rough idling because of alternator going bad?? low mpg

have you checked for a vac leak?
are you still stock?
15mpg isnt too bad for all city with a moderate foot.
i see 10-12mpg going .2miles back and fourth to work, and i pretty much floor it all the way across the intersection to my work
your IAC could be sticking and causing high idle, but it is usually much higher than that.
a bad alt or bad belt could cause those symptoms too. how old are the belts?
do you have a multimeter to check the output voltage at idle of the alternator?

sounds like a misfire...under load!

Mr.Riviera wrote:

have you checked for a vac leak?

do you have a multimeter to check the output voltage at idle of the alternator?

i agree with starting here.

Hi, Thanks for all responds.

Auto zone checked my alternator and it's working fine- thanks to them
I grabed set of spark plug wires replaced them but nothing changed
I'm just a beginner with small repairs so this is my first car that i'm trying to fix myself and all the help is grately appreciated!!!!

Is there any write -up on how to check for vacum leak and wihch places are most common for it to happen??

My belts are 3 years old and about 30k but they look good and don't squek or anything. Should I think about replacing them??
And my Riv is stock only mod I have is gutted airbox THX.

This sounds like maybe more than one thing going wrong at the same time, and perhaps some things that are normal but you were not aware of. I'll try to make helpful comments.

First - 15 MPG in the city. That is no surprise. It takes a certain amount of energy to move a certain amount of mass. So the riviera with a passenger or two and some gas is about 2 tons. A Ford Escort with some gas and a couple passengers, in comparison, is about one ton. It takes more energy to move the Riviera - unless maybe if you caould always drive it downhill...

Second - you say that in park it idles smooth, but in drive the car shakes. Actually - that sounds like bad motor and/or transmission mounts. See, when you put the car into gear, the idling engine puts torque (energy) into the transmission's torque converter. The torque converter attepts to turn the wheels (throught the tailshaft and axles). But the wheels are not moving, if you are holding the brake. Let go of the brake, and under most conditions (unless, say, pointed steeply uphill or with wheels straight against a fairly tall curb) the car will start to move. So if the wheels are not moving and the torque converter is trying to turn the wheels, each time a cylinder fires basicaly the engine tries to push a little. If the motor mounts or transmission mount are worn, they will allow the motor and transmission to rock. How to figure it out? One way is you need 2 people. Put the car in park, open the hood and watch the engine idle. One person sitting in the car holds the brake and shifts the car into drive. The other, watching the engine from outside the car,, will most likely see the engine will shake. You see, one of the engine mounts looks lind of like a rubber ninja star in a metal sleeve. If any of the points of the star breaks, there is not enough rubber to hold the engine/drivetrain from vibrating. You have to get under the car nad look at all the mounts to ascertain damage and wear. I think somewhere else on the forum you'll find instructions on replacing the motor mounts.

When you move the steering wheel the idle speed drops simply because of hte load of the power steering pump.

Interior lights dimming? you need to take the car to someplace that can test the batery under load. I think you will find that your battery has inadequate reserve capacity - as measured, say, by the 'cold cranking amps' output. On the Riviera, honestly I forge what the spec is. But I think if you have less than I think 680 or 690 CCAs you are supposed to replace the battery.

Good advice albertj. I agree this is probably a case of a few little things gone bad, making the problem harder to detect.

Hi guys thanks for all the advice!!

I think I don't have vacume leak, Checked it with the very profesional carburetor cleaner

anyway I still have a few question :

1. Can anybody tell me how many engine/trans mounts are in riv and where should I look for them( I see only two from the top) pics please if available or link where i can find it and also get an idea how the good one looks

2. Is it possible that when I shift to drive the engine is twisting toward the front of car and touches any part of the car cousing vibrations. What about Reverse is then the engin moving the other way, because then I don't get any vibration.

3 If I would get any misfires would it couse SES light to go on?

4. What about ignition module could it be the cause of my problems, what are the symptoms when this part is bad ??

Thanks for all help!!

1) get the car on to a lift, or jack up the front end and support it with jackstands, and crawl underneath to find the engine and transmission mounts. Will be *obvious*

2) you were already told how to check this.

3) Uh-huh.

4) no idea.

Albertj

Thanks albertj, I didn't have a chance to go under car couse my garage is kind of packed and it's been raininig alot lately so when i have chance I just want to know what to look for!! anyway no misfires because i dont have SES light. One guy told me that ignition module is also responsible for idling and it might couse the rpms to go to low. Can somebody tell me how many rpms you get on riv when in idling under load(in drive)- it can help me to see if i get too low rpms or something alse( probobly bad engine mount cousing vibration on my car )!!

Thanks

Dirty MAF sensor
Coil Packs/Plug Wires

These have both caused me to have a rough idle. When you cleaned the TB, did you remove the MAF sensor and clean it on its own? it could be simply bad, or just need cleaning.

Buy 3 coil packs. (make sure you can return them) Install them and see if it clears up the idle.

So engine mounts are bad that's for sure, and it means 800$ for repair (parts are over 600$ )- does anybody know SANTA??
Thanks for all help !!!

you might try buying used mounts from Ed Morad. Look up with Google or on EBay.

AlbertJ