Overheating and misfire, coils keep failing

I’m having several problems occurring together and curious if they may be related.

Two weeks ago, my car started overheating for no apparent reason, and an ignition coil also failed(these events within a few days of each other). In the two weeks since, two more coils have failed and now today I have a misfire on a cylinder(#2) which is running a brand new Hitachi coil.

Overheating continues, happens in hot weather or when going uphill. The radiator is full, no leaking, no consuming coolant, clean inside and out, fans work, cap holds pressure, heater blows hot, radiator hoses hot, hot air coming off radiator, and no signs of headgasket problems. No reason it should be overheating.

The sparkplugs look perfect, show no abnormal deposits or coloration, and are gapped correctly. No apparent cause for three failed coils within a couple of weeks. Now this new misfire, I have no idea whether it is a new coil going bad, or now an injector? I am absolutely certain that none of the previous misfires where caused by injectors because replacing the coils fixed them.

I should probably compression test the engine but can tell from disconnecting coils one by one at idle that each cylinder is pulling it’s weight and engine still runs great despite all this.

It has never had any codes except ignition circuit malfunction and cylinder #X misfire when a coil has failed.

Basically I’m at a total loss as to what could be causing all this and where to go from here. Seems pretty coincidental to all be unrelated, right?

Don’t throw any parts at it before consulting an independant mechanic. They have the tools and knowledge to find your problem in no time.

I agree with @COROLLAGUY1, take it to an independent mechanic for evaluation. I do wonder, though, have you checked your water pump yet? I didn’t see that in the litany of things you’ve checked in your initial post OP

maybe its a bad temp sensor. as gauges rarely fail

If it helps by putting your heat on full blast, possibly plugging radiator or eroded water pump impeller. Thermostat, maybe.

I agree that it must be thermostat or water pump at this point. But how can I test those?

I can see water pulsing in the neck of the radiator due to the pump, but how could I tell if there is enough flow? When I rev the engine, this pulsing smooths out. Does that tell you anything?

Thermostat is cheap, start with that.

You’re sure it’s clean on the outside?
You can shine a light through it?, feel air being sucked through while fan is running?

It doesn’t take a whole lot of dead bugs to start plugging the fins on a radiator.

Yes, it’s perfectly clean between the fins and I can feel from the front the air being sucked through.

This video is after warming it up with the cap off and seeing some bubbles and coolant rise when I rev the engine. Does this all seem normal? Also temps are stable at 160 - 180 as best as I can read them.


Bubbles may indicate troubles: head gasket leak. There are chemical test strips to help diagnose unburned hydrocarbons in the coolant; an exhaust gas sniffer will do this quickly.

That’s a good idea but I have pressure tested the cooling system and it does not loose pressure, no leaks. Does that pretty much exclude head gasket?

The gasket could be failing when hot only. A pressure test when cold would not pick that up.

No. Head gasket leak will pressurize the cooling system. The radiator cap may release the excess pressure.

What year is the Maxima? In 2000 and 2001 or 2002 they had a run of bad coils and there was a recall.

I just blocktested it and there is no headgasket leak. So those bubbles must be trapped air coming out right? Even though a lot of bubbles came out it still quickly overheats on the road.

I don’t understand how I could have driven it for a year with trapped air in there it hasn’t caused a problem until now. The cooling system has never been opened for the last year, since I’ve owned the car.

It’s a 97 and I think the original coils were still in it when the failures started, only at 115k. The new ones are Hitachi and supposed to be very good quality so I’d be surprised if they are coincidentally bad.

That test can miss a small leak.

Typical “mystery overheating” procedure:

New thermostat.
New water pump.
New radiator.
New head gasket(s).

If the vehicle has an automatic transmission, check the color of the transmission fluid.

If the color is black, the transmission is overheating and causing the engine to overheat.