Rough idle then a bad miss with blinking check engine light

[rocky]

Started up with rough idle then as i accelerated felt a bad miss then check engine light started blinking , pulled over and light quit blinking and went out . Still running rough ...............260k miles , this happened before and i believe the shop replaced a coil pack , probably another has gone bad ?

 

[docraymund]

You need to get codes pulled.

 

[Judge Mills]

Sounds like a bad coil, but, you need to pull the codes first. Places like Autozone will read your codes for free.

 

[MWguns]

Def need to pull codes first. I had an issue similar to yours, and was only getting a single lean code P0174 i believe. I checked all my vacuum lines, and ended up needing to put a fuel pump and filter in it. Runs like a top now.

 

[1997SCEBFEX]

++ on codes to get your baseline.

 

[jaytron]

I second checking for vacuum...the PCV line/valve is common problem.....spray some brake cleaner when idling rough in area along the PCV line and if it picks up to normal then you have a leak somewhere(might not be the PCV line just a vacuum leak also)

 

[Judge Mills]

Doesn't brake cleaner melt certain types of plastic?

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[jaytron]

my "98" old lines never melted and still running strong

 

[texasscot]

Get codes (best to buy a cheap reader).
Identify which cylinder is misfiring.
Swap coilpack from the misfiring cylinder with one of the others.
Clear codes.
Start engine.
If code reappears on the same cylinder, pull spark plug and check gap. If gap is big get new plug.
If code appears on the cylinder you put the coilpack from the original misfiring cylinder on, change the bad coilpack.
You can buy 8 coils on eBay for around the price on one at the local autostore.
If this doesnt work then its something else

 

[cmeswme]

I have a 2003 Ford Expedition with the 4.6 engine, 2 wheel drive. Having similar problem. Inconsistently go to accelerate and I get the hesitation or mild sputtering. But no check engine light. Funny though, I notice this happening on and off around 41 mph. I'm scratching my head to change all the plugs or coils, maybe replace the injectors ??? Checked for codes, nothing there, no codes.

 

[texasscot]

My experience is pull coils and check for random liquid in plug holes. If dry then pull plugs and check gaps. If wet, blow air in and clean holes. Then work out where the damn liquid is coming from. On one occasion on my 5.4 it was coolant from the leaking heater control valve.
Then pull plugs and check gaps.
If plugs need changing, change them.
If plugs ok then buy set of 8 coils on eBay for $50 and use them all.
This is my 80% most likely shot.

 

[cmeswme]

Thanks texasscot, just not looking forward to pulling the plugs, not a fun job ! LOL

 

[texasscot]

You just have to hope the problem is 1 to 3 or 5 to 7. A code reader will pinpoint problem cylinders. I forgot to mention that. Sorry. Good luck!

 

[Bedrck47]

I have a 2003 Ford Expedition with the 4.6 engine, 2 wheel drive. Having similar problem. Inconsistently go to accelerate and I get the hesitation or mild sputtering. But no check engine light. Funny though, I notice this happening on and off around 41 mph. I'm scratching my head to change all the plugs or coils, maybe replace the injectors ??? Checked for codes, nothing there, no codes.

Being you have the 4.6 engine I would suggest that you pull the throttle body and clean the exhaust ports in the throttle body.

There are some very good videos on you tube on how to clean them

 

[Bedrck47]

Rather than brake cleaner use carb cleaner to check for vacuum leaks

 

[1955moose]

All good advice to a point. If you've been a part of this forum for a while, you'll see the usual diagnostic checks for a misfire. #1, run the diagnostic code checks, #2, run a fuel pressure test, #3 clean out throttle body as bedrck 47 suggested. Your problem is probably a combination of many things. If you get a single coil over plug code, I would pull just that one, test or replace it with either a Ford or Standard brand coil. The cheaper ones from eBay either won't fire proper or burn out quick. You probably should pull and replace with Motorcraft spark plugs. Again they seem to fire the best with these engines. If any of the cylinders have coolant leaking into spark plug area, fix leak immediately. Lastly if you do pull coils, and you probably will, replace all the boots on the coils.
Let us know how it turns out, Moose.


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[texasscot]

Good advice 1995moose. However, I've been running cheap coils for over 30k on my 5.4 with no issues. I did do the Motorcraft plugs however.
Good luck to all, and happy Sunday when it comes.

 

[1955moose]

Your one of the lucky ones with the coils. I guess if one or two of the cheaper ones does fail, you've got 7-8 good ones left of the motorcraft ones that came off. It's always good to hang onto a few known good parts. Saves so much diagnostic time, on a plug and play item like a coil. I always kept a known good ignition module for chevy hei ignition. And one for ford. It's cheating but why troubleshoot for 20 minutes when popping in a part takes about 3 minutes. If it didn't work, no harm, no foul!


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[cmeswme]

All great advice, much appreciated. I'll likely go through it all and overhaul the entire vehicle. Not worth paying the dealer for all this work. I'm thinking Accel SuperCoil for the coil packs, any thoughts ?

 

[texasscot]

When I had my first misfire coil problem I bought a couple of accel coils cos they were cheap compared to OEM. Months later when I had other coils go I decided to by the whole eight and found the accel coils had rocketed in price, presumably because everyone was recommending them on forums! I haven't looked at recent prices though. That's when I just went cheap on eBay, like $60 for 8. I bought a couple of individual spares also which I kept in the truck just in case. The only problem I had was when the coolant leak filled the 1-4 holes, which blew 2 or 3 of the coils. I just bought another 8... Under normal running conditions I've never had a problem with cheap ones (although I know 1955moose has other experiences as he pointed out above). As they say "your experience may vary"! Best of luck, and be gentle putting the coils bolts back as they cross thread easily (ask me how I know) assuming they have the same system as the 5.4.