Rough idle -could it be the Alternator?

[iangeideman]

1995 165k mi

did full tune up
changed all the fluids
running 91 octane
cleaned fuel injectors/vacuum lines
new egr/egr solenoid

maybe the alternator is weak?

 

[HeadLightBulbs]

Rough Idle?

1995 165k mi

did full tune up
changed all the fluids
running 91 octane
cleaned fuel injectors/vacuum lines
new egr/egr solenoid

maybe the alternator is weak?

Was it running this way prior to you doing all of this work to your truck?

Is the check engine light on?

You mentioned the alternator.. Have you had that tested? Im not sure where you are located but I have gone to Auto Zone to check the alternator.. Which they test for Free..

What is your indash volt meter displaying?

 

[iangeideman]

Was it running this way prior to you doing all of this work to your truck?

Is the check engine light on?

You mentioned the alternator.. Have you had that tested? Im not sure where you are located but I have gone to Auto Zone to check the alternator.. Which they test for Free..

What is your indash volt meter displaying?

no check engine light
voltmeter = ~12v while running

just bought it so IDK

 

[lesterl]

Normal op voltage is 13.8~14.4 floatcharge/fullcharging...

Check the TBI Base gasket, mine was rough, it actually threw an EGR code and the Base gasket was toast.

How about checking the IAC setting/ base screw setting?

 

[GREYGHOST1978]

Mine did the same. Changed the alternator. Works great now.

 

[Jounier11]

Maybe ive heard people having hard and i mean HARD tranny shifting then he replaced the alternator and now runs like a beauty!!!!

 

[robbt]

If the alt is not putting out the 13.8-14.4v. the computers are not getting the voltage needed. Results, poor running, hard shifting, and there should be some sort of error codes. If the alt is new, have it check again, I have had new alt be bad right from the get go. Afterall they are reman alts. If alt is good then check those vacuum leaks.

that being said, 91 octane??? Don't waist your money. A stock 95' 5.7l only has about 8.5:1 compression. No need for that high dollar fuel. My 95' 5.7 uses the cheap 87 and does fine, even at 7500 foot elevation. Now if is modified to 9.5:1 to 10:1 comp. then use the 89, if over 10:1 comp. then go with the 91 stuff. Just my opinion.