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X-90 engine bogging under acceleration
#13
thanks bill, it is the same engine, just has unique wiring harness route's.


top fails are EGR is sticking open.
them main valve,
but it starts fine and idle fine, just total lack of engine power. (the egr likes to cause stalls , as you stop car? and if it stays stuck open, it will never idle right. at 800 so it is not EGR.
i think idles fine means, 800rpm, and the engine is not shaking hard.(misfire)
The P400s can be clogged passages, (the many) but a dead EGR, the engine has full power.

i'd say a weak MAF . (clean it) (tap it gently to see if it wakes up)?
The MPI TB has very few passages. (a blessing compared to the 8v)
if the IAC clogs?. the idle is way too low cold started. not 1200 to 1500 or so. rpm.
if the ISC electric clogs?, the idle speed, will be very low all times. (if it sticks , rpm can be almost any thing)
if the EGR port cogs the EGR 400, fails, but this will not cause low power, it only kills the EGR dead (and closed main) In, fact it will have full power, unless it pings.(not stuck open and stalling)
If the Butterfly valve sticks open? the idle screams full time, just like the a brick (or Toyota drivers floor mats) has fallen on the throttle pedal, and holding it open. a true danger in A/T cars.

In each case, full engine power happens, due to good engine, good fuel pressure and good MAF.
The maf is the one part that gives you POWER, if it ever under reports AIR, there is no added fuel and it causes way lean running.(bogging)
i think it's bad maf or bad gas. now.
The maf is easy to test with any voltmeter (better is a scan tool due to this shows what the ECU actually sees)

im sure his CAT is not melted and compression is 170+
and vacuum is near 19"hg

his FPREG was dead (only drop from 40 to 38.) the PFreg is a 1:1 reg. the reg must have full range to work right.
http://www.fixkick.com/sensors/tests/FPr...e_examples
if the pressure is too high the ecu may not correct it at light cruise. or at full throttle it will be very rich and misfire.
the FPreg regulator is what keeps wideopen throttle fuel rates correct. not in closed loop mode.
if pressure is too high those rates get to be too much.
way richer than 12.5:1 AFR.


keep in mind power loss, can be "rich misfire or lean bogging" white tip spark plugs or black.
The scan tool would show which it is.
LTFT would go way negative. like -40% trying desperately to correct a bad FPreg.
LTFT is long term fuel trim (the slow side that humans can see easy)


BTW on new cars with non loop fuel feed , the regulator is fixed and in the tank at the top of the PUMP.
so the ECU (now faster) has a a fuel rail, pressure sensor.
the new ECU (PCM) adjusts fuel Rates based on actual fuel pressure at all times. (it's just a new variable in the fuel equation in real time)
http://www.fixkick.com
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Messages In This Thread
X-90 engine bogging under acceleration - by Ken H - 04-11-2014, 12:09 PM
RE: X-90 engine bogging under acceleration - by fixkick - 05-17-2014, 11:57 PM

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