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1994 ls400 with huge power loss...sometimes

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Old 03-17-13, 09:44 AM   #61
stephen18
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decided to try bridging fp and b+ again, since last time i only did it a few hours. It seemed to get better but after about a day it threw a code 25 - afr lean. reset ecu and return fp control to normal and no code, followed manual for testing of the code and its fine, so ecu code detection seems okay, fuel pressure i would assume is okay.
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Old 03-17-13, 12:59 PM   #62
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i wouldnt assume anything at this point! gezus
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Old 03-17-13, 01:21 PM   #63
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python is correct, there is really no substitute for hooking a fuel pressure gauge, perhaps some noid lights and even a "home-made" ignition monitor in order to troubleshoot this intermittent problem, you have to see what is going awry in a "live" sense when it starts to screw up

I had a similar problem one time and we taped the fuel pressure gauge and noid lights to the windshield for a "live view" while driving
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Old 03-17-13, 02:17 PM   #64
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that's exactly what needs to be done
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Old 03-21-13, 07:31 PM   #65
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Any update on the issue? Sounds very similar to the problem with my 93 ls400. From about 2000-3800rpm it feels like it lacking power and pinging but only sometimes which is strange. Its been doing it for a year or two now. The engine is very strong in the upper rpms but i know something is just not right comparing it to my sc400. I rebuilt my ecu about 6 months ago to fix a starting issue and flashing check engine light so i knows its not that.
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Old 03-30-13, 11:32 PM   #66
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I have yet to get a hold of a fuel pressure gauge. today i replaced my 30k old denso platinum with ngk iridium,. the two rear cyl on the pass side look a little more rich than the rest.... maybe leaky injectors... i have bosch O2 sensors.. heard they arent a perffect match to oem so might shell out the $$ for oem ones

I checked the trunk hinge harness, seems ok, repaired the brake light out warning sensor, where the brake lights not mounted on the trunk lid was not working. was the copper contacts in a bulb socket melted ans semi shorting to ground... ended up burning a trace through in the bulb out warning ecu. repaired all that and hot my brake lights working correct.

replaced one of the two cat converters that was burned through, noticed lots of build up in the intake chamber, and the egr pipe is cracked... yay

thought what stumps me most is WHY MY TRANS SHIFTS 1-2 AROUND 2500 RPM SOMETIMES WHEN ITS FLOORED....makes me feel this is an electrical issue in the tps circuit,
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Old 03-31-13, 07:23 AM   #67
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does the engine bog under load?
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Old 04-04-13, 01:21 PM   #68
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no, when its running right it runs rather strong. when its having its fit, it still pulls, but at what seems 2/3 the normal power.

Most of my tools, special gauges, and whatnot are several hours away as i moved and havent brought all the crap (as the lady would call it...) from storage in my hometown. I really REALLY want to get a fuel pressure and compression gauge on it soon. Will probably need to find some stupid special fittings though.... Anyway, it seems to happen more with the ac on...
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Old 04-04-13, 11:46 PM   #69
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the OEM sensors are cheap if you buy them as Nippon Denso as opposed to buying them as a Toyota part, same part!

when you rebuilt the ECU, did you use the premium Japanese low-ESR caps as specified in post #1 of my ECU repair thread?

did you ever set up the "live view" as I explained in post #63 above?
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Old 04-10-13, 10:07 AM   #70
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unfortunately my gauges are not close by.. might go buy a new set though... but i did replace caps with only the recommended ones in the thread

news, codes 25 and 26 are coming up with cel on intermittently.

at idle and LOW speeds (no gas, brake applied but still moving) i can feel something like a misfire, constant when it happens, but does not always happen. it idles at 400 with ac off when i feel it. ac off and it idles at 450 i cannot feel it. ac on i cannot feel it. so what ever is making the slight misfire is happening so ... slightly the higher idle with the ac on masks it. i cannot hear a misfire in the exhaust, either. So when i get free time i will go though the troubleshooting for those codes... hopefully comes up with something

I had something like this in a celica i owned. it was constant though... it had two if its injector connectors swapped.
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Old 04-10-13, 10:15 AM   #71
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Speaking of sensors, is the denso brand from autozone the same as oem?

i have bosch universal sensors in there now, i feel they may be causing issues especialy since i read somewhere they read differently than oem
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Old 04-10-13, 10:53 AM   #72
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yes..use denso 02's they are much better than bosch
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Old 05-17-13, 08:35 AM   #73
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a few weeks ago i replaced the bosch o2s with denso o2s, took out the injectors and soaked in pb blaster, then carb cleaner and rinsed with brake cleaner... cleaned buildup from upper intake chamber and throttle body. (surprising how many of these "CARBON REMOVING" cleaners, actually dont do crap ....)

throttle response is better, and havent felt the power loss as of yet.. the surging/rough idle thing has gone completely away as well.

STILL shift wonky 1-2 sometimes... also seems to slip a little first thing in the morning... i think the PO might have used generic ATF, gotta get that flushed.

Last edited by stephen18; 05-17-13 at 08:35 AM.. Reason: added time
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Old 07-04-14, 09:03 AM   #74
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@stephen18 did you try replacing the vss (vehicle speed sensor) located on the transmission?
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Old 07-04-14, 09:03 AM
 
 
 
 
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