I have a 91 Firebird I converted to TPI using the knowledge contained here. I replaced the in tank pump with one for the 5.7. I got a 5.0 with a TPI set up but needed injectors at first I sourced a set from ebay but after running into this problem I sourced a set of stock ones from rock auto. The only modifications to the engine are a port match throughout the intake and a set of 1.6 ratio rockers with a 3" intake, headers and exhaust. To make the headers work I removed the AIR system and disabled it in the eprom. The problem I have is the engine runs rich at low RPM and when it goes into closed loop the BLM will drop to 108 and when the integrator drops the injector pulse width to .96 the injectors quit working and the O2 readings drop to around 20mv. this causes the integrator to jump up to 128 and start all over. Checking fuel pressure I get 46psi with the vacuum disconnected and 40psi at idle.
What have I missed or not seeing.

 

What do you mean by "stock ones" in terms of injectors? Just curious, because lots of times after people replace injectors with seemingly "stock" injectors, they start having problems.

 

I had no injectors to start with. After reading everything I could find here, I determined that I needed 19lb injectors. When I ordered the injectors from ebay they were listed as 19lb injectors. When I ordered injectors from rock auto, I made sure I was ordering for a 5.0. I would only hope that they are a 19lb injector. That having been said both sets are running the same.

 

Can you post a picture of the injectors they sent you as well as the ones you bought from ebay?

 

the one on the left is an ultra power MFI101 from rock auto the on the right is from ebay.

 

I went back and checked emails and the ebay seller was ultimate components.

 

19#s, but at what Fuel Pressure?

 

As stated in the O.P. the pressure measures 46 psi with no vacuum and 40 psi at idle.

 

I am thinking since I do not know what was done to the fuel pressure regulator before I had it and the pressure seams about 3-4 psi high I would get an adjustable fuel pressure regulator and try to set pressures to 43 psi no vacuum and 35-36 at idle and make sure I do not max out the injectors at WOT. I am out of ideas here and have searched the forums and found nothing similar posted. All opinions are welcome.

 

how are you taking data? Tunerpro?

 

My question had to do w the injectors u bought and their rating. Were the ones u bought rated at the same pressure ur using?

 

As far as I know these are supposed to be stock replacement injectors. I have no other data on them.
Yes I am using tunerpro and the moates ALDL cable.

 

Post your xdl data file up on the board here... let's take a look at it. Could be a clue...

 

I am using tunerpro v4.14 and having trouble getting a recording. I am going to try to export a spreadsheet file. If would would tell me what you are looking for, I will try to describe what is going on.

 

I'm not sure what we're looking for specifically... we'd just look at the sensor data, various voltages, trouble codes, etc... see if anything jumps out as being off-nominal.

 

When I get home I will try to get something up on here. I found a small sample I could get to load into a spreadsheet.

 

Here is the bin and the data file in a spreadsheet format, should be able to see it with any spreadsheet program.

 

Nothing jumps out at me from the data.

I think we can rule out the O2 sensor if you're saying the engine already runs rich in open loop. The O2 sensor is simply reacting to a pre-existing condition.

You're saying the problem only exists at low rpm? So when you're running above idle speeds, things return to normal?

Since you converted to TPI, my first thoughts are going toward some sort of wiring error... missing ground or something. How did you do the conversion? Aftermarket harness? Repin an existing harness?

What I would do first is validate your wiring by backprobing the ECM connectors using this link...

http://chevythunder.com/fuel%20injec...20(ecm#1227730)

Also, what adx file are you using to log data? The data export you sent is highly abbreviated vs what TP can log with the right $8D file. Try using this one I attached here.

 

I re wired and re pinned the existing harness. The proceedure was remove pin from old ecu connector, verify function by checking continuity to the other end, then inserting pin in new connector. After I was done with that I rechecked everything.

 

Thanks to everyone who tried to help. I seem to be having some other problems as I was driving it the other day and it is down on power.