Hello, I have a 305 TPI 91 RS and my car is idling extremely high. Its currently at about 1500-1600 rpms and have no clue where to adjust it or what could be the possible cause, any help would be appreciated thanks.

 

Your idle air control (IAC) motor is probably sticking. Probably need to clean it out or eplace it. It's located under the throttle body with the square four-wire plug. Either that, or you have such a horrendous vacuum leak somewhere that the IAC can't lower the engine speed enough to compensate.

 

Thanks for the help, i'll be sure to check it out tomorrow.

 

Mine was doing that just yesterday and i took it in to the shop. They replaced my TPS (Throttle positioning sensor) and that took care of the problem....check that. It should be running at 1 volt; mine was running at 2.5 volts.

 

Actually, I believe the TPS should be set at about .6 to .7 Volts.

 

0.54 volts

 

Thanks for the help guys, about to check it out now.

 

If that doesnt fix it try checking your timing mine was to high and cause the idle to be high.

 

I noticed my time was off and it was jumping under the light last night, anyone know the specifications for a V6 91 RS?

 

The timing for a '91 V6 is 10 deg BTDC w/the bypass open.

The timing for a '91 305 TPI (which is a V8) is 6 deg BTDC w/the bypass open.

While the bypass is open the timing should be rock steady.

Once the bypass is connected and the car re-started the timing will be ~ 21 deg BTDC and will vary as it helps to control the idle speed.

In order to check which engine you have count the spark plug wires at the cap: 7 for the V6 and 9 for the V8.

RBob.

 

when I got my car I have no idea that this was such a common problem. I think someone on the board runs into it every week.