Misfire when cold

[fast_dave]

masospaghetti

Wait a full week of driving, and then add coolant to actually watch your pour-in and get the true idea of how much has been lost to get back to your reference line. It gives you a better idea than watching for a day or two.

BTW - What side were those last three plugs off of?

In my opinion, when clicking on the pictures you attached so as to make them larger, those last three plugs external electrodes and ceramic centers look like they're covered with the ash that forms when coolant is burned. Exactly like what forms on top of the passenger side exhaust manifold when coolant drips off of the heater valve.

You're truck will continue to run with a micro-cracked head.

It really only rears it's head and is noticed during the morning cold start.

Once warm, the engine runs fine the rest of the day.

BUT - you need to keep an eye on the coolant level and make sure it never goes dry. And as you have just written, after watching the coolant level since Friday (two days ago), you lose only a small amount of coolant.

The amount of coolant enters the combustion chamber on a daily basis is very small, and not enough to slip past the rings and contaminate the oil. It enters the combustion chamber and gets "steamed" instantly when the cylinder fires.

Your Ex is using coolant - OK - BUT try and see how much over a full week/full tank of gas it's using.That will then account into your "new" maintenance schedule - (i.e add a half-pint a week).

Bottom line on an Ex w/ 252,000 Miles; As long as your tailpipe isn't blowing white (steam) smoke after warm-up, and you're passing smog, I'd live with it, and just up your maintenance schedule - plugs every 15,000 and oil/filter every 3,000 miles.

 

[shucker1]

Looks like heavy ash deposits on last tow plugs in picture of all plugs you posted. Those (2) guys look a lot different than the others to me.

 

[masospaghetti]

In the picture above, the forward 3 plugs are from the driver's side bank, the rear 3 from the passenger side. If multiple plugs are showing deposits, could it be a leaking lower intake manifold as well?

@fast_dave

Thanks for the tips. I'll keep an eye on it and continue to drive it. However I do intend on keeping the truck around, and if the head is cracked I don't mind changing it out. Honestly, I would swap in a fresh motor if I had enough space in my garage to do it seeing the bottom end is probably original with a lot of miles. I just want to make sure I don't do a bunch of work to replace heads that are actually fine (who likes doing work for no reason, after all??)

 

[J_C]

Pulled the plug today, wasn't wet or oily, couldn't smell anything either - although admittedly my sniffer isn't very good. I did notice that my coolant level in the expansion tank has dropped a bit.

What else can I do to verify a cracked head before I pull them?

Does it still misfire cold? How long had it been doing this, or did it seem to coincide with colder mornings? You stated 6 years for the wires and probably plugs then, which isn't a bad run for plugs in an aging engine.

You could do a compression test. You could put a (USB or wifi or $$$ standalone) borescope down in suspect cylinders to examine. Otherwise I'd still keep an eye on the coolant loss rate, wait and see since you aren't seeing anything on the plug(s) yet.

It still seems odd to me that this only happens a few seconds cold in the morning but we're into playing odds now... odds are that if you had a leaking lower intake, you'd have more deposits on more plugs.

I'm leaning towards agreeing with fast_dave, it has 250K mi on it so replacing heads seems like too much work for too little additional life out of it, depending on your coolant loss rate. Eventually enough coolant will foul the O2 sensors and cat which comes back to how long it happened, if it's getting worse, coolant loss rate.

 

[masospaghetti]

I owned the truck from 2011 for about a year and did a bunch of work to it, then my brother took it. He drove it for about 4 years, and then it sat until I recently picked it back up. I also did a compression test and all cylinders were within a few pounds of each other. Since I've picked it up a few months ago, it's been misfiring on cold startup.

If this were your truck and you were intent on keeping it, would you bother with new heads?

 

[Turdle]

If you diagnose a cracked head, I would drain some coolant, then get a double barbed nipple and use it to connect both heater core hoses to bypass the heater core, then try k seal first. Then reconnect the heater core.

 

[fast_dave]

In this case, I think what is being called a "misfire" is actually a difference in combustion between the two banks.

You're really getting a rough idle that is causing the engine to bog/rough idle until the coolant is "steamed out" on the passenger bank.

If you put your foot on the gas pedal when the rough idle is occurring it doesn't help that much, because despite getting more gas injected you still have to "steam out" the coolant to obtain a balanced combustion between both banks. So I completely understand why your condition is being characterized as a misfire - that what it feels like.

NOTE: Gasoline mixed with water WILL combust/ignite, just at a lower temperature/btu. Think about 1960's & 1970's turbocharged engines - many had had "water injection" to keep cylinder temps low, and thus prevent pre-ignition while under full turbo pressure.

masospaghetti you write that the first 3 plugs are from the driver's side bank, the rear 3 from the passenger side. I guessed that before you even confirmed which side the plugs are from. The passenger side of the engine has BOTH the alternator and the A/C evaporator = a lot of heat tight in a space - especially around the evaporator.

You asked if the condition that your Ex is experiencing could be a leaking lower intake manifold. I'd say "yes" , that could be your problem. I hope that's your problem because that's a somewhat easy fix. Hopefully someone here can help you diagnose the difference.

What I'm going on is the history of the OHV heads. The micro crack issue is frequent enough that the aftermarket felt it profitable enough to manufacture NEW heads for this engine. Keep in mind how many millions of these engines have been built - engine rebuilders had issues with not being able to rebuild so many of original OHV heads that the the aftermarket saw $$$ and stepped in with new ones.

The question you have to ask yourself is are you willing to open Pandora's 252,000 Mile box?

You could tear it down to the lower intake, only to find that is not the problem. At this point your truck is down and you have to choose your next path, as well as obtain another car to get to work.

Your next choice is do you order new heads before removing the old ones, OR do you roll the dice, remove the original heads, and have them Magnafluxed. If they're bad and/or a machine shop won't weld them (due to their previous OHV head experiences), you'd have to spend the overhead involved with buying a rebuilt set of heads from a machine shop (as opposed to the new ones you could have ordered and swapped right on obtained from Rock Auto). BUT - no matter what, you'll never change the fact that all that time & $$$ will be spent for rebuilding 50% of a 252,000 mile engine...

Here's a link for heads New & Rebuilt:
1998 FORD EXPLORER 4.0L V6 OHV Cylinder Head | RockAuto

If it were mine, I'd drive it for years, watch the coolant on a weekly basis, up the maintenance schedule with regards to plugs and oil, and set aside $$$ every paycheck to save up for a complete engine rebuild so you could repair the truck completely AND on your terms/timeframe.

I'd save up for a two week rental of an econobox from Enterprise for $25 a day, buy a Harbor Freight cherry picker, read the OHV rebuild articles and pick and choose the BEST rebuild parts, and then talk to a few machine shops and choose who will do the work. The local machine shop (with a good rep) where I live even has a p/u truck that will come out to your house and p/u & d/o your engine, from your cherry picker, for no fee...

Hope that helps -

Addendum: Now that I read what Turdle wrote, you could always try "K-Seal" - many people that have had cracked heads have good results with it. It would be interesting to read a review of it on this forum. I've read the reviews on Amazon and on the internet.

 

[masospaghetti]

@Turdle -- Would you consider K-Seal a "permanent" repair or just a band-aid?

@fast-dave - thanks for your input, I really appreciate it. I definitely struggle with the thought of putting new heads on a 252,000 mile engine, but unfortunately I don't think my garage is large enough to get a cherry picker and swap motors -- which means paying someone else to do it. So a $750 DIY head replacement turns into a $5,000 engine rebuild done by a shop.

Luckily, I have a second vehicle to take to work, so having my Explorer down for awhile isn't a problem.

However, I rented the cooling system pressure tester again, pressurized the system to 16 psi cold, and went and ran errands for a couple hours. Came back and sure enough, the pressure had dropped -- but I saw coolant dripping onto the ground. Another heater hose was leaking, but so slowly that there was no evidence when the engine was running, the coolant was evaporate before dripping. Put on a new hose and new clamps.

I also got a USB borescope and checked out the inside of each cylinder -- I figured if there was a cracked head or leaking intake manifold, leaving the system pressurized for awhile might flood the engine. No evidence of coolant! However, the pistons in #5 and #6 look a bit oily to me, and I got a good look at the cylinder wall in #3 (it's hard to see everything with the borescope, so I couldn't see the walls in every cylinder).

Piston from #5:

#3 piston and cylinder wall:

 

[fast_dave]

masospaghetti -
Thanks for the update and I'm rooting for you - hope it's simple!

Love the bore scope pics!

Keep us informed!

Merry Christmas & Happy New Year!!!!

 

[shucker1]

#5 looks like a dirty burn to me.

#6 still shows crosshatch from what I can see.

I would really start looking at plug wires or leaking injectors to start.

Easier fix than ripping the engine apart!

 

[masospaghetti]

@shucker1, what do you mean by "dirty burn"? New plug wires on order...

 

[shucker1]

If that is the top of #5 piston it looks like a really dark black carbon color to me.

If the other picture is the top of #6 it looks a different shade. Perhaps rather dry in appearance?

 

[masospaghetti]

I agree, its hard to tell from the boroscope pictures, but piston #5 looked darker and oily.

Of note - the ignition coil is still the original. Would you change this as preventative maintenance?

Plan of action:

- Monitor coolant tank, see if it's still dropping
- Running Redline and BG44k injector cleaner, maybe help clean a leaky injector
- New Denso plug wires on order

Merry Christmas everyone!!!!

 

[fast_dave]

masospaghetti -

I have the same engine/transmission combo as you, and on 1/28/2018 @ 202,415 Miles I had to replace my ORIGINAL ignition coil pack with a Motorcraft DGE-446

NEW Motorcraft coil on EBay for $55 w/ Free Shipping & No Tax (NOTE - LAST ONE - LOWEST price for FACTORY COIL I could find).

Link: New Motorcraft Ignition Coil DGE-446. | eBay

Merry Christmas!

PS - Good to see that the DENSO plug wires have the OEM REQUIRED "hold down clips" where the wire attaches to the Coil. Same as Motorcraft/FORD wires!

 

[masospaghetti]

@fast_dave

What were the symptoms that caused you to replace your ignition coil?

 

[fast_dave]

@fast_dave

What were the symptoms that caused you to replace your ignition coil?

Cold Start Rough Idle (until warm) the first two weeks it reared it's head (no check engine light).

Cold Start Rough Idle (until warm) the third week (still no check engine light). Then another symptom added to the scenario at the beginning of that week; for 2 days in a row a slight misfire/skip on a pretty steep grade while in 3rd gear. I drive this steep grade every day on the way to work, so I positively knew that this was yet another addition to the cold start rough idle. Man - it was bugging me and was going over every possible scenario (ignition vs fuel system) in my head. FINALLY, sometime at the end of that week, the Check Engine Light came on, and pointed me to a misfire on two cylinders.

I did more investigation, and found out that those two cylinders the scan gauge showed as misfiring shared the same coil pack (when turned over, you can see the coil pack is made up of three separate coils, 2 cylinders on each).

At the time all of this was occurring, my records showed that I had relatively new wires (39, 042 Miles on them) and plugs (5,151 miles on them) .

So - Seeing that the misfire was on a coil that shared the 2 cylinders, I deducted that that particular coil pack was bad and replaced the entire coil assembly. I cleared the Check Engine Light, and drove on the new coil assembly for 2 weeks, and the Check Engine Light never came back.

With the new coil assembly, the Ex felt like she gained a few Horse Power, especially from a standing start. But in the back of my mind I was worried that possibly - other than age - perhaps a bad wire or plug caused the Original Coil to die. So, just to close all of the possible parameters behind the previous misfire condition, I chose to throw a new set of wires and plugs in - just for good measure. I was like "what the heck, it's only another $30 - 35 TOTAL to get piece on mind and close the misfire saga."

Check it out - Re; the OHV Ignition System: OHV Ex's have what's called a "lost spark" ignition system, and it fires off twice for every 360 degree engine revolution. One cylinder is on the compression stroke, while the other cylinder is on the exhaust stroke - hence the term "wasted spark". This type of ignition system, in effect, DOUBLES the amount of wear and tear on your coil, wires, and plugs....

So in your coil's case, at 252,000 miles, it has the wear and tear of 252,000 X (2) = 504,000 miles...

The Wasted Spark Ignition System is a good reason why on OHV Ex's it is so important to maintain and upkeep the Wires, Plugs, and at some point the Coil.

Additionally (since I'm on a roll) - The crankshaft position sensor (CPS) is also another good part to replace as a wear & tear maintenance item when you hit around 200,000 miles. It's easily located next to the crank pulley, and because of it's location it absorbs a lot of heat, vibration, fluids, and road grime. Only two screws hold it on, and you can remove it by simply sliding under the front of your Ex - a 10 minute job at most.

Standard Motor Products Part #PC250 is $11 and has a MUCH STRONGER MAGNET than the factory original CPS - it was like a super magnet compared to the factory original one - seriously. Here's why I replaced mine: I never got a Check Engine Light, BUT I replaced mine about two to three months after replacing the Coil, Wires and Plugs because I noticed that rather than starting instantly (as I was used to), my Ex started to hesitate and took at least one revolution before firing off. As soon as I swapped out the old CPS for the new one, we were back to instant starts as soon as I turned the key - just how I like it. In effect, all the new ignition parts "showed" me that the CPS was on it's way out. Whenever possible, I try and NOT throw parts at a problem before researching it, but at $11 it was a no brainer (and it worked).

LINK: 1998 FORD EXPLORER 4.0L V6 OHV Crankshaft Position Sensor | RockAuto

With all that said - did you buy that OEM Coil on Ebay? I see that it's recently been sold.

Hope all this helps & Happy New Year!

 

[masospaghetti]

Thanks for the helpful tips. Going ahead and ordering a new coil, sounds like it's overdue and the symptoms sounds suspiciously familiar. Also getting a new CPS.

A note about the waste spark system - This is why it's important to use the correct plug type. Normally, I am all for using standard copper plugs but with waste spark they will wear out much faster than anticipated. See this:

Unlike conventional ignition systems, waste spark DIS ignition systems use half the spark to fire the opposite spark plug unconventionally from the side electrode to the center electrode. Copper core standard plugs and copper core single platinum spark plugs are not designed to withstand this reverse polarity firing and will suffer premature gap growth due to center electrode erosion. Gap growth will stress ignition system components by requiring more voltage to fire, eventually leading to misfire, loss of performance and fuel economy. This degradation can be noticeable as soon as 20,000 miles after the plug is installed. Source: Spark Plugs for Waste Spark DIS Ignition Systems

I don't know specifically if AA1car is a reputable source, but it sounds reasonable enough to me, and reasonable enough to spend the few dollars to get double platinum plugs.

 

[239]

For anyone who loses coolant and has a cold misfire:

My 2000 OHV had a misfire on cylinder 4 when it would start cold. Sometimes it would happen just a few hours after turning it off, sometimes it wouldn’t happen at all, even after being off all night. But it would return internmently. My coolant was disappearing and I had air in the coolant system. I used k seal and it stopped the misfire since no more coolant was getting into the cylinder. But exhaust gases were still getting into the coolant.

I wasn’t burning coolant anymore but I didn’t want to risk complete head gasket failure, so I had the heads replaced and discovered that the head surfaces and gaskets had warped. I’m planning a full rebuild in the next year or two with a 4x4 auto conversion. Since I plan on keeping the vehicle. Note that my engine passed compression tests even with the warping.

 

[masospaghetti]

Got around to doing some work over the holiday weekend. New Denso wires, Motorcraft coil, and crank position sensor. Engine does seem to fire up more easily and crisply - not sure if it has resolved my cold start issue yet. Still monitoring my coolant tank.

@fast_dave
I bought my coil from Amazon -- didn't get the eBay one - I am a sucker for their customer service (and how easily they make it).

 

[239]

Got around to doing some work over the holiday weekend. New Denso wires, Motorcraft coil, and crank position sensor. Engine does seem to fire up more easily and crisply - not sure if it has resolved my cold start issue yet. Still monitoring my coolant tank.

@fast_dave
I bought my coil from Amazon -- didn't get the eBay one - I am a sucker for their customer service (and how easily they make it).

What engine do you have? I bought the coil for my ohv from amazon too. It’s the DGE446.

Also, what cps did you install? I’m thinking of replacing mine since I’ve had trouble with it’s connector corroding in the past.