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Flashing check engine light

LYKOS

LYKOS

NAXJA Forum User
Location
Bent Mountain Va
2001 Automatic

Driving home from work yesterday morning, -4° , my rig started running a little rough and the check engine light started flashing. At this point it started limiting rpm's at 3000.

Three codes came up on the scanner.

Gross evap leak (that I've been trying to chase down for a year)

Misfire #3 cyl

Misfire #5 cyl

The Jeep is not hard to start, it does appear to have lost a bit of power. It idles a little rough and the check engine light doesn't start to flash until RPMs exceed 3K and the rev limiter kicks in and then it continues to flash.

Thinking it may be ice in the fuel line I filled it up with non ethanol gas to no avail.


There are two precipitating factors I can think of.

One is the cold

Two the fact I flushed the heater core Sunday and got water, antifreeze and Vinegar all over everything in the pass side off the engine.

My planned next move is to remove cool packs, inspect spark plugs and clean connections.


Thoughts?
 
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I'm betting your coil pack is cooked.
You may or may not have killed it when you got it wet. Probably not your fault.
How's your coolant & oil look?
Has it ever over heated, or recently over heated?
A fuel supply issue should affect all cylinders pretty evenly. The computer can sense, though, that #3 and #5 in particular are running really poorly. Might even be "dead". That the other cylinders are running fine (if they actually are) suggests that the fuel line, at least, isn't the issue. Fuel supply comes in to the rail, which all the injectors / cylinders have in common.
I suppose it could be that the injectors for #3 and #5 are bad, in theory, but in practice it's much more likely to be an ignition problem. Injectors are in general stupid reliable.
So, yeah. Most likely thing is that your coil pack is bad. Spark plugs wear out or become fouled if there is some other engine problem but they don't spontaneously start causing problems on their own. You don't have a distributor so you don't have a cap, rotor or wires...
I don't know of any way to test specific sections of the coil pack. It's about $100 to replace. Go ahead and remove it, clean the connections, make sure it's all dry before reinstalling, and see what happens. Or just spend the $100 and replace it.
I could be wrong but I can't think of anything else that sounds likely. Update us with whatever fixes it!
 
The coil pack sealed and physically intact.

Pulled the plugs and the 3 and 5 plugs are toasted. Dark brown, wet, crapped out. firebrand regapped for the time being with no change to how the engine is running.

Gonna replace all the plugs (need to anyway) and go from there.

So what would be next?
Which sensors cause intermittent misfires?
 
Re: Re: Flashing check engine light

yossarian19 said:
I'm betting your coil pack is cooked.
You may or may not have killed it when you got it wet. Probably not your fault.
How's your coolant & oil look?
Has it ever over heated, or recently over heated?
A fuel supply issue should affect all cylinders pretty evenly. The computer can sense, though, that #3 and #5 in particular are running really poorly. Might even be "dead". That the other cylinders are running fine (if they actually are) suggests that the fuel line, at least, isn't the issue. Fuel supply comes in to the rail, which all the injectors / cylinders have in common.
I suppose it could be that the injectors for #3 and #5 are bad, in theory, but in practice it's much more likely to be an ignition problem. Injectors are in general stupid reliable.
So, yeah. Most likely thing is that your coil pack is bad. Spark plugs wear out or become fouled if there is some other engine problem but they don't spontaneously start causing problems on their own. You don't have a distributor so you don't have a cap, rotor or wires...
I don't know of any way to test specific sections of the coil pack. It's about $100 to replace. Go ahead and remove it, clean the connections, make sure it's all dry before reinstalling, and see what happens. Or just spend the $100 and replace it.
I could be wrong but I can't think of anything else that sounds likely. Update us with whatever fixes it!
Click to expand...


I tend to agree...

Definately thinking ignition at this point. The coil pack is about two years old but an elcheapo parts store brand.

I just can't think of what else would cause this. Call me dumb but what about the cam position sensor? I'm not sure what it does exactly but think it has something to do with timing?
 
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Cheap parts are cheap for a reason. Replace the coil pack with a good quality part.


The original post notes lots of water spray, I would also buy a new genuine Jeep TPS. The TPS hates getting wet and it failure can cause the engine to run oddly and also cause shifting issues.
 
In my experience, the flashing CEL and misfires = toasted Cat,,,,,way too much fuel going into cat...your probably going to need one soon.
 
Wayne Sihler said:
way too much fuel going into cat
Click to expand...

^ Very true. The flashing is there to signify catalyst damaging events are occurring.


Dont panic, if this is the first time the light has flashed, and the only long term code is evap related, the cat will probably be ok. Just keep the driving to an absolute minimum until the running condition is fully corrected.
 
Unplug the injectors for #3 &#5. That will keep the fuel from dumping into the cat, if those are the cylinders that aren't firing.
I'm about half serious on that. It won't really fix anything but it will keep the cat from being destroyed if you need to take the Jeep to get groceries. Def. not a long term solution.
 
Well crap

I think I've found the problem.
I've suspected a cracked head for a while now. And after replacing the plugs and finding the number three plug seriously corroded and fouled I thought "wow, its been a week since I checked the oil."

And sure enough I'm finally seeing the tell tale signs of coolant in the oil.


So riddle me this, if enough coolant is leaking in the combustion chamber to foul a plug I'm assuming it's probably a safe bet the valves are hating life as well and all of the above is causing my miss?


And yeah, I know. 0331 heads from the junk yard need to have TUPY forged in them.





Crap crap crap
 
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True, and any way it goes the head has to be replaced.

Again, crap crap crap...
 
$450 from Clearwater for a replacement and then probably another $200 in head bolts, gaskets, etc etc.

Probably right around a $600 job if you do it all yourself and it should take you no more than a weekend.

You could go look for a cheaper head replacement but if my dd crapped out I'd just pony up the money to get a new head on the way. Would be cheaper in the long run for me than going to junkyard after junkyard looking for a head.

What's your oil pressure at running temp?
 
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40 + and not overheating.
 
ok, got the new scanner and checked everything.

The o2 sensors in bank one work intermittently. As in they are both working or are not. Bank 2 o2 sensors always work normally. Cleared codes and immediately got a cyl 2 and cyl 3 misfire and then multiple cylinder misfire. Drastic drop in power while in limp mode.



I'll admit I'm lost here and quickly during that I'm a tard.

There's obviously something other than three 0331 head crack going on.

Is it possible the precat has come apart on bank one?


I don't know what would make both upstream and down stream o2 sensors flake out lie this.
 
Aside from coolant being pumped onto them?
Water got in the oil, we know that.
We also know that water is getting in the combustion chambers because it's running like poop and the CEL came on.
That water from the combustion chamber, you may safely assume, gets pumped out the exhaust.
I'm not saying you won't be replacing oxygen sensors after you do the head or that nothing else is wrong, I'm just saying - one thing at a time. Replace the head with an upgraded casting and go from there. Don't try to diagnose everything at once - it's unnecessarily difficult.
 
I'm trying desperately to avoid the head exchange until $$$ and the weather improve. But...

I'm gonna have to suck it up and do it now I suppose.
 
Coil rail fixed it. Found two bad injectors in the process...

Got a couple projects for the next warm weekend between those and the head. Thanks for all the input.
 
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