550sx

Hi ,
I have searched and found a lot of info related to the codes I am getting but none of these scenarios fit the question I am trying to answer.

I am getting a code 54 and sometimes a code 51.
If I clear the error codes than the car will go into closed loop.
second start up after clearing the codes and it stays in open loop.
I am thinking the code 51 might be when using the AUP1 , read something about the connections being bad can throw this code. Not sure obviously.
Unfortunately my car is 30 miles away because that is where I have been building it so it is hard for me to check things. I try to find out as much as
I can before I go out to work on the car again.

The fuel pump is controlled by a switch on the dash that closes a relay to send proper amps to the aeromotive voltage regulator, voltage regulator to pump.
Just realized that the voltage regulator is pulsating the fuel pump and purposely dropping voltage below a certain RPM.
I definitely am not sending any fuel pump signal to/from ecm.
Is this the problem?
if so I am assuming that I need to wire the fuel pump through the ECM and either use the voltage regulator on the mode where it keeps the voltage on all the time or set the rpm control high enough to get the same result so the voltage does not drop causing the same error code.


The car had a blow through setup prior to going with the tpi.
FPR is a relic of the old system, 60lb injectors are in preparation of putting the turbo back on once the car is street legal,
modified the fuel rails to connect to my old fuel system.

I am running tpi pulled from a 1987 formula , rewire the connectors for the 7730 ecu ,
using moates gp1 with SAUJP_V4_1026.
fuel pressure is between 45-50psi at idle( don't remember exactly ).
running an aeromotive A1000 fuel pump and Aermotive universal bypass regulator with 1:1 boost reference(vacuum/boost reference is connected to manifold), 60 lb injectors.
I have the fuel going in through one rail crossing over to other rail ,
then out and to the regulator(all 8AN plumbing).
have adjusted the bpw for injector size(now starts without needing to put the throttle down to let air in to balance excess fuel),
set cylinder volume size, injector size, runs in closed loop with without going into AE(leans out then).

12 degrees initial timing with the est bypass disconnected.
idle with IAC disconnected is about 600,
tps set to .75
VATS, AIR , CCP and EGR all currently disabled.

any help would be greatly appreciated.

RBob

iTrader: (1)

The lack of voltage into the ECM's fuel pump monitor input will cause code 54. You can turn it off in the malfunction bit mask so the SES/CEL doesn't light and the code isn't stored.

The other and more important item is which voltage input is the ECM using for the injector compensations. IIRC, on $8D it is selectable via an option word to use either the IGN+ switched input or the fuel pump voltage input.

Need to use the IGN+ input when not running a fuel pump voltage input to the ECM.

RBob.

550sx

thank you RBob,


for this one
"Need to use the IGN+ input when not running a fuel pump voltage input to the ECM."

In tunerProRT I have this set on
"Option Word 1 - Bit 6 - BATT FOR INJ Lk Up else Fuel Pump"
looks like that should mean it is using the battery reference instead of the fuel pump.

I turned off the flag "ERROR WD 4 - Bit 5 - ERR 54 Fuel Pump (Low Voltage) "
with this turned off now it will ignore the fact that there is no fuel pump signal and I should not need to rewire my fuel pump?

thank you

JP86SS

iTrader: (1)

Fuel pump still won't run like that.
The only other way I know is to use the oil pressure switch to run the FP.
This is done in case the relay goes bad and doesn't leave you stranded.
Using the pressure switch will run the pump but will have to crank before oil pressure builds up to turn on the fuel.
Disabling the error code and the compensation would not be needed.
The error code would be a good indicator if the fuse for the pump goes out and the car won't start.
The "Option Word 1 - Bit 6 - BATT FOR INJ Lk Up else Fuel Pump" is just a selection to use Ignition power input or the fuel pump volts input that will be used for injector compensation reference.
Running the pump from the distributor pulses gives you an auto shutoff if engine stops (in a crash), using the pressure switch it would be best to use a switched power source so it doesn't run on after the key is turned off.