Rick@Synergy

iTrader: (5)

So my question is, in a perfect world where you have tested every wire all the way to the pcm from the coil, what would cause two not to fire? This is an LSx based motor. Right now, the number 4 and 7 wont spark off. Like I said already, everything has been thought about from change coils, to change computers, sensors, ect. All signals are happening. It seems we can manually fire off the coil if you push the signal through the PCM, but the PCM wont do it itself. And during running the motor, I get a Cranksosition error. But that sensor is good and so are the wires because I am getting the signal all the way to the pcm as well. Cam position sensor the same. Timing is correct mechanically, ect. The car runs like ****. Way too rich. Its not the injector flow rate, because the car ran fine before with the same injectors. Now its a rebuild that was done, and I cant run this motor like this or those rings are gone. Is there something I am missing that an OBD2 computer is trying to do or look at? I have been at this for two days so far. Gonna kill this car.

Rick

Slowhawk

iTrader: (12)

I've had similar problems with a Vette.Ended up being 2 broken valve spring's.(duals).
I'm guessing you already replaced the cam position sensor.

Rick@Synergy

iTrader: (5)

All sensors have been tested. My father in law and I built testers to monitor the cam and crank sensor both in and out of car. We have tried everything. I cant see springs being broke, the heads are new and so is the motor. Its worth a shot to pull the valve covers off, but hard to believe.

Rick

wait4me

iTrader: (10)

Did you try putting in a different pcm file? And not the same tuned one? A compression test on the cyl? The coil would still fire if the springs where bad, Pink have power and black is ground, then the two feeds, Is the computer set as a 6 cyl for some reason? What year is the pcm.

jimmyblue

iTrader: (11)

There are coil and wire faults that won't show up on
low voltage testing - insulation problems that allow
the spark an easier path than the sparkplug gap,
a broken-down secondary insulation etc. Coil swap
that moves the failure cylinder would show this.
4 for 5, 6 for 7, look at the misfires. Same for the
plug wires, a pinhole could take the spark.

Not sure if "spark off" means spark generated, or the
cylinder firing (which could be fuel side as well).

Rick@Synergy

iTrader: (5)

We thought the same thing. Could this be on 6cylinder mode. I dont see how though. I will try a completely different cars stock OS in the same year and car and see what happenes though. We tested every wire you can think of.

Rick

Rick@Synergy

iTrader: (5)

Right now its 4 and 7 that are down. According to my father in law, those are the begining of the trigger wheel cycles. If you look at how the sensors are reading, they read in a pattern and split the difference between the 8 coils. So when the cam trigger hits TDC it fires off the first 4 in line, then the other side fires off the next 4 in line. The triggers all line up. We can even go to the computer itself, and add the 5V signal and fire off the coil and whatch it spark, but cant get the computer to do it alone.

Rick

wait4me

iTrader: (10)

What does the coolent temp sensor read?

Rick@Synergy

iTrader: (5)

Normal, and even under normal. We even tried it without the sensor to make sure the computer does not shut down the spark due to over heat.

Keep in mind I wont run the car anymore because this motor is new and I cant afford to burn up some new rings.

Rick

wait4me

iTrader: (10)

is it an aftermarket crank?

The crank posistion code is normal. That is because you changed it far enough to where the old "stored" crank data is not correct anymore,

But are their any other codes at all?

If the computer didnt "Think" it should not shut it down, It would throw a code about the coil not working correctly.

SO, If no code, then something is making it think it needs to shut off???

Im going to california to train a company that bought a workshop version of efilive next week, If you are close to where i am going, then maybe i might make a run over to help you guys for a couple hours, when im done.

I like trouble shooting stuff. They are like rubix cubes with wheels...

Rick@Synergy

iTrader: (5)

Aftermarket crank, but here is the kicker. This motor has been in the car before and ran fine until I had to rebuild it for this guy. The crank seized to the rear main bearing and the crank was reground down to spec. Do you think they had to take the reluctor wheel off to grind down the crank and put it on wrong? You are more than welcome to come down and check this out. This is the first time we cant get past something like this.

Rick

wait4me

iTrader: (10)

Have you asked the grinder if they cut the welds on the ring? I wouldnt see why they would, but you never know... That would suck, because out goes the motor...... I hate tearing stuff back apart after taking all the time to get them perfect.....

Rick@Synergy

iTrader: (5)

MY machine shop said the wheel was tig welded when they where doing the balancing to it. So not sure if thats a sign that the other shop took the wheel off already or if it came that way from callies.

I tried to do a crank relearn once, but everything was glowing so bad because of the fuel issue from not being burnt up that I never want to try it again. Its not worth breaking this motor.

Rick