February 2, 2017

I have decided to try to actually use this section on my site as a log (blog?) of what is going on because I manage to forget when things happen and in which order. With this first entry of this type I will try to catch up on what has happened lately.

The FiTech mystery of today is why my FiTech throttle body is on its way back to me after being at the FiTech shop for less than a day. I sent it to them using an RMA and following all of their requirements like including a copy of my original invoice (I bought it directly from them?) and by filling out a standard form that Cody, their tech guy, sent me with the RMA#17-052 filled in. I sent it via UPS on Monday, it arrived at FiTech yesterday (2/1) morning and they sent it back to me today via Fedex. The only reason I knew it was on the way back was that I got an email message from Fedex. Cody did not know why they would have sent it back and he promised to call me right back but so far, 2 hours, has not.

I’ll go back a couple of weeks and recount what has happened. First thing was that from the very beginning of using the FiTech system I had a definite, measureable (1/2 second?) hesitation when hitting the gas pedal, especially when it was cold. Many times I had a hard time keeping it running at idle. I called FiTech many times (20 or so) and was told to try a lot of things like adjusting IAC Steps at idle, changing the ACC (accelerator pump) settings, and probably others. They asked if I checked for vacuum leaks, I could not find any leaks. 

It did turn out that my brake booster was leaking vacuum. I figured this out because my vacuum pump ran when it should not need to and with the engine stalled (happened quite a lot when cold) I had no brakes. I ordered a rebuilt vacuum booster from Applied GMC and a new vacuum pump from a guy on eBay. After a very difficult removal and replacement of the booster and the pump, the pump would hardly shut off because the booster was leaking ‘internally’. Applied replaced the booster with another rebuilt and this one actually failed while I was driving and I had no brakes a couple of times. I ordered a rebuilt booster from Dave Lenzi and I returned the second one to Applied. Dave explained what was probably going on and it involves the bracket that holds the master cylinder and the booster to the upper part of the dash. I am still working with Dave to improved the booster/pump configuration but my brakes work great now.

With the booster and the associated leaks fixed I still had issues with the FiTech unit. It was actually getting worse. One of the symptoms I could see via the FiTech Handheld unit was that the engine was running rich most of the time. A possible reason for this, according to advice and research, was an ignition problem – misfires. I decided that maybe my ignition module was going bad – they can fail in some mysterious ways and it is really hard to determine if it is fuel or ignition related. My fellow GMCer and good friend, Dan Gibb, had wanted a little tutorial on how that was done so I called him and told him my plan to swap the module on Saturday. 

On Saturday morning, with Dan watching and listening, I replaced the ignition module. It made no difference. The engine would hardly idle at all. With everything I knew to try exhausted I was drawing a blank when I thought of the perfect thing to try next – swapping his FiTech unit for mine. Dan agreed to give it a try – I had let him borrow my FiTech Command Center when his was not working so he was returning the favor.  We drove to his house, uninstalled his FiTech unit and installed it on my engine and all of the problems I have been fighting with the FiTech unit went away. It ran like a new car. We took it for a test drive and I could not believe how great it was. I tried it again on Sunday morning when the temperature was in the 40’s and it did not have any problems that were constant with my unit.

Monday morning I called FiTech. Cody answered the phone, I explained what was going on, and he sent me the RMA stuff. Below is what I sent back with the unit:

Problems:

  • Does not respond to throttle – seems like accelerator pump issue if it was a carb – has been doing this from day 1 – vacuum gauge dips to “0” but no engine response for measurable amount of time
  • Idles rough and sometimes stalls in idle – hot or cold
  • Stalls and even backfires back through TB when throttle applied at low speed – cold
  • Runs rich – has hard time matching target AFR – hot or cold
  • These problems have gotten worse over time
  • I have adjusted IAC Steps multiple times. Each time it has needed readjustment after driving for a while.
  • I have restored factory defaults multiple times with no help.
  • A friend has the same vehicle and engine with a FiTech 400 model (I am not using spark control) – we moved his unit from his vehicle to mine and all of my problems went away. It ran perfectly.