Check out our list of Common Fox Body Mustang Idle Issues! In this list, you are sure to find the issue that is causing you so much trouble!
There is nothing worse than starting up your car only to find that your engine's idle is off. This can be from a number of different issues, and we will go over some of these common areas to look over.
This is going to be your primary "go-to" when you are experiencing any kind of idle issues with the Fox chassis. This will generally fix a majority of issues that could be causing an erratic idle quality.
The Idle Air Control Adjuster spacer service kit is used to correct some idle issues that you may have after mods such as a cam installation. It needs to be verified that the idle speed concern is not being caused by the fuel system, IABP solenoid, throttle linkage, ignition system, PVC system, EGR system, cooling system, or vacuum leaks before you proceed with the install of the idle air adjuster. Check out our article explaining a step-by-step process on how to get this installed!
The salt and pepper shakers are the 10 pin connectors located on the rear of the upper intake manifold. One is white and one is black, this is why they are commonly referred to as the salt and pepper shakers. These connectors are where the main PCM harness meets the engine side of the harness. These are very common to breakage, or they become corroded causing drive-ability issue throughout the vehicle. Normally the clips break upon removal and can cause many issues. These connectors control a majority of engine functions. This will include EGR, ECT, TPS, ACT, O2’s, and all of your injector’s functionality. If the 10 pins are not making proper continuity across all of the connections, it can cause a laundry list of issues in the long run including idle quality. We have made an article going more in-depth about these salt and pepper shakers.
The ignition system of your Mustang is also an integral part to help control a good idle. If anything is worn or defective, these areas will need to be addressed. You will need to verify the actual timing as well on the vehicle. Common items will include the following list below:
Vacuum leaks are another common issue due to age. These plastic and rubber lines and tend to rot or break over time. When the engine vacuum is off, idle quality can suffer and be very erratic. Common areas will include the following:
A very common problem we enthusiasts run into is adding performance parts to your ride and then experiencing idle quality issues. This can be anything from a cold air intake to a cam swap. Everything we have covered so far can fall into this category. Missing gaskets, TPS voltage setting, the 10 Pin connectors, ignition, and vacuum can all be affected to adding new parts. If we take an intake manifold for example. To replace this, you have to encounter all of these possible issues that we have gone over so far. Taking your time can be key. Proper orientation of parts and following instructions will benefit you tremendously here.
This is a common area that is overlooked. If your engines charging system and battery are not up to par, your idle quality can also suffer from this. Here are some ways to help you in this area of your diagnosis.How To Test Alternator
This can be anything from a leaking gasket to a completely dead cylinder. If you have any imbalances on the engine like this, then you can run into idle issues. Most local shops will be able to help you properly diagnose these situations.
These common areas will be a great starting point when trying to diagnose your Mustang's idle problems. Please remember that if you are not comfortable with these procedures, you do need to rely on your local shop or professional technician to help you with this. Some of these steps will require the use of some special tools that not all of us have readily available. As always, make sure you are subscribed to our YouTube channel to ensure you are up to date on everything Mustang and Lightning-related.
Find all of the 1979-1993 Mustang parts you need to get your car looking and performing better than ever. Late Model Restoration carries a full line of Fox Body restoration and performance parts from top names in the industry. Shop top brands such as Steeda, Ford Racing, BBK, Eibach, Flowmaster, JLT, K&N, SCT and many ... more