Engine misfire?

Engine misfiring can be caused by worn or fouled spark plugs, a weak spark (weak coil, bad spark plug wire), loss of compression, vacuum leaks, anything that causes an unusually lean fuel mixture (lean misfire), an EGR valve that is stuck open. This guide will help pinpoint the issue

https://www.2carpros.com/articles/engine-misfires-or-runs-rough

Please run down this guide and report back.

thanks for the guide it was the #4 injector the guide help me find it

The car idles just fine and as long as I slowly ease up to speed I can get up to about 45mph. If I try to accelerate too quickly it starts missing and bucking.

Any ideas??

When was you last tune up and fuel filter change?

3500 since tune up and filter change

Let's try a little experiment. Under the hood on the fuel injection feed rail, where the fuel line connects, is the fuel pressure regulator. This will have a vacuum line running to it. Unplug the vacuum line and plug the line with a "golf tee" or something similar. Take it for a spin and let me know what happens.

[quote:624e04a07b="James R. Weizel"]Let's try a little experiment. Under the hood on the fuel injection feed rail, where the fuel line connects, is the fuel pressure regulator. This will have a vacuum line running to it. Unplug the vacuum line and plug the line with a "golf tee" or something similar. Take it for a spin and let me know what happens.[/quote:624e04a07b]

It works like a champ. What do I do now??

Change the fuel pressure regulator. Then you should be good to go.

[quote:c24899ddef="James R. Weizel"]Change the fuel pressure regulator. Then you should be good to go.[/quote:c24899ddef]
Thanx. I am taking it ovetr to the mechanic at 5:30 an now I won't get screwed.

Let me know how it pans out.

Hi, I have a big problem on my car. I bought it used about a month ago, and I can't find what the problem is. It was fine when I bought, up to like a week later. It misfire (hesitates) everytime I keep a low acceleration. If I don't accelerate or if I speed up (press the accelerator harder) it will not misfire/hesitate. Would you guys know the problem?
The only thing I found that could be the problem was a little bit of oil inside of the distributor cap, but I cleaned and even changed it, but still misfiring.
Thank you very much for your time.

Anderson

Could be an ignition issue.At that mileage you should be on your second major tune up (plugs/wires/cap/rotor/fuel filter). Making sure all of the basic ignition is in proper order is the best place to begin, especially for misfires like you describe.Also you should always use OEM (original equipment manufacturer) parts to keep it running right

Thanks for the reply. I already changed half of this parts, I will change the fuel filter today. If it doesn't fix it, any other suggestion?

Thank you for your time.

could be an injector issue, but get all of the ignition replaced first

Thanks to all whom have responded to previous posts.

See "Misfire at 1200-1900 rpm" and "Misfire at 1200-2100 rpm" previous.

Misfire has been traced to improper operation of the backpressure transducer valve. Removing the tube attached to the exhaust port to the intake manifold (which leads to a vacuum hose to the bottom of the transducer) and inspecting it, I found the tube to be completely blocked with carbon deposits. By thoroughly cleaning with carb cleaner, and ensuring clear passage, I was able to get the transducer to modify the opening and running behavior of the EGR. The EGR does not open initially as much and responds much more quickly to throttle and load changes.

I did replace the backpressure transducer with new from the dealer. When the same behavior as before occurred, I looked next at a possible blockage at the tube leading to the transducer.

I have replace all plugs, cap and rotor, ignition wires, fuel filter and upstream 02 sensor.

Each replacement of above parts did result in improvement in the misfire, though it is only incremental so far.

I still have a misfire at the above rpm speeds, what may I be missing? Does the 2.4 DOHC require periodic valve adjustment?

Hi steveo,

Now that you have got the EGR system under your belt, it is time to look at the spark plugs again.

After misfiring for a period of time, they could be faulty.

Most cars nowadays requires minimal valve adjustments.

I have a 94 altima that, when i start it when cold, runs just great. But within a minute, if i step on the throttle fairly quickly it starts to misfire. The warmer the engine gets, the worse the misfire, and dies at times. If I step on the throttle slowly, the engine runs fine at times, then after about 10-15 minutes its hard to restart. I have already replaced the injectors,fuel pressure regulator, plugs, fuel filter, fuel pump, mass airflow sensor, distributor, wires, cap, rotor, map sensor, ecm, o2 sensor, ignition control module, distributor transistor, and ignition coil. The check engine light never comes on, but is functional. I have checked for codes and brings up the knock sensor but is very difficult to replace. The sensor and harness are fine when I checked it with a meter. I have checked and bypassed the knock sensor with and without a resistor but ends up the same.I have even removed the exhaust and ruled out the converter and did a compression test with good results 170-175psi on all cylinders. I am stumped and have been fighting this all year.

Hi chesterco,

Thank you for the donaton.

You have replaced almost everything that can be related to the issue so there is nothing much left to check.

I would suggest checking the Throttle Position Sensor and Engine Coolant Temperature Sensor.

Are the spark plugs running rich? An out of range ECT can cause that and difficulty in starting due to flooding.