Check engine light blinking

Hi, Our 05 mercury monterey is riding rough and the check engine light is blinking all of a sudden. Two days back while driving home it was raining and we accidently drove through a puddle, did not notice due to night time. After that it suddenly the light started to blink and engine felt rough. Checked the code yesterday morning and it showed cylinder 3 misfiring, no other codes came up. No one was available to check it yesterday and today. Have not started it again. Can you guide me if anything can be done before taking to the mechanic? I believe the number 3 cylinder is at the back side and not accessible easily. What could have happened? What do you suggest? Thanks,

Aged spark plugs more than likely in conjunction with moisture in and on the plug wires. My suggestion would be to replace the plugs (assuming they’ve been in there for infinity…) and plug wires as odds are the car has the original 11 year old wires on it.

It would not hurt to spray the coil and wires down with WD-40 when done as that can help protect against moisture issues in the future. Hope that helps.

Always the one that’s a pain in the neck to get to, huh? :frowning:

ok4450, Thanks for prompt reply. Yes, plugs and wires are not changed and was thinking to replace them anyway. I have to get brake work done too. Hopefully the shop also diagnose what we are thinking. what if he points to different thing like cat convertor which is expensive fix? How much do you think it will cost to replace the plugs and wires?

05 merc? Which motor? OHC like duratec? I don’t think that motor is pushrod. Might not even have plug wires if it has COP style coils. Do u know?

I don’t know what engine it is. Any idea how to check it out? This vehicle is premier model.

The '05 Monterey would have the 4.2 engine which has conventional coils and wires, not COP. That is most likely where the problem is. I urge you not to drive it any more with the flashing CEL. You could wipe out the catalytic converter(s) with a constant misfire.

Edit: Also change the plugs.

Is it ok to drive couple of miles to the shop? we have already driven it 10 miles bringing it back when it started acting. Do you think cat converter might have damaged?

If it were mine I’d have it towed. Ten miles with a flashing CEL is scary but maybe you’ll luck out.

Try starting it. The wires may have dried out and work fine (for the short term).

It still had same problem this morning so took it to repair shop. He said I need ignition coil to be replaced @400+. Plugs and wires will be additional 500+. are these fair prices? I thought plugs and wires could be around half of that. I am thinking doing the coil to get it running and price around for plugs and wires. I am also doing brakes which is around 600 for both axles for rotors and pads. Let me know what you think…

Replacing the plug wires is a must with this job. They are old and failing. They are arching the the motor when wet and causing your misfire. If you replace the wires you replace the plugs at the same time. Labor in getting to the plug is the same as labor for the just doing the wires. It will save you in the long run.

What is their labor rate per hour. Here a the book hrs for each job. Coil pack $137 1.7 hrs labor Your quote seems high. Plugs take 1.4hrs labor and wires 1.3 at $73 a set. Plugs should not be that bad as far as cost.

The labor is around $95-100 I believe. Don’t know how much he is charging for this job. He is charging high for sure, but need to get the car running. He has already charged $90 for diagnostic, the car is not in driving condition, so may come to same price if I tow it somewhere. Trying to find how to make him aware that he is charging more.

Ask for an itemized quote and list it here.

I believe this engine has 1 massive coil, and the wires run from it, to all 6 plugs

So this coil is obviously more expensive than the old canister-style

But $400 seems kind of high, even if it’s a Motorcraft part. Maybe $400 includes a fair markup, plus labor, testing and tax . . . ?

For that matter, all of the prices seem a bit high, IMO

The car did get not ready today, so tomorrow hopefully will come to know how much he is charging for parts and labor. As for brakes he quoted 285 per axle for rotor and pads, similar to what Quicklane also quoted.

$90 for the diagnostic seems fair, it probably took at least an hour. I can’t speak to the other prices but they do seem on the high side of things, but not outrageously high. A little high is ok if they do a good job in my opinion. Do you have a good recommendation from a trusted source, friend, relative, etc for this shop?

I’m a little concerned the problem isn’t just the coil, as if the coil was bad I’d expect a random misfire rather than always on number 3. If I had this problem and believed the coil was in fact shot – which could be the case if a blast of cold water hit it and cracked the coil housing – then I’d replace the coil, plugs, wires, distributor cap, and ignition rotor. The entire high voltage system in other words. And I wouldn’t be surprised to find out that the igniter turned out to be involved too.


Did you catch the bit about the coil being a massive beast, responsible for all 6 cylinders

This is what it looks like

I’ve seen coil packs, where only one single cylinder was affected, because just that part of the coil pack had failed

Update: Got the car back. He has charged $175 for DG532 coil + $180 for labor. The diagnostic charges $90 are separate. I thought they would absolve the diagnostic charges once we do the service too. What you think? Looks like some markup for the part.

He has recommended to replace sparkplug and wires and has quoted $500 + tax for it. Looking at the recommendation I am stumped that he has included $180 for removing and replacing ignition coil again. $13*6 for sparkplug, $70 for wireset and $170 for labor.
Considering these too high I declined the service. He should have removed the coil charges since it is getting replaced and charged differently right? The price would have dropped to $300+ which would be reasonable I guess. Let me know what you think.

Each part has a separate labor charge listed in the labor guide however some repairs have overlapping labor, like your spark plugs, coil and wires. If these items are replaced in one repair a reduced labor charge should be expected but if only the coil is replaced, then after completion the wires and plugs are authorized for replacement there may be no savings in labor.

On the other hand some mechanics will squeeze as much labor out of customers as possible.