View Full Version : LTF: CFI Injector timing diagram

11-06-08, 01:22 PM
I'm trying to find an electronic copy of some GM technical documentation about the Model 400 CFI system. (I have an old hard copy, but it's packed away in storage offsite while we're in the process of moving.) This booklet was for dealer technicians, and had a diagram of the injector(s) timing relative to the distributor REF signal under closed loop fuel conditions, and another diagram for WOT conditions. I've looked on the web several times, but have been striking out. Can anyone help me out here?
Thanks a bunch!

11-07-08, 12:08 PM
You have a turbo on your 84 crossfire? Please show pics and info.:thumb

11-08-08, 07:27 PM
You have a turbo on your 84 crossfire? Please show pics and info.:thumb

Yeah, been running it since about 1990. I've got the Z51 suspension on the car, so the combination is a lot of fun on roadcourses.
I'll post some pictures when I can. For reasons I haven't figured out, I haven't been able to pull pictures out of my Photobucket account for the last couple weeks. Still working on figuring out what the problem is. Wish me luck.

11-08-08, 09:57 PM
You have a turbo on your 84 crossfire? Please show pics and info.:thumb

Finally managed to do a workaround on Photobucket to get the picture to post. It's an old picture, with lots of instrumentation wiring (WBO2, EGT, ESC tap, and vacuum/boost gauges) while I was tuning it. I've put a few thousand track miles on it, and pretty happy with the way it runs. The pull under boost is a feeling that's hard to describe. Much different than my big block.
It's due for some updates when I get some time. (I'm presently working on putting a C4 suspension on my spare frame for the '69, so the '84 has been put on the development backburner for now.) I've pretty much exhausted my interest in continually updating the PROM calibration contents of the stock ECM, so a later version ECM is planned for installation when time permits. The engine runs great, but the software just isn't as flexible as I would like. No bad reflection on the software engineers, as they weren't intending this software to be used in a boosted application.
The turbo has great response, but there's newer more efficient ones on the market since I put this one on, so I'm going to entertain upgrading that, too. (I've got a '51 Chevy pickup with a C4 suspension and a similar turbo setup, using the original engine from the '84, so any parts I take off the '84 are usable as backup parts on the truck.)
The engine is an 8:1 CR aluminum head 355. Under the air cleaner is a two barrel TBI off a 454 (w/2" throttle blades) that is connected to the original harness setup, although I needed a short adaptor harness to hook up the IAC motor on this setup.
It's not intercooled (I run about 7 pounds of boost max due to limitations in the ECM control of the engine), but I've been pretty lucky using a high percentage ethanol aviation fuel (>100 octane) mixed in with 94 octane gas to give me the octane I need, along with the mixture cooling ability of the alcohol in the fuel.
I did a boatload of bandaids along the way trying to cool this thing out on the track, but I finally got wise several years ago and installed a DeWitt radiator. The stock HD radiator is pretty anemic compared to a DeWitt radiator.
As I mentioned, it's ready for a few updates, and I'm looking forward to completing the '69 project so I can get back to working on the '84.


11-10-08, 02:46 PM
Given the lack of replies to my original post topic, I'm guessing I must be either the only person interested in this bit of trivia, as it were, or everybody has had the same poor luck as me finding this info on the web. Whichever, I still do appreciate it if anyone does happen upon this information.

11-10-08, 04:40 PM
is the turbo emblem on the back off a monte carlo?

11-10-08, 09:17 PM
is the turbo emblem on the back off a monte carlo?

You are correct. I bought the last four of those emblems I could find years ago. I was going to turbocharge my '87 SS, but decided to spend my time and energy making the '84's engine capability match the Z51 suspension's capability. I liked the looks of the emblem, and transplanted it to the Corvette.