Engine Misfires on cylinders?

I would suggest switching the coils and plugs one at a time with a cylinder on the opposite bank just to make sure they swap sides. Due to these two cylinders being next to each other we cannot rule out a head gasket issue so we may need to do a compression check if the plugs, coils, or injectors are not the issue.

Here are guides on how to do these tests:

https://www.2carpros.com/articles/how-to-test-engine-compression

https://www.2carpros.com/articles/head-gasket-blown-test

Let me know if you have questions or what you find and we can go from there. Thanks

Please have a look at the lower cowl panel seal. At my dealership we usually have to remove it and replace the one-sided sticky seal because the original is flattened and does not give the upper rubber cowl seal a positive seal against the hood thus making water leak onto the top of the engine, and consequently into the plug holes and onto the coils.

Test show misfire on cylinder 8. I changed spark plug and coil and still has misfire. Whats wrong?

When you changed the plug and coil, did you replace the boot? And was the plug fouled?

what do u mean by fouled plug? And the boot do u mean the piston?

By fouled, is the plug black? Wet? Melted electrode? Anything abnormal about it? Did you change all plugs or just #8? . Is it a single coil pack, or coil on plug system? Were the plug wires if coil pack all changed? Coil on plug, where the Boots under the coils changed? And can you feel the injector clicking with the engine running? You may need a fuel pressure and injector leakdown test.

acts like engine misfire but it does it when its going to shift. all coils fine
it does it on reg. driving
will not do it going fast or real slow

If the check engine light is on let run the codes tis guide will help

https://www.2carpros.com/articles/checking-a-service-engine-soon-or-check-engine-light-on-or-flashing

If not, check fuel pump pressure to confirm it is within spec. If a tune up hasn't been done for a long time look at this guide.

https://www.2carpros.com/articles/how-to-tune-up-a-car-engine

and

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

Please run down these guides and report back.

Have a misfire on # 4 according to my tester.
p 304 is the code, is it my coil or fuel injector an how do i test it? Please Help!

The injectors in these vehicles are very dependable. Chances are the coil pack is bad. You can check to see if it is getting spark. Also, I have seen the rubber boot actually go bad and cause the coil to short.

Let me know what you find.

I have a '99 Ford Expedition (4wd) with 5.2L V-8 (GAS) engine and it as been thru the routine Ford maint per the book at proper intervals.

Recently the truck started running very-rough and then the "Engine Needs Service Soon" alarm-light came on...

Seems roughest at idle and at all shift points as well.

Put my OBD2 on and confirmed CODE P0304 for #4 Cylinder Misfire

Please advise on the most likely things you would to check out in order please. Advice appreciated!

Thx

Bill

check to see if you have spark. could be a bad coil, wire or spark plug. if those three are good you more than likely have a bad injector. if thats not it you don't want to know what it is...$$$$$$$

The truck has been misfiring on and off for about a month. Changed out all spark plugs, ignition coils, and ignition coil pigtails. Checked for vacuum leaks and there were none detected and when checking for misfires there are none found. There is a heated o2 sensor code but I think it’s due to a leak in the exhaust. What other possible causes can cause the truck to run the way it is ?

Hi,

You have done a lot already. Are you certain there are no vacuum leaks? There is a vacuum hose that runs off the back of the throttle body and will have a 90° bend in it. They commonly dry rot and leak.

If that isn't the case, what code are you getting for the sensor? Also, are you sure it is the engine and not a transmission issue? I ask only because there are no misfire codes.

Keep in mind that the O2 sensor could cause an issue, but I would think you would see a code and the exhaust leak, as you already know, can be the cause. So I would really like to know the code you have.

Next, have you checked fuel pressure to confirm there isn't an issue? Pressure that is too high or too low can also cause a misfire.

https://www.2carpros.com/articles/how-to-check-fuel-system-pressure-and-regulator

Here are the specs for pressure:

1998 Ford Truck Expedition 2WD V8-5.4L SOHC VIN L
Pressure
Vehicle Powertrain Management Fuel Delivery and Air Induction Fuel Pump Fuel Pressure Specifications Pressure, Vacuum and Temperature Pressure
PRESSURE
Engine Running .................... 193-310 kPa (28-45 psi)
Key ON Engine .................... 242-310 kPa (35-45 psi)

Also, a partially restricted exhaust system (converter) can cause a misfire often along with a loss of power.

https://www.2carpros.com/articles/bad-catalytic-converter-symptoms

https://www.2carpros.com/articles/how-to-test-a-catalytic-converter

______________________

If you have a live data scanner, could you let me know what the short term fuel trims are?

Let me know.
Joe

P0133 , P0135 and I’ll have to check that hose.

See pic 1 for P0133 possible causes. You are very possibly right with the exhaust leak. If you look at pic 2, it indicates possible causes of the P0135. That is different and not related to a power issue. I believe the two are related for the same reason, a lack of power. Check the connector for corrosion, damage, skinned wires, disconnected or pushed in pins or anything out of the ordinary.

Let me know what you find.

Joe

Checked that vacuum line you talked about and the line was fine. But I’ll get to checking that connection and is that what could possibly cause the lack of power? It’s usually around 35-45 mph.

Based on the codes, I feel that is a good place to start. If the computer is trying to adjust air fuel mixture based on faulty readings, anything is possible. If your scanner shows live data, let me know what the short term fuel trims are and see if it is running the fuel system in a closed loop when at operating temperature.

Joe

I’ll check the trims tomorrow.

Sounds like a plan. Let me know what you find or if you have other questions.

Take care,
Joe

Hi, When I press my accelerator it seems like the gas is not getting to engine. The car doesn't move then all of a sudden it jerks forward. When I come to a red light, the car will start smoothly if I can coast down hill a bit first. If I am stopped going up hill, the car jerks forward about 5 seconds after I press the accelerator.

a few things come to mind like a bad mass air flow sensor or ignition skip. is the check engine light on? if it is bring it to autozone, hey will scan it for free then give us the codes and we can go from there.

The check engine light in my 1998 Ford Expedition, 5.4L engine, came on. The diagnosis was a restricted EGR flow. A mechanic friend suggested I just clean the ports connected to the EGR valve. Did that, had the check engine light reset and within 10 miles, it came back on. I then replaced the EGR valve and the DPFE sensor, again cleaned out all the connecting ports for carbon buildup. Check engine codes now say, mixture too lean in bank 1 and bank 2 and misfire in cylinder 1. I am going to change spark plugs and coils this weekend, but not sure that will solve all the problems.

My question, is this more likely a vacuum hose problem, given the lean mixture codes? If so, which hoses should I look at and what should I look for?The vehicle will sputter upon acceleration, but then respond normally. It idles rough and will sputter while cruising. It also has a terrible vibration at around 50 miles an hour. Any advice will be appreciated.

The check engine light in my 1998 Ford Expedition, 5.4L engine, came on. The diagnosis was a restricted EGR flow. A mechanic friend suggested I just clean the ports connected to the EGR valve. Did that, had the check engine light reset and within 10 miles, it came back on. I then replaced the EGR valve and the DPFE sensor, again cleaned out all the connecting ports for carbon buildup. Check engine codes now say, mixture too lean in bank 1 and bank 2 and misfire in cylinder 1. I am going to change spark plugs and coils this weekend, but not sure that will solve all the problems.

My question, is this more likely a vacuum hose problem, given the lean mixture codes? If so, which hoses should I look at and what should I look for?The vehicle will sputter upon acceleration, but then respond normally. It idles rough and will sputter while cruising. It also has a terrible vibration at around 50 miles an hour. Any advice will be appreciated.

A few weeks ago my vehicle started misfiring, my OBD scanner said cylinder three misfire, and two bad o2 sensors. I replaced all the coil packs, plugs, and the two downstream o2 sensors. I also went ahead and replaced the intake, plenum, throttle body and EGR gasket(s). It ran great for about a week then started missing again. No CEL but scanner said cylinder four misfire. So I replaced all the injectors and o-rings, and moved cylinder four coil pack to cylinder five. When it is cold it runs fine but when it warms up it starts to miss, every so often, and has multiple misses in a row, after switching the coil packs the next day the scanner said cylinder five miss, so I checked and changed that coil pack. Again ran fine when cold missed real bad when warm, and especially when accelerating. I changed out the MAF, fuel pump, fuel filter, throttle position sensor, and the vacuum is at a steady twenty, quick throttle bump and it goes to two, back up to twenty five to twenty seven, then back to a steady twenty. At this point i am not sure where to go from here, could it be the catalytic converters, EGR or coolant temperature sender?

I have had this happen in the past if someone tries to use anything other than Motorcraft brand spark plugs. I have personally had this problem in three different vehicles that was being caused by using Bosch spark plugs. For some reason these Fords just do not like them. You also have to check very carefully that nothing has leaked into the spark plug tube and none of the plugs got cracked during installation.

I originally put in NGK plugs with a heat rating of five, a week later I changed it to Motocraft with a heat rating of two, it did not make any bit of a difference all the holes were clear of any fluids or debris and the NGK plugs looked as If the engine was running lean.

It is easy enough to tell if it is running lean. Just use a scan tool and look at the long term adaptive data and see if the computer is trying to richen the mixture.

You might want to do a compression test also.

Bank 1 is at +5% at idle 0% at 2k, bank 2 is +8%at idle and +2% at 2k.

Okay, that puts the lean question to bed.

At this point i am not sure what I should check next or what else it might be. it is a very inconsistent miss/misses at idle then a constant miss when under load.

As I responded earlier, you need to do a compression test.

Alright I will first thing in the morning. what do I test If the compression is good?

Compression is as fallowed (dry test) 1. 155 2. 165 3. 155 4. 150 5. 160 6. 165 7. 145 8. 150
(Wet test) 1. 170 2. 185 3. 165 4. 165 5. 175 6. 180 7. 165 8. 170
All +/- 2

7 is a little low but I doubt that is your issue. You are going to have to somehow determine if it is spark of fuel that you are lacking. That may require using a lab scope.

So you do not think it is a catalytic converter issue?

Why would you suspect a catalytic converter? That is not a symptom of a plugged catalytic converter.

Was thinking a restricted exhaust system might cause the exhaust to build up in the cylinders and cause a miss

1997 Ford Expedition has diagnostic code for misfire on Cylinder #3. Changed sparkplug and coil, but code has not changed. What else could the problem be?