Blinking check engine light

[stew47]

So the light started blinking and stayed on under hard acceleration. It's a 2008 f350 with 6.8. Truck didn't seem to be lagging in performance. Tomorrow I'll go to autozone and see what code it threw but first anyone have any experiences of what they did?

[stew47]

Update.... I took to mechanic and they eliminated all but the plugs. They gave me price on changing and I said I'll take a crack at it. lol I prob should've paid them but I finished the plugs today. Worn down electrode on 3 of them. We will see what happens. It wasn't terrible and I watched a lot of YouTube videos to prepare me.

[westend]

Does any one have a recommendation for a COP tester that can be used without disconnecting the coil? In other words does a tester that you just hold near the coil and lights or not, available since this misfire situation due to bad COP is somewhat common.

There may be an inexpensive one out there. Most garages have a scope system that is used. They are big money.
Your truck has this built in. If a COP is failing or has failed, the engine computer will set code for the individual cylinder. It might not be the COP, though, since the code is for cylinder misfire. There can be other causes for that. In most Ford trucks, the reliability of the plug and wire is good enough so that an individual cylinder misfire would assumed to be the COP.

[PUCampin]

I was getting hesitation and bucking with no light at all. The Torque app with a blue tooth reader allowed me to monitor the misfire count for each cylinder on my 07 Expy 5.4 and see which ones had the problem. This was extremely useful. In my case, several cylinders were misfiring under load, but not enough to reach the limit required to cause the light to blink or set.

Another useful device is a HEI (High Energy Ignition) spark tester. You have to disconnect the coil and boot, put it on the end of the boot and connect to a good ground. It has a very large air gap and will stress test the coil. A failing or weak coil will not create a spark. This really is the absolute best tool to check a coil. They are actually very easy to remove, one screw holds them in place and disconnect the wire and pull out. Then reconnect the wire and put the tester on the end. Remove the fuel pump relay or disconnect the collision sensor so you do not flood the engine while turning over to check for spark.


Since all my coils produced spark in the HEI tester, I knew it was plug change time. Since this was the first, I just paid Ford to deal with it. I did not want to deal with broken plugs.

[fourthclassC]

Howdy,

Big Thanks to GDTrailer for all the technical input. I really learned a lot.

Does any one have a recommendation for a COP tester that can be used without disconnecting the coil? In other words does a tester that you just hold near the coil and lights or not, available since this misfire situation due to bad COP is somewhat common.

[stew47]

Lol don't let some of the other posters aggravate you. I appreciate you following my thread and helping me. Also thanks for the advice about the ford forum. I've had some good suggestions over there. Simple not costly suggestions like replacing the boots and making sure there's no moisture. One suggested cleaning the maf sensor since its always under near full throttle. Oh and I posted a tranny problem and a guy is pointing me towards the solenoid for reverse. That beats a new tranny.
Anyways I will pursue figuring out how to read the fuel values and look for vacuum leaks as well. I'm torn about the cops but if needed I'll put one in and move it. It does irritate me that shops will pour tons of parts into things but what do they care it's not their money. Lol I can't pour tons of money in cause then I can't camp....and that's why I have truck. Anyways thanks so much.

[Gdetrailer]

kevden wrote:

Gdetrailer wrote:

wa8yxm wrote:

Bobbo wrote:
A solid check engine light means check the codes whenever it is convenient.

A blinking check engine light means pull over, stop and call a tow truck.

Happened to my brother once as he was pulling off the freeway in his Detroit Diesel Powered Semi. His made it to the end of the ramp and coasted onto the shoulder.. Buddy said "Wooee, Looks like the clown car at the circus with flames shooting out from under the hood"

He left the terminal with a Detroit Diesel under the hood. By the time he stopped (near instant after the light came on) He had two halves of a Detroit Diesel under the hood.. Not so little brother (6'6.5" tall to my 6'3" but younger) is a certified Diesel Mechanic (Also Auto) Inspected it, Hitched a ride to the truck stop a short distance away..Called Detroit D His buddy dropped his trailer and they went back intending to pull his tractor out from under his trailer, then pick up his trailer and tow it to the truck stop.. Tow truck was already hooking up to tractor (Detroit D sent the Tow) so they took the trailer back.. Detroit had a new engine, AND an installer, on a plane the next day putting it in and he was on the road again.

Blinking Check Engine is serious.

Blinking engine light on a DIESEL is a DIFFERENT BEAST..

Each manufacturer has their own "system" to what functions a particular light means.. So no way to compare the actions of a Detroit Diesel to a Ford 5.4/6.8 engine light.

NOT THE SAME AS A FORD 5.4/6.8 gas engine, PERIOD.

I have personally been down this road with a 2006 5.4 and am very well versed on this..

Fords CEL (which in this case looks like a little engine Icon) ONLY MEANS a malfunction has been detected which can affect engine performance power wise or emission wise..

IT DOES NOT MEAN THAT ENGINE DAMAGE IS OCCURRING!

I can assure you and anyone else on Fords of this vintage and most since the 1990s there is not going to be flames, broken engine parts or severe damage done with a blinking or steady CEL.

Engine damage might not occur, but catalytic converter damage will likely occur if the cause is lack of ignition. Unburned fuel will enter the cat and temps will skyrocket and kill it in seconds.
So, instead of a $150 tow bill you now have a $1100 or more cat(s) replacement bill.

UMM.. NO.

Generic replacement CATS are LESS than $200 each INSTALLED for the 5.4/6.8 engines.

I sure as heck would not want to live around where YOU ARE if you are paying $1100 for Cats.

You do not seem to understand the WAY Fords light works, the OP did not feel any miss, but the computer noticed.. In this case the computer BLINKS the Service engine soon light.. When the event is over the blinking stops..

It is merely letting you know that an even happened, the event STOPPED, no code was stored.. But may have kept the event as a pending code..

In this case also the OPs vehicle HAS SO MANY MILES on the cats they actually may be near done..

Unfortunately there is NO WAY ANY GARAGE WILL EVER "FIND" THE PROBLEM WITHOUT FURTHER CODES SO TOWING IT TO A GARAGE WILL COST THE OP MUCH MORE THAN A SET OF CATS!!!

It is INTERMITTENT AND ALL THE GARAGE WILL DO IS BLAST IT WITH BUNCHES OF PARTS AND A LOT OF LABOR!

I have personally been down this road.

Our 2006 truck cost us $2500 in "repairs" over nearly 9 months with over 8 "returns" to the garage..

The garage in their wise wisdom TOSSED PARTS at our problem and even one of their badly handled repairs DAMAGED one of the CATS..

I ended up PERSONALLY finding and fixing the problems the garage caused in order to eventually find and fix the original problem which turned out in my case to be a sticking throttle plate.. But not until I was fed up spending money at the garage (which by the way IS a FORD DEALER GARAGE, if THEY can fix it without throwing parts at it I doubt any other garage could either, after all they HAVE all the tools and manuals).

Your "know it all" BS is boring me and if the OP follows your advice most likely will end up hauling their vehicle to the scrap yard when they start seeing several thousands in repair bills and still not fixed.. I know, I was at that point..

OP does need to check the COMMON "problems" with this engine..

#1 VACUUM LEAK, a well known issue with the PVC vacuum line CRACKING.. This CAN cause random miss fires.

#2 is possible bad COP, Buy ONE Motorcraft COP, one at a time sub the new in for each cylinder.. If light blinks under heavy acceleration after all cylinders has had the new COP then that is not the problem. COPS do not always set a check engine light (ran into that with my 2003).

OP HAS a reader now and can check the fuel trim values this will help to pin point what is going on.. Fuel trim tells you if it is too lean or too rich which COULD lead to EVENTUAL CAT damage if not corrected or if EXCESSIVELY over lean or rich.

The front OXY sensors handle the lean/rich of the engine for fuel trim numbers, that is why that info is so important..

One must think like a detective and not haphazardly toss parts at it.

[kevden]

Gdetrailer wrote:

wa8yxm wrote:

Bobbo wrote:
A solid check engine light means check the codes whenever it is convenient.

A blinking check engine light means pull over, stop and call a tow truck.

Happened to my brother once as he was pulling off the freeway in his Detroit Diesel Powered Semi. His made it to the end of the ramp and coasted onto the shoulder.. Buddy said "Wooee, Looks like the clown car at the circus with flames shooting out from under the hood"

He left the terminal with a Detroit Diesel under the hood. By the time he stopped (near instant after the light came on) He had two halves of a Detroit Diesel under the hood.. Not so little brother (6'6.5" tall to my 6'3" but younger) is a certified Diesel Mechanic (Also Auto) Inspected it, Hitched a ride to the truck stop a short distance away..Called Detroit D His buddy dropped his trailer and they went back intending to pull his tractor out from under his trailer, then pick up his trailer and tow it to the truck stop.. Tow truck was already hooking up to tractor (Detroit D sent the Tow) so they took the trailer back.. Detroit had a new engine, AND an installer, on a plane the next day putting it in and he was on the road again.

Blinking Check Engine is serious.

Blinking engine light on a DIESEL is a DIFFERENT BEAST..

Each manufacturer has their own "system" to what functions a particular light means.. So no way to compare the actions of a Detroit Diesel to a Ford 5.4/6.8 engine light.

NOT THE SAME AS A FORD 5.4/6.8 gas engine, PERIOD.

I have personally been down this road with a 2006 5.4 and am very well versed on this..

Fords CEL (which in this case looks like a little engine Icon) ONLY MEANS a malfunction has been detected which can affect engine performance power wise or emission wise..

IT DOES NOT MEAN THAT ENGINE DAMAGE IS OCCURRING!

I can assure you and anyone else on Fords of this vintage and most since the 1990s there is not going to be flames, broken engine parts or severe damage done with a blinking or steady CEL.

Engine damage might not occur, but catalytic converter damage will likely occur if the cause is lack of ignition. Unburned fuel will enter the cat and temps will skyrocket and kill it in seconds.
So, instead of a $150 tow bill you now have a $1100 or more cat(s) replacement bill.

[stew47]

DownTheAvenue wrote:

wa8yxm wrote:


Happened to my brother once as he was pulling off the freeway in his Detroit Diesel Powered Semi. His made it to the end of the ramp and coasted onto the shoulder.. Buddy said "Wooee, Looks like the clown car at the circus with flames shooting out from under the hood"

He left the terminal with a Detroit Diesel under the hood. By the time he stopped (near instant after the light came on) He had two halves of a Detroit Diesel under the hood.. Not so little brother (6'6.5" tall to my 6'3" but younger) is a certified Diesel Mechanic (Also Auto) Inspected it, Hitched a ride to the truck stop a short distance away..Called Detroit D His buddy dropped his trailer and they went back intending to pull his tractor out from under his trailer, then pick up his trailer and tow it to the truck stop.. Tow truck was already hooking up to tractor (Detroit D sent the Tow) so they took the trailer back.. Detroit had a new engine, AND an installer, on a plane the next day putting it in and he was on the road again.

What, exactly, has this got to do with the original post and the problem it indicated?

I don't know but it's a great story!

[DownTheAvenue]

wa8yxm wrote:


Happened to my brother once as he was pulling off the freeway in his Detroit Diesel Powered Semi. His made it to the end of the ramp and coasted onto the shoulder.. Buddy said "Wooee, Looks like the clown car at the circus with flames shooting out from under the hood"

He left the terminal with a Detroit Diesel under the hood. By the time he stopped (near instant after the light came on) He had two halves of a Detroit Diesel under the hood.. Not so little brother (6'6.5" tall to my 6'3" but younger) is a certified Diesel Mechanic (Also Auto) Inspected it, Hitched a ride to the truck stop a short distance away..Called Detroit D His buddy dropped his trailer and they went back intending to pull his tractor out from under his trailer, then pick up his trailer and tow it to the truck stop.. Tow truck was already hooking up to tractor (Detroit D sent the Tow) so they took the trailer back.. Detroit had a new engine, AND an installer, on a plane the next day putting it in and he was on the road again.

What, exactly, has this got to do with the original post and the problem it indicated?

[Denny___Jami]

stew47 wrote:
Thanks guys. Yea I'll take my time to narrow things down a bit. I'll replace a cop or an 02 sensor if can narrow it to that.
Lol reason I can't just throw parts into it....
Since I bought in May.....
This issue
Tranny hesitates going into reverse when warm
New front drivers wheel bearing
New belt
U joints
Balance tires
Backer plates and ebrake parts.
I think I have 1200$ in it since May. I wouldn't call it a lemon yet I just want to NOT put any more money in it for few months lol.

You bought a high mileage truck so some things will have to be replaced. Last year I bought a 03 F150 to save putting miles on my DRW, I changed all the fluids, belt and idler pulleys, front rotors and pads all around , idler arm, rotated tires, new battery and a few other things to make sure it was relable truck, it's all part of buying used.

Denny

[dclark1946]

stew47 wrote:
Gde trailer thanks for all your help. Just an update then I'm going to that ford enthusiast page. I got truck in to shop and they scanned, only saw the po300, checked plugs and found to be in good shape. Found nearly plugged fuel filter so replaced. Lol accelerates again. All was well for couple weeks and when passing a car today the light blinked a few times and didn't stay on. I'm gonna check for code with my neat new blue tooth scanner. Thanks again all.

What APP are you using with your ELM 327 type OBD2 adapter? I have had good luck with the Torque APP for Android. The APP has explanations for the codes as well as links for troubleshooting the specific code if you have Internet connection. I can also monitor and graph much of the available realtime parametric data such as trim,O2 sensor voltage etc.

[stew47]

Thanks guys. Yea I'll take my time to narrow things down a bit. I'll replace a cop or an 02 sensor if can narrow it to that.
Lol reason I can't just throw parts into it....
Since I bought in May.....
This issue
Tranny hesitates going into reverse when warm
New front drivers wheel bearing
New belt
U joints
Balance tires
Backer plates and ebrake parts.
I think I have 1200$ in it since May. I wouldn't call it a lemon yet I just want to NOT put any more money in it for few months lol.

[westend]

When I had a similar 0300 code appear, I waited a few days and the OBD code eventually listed the individual cylinder where the misfire was located. Since I knew all plugs were of the same vintage and firing correctly, I extrapolated that wiring or coil had failed. Wire looked OK so I replaced that cylinder's COP. I haven't had a misfire since. This is a Ford modular 5.4. Failure was at about 165K miles.

[Gdetrailer]

stew47 wrote:
Gde trailer thanks for all your help. Just an update then I'm going to that ford enthusiast page. I got truck in to shop and they scanned, only saw the po300, checked plugs and found to be in good shape. Found nearly plugged fuel filter so replaced. Lol accelerates again. All was well for couple weeks and when passing a car today the light blinked a few times and didn't stay on. I'm gonna check for code with my neat new blue tooth scanner. Thanks again all.

Good catch on the filter but obviously not the cause for the blinking light..

Most likely you will get another P0300 random misfire code..

Hopefully you will get another P03xx code which will help pinpoint which bank..

If your BT scanner is able to read deeper you need to check the fuel trim values and the Oxy sensors.. Weak Oxy sensors tend to switch on/off very slowly.

If Oxy sensors are not acting fast enough it can cause a lean fuel mixture under heavy acceleration.. That can lead to random misfire with or without an additional P03xx code..

Code reader should be a help but it may take time to catch it.