Hi,

I have an '86 camaro with the 2.8L V6, sort of. Is the MPFI system mass flow or speed density?

My bottom end is actually a 90ish 3.1L, If the MPFI is speed density i'm wondering if the displacement increase is enough to screw up the ECM since speed density relies on fuel maps. I'm thinking the O2 sensor could probably compensate for the small difference in displacement but I'm not sure.

I've only had the car for a week and don't have any manuals yet (although they are on the way). I also searched the FAQ and Google but could not find a definitive answer on this for the F-body cars. Sorry if this is a question you here all the time.

Frank

 

Which computer are you useing, 2.8 or the 3.1??? Sure it depends on it.

 

my 2.8 is MAF

I would assume you would use what ever parts were used with, which ever computer.

so if ya got the 3.1 computer in, ya use the 3.1 systems.

or flip it and use the 2.8 computer, ya need a MAF.

 

The 85-89 electronics in there should be MAF... but you're right, having just bought the car, who knows what the previous owner did (ahh.. previous owners.. gotta love 'em)....

Pop the hood and check the intake ducting between the air filters and throttle body for a 4" long cylinder with a rectangular box attached to the side and a 3 wire connector plugged in. Mass Airflow.

Check the top of the firewall (the cowl) for a 1.5"x3"x.5" box hainging off it on a bracket with a 3 wire connector and a vacuum line plugged into it. Speed Density.

If both, pop passenger side under-dash panel off, remove the 2 screws retaining the ECU carrier, pull it down enough to read the numbers off it, and post them

 

"Pop the hood and check the intake ducting between the air filters and throttle body for a 4" long cylinder with a rectangular box attached to the side and a 3 wire connector plugged in. Mass Airflow. "

Got one of these.

"Check the top of the firewall (the cowl) for a 1.5"x3"x.5" box hainging off it on a bracket with a 3 wire connector and a vacuum line plugged into it. Speed Density. "

Nope. Guess its MAF. Is that a good thing? seems like it addresses the increased displacement concern I had.

"If both, pop passenger side under-dash panel off"

uh, panel?

" remove the 2 screws retaining the ECU carrier"

uh, screws? carrier? my ecu is just stuffed up there. No panel, no screws. I suspect that is a bad thing.

The numbers are 01227302. also KK98123.

Can you look these up and tell me what they say? I ask because I was told when a repair shop tried to order a box for this car using the vin number they got the wrong box and had to send it back and order another one using the number off the box. That makes me think it could be unstandard for the car.

Oh, did I mention this car is something of a S#@t Box? I like the car, being a S#@t Box is actually part of the charm.

Frank

 

The ECU is part number 1227302, stock ECU for 1985 1/2-1989 2.8 V6 MAF cars. It will compensate for the increased displacement fairly easily. You should be good to go

If you really want to diagnose further into this, take the two hex screws out of the inspection cover on the ECU and make sure the chip is labelled "HNJ" ... but it's pretty unlikely that you're running the wrong chip

 

Thanks!

 

Thanks!

Hmmm... must have hit the wrong button to send this again.

Oh well, i'll take this opportunity to say that the story goes that when the mechanic at the dealership ordered a new ECU by VIN he could not get it to communicate with his diagnostic tool. He then ordered another box by the number on the old box and that worked fine.

Based on the info that the box appears to be correct i'd assume that was a BS story to buy some time or maybe the first box was bad.

Frank

 

tell me... if someone were to take a 2.8L from an 85 and drop it into a 92 where a 3.1L once sat, with all the 3.1L sensors, injectors, intake, accesories and emissions crap... would the 3.1L computer be able to compensate for the lack of displacement?

 

Well I'll you this. I have an 89 2.8 in a 90 which had a 3.1. No problems. The only things we did was used the 3.1 upper intake since the Throttle Body has a different style sensor. As for the other sensors, never replaced any of the 2.8 sensors for the 3.1. Also if I buy a new sensor, its for a 2.8 and not 3.1.