if you can. Just my two cents.

I disconected the battery twice and let it idle without load until it got to operating temperature and let it idle for another 5 minutes and then let it idle with AC on for another 10 minutes and then went out and drove it------no changes and still the same thing.

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[FIREBALL]

Was hoping to get others opinions/advice on this, but one thing I can say is Ive had the batt. disconnected many times on this car as well as my f150 and honda and they never had to relearn idle!!------they always idled correctly right from the start with or without ac running until now??

 

[shurur]

One thing you could do...and it is a PITA..is to go back to the original OEM pulley set.
Then you would know whether something just happen to fail while installing the pulleys or the pulleys are involved....just my .02.

I'm starting to think it may be the alternator too...but it would be just a guess.

 

[DSG2003Mach1]

if the crank pulley didnt fully seat it the reluctor wheel might not be held in place correctly. When I did my first crank pulley swap I guess I didnt get it all the way down, when we went to build the motor the key way on it was messed up because it had room to wiggle. Just another thought, not sure how to verify the crank trigger signal

 

[FIREBALL]

Just discovered there are overdrive (smaller)pulleys available for the alternator , CJ Pony parts is one supplier. from what I read one of those should put the alternator rpm back to stock. $25, this might be a cheap way to find out if it is the alternator rpms that is causing the trouble.

 

[01yellercobra]

You could always go by a parts store and have them load test the alternator on the car. It's usually free.

I think your issue is elsewhere though. I think the timing is just coincidence. Think of the times your alternator died and the battery ran low. The idle doesn't get all wonky at those times.