What is causing miss fire on three out of four clyinders?

If your 96 E250 300ci was running perfectly and then started missing and the code is indicating a miss fire in cylinders 1 and 2, there could be a few potential causes. Here are a few steps you can try to troubleshoot and resolve the issue:

1. Check the ignition system: Make sure that the ignition system is functioning properly. Check the distributor cap, rotor, spark plug wires, and ignition coil for any signs of wear or damage.
2. Check the fuel system: Make sure that the fuel system is functioning properly. Check the fuel filter, fuel pressure, and fuel injectors for any signs of wear or damage.
3. Check the compression: A compression test can help to determine if the engine is getting enough compression to run properly. Low compression in cylinders 1 and 2 can cause the engine to miss fire.
4. Check the vacuum lines: Make sure that the vacuum lines are properly connected and not leaking. Any vacuum leaks can cause the engine to run poorly and miss fire.
5. Check the PCV valve: The PCV (positive crankcase ventilation) valve can become clogged or malfunctioning and cause the engine to run poorly and miss fire.
6. Check the EGR valve: The EGR (exhaust gas recirculation) valve can become clogged or malfunctioning and cause the engine to run poorly and miss fire.
7. Check the Engine Control Module: The Engine Control Module (ECM) controls the ignition and fuel systems and if it's malfunctioning it can cause the engine to miss fire.

It's important to note that some of these steps may require special tools and knowledge of the vehicle's engine system, so it's best to take it to a professional mechanic to avoid causing more damage.

Not sure what type of vehicle you are referring to however most vehicles come with a vaccum diagram inside of the engine compartment , either on the bottom side of the hood or on the cross member in front of the radiator. Same can be said of the spark plug wires. If they are not availablein those places , I would suggest googling the engine year ,size and yr/make /model of your vehicle or see if youtube has a video clip of firing order/spark plug wiring .Good luck

remove the plug from the #1 cylinder, and install it into the #2 cylinder , and put plug from # 2 clyinder in to #1 plug hole, connect plug wires, and start up vehichle, and if computer shows misfire on # 2 cylinder , then you have a bad plug, possibly porcelin insulator could have a hair line crack in it, hope that this information has helped you.

Hello crey60
Try checking the fuel injector on the #3 clyinder for dirt or damage. A faulty injector will cause a missfire code and trip the check engine light. Hope this is helpful.

If you are saying that when you first start up the car it misses and then if you rev up the engine the miss goes away, I would say that you have a head gasket leaking coolant into one or more of the clyinders. Check your spark plugs. If one of them is really clean that is the clyinder that is leaking coolant.

There are so many things that could cause this. There should be a misfire code in the computer. If there is you can identify the cylinder that has a problem. It could be a fuel injector, wire, or if it has individual coil packs, (There was a change around that time), it could be a bad coil pac. It may also have jumped time. The timing belt should have be replace around 90G and every 90 thereafter. They don't always break, sometimes they jump.

Another thing that is a little easier to diagnose, but not what you want, is there could be a valve problem. I have seen a valve have a chip in it that does not allow compression. Do a compression check on all four clyinders.

One final thing, if the repair shop told you that it was the mass air flow, hold them responsible for the miss diagnosis. have them credit what you paid towards a repair that will fix it.

Switch it with another and check if the miss follows the injector.
Also you should check for a voltage pulse at the missing cylinder injector connector.

check all of the vaccum lines also check the one behind the throttle body, also check the fuel filter and also just maybe one of the spark plugs is not gapped right.

yes try new plugs and wires. if it still happens change the coil to

Check the wire pigtail that plugs into the coil pack. The plastic insulation around the four wires become hard and brittle, this can cause shorting and cross fires. Carefully pull the protective cover back to expose the four wires that go into the plug, check visually then bent the wires to see if they are flexible. If they are flexible and not brittle it is something else. Check out this link for detailed information and tests.