I finally got an ALDL cable and began with some datalogging to see if my BLM's were within range. Right away I noticed how far off my tach is from the RPMs shown in WinALDL. I then thought which one to trust? I figured the WinALDL is probably more accurate, but wanted to make sure. So, how accurate are my RPM Readings in WinALDL? Thats my first question. I had a hard time getting anywhere near 4000rpms with winaldl because my tach was showing 7000+rpms at that point. I really wanted to make sure im not revving my old L03 more than 6krpms. Can I trust WinALDL and go out and do some more data logs and get those readings from 4 - 6k? I have a feeling i'm going lean since I recently did a full exhaust on my car.

Thanks

 

As long as you have the correct definition file for WinALDL, trust the ECM. To fix the tach head over to the electronics board. There is a great thread on fixing the resistor that goes away in the tach driver PCB in the cluster. Common issue in 3rd gens.

I don't get over there much but I have they sticky'd the thread. Other wise will need to search for it.

RBob.

 

Many thanks for your input. I did another datalog today and pegged the tach to past 7000k while only showing 4800 from the ECM using WinALDL. I'm not too worried about making the tach work properly, just want to know I'm not over revving it.

I attached a BLM datalog from today. If I'm reading it correctly fueling looks pretty good except for running a bit rich at lower rpms. I'm trying to learn about some basic tuning before I do some major mods. I hope to get the EBL setup one day to simplify things.