Why is my engine misfiring?

This sounds like the ignition coil is out which is common here is a video and some guides to help fix it.

https://youtu.be/iDgXwKA-IIc

It is possible you need a tune up but it could be a fuel injector as well we should run the codes to see what's going on first.

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

and

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

and

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

Please run down these guides and report back.

Engine Performance problem
1997 Ford Taurus 6 cyl Front Wheel Drive Automatic 197k miles
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Car starts and idles fine. No engine codes. Around 45mph I get a intermittent misfire. The car stumble every 15-30 seconds. It will do it at 55mph also but not near as frequent. Have replaced plugs and wires, no help. All the old plugs looked the same and prett clean. Any help? Fuel or Ignition? Thanx

Is it a missfire in more than one cylinder? Check coil...and fuel pressure.

It is so small of a stumble, I would say one cylinder. Fuel pressure, wouldn't that make it worse at 55? Six coils, how do I check them?

If your check engine light comes on it will tell you which cylinder is missfiring...P0301- #1 cylinder 0302 #2 cyl and so on, then you can pull the COP for that cylinder and cvisually inspect it for any damage to the plug boot...

No Check Engine Light, no Codes. ???

Engine Performance problem
1997 Ford Taurus 6 cyl Two Wheel Drive Automatic 130k miles

My Taurus runs fine about 75% of the time and misfires about 25%. It will run fine for 10-15 minutes and then misfire for a few minutes and then go back to running fine. My code reader says codes # P0352 "ignition coil no. 2 primary circuit fault" and #P0303 "cylinder #3 misfire detected". I replaced the coil, spark plug wires and the spark plug to cylinder #3 and it still does the same thing. I removed the spark plug wire while it was misfiring and it certainly is cylinder # 3 that is the problem.

Got a solution?

If it has good compression, and good spark, teh only thing left is fuel.This may be an injector that is slowly going away, working sometimes but not always.I have seen injectors set ignition fault codes before.

Hmm, sounds like you're guessing too!!

I only presume that it's got good compression since compression is not usually a part time thing. I don't know whether its got a spark on cyl. 3 or not, I only know that I replaced the coil, wires and cyl. #3 plug. What ever signals the coil to spark that cyl. may be out of whack (it used to be the rotor in the distributor cap, which they don't have any more). How do I figure that out?

How can you find out if it's the fuel injector without having to go to the trouble of replacing it?

To see if it is the injector, you would need the proper scan tool to watch the injector waveform for that cylinder, when it is acting up.If the PCM was having an issue firing that coil, it would give a driver code most likely.I wouldnt think it was compression, like you said it comes and goes, tht usually goes and doesnt come back.Yes, I am kind of guessing, without having the car to drive and watch on my scanner, its all guess work...lol

My car is misfireing on the # 1 cylinder I cheaked the pluges and wires. The coil look like its new . What could the problem be im out of ideas. Thank you Allan Zolinski

switch the #1 plug and plug wire with a different cylinder, does problem move to the other cylinder? if so repalce the plug and wire. if not check the injector and the compression of that said cylinder.

Greetings. This is a 3.0 GL model. Recent blown head gasket between #1 and 2 cylinder. While off I had the heads pressure tested and magnafluxed; discovered several cracks. Acquired a set of aftermarket heads, and populated them with the old valves after cutting, new seals, etc. Put it back together and it started posting 302 code w/check engine light blinking. Replaced plugs, wires and swapped coil pack with a known good one. Code returned after 5-10 miles driving. A miss can be felt during driving. I decided to remove and clean the injectors. All injector coil resistance consistent around 19 ohms.

New seals, pintles and filters as well. Upon re installation I moved the #2 injector to the #4 cylinder position. Cleared the codes. After a short drive it posted codes of both 302 and 304. I plan to move the injector from #4 back to #2 but have yet to do so. There are no apparent vacuum leaks, and least none observable. Compression is consistent and steady between 155 and 160, with the exception of #2 which is 125lbs. which seems odd. At this point I'm just soliciting opinions to see if I'm on the right track or overlooked something that could be obvious to you. Any suggestions would really be appreciated. Thanks.

That #2injector may be bad, but the wiring to the #2 is also suspect, when the problem moved with the injector, that tells you the injector is either bad, or clogged, and the fact that the #2 stayed bad, the wiring could be a problem...

Thanks. I was leaning toward that possibility. Two questions though. Do you know where I could get an illustration of the individual injector wring that corresponds to contact points on the ECM plug? And secondly, any thoughts on that #2 cylinder having compression about 20% less than the others?

If the ompression is less than 15 psi of the next lowest reading, pull the head and re check the grind of the valves, or make sure the valve lash is right, overhaed cam folower may be the wrong size, any valve noise? Also to eliminate a ring problem, did you wet test the compresion too? Put a few drops of oil in the cylinder and recheck, All plugs removed please!

I just wanted to follow up on this. I checked the valves in #2 just to be sure the rockers were torqued properly since there's no valve adjustment on this engine; all good. While I had it apart I swapped injector 4 back to #2. When reinstalling the upper intake manifold it seemed to not seat properly. After rocking it around a bit it appeared to seat fully. When I started it up, miss was gone and the engine ran smoothly. Drove it for about 50 miles to test it and it continued to run strong; no miss and no 30x codes. I can only think that the upper intake manifold was not seated properly on the first go round.
After a couple days new codes postes; 0430 and 1744 but I think that's unrelated. Just wanted to let you know the outcome.
By the way, for a 1744 is the TCC solenoid actuator internal or external to the trans?

First, if this is a 95' it should have OBDI and you are giving me OBDII 96' and newer codes?

Merlin, first off, right you are on the year. It's my son's car and I just had 1995 in my head.
Anyway your reply is quite a mouthful and i appreciate the detail you provided. Considering the specialized equipment, familiarity with what a Quick or KOEO test is for example, detailed wiring and connector diagrams or the Maintenance Analysis procedures of the manufacturer; you made it very apparent that I would be biting off more than I could chew if I started messing with the transmission.
Thanks again for all your help. Although it appears to be running/shifting fine over the past 500 miles or so, I guess he'll just have to drive it until the trans gives it up. Tom

OK.

SHO. 3.0L 6cyl MTX 147K. engine runs for about 20 minutes. Gets up to operating temp. Then starts misfiring (speed up, slows down ... jerking the car around.) When it cools down, it stops. Just started happening a week ago. If I shut down while hot and try to start ... it is hard to start (lights fade, hard to turn over ... like the battery is almost dead) then it turns over and misfires. If it is cool, runs perfect. It is definitely heat related. Coolant is fine, oil is fine. Battery is a year old and tested good. Could this be a thermostat, head gasket (no white smoke), alternator (alternator was replaced 3 years ago)?

Tim

Hello paceclassa it is heat related and the most likely is the ignition module or a weak residual fuel pressure could cause the same problem.

you will need to check fuel residual pressure if module is good.(fuel pressure in fuel line after engine shut off).

Awesome!! I am pretty sure it wasn't the alternator or thermostat. I was hoping it wasn't electrical. It doesn't appear to be. Here is what I did. I researched and figured either the ignition coil or the coolant temperature control sensor. So I opened the hood to look at them. The coolant temp. control in the car looked different than the one in the picture I had of it. Same with the ignition coil. So I removed the connectors and took them both out. Blew out the dust from the connectors and cleaned them up a bit and put them back in. Just drove the car for 90 minutes, fast, slow, stop and go, highway, city. Not a problem. But, if it happens again, I will replace the ignition control module. All three just kind of sit top of the intake manifold or the throttle body. Hopefully, car is safe to drive now. What do you think before I get in rush hour traffic in the morning? Thanks for the help!!

Thank you for your donation and for visiting 2CarPros.com we hope to help you again the next time you need us

you think it is safe to drive? its my everyday commute car.

hello,
yes it is safe to drive it.
Dust in connector specially with the ignition coil won't help for current flow.
you did a good job.

Ahhh ... the wonders of electronics. So it started again, but this time the check engine light came on and then the car stalled. Had to wait 5 mins for it to cool down enough to start. Got it home, pulled the engine control module (really easy) and took it in to get a replacement (internet said it was available at the store, but it wasn't - had to go to a store about 10 miles away). While I was at the store, they tested it (about 10 times to get it hot) and it tested good so I thought ... replace the ignition coil and the guy at the store said that was probably the cause. So I bought a coil and put it in. Didn't solve it. So i drove the 10 miles, picked up the module and put it in... Mathiaso was exactly right. It was the ignition control module. The moral of the story. Sometimes tests are wrong and the guy at the autoparts store is wrong too. But I saved a ton doing this myself with reman'ed parts. Thanks guys!!!

Hi paceclassa, Were glad you got your problems resolved and mathiaso took good care of you. Thank you for using 2CarPros.com. We appreciate your donation and look forward to helping you in the future. Have a great day!

Have a great day and thanks for your donation

So ... after all of this stuff, it wasn't the ignition control module at all. The car went back to doing misfiring and hesitating like a person learning to drive a manual. Then stalling. It was the Camshaft Position Sensor. I also found the oil leak. There is a gasket around the crankshaft flywheel and that is leaking, getting oil all over the sensor and the sensor was failing. A $30 part.

Benn driving it for a few months and now the car won't start. It will crank but not start. I have had it at two shops and they can't find the problem. They both tell me the plugs aren't getting a spark, but they tested everything on it and it tested good. They can't figure it out and gave the car back to me. I thought it was the cam position sensor that failed again (the cranking but not starting is the indicator) since I used a reman'ed part, but both shops said it tested good.

coil, cables, ignition ...etc have all been tested. Timing belts checked out OK too

Any ideas?

I drove my '94 Taurus from NC to AZ with no problems. Now that I'm here in AZ, though, my speedometer has stopped working and my entire car jerks violently whenever I'm doing anything BUT accelerating, including braking, coasting, or even sometimes when I ease off the gas a little bit. When I get up to highway speeds, 60+, everything gets better. My speedometer suddenly works, my transmission is fine, I have no problems. When I slow down again, the transmission acts up again, though not as badly, and the speedo keeps working until I come to a dead stop, like at a red light.

I have two more days of pretty serious driving ahead of me before I can stop long enough for a serious repair job. There's a mechanic across from my hotel and I can stay a day - is this the kind of repair that can be done in that time? And if I keep driving it until Tuesday, will I be okay?

Loosen the retaining nut/bolt holding the sensor in the transaxle. Remove the driven gear with the sensor from the transaxle. Disconnect the electrical connector from the speed sensor. Disconnect the speedometer cable by pulling it out of the speed sensor. Do not attempt to remove the spring retainer clip with the speedometer cable in the sensor. For 1992-95 vehicles equipped with and automatic transaxle, remove the driven gear retainer and driven gear from the speed sensor. To install: Position the driven gear to the speed sensor. Install the gear retainer. Engage the electrical connector. Make sure the internal O-ring is properly seated in the sensor housing. Snap the speedometer cable into the sensor housing. Insert the sensor assembly into the transaxle housing. Tighten the retaining nut/bolt to 30-40 inch lbs. (3.4-4.5 Nm). Install the retaining clip.

Yeah, but will it hurt to wait to do it? Can I keep driving or will I blow up?

how far of a drive

[quote:f683a25dd4="jnovack"]how far of a drive[/quote:f683a25dd4]

About 250 miles.

i would replace before but should not hurt car will run bad

While driving, my car seems to "skip". I am thinking maybe needs a tune-up or alternator? I don't know much about cars and don't have much money. Any posts from someone would be greatly appreciated. I can take the car to the shop on payday Fri. but I would like to give them some kind of idea what it might be. Also it cranks up okay, it just seems after I have got to a "cruising" speed that is when it starts the "skipping". THANK YOU in advance for your help. Greg W.-- Alabama

Hello

The charging system would have nothing to do with this symptom so the alternator is not at fault here. If the engine cranks up good and vehicle runs fine and has no unusual shakes, smells, sounds etc.. other than the little skip then it is probably just due for a tune up. May also have a little water in fuel if it has been cold there or if fuel was just bad. When was last time to receive tune up including plugs, wires, fuel filter, oil, oil filter, air filter?




Thanks for using 2CarPros.com!

When I'm driving 50-60 mph and I need to pass another vehicle (2-lane hwy) when I accelerate faster the car jerks strongly. As I continue this I lose pick-up and it takes a long time to pass the car. All the other times I drive the car (besides passing) it operates fine. I took the car to my local ford dealer, nothing showed on the computer scan. They recomended a tune-up, the fuel injectors cleaned, and a new fuel filter. My check-engine light is always off. I installed new plugs, a new fuel filter, and had the injectors cleaned professionally. I still have the jerking problem. Any Help appreciated Thanks!

The best way of going after this is to use this guide.

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

Please run down this guide and report back.