Ok. Got the 1985 TPI unit. Will be porting the plenum and installing in the next few days.

BUT...It looks like I'll have to drill an additional hole on the 85 plenum to allow my 91 throttle body to bolt on AND holes tapped onto the right rear of the 85 piece for the MAP sensor to bolt to.

I noticed on several parts sources that they show seperate listings for 85 thru 88 units, 89 units and 90-91 units. Also, found a site on "GM Port Injection" that mentions these differences.

Anyon swap a pre 1990 unit onto a 90 or 91?

Trying to save myself a surprise when I go to do the install !!

Gifman

 

No big deal.

If you don't want to bother with mounting the MAP sensor on the plenum, non-TPI EFI cars had the MAP on a little cowl bracket that mounted it near the heater box. Shouldn't be hard to find one on a stroll through a junkyard. With that bracket, and a bit of vacuum tube, you're good to go.

Obviously, mounting the MAP sensor on the plenum like the '90-92 cars have is fine too.

As far as the MAP sensor connection to the plenum, my personal preference is to have it on it's own separate nipple, rather than "teed" with anything else. So, that may involve drilling and tapping another hole, if you've got all the other factory stuff hooked up to the plenum. (note that not everyone seems to agree with me on this; some folks do tee the MAP off of other vac lines when doing SD conversions)

IIRC, it's not a problem to use a '90+ TB on an earlier plenum. It's trying to use an '85-'89 TB on a '90+ plenum, that's a problem, since the IAC system won't work without modifying the plenum.

HTH,

 

I think I have seen the MAP sensor also relocated into the air lid... I didn't like that idea - but it worked.

 

MAP sensor in the air lid? Let's just say it'd be a horribly bad idea.

Moving the MAT sensor into the air lid, or intake ducting, is a lot more common. Not to say that I particularly agree with that practice either, but it works for some folks.

 

It is very possible I am confusing the MAT with the MAP... I cannot remember, but the point is, don't do it.

 

Bolt the map to the cowl like the TBI cars, and use a small section of hose. You can replace the hose later with some better tubing.

The plenum should be fine. I'd (infact I did) drill and put a barb in the back just for the MAP however.

-- Joe