pcmhacking.net

Hey,
When you say restricting the fuel helps are you crimping the return or supply line from fuel pump?

Def check map sensor.
Have seen them run 100psi fuel pressure without issues like
Your having.

Map sensor is mounted on firewall above the engine and has been tested (i spent a day swapping bits from a borrowed vs) hose is in good nick but have not checked for blockages so will go do that now. Have restricted fuel by crimping the supply or disabling pump and can get engine to fire and run for a few seconds but cant regulate fuel well enough to keep it running long.

the only way you are going to get anywhere from here is to get a data log with an ALDL cable

If there are no fault codes and every thing else is to spec as claimed then the ecu is kaput.
but I still don't think the fuel pressure has been checked as you should be able to give a definite reading?
as mentioned earlier have you checked pressure regulator for fuel leak into vacuum line

Might pay to let it known where you are.
If you are located near to me I can put one of my real time ecu's in the car and see what is happening?

Given it's an ebay chip wonder whether it's corrupted and now running of limp home resistors.
Also may not be a genuine v8 memcal but a mod'd v6 one which would make it very interesting running of the limp home resistors.
If you can datalog then chip is ok, otherwise try to set up a check engine light and flash out codes.

Fuel pressure WAS checked but was done a couple of weeks ago at the same time as the coil, ignition module, map and throttle body were all swapped and checked against known good parts from a borrowed running vs ss parked nose to nose. I dont recall the exact fuel pressure but discounted pressure as an issue when it came up within specs as per the manual. The only things we were unable to swap were the ecu as it was different and the chip due to security on the vs. All parts swapped were tested on the vs as well as the vs stuff tested on my car so i am sure the problem is not in those parts. I do not have a check engine light so do not know if is logging any faults. The chip is an ebay special but as stated it was running fine both before and after rebuild. The electronics is where i hit the wall, the mechanical stuff i have done for 30 years and can do in my sleep (yes i do know how to check fuel pressure and have nothing to gain from bs,ing the ones i am asking for help). I am thinking the next thing is to get a good auto elec to come and bail me out, i am near Ballarat in vic so if anyone can suggest someone with the right skills and equipment (and not a thief) i would appreciate your input

I can see why your username is "carbysaregood" after this sort of trouble. what type of pcm is it? the long auto pcm ? or the short manual pcm ? its not really hard setting up a check engine light, I can send you a diagram, its just a light, one pin to +, other pin to the cel wire on the pcm (which is different between auto and manual, hence why I asked). then earth the diag wire on the pcm to make it flash codes.

Thanks Jayme. A harrop inlet with a holley is a tempting fix but i really dont like not being able to find a fault or make something work. Pcm is the long auto one and i would appreciate your advice with setting up an engine light.

carbysaregood wrote:Injectors are standard and hold pressure with pump off

We can eliminate the injectors leaking being the source of the fuel oversupply since they hold pressure, therefore they will supply fuel in accordance to the ECU's instructions.

carbysaregood wrote:All parts swapped were tested on the vs as well as the vs stuff tested on my car so i am sure the problem is not in those parts.

carbysaregood wrote:The only things we were unable to swap were the ecu as it was different and the chip due to security on the vs

So I can see only 3 possible scenarios:

1. The EFI system is not in limp home mode and the ECU is supplying fuel in accordance to the tune in the main chip.
2. The EFI system is in limp home mode and the ECU is supplying fuel in accordance to the netres.
3. The ECU is FUBAR and now doing its own.

You've eliminated everything else so assuming the tune hasn't changed and the netres is the correct one for the engine then the only possible scenario is the ECU is FUBAR.

Put your VATS removed chip into a known working replacement ECU and it should work.

If the problem persists, then either your tune is now corrupt or the netres is wrong.