Hello,

I'm a bit lost here...

I've done several job on my car: timing belt, water pump, auxiliary belts, cooling system flush and coolant change (g12+ conversion), etc.

All seemed good at the time, except for a faint noise (like worn ball bearing) at a certain RPM.
After few weeks, my engine starts to cut-off the power every time I reach a specific rpm (3600rpm).

After that the same problem appears when I reach 2500 rpm (yellow engine light turns on just for the time needed for a drop in rpm, then the light turn off).

No error shows up on ecuscan.....

Any suggestion? faulty water pump? excessive timing belt tension (I've use the rule of the thumb that I've found on the forum to tensioning it)?

Thanks for hearing me out....

That's a strange one.

Belt tensioners tend to whine if overtightened, so if the belt has the recommended deflection it's very unlikely to be related. Though i would suggest checking your timing marks line up in case it's a tooth off.

Again, Water pumps tend to whine and i don't see it causing an RPM cut.

Are the bolts definitely tight on the lower crank belt pulley? and the dowel lined up on it?,the noise could be at a certain RPM that causing a flutter causing the crank sensor to misread, hence the cut and light.

I will check it.

I wonder.... the symptoms my car is showing, can be related with pistons seizing or something like that? I never experienced it so I'm not sure which are the symptoms.....

It seems I haven't any power loss, all seems normal till I reach the incriminated rpm....

Can you live scan it? I think a sensor aint getting a message.

D

eolonano said:

I will check it.

I wonder.... the symptoms my car is showing, can be related with pistons seizing or something like that? I never experienced it so I'm not sure which are the symptoms.....

It seems I haven't any power loss, all seems normal till I reach the incriminated rpm....

Click to expand...

Nope, it doesn't sound like a physical mechanical issue, more electronic/sensor related, or something causing a misread of said sensors.

A live scan whilst trying to trigger the light would likely point you to the problem.

Ok. Any advice on how to do a live scan will be appreciated.....

For example, using MultiEcuScan, I see that when I reach the incriminated RPM (and the light goes on), the RPM parameter shown by MES goes instantly to ZERO, and after half a second all turns back to normal.

If I check for stored errors, nothing can be found there...


I'm not sure if I can say that the sensor is a cause (the sensor goes berserk an so the engine cut power) or an effect (the engine "seizes" and so the RPM drop down).....

Hmm, that's interesting, i can't say for definite not knowing the software, but while the engine is running it should never read 0 rpm. Sounds like ECU is losing sync with the crank sensor signal, causing the spark to stop (and the engine to cut until it resyncs/reads again).

I'm leaning towards crank sensor/crank pulley problem. Everything definitely secure? Pulley and the sensor itself?, i'd be tempted to try another crank sensor given they aren't expensive and always good to have a spare.

Update:
crank pulley and sensor are firmly secure;
Ihave two sensors: one on the crank and one on the camshaft: it'll be better if I change both?

Mechanically speaking, I've found that the sealant I've used on the water pump is not right (a little leakage), the oil seal on the crankshaft is leaking, and it seems that I've tensioned the timing belt too much: I've read somewhere that when you pluck the belt it must not vibrate like a guitar string ; mine seems to be doing that.....

And the winner are......


MrCinquecento and RallyCinq!!!!:worship::worship:

It was the damn crank sensor..... :bang::bang:

I was so sure that it was my fault (other jobs I've done on the care) that I've refused to accept an independent cause....

...so I've bought, as usual, a certain amount of various spare parts

But they could be useful in case I would decide to build another Sei from scratch!