The technical services team at Airtex Vehicle Electronics was recently presented with a confounding diagnostic challenge on a 2001 Dodge Caravan, and the troubleshooting process and ultimate solution have been captured in a fascinating new diagnostic video available on YouTube.
Mark Hicks, technical services manager for Airtex Vehicle Electronics, was contacted by a skilled local technician who was struggling to find the cause of unusual misfires, loss of power and intermittent backfires through the throttle body on a 3.8L-equipped Caravan. The owner had replaced the vehicle’s spark plugs approximately six months before the problems arose.
Hicks performed a thorough diagnostic check, including tests of fuel pressure and crank and cam sensor signals. He also scoped both sensors simultaneously to confirm they were in synch and that the timing chain was sound. Visual inspection of the plugs showed carbon tracking and cracking of the ceramic material.
“This was a classic case of a fouled plug and a spark that couldn’t jump the gap,” Hicks explained. “When we replaced the plugs using our normal process, the problem went away.”
The blame, Hicks decided, was the vehicle owner’s excessive use of anti-seize compound on the plug threads. But why would this trigger a backfire through the throttle body? The answer is provided in detail in the video by Airtex Senior Project Engineer Mike Dale, who examined and tested the faulty plugs and eventually discovered that the properties of anti-seize compound are incompatible with the characteristics of many of today’s distributorless (DIS) ignition systems.
“Mark and I enjoy these challenges and take them very seriously because they represent time-consuming and potentially expensive problems that are facing our customers on the job,” Dale said. “We believe technicians and parts professionals will learn a lot from this new video in terms of best practices for replacing plugs and diagnosing driveability issues on today’s DIS-equipped vehicles.”
The new Airtex Vehicle Electronics video can be accessed by entering the search term “Unusual misfire” on the YouTube.com home page. The Airtex video library on YouTube includes more than 20 other in-depth diagnostic case studies covering a broad range of common driveability issues, as well a series of vehicle system overview programs developed specifically for automotive parts professionals. To find these videos, simply enter “Airtex Vehicle Electronics” into the YouTube search bar.
For additional information regarding the Airtex Vehicle Electronics brand and product line, contact your Airtex provider or UCI International sales representative, or write to: Marketing, Airtex Vehicle Electronics, 26 S. Brooke Street, Fond du Lac, WI 54935.
