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Discussion Starter #1
whats up...i have a bpu 6 spd and recently out of nowhere it has been running liek shit...

the other day my friend who had never been in a supra wanted to go for a ride..so i said ok its a real nice day out so lets take the top off and go...so i get in the car and start it up for the first time in about 5 days and i notice that when i started it..the car didnt idle higher like any car would when its cold..instead it just idles at about 1100 rpms the whole time it was warming up...then when i was driving i noticed that everytime i took it out of gear to come to a stop the rpms would drop down to about 400-500 rpms and start bouncing up and down for a few secs until it finally stabilized at a lower then normal idle..about 700 rpms and it would continue to idle a little rough....but one time when i was comign to a stop i took it out of gear and the car stalled..and i started it back up and that was it...
now i notice that everytime my rpms drop back to idle they drop below idle and then come back up...basically it feels like i am driving a big block with a lopey cam in it for a few secs when it comes down to idle...
my car has never done this before...it would just drop to idle (about 900 rpms) and stay there like normal...then out of nowhere it started doin this...i dont drive my car daily and it is garage kept...befroe this started happeneing the car was perfect...i dont know how this happened becasue the time i drove it before this it was fine and then i started it up the enxt time and it ran like shit from the second it started...
about 2 months ago i got a CEL and the car ran liek shit..just liek it is now... i got the code 27 and i bought a new oem O2 sensor and installed it in the DP(the second sensor) and the CEL went away and the car started to run perfect again...then all of a sudden this happeneds..the car is runing like shit but i have no CEL this time and idk what to do...when i installed the O2 sensor i reset the ecu by pulling the fuses..but i never insatlled new spark plugs yet...could this be the problem..or possible do i have another bad O2 sensor..possibly the one closer to the turbos????
if anyone has any idea what is going on here please let me know...

i am stumped because i dont get how i could drive the car and it be PERFECT ..then i put it away in the garage and the next time i start it up and drive it runs like a shitbox..

when i start the car it idles like i just reset the ecu..so i decided not to reset it this time because it might really run like absolute shit...
ok thanx in advance

Anthony
 

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'95 SC300 2jzgte/T78
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Man that sounds like MAF issue or the 02 sensor went bad again?
 

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Most likely NOT a vacuum leak as that would most likely cause a HIGHER idle. more likely your IAC motor has gone caput. Check that, check your 02, check your MAF.
 

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Discussion Starter #7
Rotarytoy said:
Most likely NOT a vacuum leak as that would most likely cause a HIGHER idle. more likely your IAC motor has gone caput. Check that, check your 02, check your MAF.

yeah i check and recheck the vac lines religously..even if i dont suspect anything i check them just becasue ive done this in the past and found 1 or 2 that were close to popping off..
also how can i check the maf, IAC, and o2 sensors to see if they are bad...
also since i just replaced 1 o2 sensor and fixed my CEL...and its possible that i got a bad o2 sensor again..can this potentially be a sertious problem that keeps fouling my sensors or what...

damn this sucks
hopefully its nothign major...i want my car to be normal again..

Ant
 

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If you pull the hose off your IAC, located toward the rear of the intake manifold above the fuel rail, while idleing, you will hear air being sucked in. As the ECU tries to maintain a certain RPM, it will open and close the valve. You should hear obvious pitch changes as it is doing these adjustments. Put your hand over the IAC to block the flow of air, this should REALLY drop the RPM's. If nothing happens, that is your problem.

O2 sensors go bad all the time, most cars will go through 2 or 3 in their lifetime. Just replace it with a new one. A bad 02 doesn't always throw a CEL.

To check the MAF, just replace with a known good one.
 

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Discussion Starter #10
spl said:
BTW. are you talking about bad primary o2 sensor (near turbos) or secondary o2 sensor? I remember reading that primary one is the important one, the other is basically used for checking that you have a functional cat installed:

http://www.mkiv.com/pipermail/mkiv/Week-of-Mon-20020603/004933.html
\
yes i know but i olny replaced the second one with a new one...i assumed it was the bad one becasue once i changed it out the CEL went away and the car started to run great again until this happeend...i will have to do these tests to see where my problem is and go from there...thing that i dont understand is that even tho my car is running liek shit..when i drive it runs good..it pulls strong and i dont seem to have any power loss ..only when the car comes to idle it seems to have problems...also someone toild me that i could have bad coil packs..i am going to check these also...

A
 

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dude, just check your spark plugs first and/or r&r them, what's your vacuum reading at idle with the engine fully warmed up? also try some italian style tune up :) , Rob NJ.
p.s.
replacing secondary o2 sensor= waste of frn's ($$$$).
 

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Discussion Starter #12
:scratch:
mydawgsupra94tt said:
dude, just check your spark plugs first and/or r&r them, what's your vacuum reading at idle with the engine fully warmed up? also try some italian style tune up :) , Rob NJ.
p.s.
replacing secondary o2 sensor= waste of frn's ($$$$).
whats up rob..thought u might have gotten abducted by aliens or somethin man...anyway hows the car..u still owe me a ride in it...

anyway well it seemed that when i got that CEL the car ran like shit..i then replaced the second O2 sensor and the CEL went away..and the car began to run great again..until this happened..whatever it may be...but also if this helps any today i decided to take the car for a spin and when i started it up i expected it to run shitty and it didnt..on the first cold start it started perfect and idled high like it normally should until it warmed up and also the idle was normal agin...so wtf does this mean..my car has a mind of its own and it seems to only want to run good whenever it feels like it...again this is out of nowhere..i didnt fix or change anything..just started it today and everything seems fine...

also i am gonna change the plugs anyway and probably get another O2 sensor by the turbos and hopefully problems solved...
but in the meantime can anyone explain why my car runs normal when IT wants to...i washed it today even tho it didnt even need it..maybe it was happy :scratch:


Ant
 
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