Hey, Choprods...Olds/Caddy EFI from the Disco Decade!

[Fat Hack]

Okay, you got me thinking and I just HAD to do some research!

Olds 350 and Caddy 500 engines are listed as having EFI optional in certain models starting with the 1976 model year. According to my Chilton's manual, it is a very similar system to any of the more 'modern' port-injected factory fuelie set-ups. The schematic shows an in-tank "boost pump", an in-line pump, filter, regulator, fuel rails and eight injectors.

The air metering side of the system utilizes a throttle body, fast idle valve and a Manifold Absolute Pressure (MAP) sensor...in addition to the obligatory Throttle Position Sensor (TPS), Temperature sensors, speed sensor, and Electronic Control Unit (ECU).

This was obviously the system that lead up to the standardized systems in use by all domestic automakers ten years later. MAP systems gave way to MAF (Mass Air Flow) systems and eventually evolved into Tuned Port Injection (TPI) systems which offered more performance through long, tuned runners delivering the air to each port where injectors fired the fuel charge.

In 1982-1984, GM also used a system known as Cross Fire Injection (CFI) on Vettes, Camaros and Firebirds. These set-ups looked sorta like early Z28 cross-rams with two throttle bodies mounted at diagonally from each other on a large intake manifold. It earned a bad reputation, but actually worked very well when properly tuned and calibrated. However, by 1985, TPI systems became the top performers in the GM camp, and are still in use today.

Going back to the early Cad/Olds systems, it's neat to know that there were such things being toyed with in the late 70s! My Chilton's manual is from 1979, and so it only covers what was known up to that point in history...but it clears up the mystery over what fuel injection system was used on the Oldsmobile and Caddys you mentioned!

It WAS an EFI system, though...and not mechanical.

Cool...I dun learned sumthin new today!!!

Thanks for bringin' it up, Chop!

[50mercfan]

hack, the wife drove an 83 Z-28 for years it had cross-fire. as you said the system had a very bad reputation. i knew several people at the time that had them and they were trouble. but i'll tell ya, that was the best car i ever owned. it had 275,000 miles on it, thats not a typo, when we got rid of it and it was still running fine. they ONLY thing i ever did to the car was to change one valve cover gasket and once a year i had to put plugs and a fuel filter on it. i did have to change the transmission out once. i've got another cross fire hanging on the garage wall now that i've had for about 10 years. a buddy of mine took it off his sisters 82 trans-am because it just wouldn't run right.i've thought about putting on the merc, there are companys now that have after market systems for cross-fire. i know this isn't traditional but i thought i would share my experiance with the cross-fire. also- i heard years later that the problem with the system was too much fuel pressure. just add a regulator and it's fixed.

[RileyRacing]

Did you ever google search Crossfire Injection? There is a guy who did a hell of a buildup on one. Even cut the manifold open to enlarge ports and stuff. Read about it this summer. Way cool.

Jay

[carkiller]

We changed a bunch of 76-79 sevilles over to 350 olds quadrajunk intakes and carbs w/fuel pres regs. and HEI distrbuters. The EFIs wouldnt run and when they did ate lotsa gas.

[Rocky]

One of the guys that awapped over to Q-jet carburetion on his seville was a freind of Carkiller's and mine. He tossed the complete olds EFI intake, throttle bodies, guts, feathers and all on the ground where he did the work. I usta see it lying in the grass of his backyard and think of doing a little tweaking on it myself but I had no olds engine to bolt it to...I think a guy could whip up a simple adapter to adapt a couple bigger GM 2 barrel carbies to the EFI intake for a death rod [tm] application.

[choprods]

The one I saw had one large[4hole]?venturi on it-also wont that intake fit the big block olds?

[chopolds]

Yes, that's my era for learning all about cars. The Crossfire set-up, and, to generalize, all early EFI's, suffered from similar problems. Today, it would not be an issue. First, the computers used to run them were Extremely slow! You can imagine, if you look at how far technology has come in PC's since then. A common problem was a 'wandering' idle. The computer would try to adjust idle speed, but could never keep up with itself, so the idle would wander from it's set-point to 2000 RPMs and back again, compensating, and over-compensating, trying to get it right. It was just too slow.
Another common problem, not really addressed until about 84-5, awas that the quality of the fuel in those days was geared toward carbs. Larger particles of dirt, etc., would flow right through a filter, and carb, but would clog up an injector. The detergent used in the fuel was also not up to the task for injectors. The heat/cool cycle of the engine would produce varnish inside the injector, and the detergent was not strong enough to clean it out, so it would build up, again, clogging the injectors. The closer the injector was to the intake valve, the worse it got. Heat was also an issue, so the early Turbo Lebarons were a severe candidate for problems.
The gas companies jumped on the bandwagon in 85 to clean up dirty injectors, Chevron first, with Techron, and later Exxon with it's XCL-12. I worked at Exxon during these times, initailly, a dyno operator, first letting cars run on 'bad' gas to foul the injectors, then to see how many tanks of fuel with the new additives it would take to clean them up. Later I worked in the test car lab, removing and installing injectors, running diagnostics, and building "stand-alone' fuel systems in new cars so you could run different fuels through them easily, and flush and change fuels quickly, for testing. Really taught me a lot about the new EFI systems, as well as other computer controls.