Home News How To Troubleshoot An Engine Malfunction?

How To Troubleshoot An Engine Malfunction?



Here are some simple steps you can take to fix your engine troubleshooting problem.

Mechanical problems such as worn piston rings or cylinder walls, seized valve or piston, and worn valve seats can cause misfiring. Perform a compression test with a compression meter to determine if there is bad or uneven compression between the cylinders. Then perform a leak test to find the weak cylinder.



One of the three used ignition coils found on the Toyota V6. They usually do not fail for more than 200,000 miles. So expect them to be dirty and intact.

Posted by Justin Fort, automedia.com
Estimated time:180 minutes

The engine does not light up. It’s a sensation that you recognize immediately, but it fades away just as quickly. Engine stumbles for a moment, then picks up speed. However, as soon as the speed is set, the engine will stop running again and you will feel that all automotive problems are associated with a shadow of your wisdom: “Something is wrong.”

The feeling of shipwreck is often followed by either “It will be expensive” or “Why am I / now / here?” Everything is planned, but reasonable? Instead, we recommend, “How can I fix this?”

Engine misfires can be caused by a list of errors, but some suspicions arise more often than others. The main bad guys are simple – sparks or fuel – that are usually found in spark plugs, spark plugs, coils or topshower system. There are other, more serious reasons: computer or wiring problems, broken rotating mass (pistons, connecting rods, crank bearings), valves and heads can fail or become deformed, cooling difficulties can lead to overheating and sagging of unlimited gaskets. Most of these are rare, and most importantly, most of the daunting things are likely due to your inability to solve simpler ignition or injection problems.

Unlucky Engine: Collect Common Suspects
Consider the circumstances: Toyota truck is 14 years old, 175,000 miles, 75% of the road, a lot of off-road time in the last 25,000. This means that many mechanics are used diligently and show their age. Yes, it’s our fault: parts that were worn out on schedule now tend to do so as quickly as possible. This is the expected wave of maintenance that comes with new used car owners. Don’t be lazy – just be one step ahead.

Although our mistake was inconsistent, there were severalto the remarkable parts (always watch the parts for engine diagnostics). The error occurred when the truck was moving at a constant speed (like on a highway). This did not happen when the truck was cold, but appeared when it was warmed up. This engine misfire did not occur only under load: it can occur both at idle and during acceleration. A misfire during acceleration naturally meant that the Toyota V6 was slowing down even more.

The correct method is to gather the available engine misfire information, focus on the action required to eliminate the suspects, and let the process tell you the cause. Let’s call it the scientific method after taking a few smart steps. If your car or truck is controlled by a computer, you need to connect it first. A code scanner, available at the parts store, allows you to enter the engine control module (ECU) and get a dialogue about what is happening, what is happening and where it is going. The ECU may not always tell you which part is faulty, but our truck has saved data indicating Even though the engine did not have cylinder 4. Okay, six cylinders with potential problems were reduced to one.

If we weren’t computerized, studying spark plugs would allow us to focus on the possible causes of misfires. Stubs are easy to read: with a little care and good advice such as those found in the Chilton and Heine manuals, stubs make it clear where problems arise when cylinders are empty, and if they are. ‘agree. thin or thick.

However, before you start, you must follow all safety protocols when servicing your vehicle, using safety goggles, gloves, and whatever else is necessary.

Diagnostics and examination: ignition
Pick your attack plan – cheap or expensive, light or heavy – and stick to it. Getting started with spark plugs is cheap and easy, which is why we chose spark plugs. Since P0304 repeated, connector # 4 came out first. He read poorly (gray-brown, not bad, but usually hot and bad for fuel) and predictedA fuel problem, not a spark problem.

Repair and replacement of nozzles (right and right) is a larger project than candles. So we stuck to the plan and wrote down the information in case an ignition repair could not solve the problem. Other candles had been replaced about 20,000 miles earlier and looked nearly perfect. Everyone was in good shape just before the # 4 meager reading. We cleaned them up and replaced the # 4 plug with # 2. If the problem was with the spark plug, then the misfires were the ignition will go to # 2. This is not the case. P0304 is back.

Read the connector: ash brown with a touch of green is a good combination for the latest generation engines. A little greyness from the hot and tough Blackrock race. White spots, bad gasoline?

Plug in good, don’t you plug in? The inherent dating of plug cables is easy to find on Toyota products – it is printed on the cable. The vehicles on this truck were as old as the truck itself, and probably original. Although they drove well and looked good – albeit dusty – over 175,000 miles, newThe set wasn’t hard to justify. The P0304 returned immediately with a new seat belt, so this was not a problem with the wire. On the other hand, we now have a nice spare kit and a new engine kit that should cost at least $ 100,000 (this is Toyota, so we’ll let you know).

There are a few simple methods for checking outlet cords. Inspect them in the dark with the engine running and watch for sparks. Then spray the wires with water and see if there are any sparks (in the same dark environment). You can remove the wire and gently bend it to see if there are any cracks in the rubber cover. These all point to faulty wires (and don’t worry, you’re looking for tiny sparks).

Flex Test: Even at 175,000 miles, the OEM connector wires will bend without breaking. Quality OEM product in place.

troubleshooting an engine miss

After the spark throwers and spark conveyors were cleared of the P0304 code, we went to the spark generators. On this Toyota, three coil banks are energized on cylinders # 1, # 3 and # 5, and each leads one outlet there and on the opposite side of the engine.spruce to No. 2, No. 4 and No. 6. The system is called residual spark: the coil ignites two sparks at the same time, and the spark plug ignites twice in the combustion cycle – once to ignite the cylinder and again to remove the residue during the exhaust stroke. Other cars may use one coil pulling through the manifold, or one coil on each cylinder, but your job is the same. Find the problem and fix it.

We checked the connectors and cables, so let’s move on to the coil. You can use a multimeter to check the resistance values ​​of the primary and secondary outputs of a worn ignition coil, as well as those that have been well tested on this truck (0.67 to 1.05 ohms on the primary, 9300 to 16000 ohms on the secondary). … Information on all test scores can be found in your Workshop Manual or Factory Service Manual (FSM). In the absence of any signs of a coil malfunction, returning to the pumping method (it makes sense), we had to replace coils # 1 and # 3, but the error with # 4 remained.

If you don’t have it, find out for yourself why the multimeter isCalled “Ten Buck-O-Meter”.

Since the P0304 hasn’t disappeared despite testing the connectors, wires, and coils, we’ve solved a few simple fixes. Moving on to the next suspect, as indicated by the connectors (see Figure 4), the misfire behavior (intermittent, related to heat and constant speed), and the elimination of other suspects: fuel. While the injector problem was previously suspected, it was best to eliminate the ignition parts before switching to a set of injectors that required a real key to access.

No matter how big your horsepower is, pulling the fuel injectors is a little work. Right in front of a four or six with fuel injectors dangling to the side of the head (and even then, probably clogged wires, gaskets and braces), pulling the fuel injectors is no easy task. Many non-corrosive penetrants help to loosen hoses and gaskets, especially the well-known rigid nozzle o-rings (try Liquid Wrench ® ). Take some spare O-rings with you. Top The fixed rails usually hold the injector in place. So be careful if you need to remove the rail to avoid damaging the nozzles or O-rings. Some of the manifold gaskets are metal, like on this Toyota V6, and can be reused if you’re careful (and they haven’t been baked). Expect gaskets to be replaced in most cases.




How do you fix an engine misfire?

Check spark plugs for damage.

Use the spark plug socket to remove the spark plug so you can take a close look. The damage you see will help you determine the cause of the misfire. If the spark plug is just old, replacing it may fix the problem. Remember to replace the spark plugs with new ones and disconnect them correctly.

How do you know if your engine is misfiring?

Here are the signs of a broken engine to look out for:
  1. The engine is losing power.
  2. The engine is difficult to start.
  3. Fuel consumption increases.
  4. Emissions are increasing.
  5. The engine makes clicking sounds.
  6. Failure of the intake or exhaust manifold.
  7. Engine shakes, vibrates, or stops.

What causes a single cylinder misfire?

Poor misfires that affect only one cylinder include a dirty fuel injector, an open or short in the fuel injector, or a problem in the fuel injector control circuit (wiring or PCM). Compression problems that can cause misfiring include a burnt exhaust valve, a bent intake or exhaust valve, or a leaking head gasket.