Hesitating stalling?

[87boostedbuick]

Hey guys I posted a while ago about this issue but didnt have much info and have been away from my computer so I couldn't replay so I thought I would post a new thread about it my 87 gn seems to have a bit of a sputter going on more so after the car warms up say 170 and up once in a while when stopped in park or drive or coming to a stop never during accel the ses light will flash 2ce and the rpm will drop to almost stalling for maybe about a min then it will rev up to about 1000 and stay there untill you start driving again when the ses light flashes my voltage will drop to about 10.8 and as of now it has only done this once but when I turned on my headlights in park it did it then stalled then started right up with no issues it is showing no codes at all and it has a brand new alt on it any help would be great


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[Hatdragracer]

I had a TPI car that would do that with a worn/broken IAC valve. That would not explain the system voltage dropping that much however.
Do you have a ground strap connected between the body and the enging head/block?

 

[Emiliano Lago]

Did you check if the alternator is charging correcly, it seems the voltage is very low.

 

[87boostedbuick]

Ill have to check tonight on the ground strap the alt will charge 13.7 untill this happens then it drops after i start driving again it will jump back up to 13.7 and stay there untill I stop when I stop it drops to about 13.1 the lowest iv seen it was 12.8 with the headlights on and fan on high


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[Hatdragracer]

Mine looked like it was connected from the firewall to the block....but it wasn't and I had a few gremlins until I cleaned the contact surfaces and reconnected.

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[87boostedbuick]

Well I just checked and there is a ground strap from firewall to engine block


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[Hatdragracer]

I would suggest start checking the simple stuff like the orange wire connection to the ECM or the connections to the alternator..etc

Good luck

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[TheCamel]

You need to check all your terminals of main power, your battery positive, your alternator positive connection, and finally, the positive on your starter. then start looking at different areas that have power to them. More often than not people change a battery and do not realize that their positive cable has deteriorated to a point it is a voltage drop from all the corrosion in the cable itself. If you notice a green funk growing on your wires, it is because of the oxidation of the copper material. A lot of times this happens after you have cranked a long time, or the battery wire to the starter has gotten too close to the exhaust. If you see 13.7 at the battery, but are only seeing 13.1 at the starter terminal, you have resistance in the wire. Each wire connection steals a fraction of voltage as it passes through. If the resistance gets high enough, the heat created causes more resistance. Which may be why you are noticing a voltage drop as the car warms up. If the starter wire is getting too hot, the resistance is increasing. Also if any of your electrical accessories are pulling excessive voltage, it will draw more amps at idle. Such as an electric fan, or the A/C clutch.

These are just a few items to check.

 

[87boostedbuick]

Thanks very much for all the help I will start looking into all my power wires the ground strap is looking a little green so I think I will replace that as well was there only 1 ground strap from engine to body?


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[Hatdragracer]

On the back of the passenger side head and block there are two grounding locations that go to the factory harness...as well there is obviously the negative battery cable.

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