I have a thread on here where I was trying to figure out WTH was wrong with my car and it ended up being the ECT wasn't plugged in good, I guess. I unplugged it, checked the ohms and volts, plugged it back in, and voila... it runs perfect!


Before... REALLY rich. Wouldn't run on it's own. Had to floor it (clear flood mode) to get it to start.

http://youtube.com/watch?v=JQgcf5KNdSQ



*two weeks later and having checked every damn thing on the car!!*


After... runs so smooth it almost sounds like a stock cam instead of the GM847. Around the 1:01 mark you can hear it hit closed loop and start sounding a little better!

http://youtube.com/watch?v=OuacJRl1M3k

 

Don't laugh at me kicking the camera in the second video at 1:26!

 

Good post. Small things like that ,which can be easily overlooked, can lead to hours of troubleshooting and replacement of other parts that aren't the problem.

 

This is a case where a scanner would have shown you the trouble right away. Everyone should have one in their toolbox. You cannot effectively troubleshoot a modern car without one.
The ECT is a most important sensor, especially for a speed density car.

 

I completely agree. There is absolutely NO way I would have gotten the 396 build running without a scanner... From what I remember, a good scanner was essiential for:
- TPS setting/slotting (possible with just a multimeter, but scanner is easier)
- idle reading/tuning
- spark timing adjustments via Knock Retard readouts
- cylinder balance tuning, especially with a large cam like the 847 (big BLM splits need to be scanned/adjusted for)
- Sensor diagnosis (I cracked the brittle green-plastic MAP harness when installing the alternator brace and didn't notice... it barely ran until the guys at Speed Secrets scanned it and picked it out quick).
- Bad passenger said O2 sensor... lazy readings on a fouled sensor were playing havok with BLMs but wasn't bad enough to through a code just yet.
- Bad driverside O2 location... I tried to put a bung a bit farther downstream than I should have (AS&M headers and the Canton oil pan needed to be massaged a bit to fit, but there was NO way the AS&M bung could house a O2 sensor... and I really didn't want to jam it in the spot I ultimately went to). Brand new O2 sensor showed "lazy" sensor sine-wave action and again the Speed Secretd crew spotted it in a few seconds on the scanner.
- Bad ECT readings... I went to a 3-wire ECT sensor like the LS1's... it puts out a 0-5v reading for the PCM, and a 0-12v reading for a dash gauge. Some dumb *** (that would be me) switched the ground and 5v signal wire... yep, it was running like crap. Scanner showed -40*F.

Scanner is ESSIENTIAL to finding out where problems are creeping up. Especially once you start tuning and get misses say at mid or high RPMs and wonder if its from knock (indicated by PCM pulling timing), or other problems like a bad plug/wire/coil/etc...

AutoTap seems like a decent OBDII scanner... but I think I'll be getting 1 or 2 of these first: Aeroforce Tech Interceptor. They're OBDII scanners built into 2 1/16" gauges. They also have 2 analog inputs per gauge so you can input a WBO2, EGT, Fuel pressure, Nitrous pressure, Boost, etc... readings as well. $400 for a set of 2 gauges (and the OBDII splitter cable that comes with them).

I think 2 of those with my DynoJet WB gauge would fill a 3-gauge A-piller nicely.

Right now they will log data (turn it on and it will record when TPS >50%) for about a minute and replay it at will... but later this year I hear they'll be offering them with a USB output to download the runs for tuning, similar to the way a WBC will now.

A dual-reading gauge that can tap 2 analogs OR any OBDII data value seems like a great idea.

These guys make a similar one with better color/graphics options, and its available in both 2 1/16" AND 2 5/8" gauge sizes... but with no analog inputs: PLX Devices DM-200 OBD For $400 it also doesn't have data logging standard... that's an add-on module for $260. (which is why I'll stick to the monochrome gauges from Aeroforce).

 

Those are good products it seems. I know gtech makes an tach that has some diagnostics built in also. I think the aeroforce would be good to keep an eye on my temp for use in conjunction with my EWP. I think I am going to sell off my LT1 scanmaster because I need alarms like the ones offered in aeroforce. Anyways your searching blind without some kind of scanner.

 

The bad thing is I had the scanner hooked up for a week and didn't know the fluctuating numbers from the ECT sensor was a bad thing!