Quote:
Originally Posted by 78F350
When I've run an engine that was misfiring, it wasn't shy about throwing codes and blinking the check engine light. Anyone know why this one wouldn't?
It ran after swapping the fuel pump relay, but that was also after sitting for several hours. Maybe the relay swap getting it running was a coincidence. (swap the bad relay back in for curiosity).
My advice is to check the oil filter (easy and decisive if there is bad stuff in there), then proceed as Blue62 advised. I'm still wondering if it sucked a bunch of oil in the intake from the AOS.
The car probably has just under 100,000 miles and had good care through it's history. No mods, a basic 1999 5-speed manual.
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So what we would see as misfires can be a tricky thing.
look at it in this light.
The primary concern of OBDII and its sensors and DTC code system "IS NOT" I say again "IS NOT" about engine performance. It is about caytalitic converter performance. Everything else is secondary.
With that in mind if a misfire is seen by the OBDII system as harmful to the cat it will flash the CEL. If it sees a misfire as possibly damaging the cat it will see a code.
Those types of misfires are generally picked up by the knock sensors.
So depending on what the sensors report to the DME/ECU when a misfire occurs determines if your going to get a flash from the CEL or a hard code or nothing???
Thats my understanding of it for what ever it's worth
In my first post to this thread I suggested to your friend to check fuses and relays because with the info I had it seemed the car just died like turning off a light switch. So with that info fuel or spark was a likely issue. Both fuel and spark have associated fuses and relays in their systems. Fuses and relays are easiest to check so they are the starting point.
Simplest things first.
After getting more info and seeing the video I see lots of smoke at the tail pipe so from the color of the smoke,(looks like oil smoke doesn't look like water or excess fuel) oil fouled plugs is the most likely issue. just need to find out why the engine is getting oil fouled.
The relay that was changed out was most likely not part of the issue.
From what I see in a very short video, your friends car sucked a load of oil into the engine and multiple plugs are fouling out. Can make it run like crap or not want to run at all.. Will cause all kinds of noise because the engine if it runs is going to run very rough. Chains are going to slap. your going to get pinging or knocking. All kinds of bad sounds.
I am not saying I am positive it is AOS failure but it sure looks like oil fouling.
So I would go with what the engine is telling me. The smoke at the tail pipe is saying look at my plugs
