X-90 engine bogging under acceleration

[fixkick]

that fpreg is dead, its stuck open , hit it smartly ,it might wake up. and close.
most of them you can see a 10 psi drop. doing your hand vacuum test. (it must work at sea-level all the way to the highest mountain)
the most important function of the MPI Fpreg is to keep pressure across the injector, the same at all times. (this keeps a 5mS injection rate the same at all throttle actions) (and the higher the altitude, the lower the fuel pressure) my theory is that the PFreg wears a groove inside and sticks or the seat leaks.


at idle with high vacuum, its low, then when you do WOT, the FPreg allows pressure to rise greatly. this magic is assumed by the ECU and acceleration will suffer. if its bad. in your case, its too much fuel pressure, at low speeds. this might cause, high MPG or flooding and spark plug fouling,.
I bet your LTFT (scan PID) long term fuel trim is a huge minus number like -30, with pressure like that or is out of control at idle.
yours is stuck high.
wires. x90, x90,, different body same driveline. ,
oop sorry, i dont know where the fuel pump wires, are on any X90.. hard to find book for that. FSM.

IAC:
cold start, below 150F , the IAC must be open , this is what gives cold start fast idles. on 16v mpi
the IAC is just below the Throttle body.

MAF
the easy way to check any MAF, is to use any scan tool.
http://www.fixkick.com/sensors/92-95MAF/...sting.html

see my 3 graph plots
here is the better one , im plotting TPS to MAF. notice how they jibe.
bottom axis is time, im driving and shifting and doing hills,etc.
the left side vertical axis is throttle angle and MAF air flow. see the MAF hit 55 grams/sec. ?mass air flow ?
if for any reason the maf can't do that (fuel pressure good) then power will be totally limited by the weak maf.
The ecu reports dead mafs, but never weak ones.

plot 2: