Was wondering what is wrong here. Swaped 87 305 to 350 TPI and got the PROM for the 350 with 25lb injectors. Too rich and engin lopes at idle. So, got an afpr to bump up pressure. I set it at 46 psi and now it's blowing fuel out the exhaust. Maybe i didn't adjust the fuel pressure right. Do I adj. with or w/o the vaccum hose on?

 

As with my other reply on the other thread,

the stock chip for a 350 is burned for 21.6 #/hr injectors. You said you have 25 #/hr injectors, therefore, you should reduce the fuel pressure to something beklow 40psi to get it running right.

The best thing that you can do here is to buy a custom chip burned for 25 #/hr injectors.

BTW: You disconnect the vacuum line and plug the open ends. Then read the fuel pressure. The stock setting is around 43.5 psi.

 

Not to be rude here but it sounds like he has a chip for 25# injectors. Maybe I'm reading it wrong...or maybe he thought 350's had 25# injectors....maybe.....
What he really needs to do it hook a scanner to it with the previous pressure setting and see where the BLM's fall, then LOWER the pressure...if it was too rich with the stock regulator, higher pressure will make it worse.
(that last was not to you doc..was for Shaggy)

 

Our answers are based on the information given, knowledge, and experience. The more information you provide the better.

Set it with the engine off to about 43.5psi at the fuel rail, and it should be about 37psi at idle. Apply 12 volts to the "G" terminal of the ALDL diagnostic connector to turn the fuel pump on with the ignition off. For best results bleed the gauge a few times to get the air out of it. To increase performance you will need scanner data to fine tune it, as others have suggested

Correct my assumptions if they're wrong.
1.) Installed XX year 350 TPI in an 87 Z28 Camaro (assumed from the side bar info.)
2.) Using ECM and PROM from XX year 350.
3.) You assume the 350 has 25lb injectors, or received incorrect data.
4.) You set the pressure with the engine running and vacuum applied.

If you actually installed 25lb injectors, they need a static pressure (no vacuum) of about 35psi to equal the flow of a stock 5.7L TPI which has 22lb injectors. The 305 has 19lb injectors.

 

Morley,

You have posted alot of good stuff for us thirdgenners. I have never known you to be rude, so dont worry.

I took it as he got the factory chip for a 350, not knowing the 25s were not factory flow rate.

I agree what he needs is a scanner and see where the BLMs are at. Adjust the fuel pressure to bring the BLMs closer to 128. However this does nothing for the WOT AFR. So if he cant get another custom chip, It might be best to tune for WOT and let the BLMs fall where they might.

What I'm trying to say is that getting the WOT AFR right is more critical than the BLMs. I dont see a problem if the BLMs are at 148 or at 112 (for example) as long as the WOT AFR is 12.8 to 13.0:1.

A good scanner is very important in tuning these cars.

 

To clarify more, sorry, I know that stock for 350 is 22lb and 305 is 19lb. I also have a stock prom not a modified one. I wanted to try the afpr first though, and see if it wold solve the problem. Then if it didn't work, I would then get a modified prom or learn how to reprogram one myself.

So you say i have to remove the vaccum line and plug it to adj the fuel pressure? I will have to give it a try. See, i was doing it wrong then. I connected the vaccum line. Probably explains why i was getting too much fuel.

With the 25lb injectors though, i would have got the sock ones if they weren't so expensive. It would have solved some of my problems, if not all.

With the higher flow inj. (25lb) I have the ability of increasing the performance of the engine, don't I???

 

No need to apologize, we're a visually oriented society we assume people "see" what we're trying to say, and write it that way.

Yes, use the afpr to increase the performance, whether you have 22, or 25lb injectors (start with 35 for the 25s, and work your way up a couple of psi at a time, use the scanner.) When you change the ECM injector size to 25s then set psi to 43, or so, and tune again as above.

 

Ok, I set the afpr to about 37- 38 psi and it runs a heck of a lot better. The Loping at idle is virtually gone and there is better throttle response. But since i have the bigger injectors I would be wasting their ability, Right?

It seems I need to fine tune it a bit more, though. Guess a scanner would help out. Where can i get a scanner. First, I should ask, what is a scanner. Is it the tool that connects to the ALDL plug used for checking the diagnostics? If so, I have seen those and I have a friend who has one for his car.

I was looking at the Tech Board on programming PROMS. I Think I need to invest in some equipment and learn how to do this. Seems too costly to let someone do it for you and not quite get the prom tuned right.

Hey, thanks for all the help you guys have given me. I should have started here in the firat place. There are too many know-it-alls who i've asked about afpr (including TPiS) and they all told me to increase toe psi to 45.

 

You're on the right track, leave the FP where it is for now, learn to tune.
This is what I use:
Xtronics pocket programmer for $149.95 Xtronics.com
The UV eraser $ 56.95
TunerCat Real-Time bin editor $ 99.95 TunerCat.com
ECM definition file $ 19.95
OPtional:
Xtronics pocket romulator $179.95
Moates G1 eprom adapter $ 35.00 Moates.Net

I use the romulator to tune on the fly. When it comes time to get emissions inspected I upload a file tuned specifically for that, then change it back once I leave the station.