New Promotion

Jan. 7, 2017

Real Fix: Mysterious Misfire

Have you been in misfiring mayhem? As you may know, misfiring will make your customer’s car run rough, and when you can’t figure out which cylinder is the culprit, it can be a hassle to fix. This is what one technician and SureTrack community member experienced when their customer came in with a 1999 Acura 3.2TL 3.2L, complaining the car was missing at idle. Let’s take a look at how this technician with the help of his fellow community member was able to manage this misfire.


Upon entering the shop the customer had already taken measures to fix their vehicle. They replaced the spark plugs with double platinum plugs; however, this obviously didn’t solve the problem. Now in the technician’s hands, he started with a scanner and got code P1399, a standard random misfire code.

The tech first checked the compression, which was 150 psi in all six cylinders. He then used the scanner to see which of the cylinders was missing with no luck. It wasn’t showing a misfire count. Discouraged but not defeated, he turned to a fellow community member.

The member suggested the tech check the valve adjustment, which is a very common issue on this model. He also mentioned checking the MAP sensor with the engine at operating temperature and idling; it should be 0.9v. If it is found at 1.0v or higher, adjust the valves with the engine ICE cold and check to make sure the EGR valve is fully seating at idle (if equipped).


After taking the suggestions, the technician found the valves just needed to be adjusted. The tech test drove the vehicle, and it ran beautifully. No longer will this misfiring menace be bothering this technician’s customer.

Real Fixes from Mitchell 1’s SureTrack® expert information resource are documented issues from actual shop repair orders and community discussions. Read the Real Fix in the Mitchell 1 ShopConnection Blog.

Sponsored Recommendations

Garage Tip: The Value of System Solutions

Learn why inspecting related parts when repairing your vehicle can save you time and money. Avoid future failures and ensure satisfaction! Click to watch now.

Access the Best Learning Resource for Professional Mechanics

Get hands-on tips, updated repair instructions, mounting videos, failure diagnosis, and best practices for professional mechanics. Click to access essential technical info to ...

From the Basics to Innovations - Transmission Technical Training Videos

Explore Schaeffler's portfolio of transmission technical trainings for the LuK brand. Tailored for all skill levels, our modules cover basics to innovations. Click to learn more...

Clutch Release Problems - Diagnosis & Failure Analysis

Explore common clutch release problems and their causes, from hydraulic issues to mechanical faults. Understand diagnostics and solutions for optimal clutch performance.

Voice Your Opinion!

To join the conversation, and become an exclusive member of Vehicle Service Pros, create an account today!