oilwell1415
Well-known member
A week or two ago it was mentioned in a thread that people didn't give enough information when trying to solve driveability issues with their trucks. I wrote this up to let them know what information is needed to help them solve the problems. If there's anything I missed, let me know and I can add it to the list. If it's worthwhile, I'll finish Part 2 which is how to actually do the diagnostics on some of the more common problems. Is it worth making it a sticky so it's easy to find?
One of the most common questions here is “My truck is doing xxxxxx, what’s wrong with it?” Unfortunately, this is often the only information given and results in nothing but pain and frustration for everyone involved. There is a lot more information that is needed to diagnose an issue with your truck than just telling us what it’s doing. Here are some things that will help us to help you, or help you describe the problem to a shop if you take it in.
First, we need to know what we're working on. Year of truck and any mods done can make a big difference in the solution to the problem. If you've got a truck with a 5 speed conversion and trans codes, we'll be working on codes for a long time if you don't tell us about the conversion. Tell us what we are working on and all of the mods it has and the chances of getting good advice go up a lot.
Second, make sure you are describing the problem correctly. No start and no crank are different, as are a misfire and a hesitation. Getting this part right is the first step towards getting it fixed. Here is a list of common symptoms and their description:
1. No crank means that you turn the key to start and the starter does not spin the engine.
2. No start means that the engine is being turned over by the starter, but does not start.
3. Misfire or miss is what happens when one or more cylinders are not producing power. This often feels like vibration or unsteady power production from the engine. The engine does not run smoothly when this happens and feels down on power. A misfire can happen all the time or intermittently.
4. Hesitation or cuts out describes a momentary total or near total loss of engine power. This can happen any time the engine is running. It commonly occurs during a rapid change in one of the engine’s operating conditions. For example: flooring the throttle from a dead stop causes the engine to nearly die instead of accelerating.
5. Surge is a variation in rpm or power output without a corresponding command from the driver. It can happen any time the engine is running.
6. Sluggish describes either a lack of power or lack of throttle response or both. When you push the throttle, the engine runs smoothly but does not respond as rapidly as it should or produce the power it should.
7. Stall is when the engine quits running after it’s been running.
8. Check Engine Light This isn’t really a driveability symptom, but it is a signal to you that something is wrong and you may have more significant problems on the way.
Obviously, this is just a few of the things that you might experience, but almost any driveability problem you have can be placed in one or more of these areas. There is no way to list every problem you could possibly have, but this will get the process of fixing the problem started.
Once you have identified your symptom, you need to identify when it happens. You may be rolling your eyes right now, but engines don’t just decide one day to cause problems. There is always something making it run poorly, and many times there is a pattern. Knowing what that pattern is can be the key to solving the problem. Here are questions that need to be answered before meaningful diagnosis can begin:
1. How often does the problem occur? All the time (95-100%), most of the time (50-95%), part of the time (25-50%), and occasionally (10-25%) are good answers. Below 10% can be very difficult to isolate and is commonly described using a mechanic’s five favorite words: “every once in a while”
2. Does it do it more when hot or cold?
3. Does it do it more when it’s been raining or is very humid?
4. Does it do it more when you first start it up or after you’ve been driving a while? If it’s after you’ve been driving a while, how many miles or minutes before it starts?
5. Does the problem happen at idle, low throttle, part throttle or full throttle?
6. Does the problem happen at a certain vehicle speed?
7. Does the problem happen at a certain engine speed?
8. What is the fuel level when it happens?
9. Is the check engine light on? If so, what are the codes?
10. Have you already changed some parts to try to fix the problem?
11. Did the problem start after you had work done?
12. Has your fuel mileage changed since the problem started?
13. Do you smell, hear or feel anything different about the vehicle when the problem is occurring?
Some of these questions may not be easy to answer, but taking the time to answer them will make it much more likely that those guys on the internet are able to help you. If you really struggle to describe the problem or when it happens, it may be helpful to get a small pocket notebook to carry in the vehicle with you to write down the specifics of when a problem happens.
One of the most common questions here is “My truck is doing xxxxxx, what’s wrong with it?” Unfortunately, this is often the only information given and results in nothing but pain and frustration for everyone involved. There is a lot more information that is needed to diagnose an issue with your truck than just telling us what it’s doing. Here are some things that will help us to help you, or help you describe the problem to a shop if you take it in.
First, we need to know what we're working on. Year of truck and any mods done can make a big difference in the solution to the problem. If you've got a truck with a 5 speed conversion and trans codes, we'll be working on codes for a long time if you don't tell us about the conversion. Tell us what we are working on and all of the mods it has and the chances of getting good advice go up a lot.
Second, make sure you are describing the problem correctly. No start and no crank are different, as are a misfire and a hesitation. Getting this part right is the first step towards getting it fixed. Here is a list of common symptoms and their description:
1. No crank means that you turn the key to start and the starter does not spin the engine.
2. No start means that the engine is being turned over by the starter, but does not start.
3. Misfire or miss is what happens when one or more cylinders are not producing power. This often feels like vibration or unsteady power production from the engine. The engine does not run smoothly when this happens and feels down on power. A misfire can happen all the time or intermittently.
4. Hesitation or cuts out describes a momentary total or near total loss of engine power. This can happen any time the engine is running. It commonly occurs during a rapid change in one of the engine’s operating conditions. For example: flooring the throttle from a dead stop causes the engine to nearly die instead of accelerating.
5. Surge is a variation in rpm or power output without a corresponding command from the driver. It can happen any time the engine is running.
6. Sluggish describes either a lack of power or lack of throttle response or both. When you push the throttle, the engine runs smoothly but does not respond as rapidly as it should or produce the power it should.
7. Stall is when the engine quits running after it’s been running.
8. Check Engine Light This isn’t really a driveability symptom, but it is a signal to you that something is wrong and you may have more significant problems on the way.
Obviously, this is just a few of the things that you might experience, but almost any driveability problem you have can be placed in one or more of these areas. There is no way to list every problem you could possibly have, but this will get the process of fixing the problem started.
Once you have identified your symptom, you need to identify when it happens. You may be rolling your eyes right now, but engines don’t just decide one day to cause problems. There is always something making it run poorly, and many times there is a pattern. Knowing what that pattern is can be the key to solving the problem. Here are questions that need to be answered before meaningful diagnosis can begin:
1. How often does the problem occur? All the time (95-100%), most of the time (50-95%), part of the time (25-50%), and occasionally (10-25%) are good answers. Below 10% can be very difficult to isolate and is commonly described using a mechanic’s five favorite words: “every once in a while”
2. Does it do it more when hot or cold?
3. Does it do it more when it’s been raining or is very humid?
4. Does it do it more when you first start it up or after you’ve been driving a while? If it’s after you’ve been driving a while, how many miles or minutes before it starts?
5. Does the problem happen at idle, low throttle, part throttle or full throttle?
6. Does the problem happen at a certain vehicle speed?
7. Does the problem happen at a certain engine speed?
8. What is the fuel level when it happens?
9. Is the check engine light on? If so, what are the codes?
10. Have you already changed some parts to try to fix the problem?
11. Did the problem start after you had work done?
12. Has your fuel mileage changed since the problem started?
13. Do you smell, hear or feel anything different about the vehicle when the problem is occurring?
Some of these questions may not be easy to answer, but taking the time to answer them will make it much more likely that those guys on the internet are able to help you. If you really struggle to describe the problem or when it happens, it may be helpful to get a small pocket notebook to carry in the vehicle with you to write down the specifics of when a problem happens.
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