dart68

I have an '87 S4. It starts ok, but when you press on the accelorator there is no response at all until the pedal moves about 1/4 of the way down. Then the rpms jump to about 2000 to 2500 and will continue up with further pedal pressure. Checking the linkage in the engine bay, the cable must move about 1/4" before any response from the engine. Any clues as to what may be the problem?

Thanks.

WallyP

Remove the air cleaner housing, and check the cable and pulley at the rear of the engine. If there is no excessive play from the bellcrank on the side of the intake to the throttle around the pulley, then you may need to adjust the cable to the pedal. Check the cable housing to make sure that it hasn't collapsed, and check the plastic retainers to make sure that none of them have broken or slipped.

dart68

Thanks for the help Wally. Unfortunately after checking, excesive play is not the problem. I am begining to think that it is the throttle switch (idle). I'm not sure how to check it though. I have the factory manuals, but they're a little vague. It discusses using a code reader, but codes weren't stored until '88 and I have an '87. I think with the reader I could test the switch by pressing the pedal and reading the result, but who sells the reader?

Thanks.

WallyP

The problem almost certainly isn't the idle switch.

To check the idle switch on the '87:
Pull the EZK plug off of the ECU - the EZK (ignition) is the inner connector.
Hold it so that you are looking at the connectors, and the cable is on the right end. Pin 1 is on the bottom end closest to the cable, pin 18 is on the bottom end closest to the other end. Pin 19 is on the top end closest to the cable, pin 35 is on the top outer end.
Pull the LH ECU connector off, in order to prevent its connections from interfering with the test. Just leave it hanging loose.
On the EZK connector, connect an Ohmmeter between pins 8 and 18. With the throttle closed, should be zero to ten Ohms. As soon as you move the throttle, resistance should go to infinity (open circuit).

While you are there, check the WOT (Wide Open Throttle) switch. Connect the Ohmmeter between pins 26 and 18. The resistance should be infinite until about two-thirds throttle, where it should drop to less than ten Ohms.

Get someone to help you. Remove the air cleaner, and use a mirror and flashlight to get to where you can actually see the throttle arm. Have your assistant very slowly push down the throttle pedal as you watch the throttle. If there is binding or excessive free play, find where it is by watching each step of the way. Don't forget to check the clearance at the throttle pedal itself.

dart68

Wally, I did the tests for the throttle switch. The idle is fine, but I have to have my foot on the flood before there is a change WOT switch. Possibly a stretched cable? How do you adjust? After doing the tests, the car runs fine. The problem is gone. I DID NOTHING OTHER THAN THE CHECKS YOU MENTION (hears the theme from The Twilight Zone in the back ground)! Hmmmm, well, at least I can drive it now and didn't have to take anything else apart or buy new parts.

Something else has me a little puzzled though. I was checking the engine temperature sensor II cold. When I connect the leads of the ohm meter (one to ground), the meter flashes about 2 ohm for half a second then goes to infinity. If I disconnect and reconnect, the same again. Is the sensor bad? At first I thought the meter was bad, but it checks out.

Anyways, thanks for your help.