I built a 408 for my truck and it was running pretty badly. The crank relearn was suggested since its an entire new long block for the truck. I did the relearn and now it sounds like I'm getting a tapping noise somewhere up top around and above 1500rpm. The scanner I used was vin specific, and since my truck is an 07 classic it uses different wheel, sensor, and ECM than a nnbs 07. Could the scan tool possibly have tried to do a nnbs relearn?

Any help would be much appreciated.

 

I was not aware that there was any difference. I can not see the relearn causing any issues.

 

Nnbs has different reluctor wheel. Idk if that's even possible or not but I find it very odd that this tapping started immediately after the relearn

 

A Tapping issue is usually a mechanical issue. Pull off the valve covers and have a quick look. Slowly rotate the motor by hand and check for loose push rods. maybe a lifter didn't pump up while it was running like ****.

I have never tried to do a relearn on an NBS while useing a NNBS style info. IMO I don't think the scanner would have worked if it though it was a a 58x reluctor motor. the scan tool portion works off the protocol OBD2 or CAN. It probally detected that it was an early model with the 24x wheel Other wise I don't believe it would have worked. The crank signals are different between the engines as well as how the engine communicates.

 

This motor has less than 200 miles on it, I hope it's nothing mechanical. I just think its quite odd the tapping started immediately after the relearn was completed.

 

If you feel that strongly please find a shop that has the capability to preform the crank re learn on your specific truck.

here is a general over view on what the procedure does for the vehicle.
https://www.performancetrucks.net/fo...d-sort-344161/

Basically your syncing up all the systems so they don't detect a misfire and they know what an acceptable amount of variations exist for your engine.

My point is that a 2007 NNBS uses CAN so if it was locked to the truck or to a NNBS vehicle it would only work on CAN equipped vehicle. Not to mention the difference it would see in the cam and crank signal. Which that alone might cause it not to take or preform a relearn.

the 99-07 classic are all Class 2 OBD2 protocol which I believe is J1850

The CAN protocol GM uses I believe is J2411

 

Thank you for your help sir. Its appreciated. I'll keep the thread updated

 

No problem!!! Hope it's a quick easy fix!!!

 

Any luck determining the noise? lifter? or possibly loose converter bolts after the swap?

 

Well, I hate to accept it, and I'm not going to accept it at the moment, but some opinions I'm getting are that it's rod knock. The motor has less than 200 miles on it, and I refuse to think it's that just yet. I haven't had the chance to really dig into the truck yet. Gonna start with draining the oil, then removing the valve covers and making my way down. Fingers crossed.