what in the tbi system sends info to the computer so the computer can do the airfuel stuff? my car is killing under a load, it idles ok, but give it gas or put it in gear and it dies. i have done all kinds of work on this thing to find the problem. yesterday i changed the ecm and it was working for a bit and then it went back to the same problem. sometimes when idling the rpms want to move up and down slightly. i need help. i want to fix it myself, i don't want to take it anywhere, i want to learn this stuff.
things i've changed;
tps
iacv
plugs and wires
ign. coil
temp sensor
cat is gutted
fuel pump and filter
throttle body has been rebuilt
injectors changed
new battery
ecm change
o2 sensor.
fuel pressure is at 13
manifold pressure at 20
timing was at 8 and reset to 0

any of you tbi experts have any advice i surely welcome it.

 

Well my friend. I am not an expect, but i have just done a 305 to 350 swap and I have learned a ton doing it and from the awesome guys here online.

To be honest with you it will be easier on your pocket book and your mind to just take it to a shop where they can diagnose the issues for you. You have replaced about everything that could be replaced with regards to the fuel system.

So, it may very well be something else, but before you go and spend a bunch more money on replacing parts either get a chilton's and learn to test all the sensors for yourself or take it to a qualified mechanic. I hate to do "guess" work and recommend stuff and that not be the problem.

First, check and test all your wires especially to your ECM, etc. Make sure they are all good and connected properly.

Next, EGR system. Please check that too. Make sure your EGR valve is functioning properly and the EGR selenoid too. Check all your vaccum lines. Make sure they are all tight and not worn out.

I assume you do not have a MAS. Correct? it should be a speed density vehicle.

Other than that I am not too sure what else it can be at this point. I need to know if there are any other symptoms at all with your vehicle.

 

Also, make sure you have the correct ECM as well. Is the ECM new? used? etc

 

its a map vehicle. and i had the map sensor checked already and it checked good. the car does the same thing with the right ecm and the one i got from a truck. this car is just a project and i want to learn this stuff myself so i'm not taking it anywhere. egr is going to be my next move, i have a haynes book and will do further checks. any other input and advice and other experiences is welcome.

 

Just a friendly tip. If you need a new EGR valve make sure it is OE. Buying the ones that are aftermarket and having to use the correct washer based on the OE part number are crap!!! Seriously, I have had 4 top notch mechanics tell me that in the past week.

AUto Zone is out of the question for OE style EGR valves. Advance Auto Parts has a much better quality but again they contain the "washers" etc. I am just going on what others have told me. I had the auto zone one and it was crap and then replaced it with a GP Sorenson from Advance Auto. i went against the advice, but the car runs a hell of a lot better now.

Anyway. you can go to GMpartsdirect.com and order an exact OE replacement for about the same price as one from Auto Zone, Advance, etc.

Good luck my friend.

 

My first impression - EGR valve stuck open, or bad solenoid sending vac signal to the valve. Replace both My total cost was $60 for both and my GPSorenson valve works great - you'll often find the advice to get ACDelco valve, but I haven't had a problem for $140 difference between the two valves.

Second thought. Is there a period in time when the problem occurs? For instance, does the car run fine for the first 3-8 minutes or does it run poor in that time and get better - or is it allows the same?

 

the car runs the same