Sparks From Exhaust???

[Cylvertip]

OK Gear Heads, this is a new one on me.

I took my 96 Pathfinder ( 3.3 V6) to a spray and wash this evening and hosed it down including the motor.  I took care not to hit the distributer cap from the side, but apparently I still got some water under it as shortly after I started it back up, it began running a bit rough.  I have had the same issue before and did not think much of it. I am sure most of us who have wheeled a bit have had water on the distributer before.  The last time it happened, the problem corrected it's self in short order.

   I was about 15 miles from home in Arlington so I figured I would run home on Hwy 9 and stretch it's legs a bit.  As I pulled onto the Hwy, it was still a bit rough, but the higher the rev, the smoother it got.  There is a pretty good hill just south of town on 9 and just as I hit the bottom of it my check engine light started flashing.  Previously with water on the distributer, the check engine light had come on, but not flashed.  I guessed that the flashing this time was because of the same issue and it just wasn't quite bad enough to kick the light on full time.  I pushed the accelerator down further and kicked it into overdrive as I went up the hill.  The engine was lagging a bit and not accelerating as it normally would.  The RPM's were up somewhere between 4500 and 5000.  That's when I see sparks coming out of what appears to be my exhaust.  I thought it might be a stuck brake pad for half a second, earlier in the day the tires were rotated and the brakes were most likely checked at the same time, but when I let off the accelerator it stopped.  When I hit the accelerator again the sparks where back.  I let off the gas again and mellowed out a bit as I came to the top of the hill.  The rig was still running a bit rough, but the temp was holding steady and normal.  I kept going and over the course of the next 5 miles or so there was no real change other than the check engine light changing from flashing to solid.  I did kick it into overdrive a couple more times, no sparks, and still no change in temp.
 As I got closer to home I ramped it a bit and the rig seemed to be running stronger now.  The last mile or so I dropped it into 2nd gear (automatic) and really reved it up and it seemed to be running as normal.  When I got home I let it sit and idle for about 10 minutes and all seemed OK, though it did sound a bit throatier than normal.  Finally I shut it off and tried restarting it.  It fired right back up.

   At first I though I might have fried a ring or possibly disintegrated a spark plug due to it not firing right from the water , but with it running fine I started leaning towards the old  "blowing the carbon out of it" or just plain blowing out the cat??? 

Any thoughts?

[NW-GSP]

It running rough and the sparks are probably from the cat, you cat might be falling apart wich made the o2 sensors not know what air fuel ratio to give.

[crazysccrmd]

In my experience (VW/Audi) when the CEL flashes while driving it is indicating an excessive amount of misfires. Given that you had water on the distributor this would make sense. If it misfired for long enough it is possible that enough unburnt fuel reached the catalytic converter and pretty much set it on fire. The sparks coming out were probably pieces of the material inside the cat. The engine sounds throatier because the cat is not as restrictive anymore. Once everything dries out it should return to running like normal, but you might have a CEL for the rear O2 sensor (measures the effectiveness of the cat at reducing emissions) if the cat is compromised.

Try taking the truck to Autozone, they can scan the computer and tell you what codes are stored for free. Will give you an idea what was going on.

[gotshot]

Usually a CEL flashes means don't drive condition.

[toothfangclaw]

In my experience (VW/Audi) when the CEL flashes while driving it is indicating an excessive amount of misfires. Given that you had water on the distributor this would make sense. If it misfired for long enough it is possible that enough unburnt fuel reached the catalytic converter and pretty much set it on fire. The sparks coming out were probably pieces of the material inside the cat. The engine sounds throatier because the cat is not as restrictive anymore. Once everything dries out it should return to running like normal, but you might have a CEL for the rear O2 sensor (measures the effectiveness of the cat at reducing emissions) if the cat is compromised.

Try taking the truck to Autozone, they can scan the computer and tell you what codes are stored for free. Will give you an idea what was going on.

Very probable answer. Though I don't think 96 was obd2 for Nissan, could be obd1. Which means typically you can check codes in your driveway.

 

Usually a CEL flashes means don't drive condition.

X2 flash baddd. Steady, okay. I drove a car for 5 years with a check engine light on. I knew the problem, it wasn't harmful.

[Cylvertip]

Yep, understood the flashing was not a good thing, but figured with the milage on the rig it would really not matter.  It kept going and no other idiot lights came on and the temp on the motor and tranny did not budge.  I made the judgement call to keep going as it did not figure to be a motor problem.

  Looks like it is the cat -   little concrete like chunks coming out of the exhaust this morning when I checked it.  Rig seems to be running fine otherwise.  I have a Magnaflow muffler that seems to be letting it through.

 I will keep an eye on mileage and see what it does.  If it holds mileage, I may just let it be.  It's still the original cat and just rolled 185K on it.  I had been told several years ago that the cat was going out, but have not seen any real issue with it other than if it is cold and I just put around after just starting it, the check engine light would pop on.  If I kept the RPM's up (overdrive off) for the first few miles in the morning, it would not have the issue.  Check light would go off after a good run on the freeway either while running or it would be off the next time I started it up.

[toothfangclaw]

Do you have emissions up there?
If you do it may not pass the sniff test.

[Cylvertip]

Nope, not required to do testing out here. 

    Warmed it up this evening following an oil change and pulling the distributor to brush off all the contacts.  Idled fine.  Ran up Mt Loop to the Robe Canyon Trail head and pushed it pretty hard.  Figured i would rather be close to home if it tanked than 60 miles away at work.  No issues.  Runs fine.  We will see if the check engine light is still on tomorrow.  I may have to do the manual reset on if it stays on past tomorrow to see what happens/ if it will come back on.  Did not see any more chunks from the exhaust when I got back.   Will see what it does for mileage tomorrow too.

[toothfangclaw]

on both accounts!

[Cylvertip]

Check Engine light was off this morning when I started it.   No issues and no light during my drive to Hellvue today, so far seems back to normal. 

[Cylvertip]

  No sign of any issues and I have gained at least a mile per gallon.