rooneyeb

Hi, I am looking to see if anyone has some thoughts on this...

- My 07 V6's pulley/harmonic balancer blew out on a trip last Friday (at 146k). A friend's mechanic was able to get me back on the road quickly. The car is running smoother/better than it has for a LONG time - I think it had issues for a while.
- Not too many miles after, the engine light came on. I drove 350 miles without issue home. I later checked the codes, and had a 300/random misfire, 301/cylinder 1 misfire, and a 0000/unknown. I cleared the codes, on the next trip, it came on again. The car still ran fine.
- Yesterday I changed the plugs and wires (about 70k old). The car did have an occasional hiccup at low RPM for a while, which is now fixed.
- Today on a 100 mile trip, 3 times the car briefly lost some cylinders - highway speed. The engine light was blinking. Each time after a few seconds the car went back to normal and light went off.
- Later, the light came back on solid, with the same codes.

I am thinking the crankshaft sensor may have been somehow damaged, as it is near the replaced balancer (or there could be a problem with the new balancer?). It could be the coil pack too (SD about 70k old) but I find it too coincidental this all happened after swapping the balancer.

Thoughts? Thanks in advance!

tx_zstang

The crankshaft sensor could have been damaged by the balancer failure or replacement. But also, check to make sure the connector is plugged into it properly.
Since it 'got worse' recently, check all your plug wires and make sure they are properly seated and 'clicked' onto the plugs. Did you gap the plugs before putting them in?

I have a good used crankshaft sensor I'll sell if interested.

rooneyeb

Hi, thanks for the reply. Here's the latest...
The plug/wire swap made no change (though the car is running better overall, so the swap was due). Everything was gapped and torqued properly.
I swapped the crank sensor (sorry, I wish I caught your note sooner)- no change.
Swapped fuel filter- same.
Swapped Screamin Demon coil with new one last weekend. Yesterday I was able to get the miss to happen again (driving highway speed in 3rd, about 4-4.5k rpm for a short time)...
So, running out of ideas, last night I re-loaded a preset tune from my SCT tuner (though I had not changed the tune in a long time). So far I have not been able to recreate the problem, but it's too early to confirm anything.

I'll let you know what happens!

jwog666

you need to take it in and have them perform the crankshaft variation learn using the scan tool. this will "learn" the variations of the new tone ring on the new balancer.

rooneyeb

Thank you! I searched and searched for causes of that trouble code before, and nothing came up about the re-learn. When I reverse searched after jwog666's reply, all sorts of info came up about it. Two mechanics didn't seem to know about this either.

Anyway, the reload of the tune seems to have fixed it - I've driven close to 1000 miles so far with no codes or high RPM miss. But if it does come back I know what to do now. I am only a little over $100 on the mis-diagnosis cost (coil and sensor) so I am still ahead.

Thank you again everyone!