RTH

Ok! Thought I'd return to this thread just to follow up for future Googlers and DIYers.

Finally got back in town, the weather is warm enough now, and I embarked on changing the Crankshaft Position Sensor, which is a royal PITA when the engine is still installed. The hardest part wasn't necessarily getting to it, but getting the wiring disconnected and removed from the engine. The connection is literally in the worst possible place - tucked tightly under the left cylinder bank where everything needs to be done by braille. UGH! Finally just broke the damned connection mount so I could disconnect it, then zip-tied the new one back into place.

Anyhew, I replaced the Crankshaft Position Sensor and reinstalled everything, with no difference. (Sigh...)

Gave up and had it towed to the Acura Dealership here for diagnosis. They called 6pm Fri and concluded it was "running very rich with misfires in 4 of the 6 cylinders" (No shit, Sherlock, I literally told you that when I dropped it off). They also said there was "no compression in cylinder #3" but couldn't give me a better diagnosis until they tore into the engine, which would be more money, which to me means they don't know WHAT the problem is. I don't think a single dragging cylinder would cause it to stumble / misfire as poorly as it is. Would no compression in a single cylinder cause it to misfire in other cylinders and literally drip unburned fuel out of the tailpipes? I don't think a lack of compression would cause a misfire because the plug would still fire, just you'd reap no power, right?

They pretty much said the most cost-effective thing to do was to install a new engine.
HA! WTF? Like hell! I swapped the engine at 228,450 miles with an engine that had less than 70,000 miles on it. The car now has 249,250 on it, which means that engine has only (lets see 249250-228450=21000. 70000+21000=91000) 91,000 miles on it!! (If you can believe LKQOnline which showed the odometer of the (alleged) donor vehicle)

No way is the engine the problem. I'd be willing to bet 5-to-1 odds it's not the engine, but the harness or the ECU, which means I'd spend months swapping the engine just to arrive at the same problem.

I'm considering having it towed to another shop for a "second opinion". Is it possible to check the ECU and/or harness? Hmm...

So what do you guys think? The crankshaft position sensor was a very good suggestion, as it literally determines when things fire. Thank-you for the suggestion!
Is it possible for a lack-of-compression in a single cylinder to cause a shit-ton of unburned fuel, misfiring in 4 of 6 cylinders and piss-poor idling??
I don't think so, but am looking for other expert opinions. No hate here - cuz I'm all out of ideas (as is Fisher Acura, apparently).



PS - sorry for the long delay, things went off the deep end the last few months, but I now need a car. Driving a longbed dually through the drive-thru gets old after a while...

RTH

Status from the Acura dealer...
They haven't told me anything I didn't already tell them (other than it's cyl #2 instead of #3 as indicated above) - apparently they haven't started my "Engine Diagnosis"?

Maybe there's more info coming...I'll find out Monday when I call.

Jon M

I am sorry if I lead you down the wrong path with the sensor. Really thought we had it. We discussed compression testing but I don't see if you had the chance to do it earlier. If the compression is 0 you know this can be many things. Hole in the piston, stuck valve(s), bad cam rocker arm, bad gasket. I can see a way the a dead cylinder can cause unburned fuel as the fuel can escape before burning, it might also cause delayed firing of other cylinders which might contribute to excess fuel. All speculation on my part. I don't see how it can be the ECU or harness if there is no compression. If you are cranking the engine for compression, fuel and spark don't matter; taking electrical signals out of the loop. Do you see anyway an electrical signal can effect the compression?

RTH

No apology necessary. You weren't the only one to suggest that. Had a few gearhead coworkers of mine as well as a diesel mechanic buddy suggest exactly the same thing.
It made perfect sense. I appreciate any suggestions from the experts here.

Anyway, prognosis from Acura is either 1) bad rings on multiple cylinders 2) bad valves on multiple heads, or 3) a combo of the above 2 combined with possibly scored cylinders.
Got 0 compression on cyl #2 and low compression on cyls 1,3, and 5, as well as oil fouling on cyls 1 and 3.
WTF? These rings fail all at once?? On multiple banks??

Tech said "we had problems with ring wear in our earlier V-6's". The engine I swapped in was a 2003. So I'm gonna pick a 2000 or a 2001 and hope for the best.
He said once one cylinder goes t*ts up, the rest go south as the ECU tries to compensate, but apparently doesn't do very well. That results in multiple mis-fires, then burned valves, and spoiled plugs.

Anyhew - embarking on another engine replacement adventure....This time gonna replace the tranny also, with another AV6, as the one I have has 150K on it and it now "whines" a lot, so I'm assuming it's near done.
Plus, it's easier to do this all at once.

Right??
Lol!

Jon M

Wow, your going all in, hope you don't mind a few suggestions. Replace the timing belt and rollers before installing. Other items to consider replacement: the thermostat, the torque converter (whining sound like torque converter issue), water pump. Check the harmonic balancer for separation. I wish you success in bringing it back to life.