help!!! st205 keeps dying no matter what i do Options

[gt4joel]

hi all, ive had my jdm st205 for 3 years and I love her but shes breaking my heart. shes stalling for no reason. its been 4 months of diy research and replacing things.
anyone got any ideas cos im just about to give up.
ill run through the best I can whats going on.
the car will run great for around half an hour then a slight hesitation on throttle then 10 seconds later the engine light comes on,the revs drop to idle (900) and stays there ,
if I try to accelerate it will stall. it will start again but with difficulty, but still no acceleration, so have to turn it off and walk home swearing

the error code comes up 54. ive done all the forum research and know the symptoms\fixes. heres what ive done.
reconditioned the wta pump, checked relay, fine
water level fully topped up and sensor ok
replaced every water hose and vacuum hose with silicon.(pig of a job)
replaced water temp oil temp radiator temp sensors.
new rocker cover gaskets, fuel filter, air pod filter, dizzy,
changed fuel pump, changed fuel in tank, knock sensor done a year ago,
disassembled throttle body and cleaned aic and visually checked tps,
new oil and filter and fluids,


all I can think of now is a busted ecu because limp mode is supposed to get me home with half power but I can only idle.
and heres the kicker, next morning it starts up like theres nothing wrong!!
its driving me insane. and wanted to know if any one got any ideas.
I want my car back!! please can anyone help

[bsamps4]

Perhaps an issue with your throttle position sensor, or perhaps the vehicle is misfiring or detecting knock. It is odd that the system is putting itself into limp mode for a w2a issue, and I could be wrong about my first assumptions. I believe there are ways to check all the electrical components for that system that are listed out in the factory service manual. Sounds like you may need to get out a multimeter and see if you can't find issues with resistance to different components of that system. Are you positive that the level sensor for your W2A cooler is working properly???

Option 2:

go front mount, and follow the how to's on bypassing code 54 and your level sensor, and w2a pump.

[enderswift]

Code 54 does cause the enginee to go I to limp mode. But it's nothing as severe as what the OP is describing. In my case boost would drop to 7 psi max in limp mode. This really sounds like a tps issue to me. So I agree with bsamps, bust out a meter and check the tps for proper resistances

[gt4joel]

thanks guys ill take it to an auto electrician and get it tested. I bought a multimeter but I don't know how to properly use it.
fingers crossed , I would ve thought the tps just causes bad idle but ill let you know what the outcome is.
cheers

[lagos]

To test the tps. Just unplug it and see if the car runs better.

[gt4joel]

well , took it to a auto electrician yesterday, and my worst fears were confirmed, the guy couldn't give a stuff about locating my problem.
it seems that if he couldn't hook my car up to a diagnostic tool, it was in the too hard basket.such a waste of time.
I took lagos advice and took the tps off to see if it ran better. but it seemed just the same just a little bit laggier on the throttle blips.
so ive downloaded the gt4dc.co.uk maintenance section for the tps and taken it off the car and hooked it up to a multimeter.
(even if I have no idea what im doing!) ill try to learn something along the way.
all the terminals have smooth deflections on the ohmmeter but the last one .Vc-E2, throttle full open. supposed to get 4.5-5.5volts.
but cant get a reading. does this mean it is stuffed?
also I don't understand how u can gut a feeler gauge in there( when its on the car). and if u could,
how the clearance of .50mm on terminals IDL-E2 with 2.3volts or less, to the clearance of .70mm with no continuity would make a difference?
does .2mm make that much difference on a tps??
and has anyone had such severe \ intermittent symptoms from one going bad?