I did a search and didn't see anything that was similar to my issue.
New Build - 427ci LS, Holley Terminator X Max ECU and Harness, Dart Next SHP fully skirted iron block, forged rotating assembly, RHS LS7 307 CNC Cyl Heads, Whipple 4.5 Blower, E-85, Comp cam, 58x Reluctor etc.
New Superflow Dyno - Engine Break-in went fine, engine revs fine on dyno without "load". Started to make first pull and engine lost crank signal at 3800 RPM. Tuner made several changes, adjustments etc., in an attempt to rule out issues and or isolate the issue. Installed another new OEM Crank Sensor same result. I contacted Dart, per Dart some of the first casting of these blocks, the mounting surface for the crank sensor wasn't machined enough so you have to "clearance" the surface, so the sensor is close enough to the reluctor. BTW - per Dart this issue was corrected in subsequent castings. The shop verified the distance of sensor and it's with-in tolerance so that wasn't the issue. When it losses crank signal, it goes back to idle and will rev fine as long as it's not under a load. Any thoughts or ideas would be greatly appreciated.

 

You will have to either keep messing with the crank sensor distance from the reluctor wheel or switch to a crank trigger. We have tons of dart block motors out there and only had this happen on one but we also run dominators on 99% of of builds.

 

Thanks for the reply, we even shaved the edges of the sensor to get it even closer same thing. What was the solution on the one you had this happen to? Crank Trigger?
Thanks again

 

Check the crank end play?

 

It's on the build sheet at the shop, I will check what it was during assembly, it hasn't been rechecked since coming off the dyno. I will go by there when I get off work.

 

A buddy is having the same issue with TermX at the dragstrip. He has not found a solution.
His is a stock block.

 

After messing with the crank sensor several times just went to crank trigger and never had another issue. We have a good number of 58x dart blocks running 30+psi and never have issue but they are all dominators.

 

I have a Wegner Front drive system the Pully for the AC, PS etc., mounts to the font of the Balancer. All of the crank triggers I have personally seen mount directly to the front of the balancer.

Current set up

 

Only under load? We are getting ready to install the 2" spacer on the blower, we will try a different Terminator that we have on the shelf.
I wonder if other people have had issues like this with the Terminator

 

Yes to the under load question. It drives around fine.
The Holley diagnostics shows the loss of crank signal.
Im not sure if he has a 24 or 58x wheel.

I researched a bit and yes others have had the issue. In typical internet fashion, most of the posts dead end with no solution reported.

I think swapping out the TermX box is an excellent idea.

 

Going to give it a shot; I will update once we get it back on the dyno an figured out.

 

Was that particular one using a Dominator?

 

Yes. It would run and drive and make a little boost but if you tried to do a full dyno pull it would loose crank signal.

 

Thanks, I’m just not aware of a set up “crank trigger” that will work with the Wegner Drive System I have for the 4.5 Whipple

 

Hey any updates on this? Crank trigger is the only solution? Current setup is bone stock low-low mile gen4 5.3, Terminatorxmax.. I lost crank signal once on the dyno after several pulls making 550-630hp, under full load at around that same 3800rpm mark! Also lost it again the first time I drove the truck on the street when I laid into it about 2500rpm this time, and seemed like it killed all power that time.. don't even want to drive the thing until I figure this out! Thought maybe it could be a ground issue.. not sure where to go from here!

Crank signal loss fireball

 

Check the end play on the crank?

 

This motor is as fresh as can be, and only just now boosted.. motor has 96k, with freq. Oil changes using amsoil only since new.. I was able to pull it due to frame corrosion, and the owner replaced the truck.. I have a feeling it's a terminator issue as most of the research I've done has shown to be happening with terminator ecus..

I'm just hoping it's either a power/ground issue, chafed wire, or the sensor maybe got wacked..




What external crank triggers are available for the 58x ls?

I can only seem to find 12/1 or 12x nothing 58x for ls

 

Does the ECU have a pull up resistor. I belive these sensors need a pull up ressitor. Without it the signal could easily not be readable at RPM. Do you have a scope to look at the actual signal?

 

I agree with the above. Put a scope on the crank signal pin, AT THE PCM side. Watch the squarewave to see the crank as the computer sees the crank. Use the computer's ground to see it as the computer does as part of your testing.

Don't assume a new Crank Sensor is good, or even two. Some strange phenomena is happening with these parts and sensors that there are tremendous failure rates right out of the box. Use OEM, or better yet switch from a known good engine. Do not use anything Dorman that's electronic.

IF ALL ELSE FAILS, and this is a LONG SHOT, check the reluctor wheel/crank for magnetism. Yes, it's a thing, albeit a very rare thing. Usually happens in long term swaps with badly placed grounds though.

Another long shot is a alternator failure causing ripple noise on the crank signal, but your scope will show that.

 

A ?
"IF ALL ELSE FAILS, and this is a LONG SHOT, check the reluctor wheel/crank for magnetism. Yes, it's a thing, albeit a very rare thing. Usually happens in long term swaps with badly placed grounds though".
Would/could this phenom be created as a result of a crank being magnafluxed and not being completely/correctly demagnetized afterward?