Suddenly misfiring! (fixed, dead coil)
#1
Senior Member
Certified GM nut
Thread Starter
Suddenly misfiring! (fixed, dead coil)
Got out of work and my car wouldn't run. It runs, usually idles, but I can't drive. It can usually hold an idle, but revving it or trying to drive it makes the check engine light flash, along with a severe power loss.
Spark wires are good, but what'* going on? It ran perfectly this morning. I have my sockets on me, but no parts.
Spark wires are good, but what'* going on? It ran perfectly this morning. I have my sockets on me, but no parts.
#3
Retired Administrator
True Car Nut
Couple things to quickly look at:
#1 corrosion between the coil and the spark plug wire
#2 the plug below the oil fill has slowly had oil and dirt get into the heat shield and is causing the wire to fail
You most likely have a failed plug, wire or coil. It only takes a few minutes to check all the coils for corrosion, ensure none of the plug wires came or one of the plug wires are failing.
#1 corrosion between the coil and the spark plug wire
#2 the plug below the oil fill has slowly had oil and dirt get into the heat shield and is causing the wire to fail
You most likely have a failed plug, wire or coil. It only takes a few minutes to check all the coils for corrosion, ensure none of the plug wires came or one of the plug wires are failing.
#4
Senior Member
Certified GM nut
Thread Starter
Before I got a ride home, I took a look at a few more things. (Sorry I didn't see this while I was still there, or I'd check the coils and plugs.)
Unplugging the MAF sensor doesn't just make the car stumble, it makes it worse to the point where it barely starts or idles at all.
My flashlight casts a blue light, so I may have the wrong colors. With that in mind, I still don't think the oil is the right color. The underside of the oil cap is yellowish/greenish, and the oil (at 3,000 miles) is a deep mahogany brown — looks nothing like chocolate milk.
The coolant overflow tank is about a half-inch below the full cold line. I didn't think to check the radiator.
I'm thinking my UIM is about to blow again. My mileage is almost twice what it was the first time it blew, so I wouldn't be surprised.
Unplugging the MAF sensor doesn't just make the car stumble, it makes it worse to the point where it barely starts or idles at all.
My flashlight casts a blue light, so I may have the wrong colors. With that in mind, I still don't think the oil is the right color. The underside of the oil cap is yellowish/greenish, and the oil (at 3,000 miles) is a deep mahogany brown — looks nothing like chocolate milk.
The coolant overflow tank is about a half-inch below the full cold line. I didn't think to check the radiator.
I'm thinking my UIM is about to blow again. My mileage is almost twice what it was the first time it blew, so I wouldn't be surprised.
#5
Retired
If it looks like this...
Then more than likely it is your gaskets going. It all fits together. Low coolant, misfire, crap on cap, miscolored oil. I seen it twice on my car.
Then more than likely it is your gaskets going. It all fits together. Low coolant, misfire, crap on cap, miscolored oil. I seen it twice on my car.
__________________
Retired Administrator
2002 *-10 5.7 V8
2023 Jeep Rubicon Diesel
Retired Administrator
2002 *-10 5.7 V8
2023 Jeep Rubicon Diesel
#6
Senior Member
Certified GM nut
Thread Starter
It seems like a UIM failure, but I'm trying to get a list of things to check tomorrow.
#7
Retired
Besides checking your oil level. If you can pull your MAF screen off, open your throttle all the way and shine a flashlight inside. You might see coolant inside. Another way, disconnect fuel pump fuse and turn it over a couple times, pull a couple spark plugs and see if they are wet.
IF IT STOPS CRANKING! DO NO PROCEED. Hydrolock is possible.
IF IT STOPS CRANKING! DO NO PROCEED. Hydrolock is possible.
__________________
Retired Administrator
2002 *-10 5.7 V8
2023 Jeep Rubicon Diesel
Retired Administrator
2002 *-10 5.7 V8
2023 Jeep Rubicon Diesel
#8
Senior Member
Certified GM nut
Thread Starter
I was doing some more Googling, and my symptoms match a partially-blocked fuel filter. I checked over my maintenance logs, and my fuel filter is about 70,000 miles old. Whoops. Think that'* the foremost problem?
#9
DINOSAURUS BOOSTUS
Expert Gearhead
Allow me to put a myth to rest. A faiiled UIM syptom is NOT coolant in the oil. Coolant would have to get past the rings to get into the oil from a failed UIM. It'll hydrolock long before you get enough coolant to see a milkiness.
As for your LIM gaskets....you put the aluminum ones in when your cam was done. No worries about them being bad.
Your symptoms are more consistent with a clogged cat or plugged fuel filter (like you posted on FB). If you have a spray bottle, spray your coils while the car is running...you'll know if it'* a coil very fast.
As for your LIM gaskets....you put the aluminum ones in when your cam was done. No worries about them being bad.
Your symptoms are more consistent with a clogged cat or plugged fuel filter (like you posted on FB). If you have a spray bottle, spray your coils while the car is running...you'll know if it'* a coil very fast.
#10
Senior Member
Certified GM nut
Thread Starter
Confirmed that it'* fuel-related. I've got an active P0300, and the long-term fuel trim is up at about 16%. I've got a new filter and some injector cleaner (and non-adjustable wrenches, if any of you remember what happened last time), so I'll try to tear that off today.