00whitebirdws6

The tunet was able to see the cranking rpm while the starter was turning the engine and I have also checked ckp and cmp signal at the pcm and at the sensors and it all looks good. The crank has a 24tooth reluctor and I am using a known good (from the ls1 I removed) crank sensor in the engine. I have also tried using one from another engine i had and it didnt make a difference unfortunately. The cost to replace the reluctor wheel wasnt bad since I already had everything torn down and going to the machine shop to get balanced. As far as usung the holley, I wanted to keep the car simple and use the factory ls stuff that communicates with the other modules in the car. I will say that I used the terminator in my ls g body swap and I am a big fan.

ryeguy2006a

iTrader: (27)

Like the others have said, try getting an oscilloscope to see when the cranking events are. Then you can determine if the reluctor is properly clocked.

There was another thread not long ago where a guy had this exact same issue and the shop didn't clock it properly. From what I remember he took the crank back to the shop and they fixed it for free, but lots of labor to get the crank out...

Fang

If you pull the distributor out of an old SBC, spin it around and put it back in with the rotor pointing to some random position, you'll have spark but the engine won't run. Same thing here if the reluctor wheel wasn't installed in the right location (rotation) on the crankshaft.

SwapStang

That makes total sense. I never considered it was just out of clock and would still produce a signal just be way out of time. Interesting... well hopefully a motor removal isn't necessary. Is there a way to verify the clocking wish some measuring? Pending the oil pan is accessible that is..

Fang

Yes, it's called a 'timing light' which is a tool from back in the horse and buggy days.

SwapStang

LOL! I am familiar with a timing light and their usage. Obviously these are clocked and measured when installed (properly) I more so meant to measure it on the actual crank.

Fang

Timing light is the sure-fire (ha!) way to check it. You can either use a dial-back timing light and preset it to the cranking spark value from the tune file for whatever the ambient temp is, or without a dial-back light, load a temporary tune with the cranking spark table zeroed out. Even without either of those tricks the TDC mark should be within a plausible range of the pointer.

00whitebirdws6

So, after setting the engine to tdc #1, marking the balancer and rigging a pointer , I blew the dust off of my old timing light only to find it no longer worked. I ordered one off amazon and fimally got around to checking the engine earlier tonight. As I suspected, the timing appears to be almost a complete 180 deg out. Unfortunately, it looks like I will be pulling the engine back out this weekend to rip it down and have the reluctor re-clocked. Thank you everyone for helping out and passinv along ideas

Project GatTagO

iTrader: (7)

Are you sure the cam isn't installed 180 degrees out?

00whitebirdws6

When I installed the cam, I installed it dot to dot and made sure the adjustable timing set was aligned correcty. Im not sure if I could have installed it 180 out. Is that possible if the cam was installed dot to dot?

G Atsma

If crank dot is on top and cam dot on the bottom, you should be OK.

QwkTrip

iTrader: (23)

Sometimes crankshafts are keyed wrong, sometimes camshafts are ground wrong. It's always a good idea to degree the camshaft. In this case it is beyond good idea and should be your next step of investigation. You can at least visually check if the intake and exhaust are dancing with the right cadence.

Fang

If the camshaft were 180* out that would simply be #1 TDC exhaust/#6 TDC compression instead of #1 TDC compression/#6 TDC exhaust, and determining which is which is the job of the cam position sensor.

If you time the cam with the crank dot up and the cam dot up, that's "180* out". Turn the crank 360* and it's now crank dot up and cam dot down. It goes "180* out" every other crank revolution.

Fang

Fun fact: On every gen1 SBC ever made (I don't know if they changed it on the LS since without a distributor there's no reason for it to make a difference) "dot-to-dot" is actually #6 TDC compression, and if you set it dot-to-dot and then drop in the distributor pointing at #1, it won't run. #1 TDC compression is actually with both dots up. This is usually never an issue as the crank usually gets turned to adjust valves before the distributor goes back in and #1 TDC is re-found using the rocker arm motion.

00whitebirdws6

Is it the ckp or cmp that controls timing on an ls? I would assume that even if the cam is 180 out or out of time somehow, the ignition event should be correct if the crank reluctor is timed correctly and it controls the timing right?

Fang

CMP is only used to determine #1 from #6, it's not used for spark timing other than that.

"The camshaft reluctor wheel is part of the camshaft gear. The reluctor wheel contains a pattern of 2 narrow teeth, and 2 wide teeth around the circumference of the wheel. The falling or trailing edges of the 4 teeth are evenly spaced at 90 degrees apart. The engine control module (ECM) recognizes the narrow and wide tooth patterns to identify camshaft position, or which cylinder is in compression, and which is in exhaust. The ECM also uses the reluctor wheel information to determine the camshaft relative position to the crankshaft position."

00whitebirdws6

How would this work with my cam gear? It just has the 1 big tooth.

Project GatTagO

iTrader: (7)

Gen 3 engines uses a single pulse cam signal, while the Gen 4 uses a 4 pulse cam signal.

Fang

From the manual for a 24x/1x engine, if you would like it in GM-speak:
"The camshaft reluctor wheel is either pressed onto the camshaft or part of the camshaft gear depending on the application. The feature-or target- is read in a radial or axial fashion respectively. The wheel is a smooth track, half of which is of a lower profile than the other half. This feature allows the camshaft position (CMP) sensor to supply a signal as soon as the key is turned ON, since the CMP sensor reads the track profile, instead of a notch."

QwkTrip

iTrader: (23)

Right, to put it in everyday speak: The crankshaft reluctor wheel provides the high-resolution position sensing of crankshaft rotation, but the crankshaft turns twice for every combustion cycle so the camshaft sprocket is used to augment that data to let the engine ECM know whether it is in the first 360° of rotation or the second 360° of rotation (720° for every combustion cycle).

Regarding when spark timing occurs, the ECM only sees the reluctor wheels (not actual piston position) so spark timing will occur according to how the ECM is interpreting the timing pattern. It is up to the engine builder to properly index the crank and cam wheels to the rotating assembly so the timing data is accurate.

Now, the camshaft itself also has to be indexed properly to the crankshaft. If I were the OP, then I would degree the cam to make sure the engine hardware (rotating assembly) is married up properly. Knowing, good or bad, is still better than not knowing and will help build confidence about next step forward.