View Full Version : Injection system in 1984/1985 vehicles (Turbo or otherwise)

02-28-2006, 01:02 PM

I'm a little unclear on the information in the V6 history page when fuel injection was first introduced on the Buick 3.8 V6.

I'm fairly certain that all the turbo cars from 1984 through 1987, got Sequential Fuel Injection, right?

I know that an NA FI 3.8 was available in the Buick Electra (or was it called Park Ave then?) in 1985. Likewise for the Olds 98 that same year. This was also a Sequential FI system, right?

How about the mid-1984 Century with the 3.8 option?

I guess it probably would be easier to ask, were there EVER any batch-fire 3.8 Buick V6 engines? If so, what years/models? I would imagine that there were not, as I figure it would be more economical for GM to have had a single system for all these engines, but I didn't want to just assume that.


02-28-2006, 07:20 PM
To my knowledge ... no batch fire or MPI type systems on BUICK motors (there were on the Chebbies, including the TPI and MPI stuff on the V8 and V6). They started with the Indy derived SFI systems that evolved to the 3x Type I CCCI system we all know on the 86/87s.

When the 3800 came out, the crank encoder/cam encoder changed to a 36/18x system (from memory ... might be a bit different, but basically more resolution than our cars).

03-01-2006, 12:52 PM
Thanks. I never quite liked the MFI or MPFI (Multiport Fuel Injection) designations because they leave it a bit vauge. Is it sequential, batch-fire, more than one batch? That's what had me confused on the V6 history page under the 1984 entry.

But if 1984/1985 didn't have the 3x system, how did things work? I'd have assumed that the 3-notch crank wheel would be absolutely necessary for sequential firing of 6 injectors. No *Buick* FI 3.8 ever came with a distributor, did they?

03-01-2006, 01:58 PM
But they DID have the 3x encoder ... I think the first year of the 36x systems was in the 1988 3800 (which went to on center and balance shafts)

BTW, you can run a V6 on almost any encoder pattern (although for obvious reasons, you usually use something divisible by 6). All the ring does is give an indication where the crank is at ... with the 3X, you get an indication every 120 degrees.

With the advent of individual cylinder timing/fueling, it was found that additional resolution was needed, so you see 24x, 30x, 36x, and even 60x encoders. This allows you to know pretty precisely where the crank is in its rotation (and in conjunction with the cam sensor, whether a cylinder is on the power or exhaust crank cycle).

A variation on the theme is "missing" tooth wheels (30 -3, 60 - 5, etc.) where there are "missing" teeth that tell you exactly where the crank is without having to refer to a cam sensor signal. Then there's the 24XE and 52XE stuff in the later LSx engines (we won't even go there).

It's all about how precisely you need to locate a combustion event ... with individual cylinder timing/fueling in the latest coil per plug systems, you can do some amazing stuff!

03-01-2006, 04:01 PM
Oh, gotcha!

Thanks for clearing up my misinterpretation.

03-06-2006, 08:05 PM
Argh!! I keep trying to search the web for verification, but about half the references I come across seem to imply that they agree with you, and half seem to say that the FWD Buick 3.8 got injection in 1984, and improved it to sequential in 1986. :doh:

And here I was all ready to make some additions/clarifications to the Wikipedia entry for this motor....

Ah well, it's got other mistakes in it that should be clarified, so I'll probably eventually work on those when I get off my lazy butt.

03-22-2006, 04:07 PM
I know that since this is a primarily Turbo V6 forum, that my searching/observations are more or less academic.

But, it seems that the FWD injected 3.8 V6s in 1984 and 1985 are batch-fire systems (as are the injected 3.0 engines, as well as the 3300, oddly enough).

Trying to do lookups of parts reveals that none of the 3.0 or 3300 engines, and none of the cars with the 3.8 FWD in 1984 or 1985 have a cam position sensor.

I also found this thread (http://forums.aaca.org/showflat.php?Cat=&Board=UBB5&Number=87149&Forum=,f5,&Words=3.0%20batch&Searchpage=1&Limit=25&Main=87149&Search=true&where=bodysub&Name=&daterange=1&newerval=&newertype=&olderval=3&oldertype=y&bodyprev=#Post87149) on some message board, that discusses the 3.0 and 3300, and has a lengthy explanation of these engines' systems, which spurred me to check for the existence of the cam positon sensor on the 84-85 FWD 3.8s.

Hmph . . so I guess GM *would* in fact have two different control systems for the same family of engines.

(why do I have this feeling that about 15-20 years ago, someone was madly kneading their hands together, laughing evilly, and saying "and this will no doubt confound people in the future!! Muahahahaaa!")