Bouncing at idle?

[mike561]

I adjusted the timing at my work today, i notice the engine has slightly more power now when i step on the gas but if im sitting at a red light or have it in park the car feels like its bouncing, it was doing this before the timing was adjusted too, im thinkin a misfire? the plugs, wires and dist cap are about a year and a half old.

[silicon212]

Check your idle speed - should be in the area of 600 RPM idle, in gear.

[mike561]

yeah i was gonne chack that first, is it best to adjust the idle when the engine is cold and the carb is running at fast idle or after its warmed up and the idle kicks down?

[silicon212]

Originally Posted by mike561

yeah i was gonne chack that first, is it best to adjust the idle when the engine is cold and the carb is running at fast idle or after its warmed up and the idle kicks down?

Fully heated to operating temperature.

[mike561]

k thought so

[bhw33191]

I just got my car back today, the guy said i had a bad TPS sensor which he said was causing my idle to change up and down randomly. So this could be related to your problem also.

[mike561]

Ill have to check that out

[bhw33191]

Originally Posted by mike561

Ill have to check that out

I'm pretty sure the TPS is buried in teh carb and requires you to take it apart in order to get at it.

[silicon212]

Originally Posted by bhw33191

I just got my car back today, the guy said i had a bad TPS sensor which he said was causing my idle to change up and down randomly. So this could be related to your problem also.

He fed you a line of bull if that is indeed the case. The TPS on the carbureted car is used in conjunction with other sensors to allow the computer to determine engine load at a given RPM. Fuel flow through the carburetor is controlled in two areas (both rely on vacuum) - the venturi draws gasoline from the bowl through the jets (metering jets) whenever the throttle is part open to completely open. The other thing is the idle circuit, which controls fuel flow when the throttle is closed.

There is a possibility that the idle air bleed in the carburetor is improperly adjusted and this can cause this issue. The idle air bleed controls the idle fuel flow on these feedback carbs by allowing a certain amount of air to be drawn with the gasoline (effectively metering the fuel) and this can be controlled by the mixture control solenoid (which is driven by the computer). Again, either of this gets back to a carburetor issue - exactly what I diagnosed your car to have.

The TPS is installed in the left front side of the carburetor (the carburetor left, when you look at it full on it's on the right), and has a 3-wire connector.

[bhw33191]

Originally Posted by silicon212

He fed you a line of bull if that is indeed the case. The TPS on the carbureted car is used in conjunction with other sensors to allow the computer to determine engine load at a given RPM. Fuel flow through the carburetor is controlled in two areas (both rely on vacuum) - the venturi draws gasoline from the bowl through the jets (metering jets) whenever the throttle is part open to completely open. The other thing is the idle circuit, which controls fuel flow when the throttle is closed.

There is a possibility that the idle air bleed in the carburetor is improperly adjusted and this can cause this issue. The idle air bleed controls the idle fuel flow on these feedback carbs by allowing a certain amount of air to be drawn with the gasoline (effectively metering the fuel) and this can be controlled by the mixture control solenoid (which is driven by the computer). Again, either of this gets back to a carburetor issue - exactly what I diagnosed your car to have.

The TPS is installed in the left front side of the carburetor (the carburetor left, when you look at it full on it's on the right), and has a 3-wire connector.

Now i'm confused. So a bad TPS can't cause the idle issue by itself? If its used in conjunction as you mentioned above then couldn't it screw up what all the other sensors do in response?

[silicon212]

Originally Posted by bhw33191

Now i'm confused. So a bad TPS can't cause the idle issue by itself? If its used in conjunction as you mentioned above then couldn't it screw up what all the other sensors do in response?

I am thinking that if you had that carb rebuilt, it wasn't adjusted properly. Someone didn't set the M/C solenoid. If it wasn't rebuilt, then that problem will show up again. The idle air bleed quite possibly was set too lean.

Did you ever have the MIL on and if so, did you ever pull the trouble codes?

[mike561]

fixed, some spark plugs were covered in carbon deposits, replaced all 8 of them

[beat88ls]

Originally Posted by mike561

fixed, some spark plugs were covered in carbon deposits, replaced all 8 of them

how long did it take you to do that? i know the last plug on both sides can be a B*TCH... i talked to the guy who owned my car before me and in 150,000 miles he never gave it a tune up... damn. i plan on doing cap/rotor plugs and wires this weekend

[mike561]

I actually took it to get that done, i know spark plugs are easy but there was some other things i wanted checked out too, i figured since i was already there why not. the ones in the back they said on previous tune ups they (dis honest mechanics) sometimes leave the back two in

[j cAT]

Originally Posted by mike561

I actually took it to get that done, i know spark plugs are easy but there was some other things i wanted checked out too, i figured since i was already there why not. the ones in the back they said on previous tune ups they (dis honest mechanics) sometimes leave the back two in

its been a while since I experienced this and it turned out to be the ignition module...at about 10,000mi before it totally died my engine had this issue...after the replacement it was smooth....carb has never been rebuilt on my 84........305.......