# Bad alternator straining engine?



## jabatasu (Dec 26, 2005)

I've been having an ongoing problem with my engine idling poorly and hesistating at low RPMs. Initially I thought maybe it was a timing issue or something like that, but I've been playing with the symptoms and determined that when I hit the power window button while the engine is idling, it almost chokes down. Same is true if I turn on the headlights.

So at that point I started thinking it was the alternator. I noticed a little squeal coming from the alternator area when I flicked on the headlights. Is it possible that my alternator is going bad, has some resistance, and is making it harder for the engine to pull the belt, and therefore causing my idle and performance problems?

Can you guys think of any way I could test that theory without actually taking out the alternator?

Thanks
Jackson


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## Tavel (Aug 21, 2004)

you can easily test it. get a voltmeter and test the batter terminals in the following:

car off; should read a little under 12V 
car on; should read above 13V


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## jabatasu (Dec 26, 2005)

Tavel said:


> you can easily test it. get a voltmeter and test the batter terminals in the following:
> 
> car off; should read a little under 12V
> car on; should read above 13V



Thanks for the suggestion... is it possible, though, that the alternator could test good (with your suggested test) but still be causing resistance and dragging down engine performance?


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## Tavel (Aug 21, 2004)

not really, it would show a deviation from a benchmark test...but you dont have a benchmark test...so for your purposes, you might not be able to tell.


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## nastynissan (Jan 26, 2003)

Its not that the Alt is dragging the engine down any more than normal.... Its the fact that your IAC (Idle Air Control) is Most Likely not compensating for it. Whenever an extra load is put on the engine... EX... Rad fans, lights, Power windows, Power steering, AC, ETC.... The ECM detects this and changes the signal to the IAC. Which in turn adjusts your idle... There are several threads (I believe) on how to clean the IAC... fDo a little search and you should find them....


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## jabatasu (Dec 26, 2005)

nastynissan said:


> Its not that the Alt is dragging the engine down any more than normal.... Its the fact that your IAC (Idle Air Control) is Most Likely not compensating for it. Whenever an extra load is put on the engine... EX... Rad fans, lights, Power windows, Power steering, AC, ETC.... The ECM detects this and changes the signal to the IAC. Which in turn adjusts your idle... There are several threads (I believe) on how to clean the IAC... fDo a little search and you should find them....


This makes sense... however, would this IAC problem also be causing the performance issues that I'm having? Whenever the engine is at lower RPMs (like 3rd gear at 30mph, or 5th gear at 60mph) the engine shakes and hardly accelerates at all. 

Would IAC problem cause this as well, or would it only been messing up my idle?


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## nastynissan (Jan 26, 2003)

jabatasu said:


> This makes sense... however, would this IAC problem also be causing the performance issues that I'm having? Whenever the engine is at lower RPMs (like 3rd gear at 30mph, or 5th gear at 60mph) the engine shakes and hardly accelerates at all.
> 
> Would IAC problem cause this as well, or would it only been messing up my idle?



The IAC is only going to affect your idle. The other issues your having I would attribute to........

A.... How long has it been since the last tune up??? Plugs, wires, Dist cap, Rotor, Air & Fuel filters, PCV valve???

B... Is your timing set correctly?? @ 10degrees BTDC is good for your "Usual" GA16DE. If its set too low or too high it can cause Drivability issues. As well as internal engine issues if it gets too far out of time, for an extended period of time.

Your driving issues will quite possibly come back to one of these 2 things. There are other possibilities but these are kinda the BASIC things to check.. Let us know what you find....

Later


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