loss of power no throttle response after driving on highway for 30+ mins

[88sogreatv8]

i have a 1988 toyota cressida with a 1995 1uz w58 swap. the issue i have is after a 30-1hr highway trip doing 60-70 mph consistently, the engine loses complete throttle response causing me to pull over to the side and coasting till it get around 40 and it seems to be fine unless i get above 60 mph. when it cools down its ok , and it drives great and rips . the only time i experience it is when i am taking a trip out of town for a car show or something and im consistently over 60 for more than 30mins

i am currently running a California emissions ecu from 95 , and from what i understand this 95 ecu had a software issue and there was a recall where there was a updated ecu to correct the drivability issues im going to attach the part numbers and bulletin info maybe someone can help on this situation

REF: ENGINE

NO.: EG003-96

DATE: OCTOBER 6, 1996

MODEL: LS 400

TITLE: LS 400 DRIVEABILITY IMPROVEMENT

To improve driving smoothness at speeds above 40 miles per hour, the components have been changed.

 

[88sogreatv8]

i am also going to hook an oscilloscope up to the tps wire to see if the sensor is acting up or the ecu. i do have to add that all my connections are butt connected for the wiring

 

[gloverman]

Are there any fault codes recorded? Code 78 or the OBD2 equilivant can cause the symptoms you are having.

 

[88sogreatv8]

the only codes that are stored are the rear 02s ( not hooked up) , egr (deleted) and trans solenoid codes ( it has a w58 swap)
before i hook up the scope, i have a digital gauge that is hooked to the obd2 port. im going to take a long trip and monitor the tps . I feel that this is the cause of the issue.? not sure but when it acts up . there is no throttle response at all

 

[88sogreatv8]

so update on the throttle issue.
the ecu threw a p1200 history code.

 

[88sogreatv8]

Are there any fault codes recorded? Code 78 or the OBD2 equilivant can cause the symptoms you are having.

p1200 gloverman

 

[88sogreatv8]

while vehicle is running the FPR never produces more than 150mv , the testing says the FPR should put out 9-14 v for 60 seconds then drop to 0-3 volts . So im guessing the fuel pump is bypassing the stage from light load to heavy load and its always running at heavy load??

Also i might add i am still running the factory cressida pump, circuit open relay ,and fuel pressure relay . the volume is the same as the lexus , and i have a factory 1uz fuel pressure regulator

 

[gloverman]

p1200 gloverman

As above. This code will give the symptoms you are having. Fix the code and it should sort your issue.

 

[88sogreatv8]

As above. This code will give the symptoms you are having. Fix the code and it should sort your issue.

Replaced the ecu with the updated ecu 89661-50224 so far no issues