Service slants

Motor, Jun 1999 by Juran, Ken

Next, make sure idle speed is set properly, and check for TCM codes and that the idle switch is working. At idle, the switch should read On or Closed on your scan tool display. At 100 to 200 rpm above idle, the display should read Off or Open. Do the same for the accelerator switch. At idle, it should be Off or Open. At 100 to 200 rpm above idle, it should be On or Closed.

Lastly, make sure the kickdown servo is set to its proper specification, according to a service manual. If everything checks out up to this point, the car most likely needs a replacement transaxle, unless it's one of the models built before the cutoff dates listed or a 1995 Sonata. For these, replace the TCM with the applicable part number:

Ford Truck

Melted glow plug relay. Too much heat can melt the glow plug relay. But why is there too much heat? On some 1994-95 F-250, F-350, F Super Duty and some 1995 E-350 trucks built through 12/21/94 with the 7.3-liter Direct Injection Turbodiesel V8, it's caused by loose nuts on the relay connections increasing electrical resistance and melting the plastic. The resulting symptoms-the ones you'll hear about-will be hard starting as well as no-starts. But the fix is simple enough.

First, pick up a new glow plug relay, some zinc-plated lockwashers (Part No. 34791-S36) and some silastic sealer (Part No. F4AZ-19562-B). Disconnect the batteries, pop the relay cover and toss the melted relay. Install the fresh one with the existing nuts, but first add those zinc-plated lockwashers on top of the wire harness connectors below the nuts. Torque the nuts to 7.9 5 in.-lb. Don't overdo it or you'll damage the new relay, says Ford.

With the lockwashers in place, the old relay cover won't fit right, so apply the silastic sealer to it to keep it in place. Reconnect the batteries and crank the engine to make sure the fix worked.

Audi

HVAC maintenance. Be aware that Audi has added an HVAC plenum drain valve to its 7500-mile maintenance interval on 1992 and newer 100, S4, A6 and S6 models. This valve needs to be checked for dirt and debris and either cleaned or replaced as necessary every 7500 miles. If the valve is found to be clogged with crud, Audi says, it must be replaced. Dealers are even supposed to send the defective piece to Audi's Warranty Test Center for analysis.

Chrysler

Intermittent rough idle. Can't figure out what's causing an intermittent rough idle after a cold startup in 300 to 50oF rainy weather on a 1991-95 2.2- or 2.5liter Chrysler product (full vehicle list below)? Don't feel bad, it's not that obvious. The cause may very well be a defective idle air control (IAC) motor (Part No. 4288298). But only if the engine is equipped with high-pressure throttle body fuel injection. Make sure to install the rubber O-ring that comes with the new IAC motor or it'll probably leak unwanted bypass air and screw up the idle fier. Torque the new unit to 17 in.-lb. Here's the vehicle list:

1991-95 Acclaim/Spirit/LeBaron Sedan/LeBaron Coupe/LeBaron Convertible

1991-93 Dynasty/New Yorker/New Yorker Salon/Daytona