944 RPM bounces, and bogs down.

[Outofhand]

I have an '87.

The car will run at idle endlessly, but if I get on the gas, the RPMs bounce. The last time this was happening it was the alternator not charging the battery. I have removed the battery and left the poor thing where it sits on the side of the road.

Can it be anything other than the battery not holding a charge, or the alternator being fried? Belt seem to be properly tensioned and only squeal if they get wet.

Any idea would be great, I found a few threads that mention the throttle position sensor, but it was running fine until I turned the headlights on. I think the headlights sapped the battery to nothing and it just isn't holding a charge.

It ran fine all day, without the lights. A little after it got dark and I turned on the headlights it started giving me trouble.

[porschetub]

Originally Posted by Outofhand

I have an '87.

The car will run at idle endlessly, but if I get on the gas, the RPMs bounce. The last time this was happening it was the alternator not charging the battery. I have removed the battery and left the poor thing where it sits on the side of the road.

Can it be anything other than the battery not holding a charge, or the alternator being fried? Belt seem to be properly tensioned and only squeal if they get wet.

Any idea would be great, I found a few threads that mention the throttle position sensor, but it was running fine until I turned the headlights on. I think the headlights sapped the battery to nothing and it just isn't holding a charge.

It ran fine all day, without the lights. A little after it got dark and I turned on the headlights it started giving me trouble.

Have you tried another battery or charged that one up?
Is your charge/ battery light on when the car is running?
The belt shouldn't squeal @ all wet or dry ,not good for pulleys or belt,if your charge lights on you may have a faulty voltage regulator- not a big fix.
Don't run for too long with your charge light on as you may toast the altenator.
Run a voltmeter over the battery when the lights are see what you get ?
Adjust your belt and sort your battery,this may be all thats wrong,good luck

[Outofhand]

I will be testing the battery at Autozone today. I'm not sure if I have a battery/charge light on my car.

How tight is the belt supposed to be? I always tightened it down to the general 90 degree hand turn that my dad taught me, I don't have a belt tension tool.

[Tcrate]

So now I am curios, what is the 90 degree hand turn rule?

[Outofhand]

You check if you can turn the belt a full 90 degrees, if its too loose you can turn it father, if its too tight it wont go to a 90 degree turn.

Anyway, Autozone says my battery is fine, and are charging it. All that's left is the alternator I guess. I will attempt to go get it soon as its parked on the side of the interstate.


Any other ideas or things to check would be greatly appreciated.

[John_AZ]

Originally Posted by Outofhand

How tight is the belt supposed to be? I always tightened it down to the general 90 degree hand turn that my dad taught me, I don't have a belt tension tool.

Originally Posted by Outofhand

You check if you can turn the belt a full 90 degrees, if its too loose you can turn it father, if its too tight it wont go to a 90 degree turn.

All that's left is the alternator I guess.

Any other ideas or things to check would be greatly appreciated.

Your accessory belt sounds OK. If you only get the squeal when whet maybe anothe 1/2 turn on the adjustment rod. I try to get a 1/2" deflection on the long top run of belt. Do not over tighten or you may cause the crank seal to leak with the extreme belt pressure on the crank pully.

Dash charging light. When you turn the key to on----does the charge light come on? IT HAS TO. When you get the battery in the car and the battery cables are cleaned and tightened------with the car running-----the light should be OFF,

If you see a real faint glow or flicker---the alternator. VR or cables are bad and the battery is not getting a full charge and the 944 is running on low voltage (if at all)

Take the alternator to a store AZ Auto Zone and have it tested.

Pull the VR out of the alternator, If the carbon contacts to the slip ring are short --1/4" or so the VR should be replaced. You have to smooth the slip ring in the alternator or it will eat the new VR carbon contacts.

If the alternator is bad the best to get is a re-manufactured alternator. The wear parts are replaced. A rebuilt is cheaper but only what is bad is replaced the rest are old worn parts that are left in.

Again, you have to have a dash light when the key is in the on position. The bulb may be burned out. Replace the bulb--without a good bulb the alternator will not charge.

GL
John

[kfray]

Check the voltage across the battery terminals with the engine off and running.
A fully charged battery with engine off should read 12.5 VDC and with the engine running and the alternator outputting the reading should be about 13.5 VDC.

[Outofhand]

Yup, no dash charging light. Looks like I'm pulling that apart to get a new bulb tomorrow or Thursday.

Drove the car home without issue today, check all the connections/terminals. Everything looks fine. Haven't tried to drive it at night with the lights on. I have a headlight harness and Hella lenses from another member on here with 130/100 Yellowstars. I don't think they'd have enough draw to sap the battery and the alternators power.

I've had those for around 5 months and this is the first time I've had issues with it.

[John_AZ]

The bulb is connected to the alternator via the small BLUE wire coming off the alternator.
Make sure this wire is connected at the bulb and the alternator.

Do you have a HID kit installed?
924Board.org :: View topic - HID HEADLIGHTS

John

[Outofhand]

These:

Complete Porsche 944 Lighting Upgrade Kit

[Outofhand]

I redid the tension on the serpentine and it seems to be running fine now. Maybe it had a little bit of lengthening to it, the belt isn't that old. No voltage loss over 30 minutes of driving with my lights on.

Charge light works now, the blue cable to it was frayed, so may be part of the issue. May have been making contact and shorting. I spliced it back together and put heat shrink over the splice. Light comes on before I start the engine and goes off as soon as its running. Does not come on while driving.

Voltmeter shows a good value across the battery both while running and off.

Thanks for all the help guys.

[porschetub]

Thats great,I didn't think there was too much wrong.