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Discussion Starter · #1 · (Edited)
Greetings. I'm new to this forum but there seems to be a wealth of experience here. I've worked on my own cars (for the most part) - it's an interesting endeavor. Until it leaves me in a dead end troubleshooting.

I had this 2000 626 V6, 65k miles on it, towed home a couple of weeks ago, but it remains where tow truck driver dropped it off. Darn.

Symptom: car cranks just fine, healthy battery, but won't fire and run. While under the hood, I noticed that oil had been running out from the left valve bank cover gasket and down onto the alternator. I figured that had caused the stoppage. Dashboard displayed Oil Light, Battery Light and the dreaded Check Engine. Connection of two different OBDII readers could see engine temp, air temp, a couple of other readings, but NO error codes.

The alternator was old, so I replaced it rather than try to get all the oil and grime cleaned out. Replaced both valve cover gaskets (geez, what a pain getting that intake manifold off and on). I noticed that the other valve bank was leaking into one of the ignition wire holes (cylinder #3). I soaked out the oil as best I could, but I'm sure SOME bit of oil ran into cylinder when I removed the spark plug.

All back together after cleaning the plugs now. On first attempt to start it, it cranked for a couple of seconds, then POP! (and some nice black smoke momentarily) from, I presume, the cylinder that had a little oil in it. Otherwise, no life. And continues to crank well, but not gonna start.

Standard trouble shooting: got both spark and fuel?

I laid a couple of the ignition wires out, in turn, with the spark plug still hooked up to them and out grounded on top of the engine - nice, healthy sparks.

Then pulled one end of the injector rails crossover tube and cranked for about 2 sec - captured several tablespoons of fuel. Yeah, kind of primitive without proper tools. Checked the power to the injector coils and it was present. Even hooked a little o'scope to one of the coils and could see the pulses firing the injector while cranking - pretty consistent. However, I did not try to analyze their width or spacing, although they did make full negative 12v to 0v transitions. So I'm concluding that fuel is OK. That POP!, when I first tried to start, had to be the cylinder with some oil in it, you suppose? Could it ignite even if piston was out out position (a timing belt problem) when spark fired?

I mention the timing belt, but all I did was pull back the timing belt cover, when I had the valve covers off, and shined a flashlight down in there. Didn't see anything much going on. Belt was intact.

So, am I looking at a bad PCM? I'm suspicious of that, since after this problem started, an OBDII reader doesn't seem to be able to fully communicate, especially that they cannot access the 'Check Engine' status or errors.

Or, as the song goes, am I "Looking in all the wrong places?"
 

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Discussion Starter · #2 ·
So, yeah, I WAS looking in all the wrong places. Well, sort of. I verified fuel (injectors all firing and fuel pressure right at 40psi) and sparks were all healthy at the plug. I had somewhat recently replaced the 'coil' assembly and plug wires.

One thing I needed to know, before finally accusing the PCM, was what was going on with the timing, whether the belt was really doing it's job. I got the harmonic balancer off, then the timing belt covers. Looking at the crankshaft gear and it's grip on the timing belt and the attached photo is what I saw!

Wheel Tire Automotive tire Motor vehicle Tread


Oil from that previously mentioned leak had definitely gotten under the cover and down into that crankshaft gear. After degreasing that area, I was able to see the real problem: the gear had completely ground off the timing belt nubs from about the 3 o'clock to the 9 o'clock position. I got ready to replace the belt and started to get the two valve train sprockets into position, when I realized those things were REALLY tight! Can't move them by hand, but could with a heavy socket and wrench.

Should they be that tight? I don't see how a belt, tough as it is, can move that belt along. By the way, BOTH valve train sprockets (this is a V6) were just as tough to turn. When this engine quit, in traffic, there was no indication of overheating on the dashboard and no MIL with an accompanying error code. I guess I could just put a new belt on and see if it hangs up and grinds away on the belt like this old one did?
 
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