maksik7

Hey guys, I have an 84 Firebird with a carbed 355. Now I have been dying to make it FI ever since I got it. I have my old 305TPI TA sitting in the garage. I plan to get the intake ready (ported, new injectors, blasted) over the next few months and swap it in around July. I already pulled off most of the tpi intake but I have some questions.

While I was pulling it off there were a couple of hoses on the PS that seemed to be emission related so I chucked them (One relatively thick one coming out from between the runners and going back, and two real thin ones that connected to the bottom of the plenum), but after talking to a friend I think those hoses were important.

Anyways to have the TPI functioning properly I just need the IAC, TPS, O2, and EGR, correct? Or is there some stuff I'm forgetting.

Thanks for the help,
-Max

sbrice18fan

are you going to convert to a speed density or mass airflow setup?

jmd

iTrader: (4)

There will be flames to this post and I really don't care.

First of all, you want TPI because it ran so good in the third gen you drove with it, right? Well, to get it to run good, you need to do it as close to factory as possible.

This means do it w/ a factory harness. The brands of harnesses out there (and I'm not afraid to mention names, but the only ones worth a crap are Howell and GM) which gang up all the wires on a few fuses are JUNK.

Now, have you ever seen troubleshooting info on a car which mentions low voltages? Certain symptoms like these will spring up, yet seem "transparent" on a car w/ a "simplified" harness. It won't run right, but everything "is hooked up and running right."

Not to mention, the ganged up wiring makes it one whole hell of a lot more difficult to diagnose things electrically. When you have everything on one fuse, you have everything to track down to find a short!

And no, going w/ just the few sensors you mention is not enough to make one run properly. You also need knock, temp, and I forget what else.

I DO understand the desire to remove some emissions stuff.

But, remember, it ran right and carried a 100,000 mile emissions warranty when it was put into a 3rd gen. Why would you want to emulate any way other than the right way? Delete the AIR stuff, leave out AC wiring, but do the other sensors complete!

You already have a complete donor. Use what is there unless you KNOW it won't be missed by the TPI (I would imagine some of the emissoins stuff to the charcoal can could be deleted, but I'm a lot wiser w/ CCC than w/ TPI)

Matthew

maksik7

Well first of all I'm converting to MAF system. Second I plan on using the harness from my donor car. I forgot to mention the knock and temp sensor, but I would need those too.

I really want to know what the hoses I mentioned above do? The thin hoses come out of a relay it look like rish on the PS of the distributor.

Thanks,
-Max

jmd

iTrader: (4)

Sounds kinda like an EGR solenoid to me; that's where mine (86 Iroc TPI) is located.

Good call on the factory harness

tpi_roc

Absolutely every sensor has a function and shorting yourself and your ecm of the informatino they provide will only have a negative outcome, even for the pennies saved.

The only ones i could say you dont need are AC related ones (you'll have to cross terminals for the pressure switch) and anything EGR related. Everything else is pretty darn important.

385TPI

You have made a good choice so far in that you are wanting to swap in TPI for a carb. Like everyone that has made their suggestions in helping you I for one can maybe add a few that may or may not help, you decide.
I have a 385 long rod TPI that is over 90,000mi. old and is installed in a '82 Chevy PU. It has a slew of parts to say the least and alot of hard learned lessons to also go along with it. When I started retrofitting FI systems 12yrs. ago I used Howell Eng. to crop my harness's the way I saw fit. I agree that when ever you can to always use a factory harness and all sensors if possible, and if you do not have that factory harness give Bill Howell a call he can come up w/ one. From there he can crop it the way you need it, add or subtract out of it what you do not feel you need.
The sensors that I feel that are the most important are the IAC, computor temp., IAT, TPS, O2, VSS, cold start sensor and if you are going mild to wild stay w/ the MAF. I'm assuming you understand the abreviations that I have written above... In my systems I do not have the emissions hooked up of any kind to include the egr system. Make a simple block off plate for the egr opening. If you are using headers hook up a 3 wire O2 heated sensor, this will help on start ups and getting the system into closed loop quicker. One sensor that you did not mention that you are running is the Vss. You need to keep this sensor, w/o this sensor you will see stalling, MAF codes and misc. other intermittent codes that do not make any kind of sence at all. Keeping the MAF will enable you to go w/ larger cams, injectors changes, throttle body modes, porting, compression changes etc... The MAF system is a much faster thinker than a speed density system is. It might cost alittle more in money and in the thought process but in the long run you will be able to tinker more around w/ your system than if you wore to run the alternitive. IF you need alittle more info on this subject, let me know, for now I will let this soak in.
Just to give you alittle insite on my truck it gets between 18 to 21mpg and will run over 140 in a half mile stretch. See ya!

Jza

That thick hose that came out from between the driver's side runners was the PCV valve hose (went to the valve on the driver's side valve cover).

The two thin hoses from the throttle body was the ported vac source for the charcoal canister and EGR solenoid.

As far as MAF vs. SD, the main reason people get away from MAF is because the MAF becomes a restriction on a heavily modified engine. Personally, I'm going with SD because of it's better tuning abilities (tune specific ranges, etc.). MAF is better as far as the computer's ability to see the incoming airflow, but like someone said before "MAF is better than SD, but thirdgen SD is better than thirdgen MAF".

Anyway, at the point you're at, just stick with the MAF setup. It'll be easier to get running and you can always convert later if you run into the MAF being a restriction (I doubt it).

junkcltr

iTrader: (1)

It isn't what is absolutely necessary. It is a function of how well you want the car to run.
J