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Discussion Starter #1
Could someone please tell me what the symptoms of a bad ecu are?......My current setup is .20 over ross pistons....ct 26, safc.....afm dial turned 11 clicks.......295 injectors etc.,etc...........................Car will start fine and if you hold the accelorator down it sound and runs great from 1500 rpm and up....the car does not want to hold an idle at all......right before it wants to shut down the rpms come below 1000.....there is a clicking sound, possibly a relay or something...noise comes from under or near the steering column......when the motor dies you can start it right back up and the rpm's jump up to 1500 and it sound fine....like it was being started for the first time on a cold day....of course it dies right after that....................I have no idea what the hell is wrong.....shes been running great until now!!! :x
 

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Maybe you have the AFM wound too tight and the fuel pump is cutting off
 

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Natro33 said:
Could someone please tell me what the symptoms of a bad ecu are?......My current setup is .20 over ross pistons....ct 26, safc.....afm dial turned 11 clicks.......295 injectors etc.,etc...........................Car will start fine and if you hold the accelorator down it sound and runs great from 1500 rpm and up....the car does not want to hold an idle at all......right before it wants to shut down the rpms come below 1000.....there is a clicking sound, possibly a relay or something...noise comes from under or near the steering column......when the motor dies you can start it right back up and the rpm's jump up to 1500 and it sound fine....like it was being started for the first time on a cold day....of course it dies right after that....................I have no idea what the hell is wrong.....shes been running great until now!!! :x

that is what it sounds liken to me as well. set the AFM back to stock becasue you are using the AFC and just turn the AFC down to -50 at idle....that should do it for ya. I had the same clicking sound when I had an intercooler pipe leak and it was causing lack of vaccum and cutting the fuel pump off.
 

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Discussion Starter #4
hum

Well, I gave that a shot....that was not it....I did'nt think it was, I have had the afm turned at least 10 notches since I finished the project and have not had this problem.....I checked all my IC pipes and they are all sealed perfectly......I don't know whats going on.......I can't tell if the pump is shutting off.....or if the ecu is bad......arg!!!!..........Maybe this will shed some light on it............Ever since the project was finished I would notice that after moderate acceleration....at least to 3 grand if you let off the accelerator completely the rpms would dip to 500 then it would pick back up and idle fine at 8-9 hundred rpm...........maybe the tps..........................where can I get a diagnostic check done on the sensors/ecu...is there such a device?....help
 

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Discussion Starter #8
whoa

toyota wants over 400 for this part new...anyone know where to find one cheaper....possibly a tps as well....400 is insane!!!
 

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see if you can cehck a few junkyards for those parts, man...

if that relay that's clicking is the fuel pump relay and it's turning off at like 1krpm, maybe you should troubleshoot that a bit more...

i'm not sure exactly how the fuel pump relay switch in the afm works. i took the connector off of my afm and it seemed like it made a really sketchy connection between the pins of the pump switch and a +v line. the pump switch connector was very long and slender and flexible and had a little ball on it and there was a little seat on the +v line for it. it seemed like something that could certainly go bad after countless jolts and vibrations and stuff.

i think you should try starting the car, jumpering the fuel pump check connector (it's by the afm, green/black wire), and then trying to reproduce the problem. if it stops then i would either get a working afm if you can find one cheaply or take apart your afm and try to see how you might be able to fix that pump switch connection or hook up a switch through the pump check connector that you just have to turn on before running your car. if it doesn't help anything then i'd start troubleshooting the tps and iscv

let us know what you find out

shiva
 

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sorry, by "green/black" i meant that there are two wires, one green and one black

shiva said:
i think you should try starting the car, jumpering the fuel pump check connector (it's by the afm, green/black wire), and then trying to reproduce the problem.
 

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Discussion Starter #11
good information

I have actually replaced the afm, I got one on ebay for 12 bucks hahahaha......this did not fix the problem.....I actually started the car with the cover off the afm and the needle would operate properly however fuel cut or engine cut off would occur when rpms fell below about 1100...the little needle in the afm would retract itself and reach fuel cut....it would not stay on top of this +v ? line...I think thats right....this leads me to believe that it is an electrical problem......since I have had idle issues in the past....so far I am thinking the ecu, tps, or idle control valve.....I would say the ecu for sure because of all the loops I have put it through while tuning the afc and the afm....I have probably put that poor ecu through some shiznit, however some say they often go bad......then maybe the tps and idle control valve are sending fuel cut messages to the ecu and in turn it relays it to the afm.........anyway I have sunk too much money into this car but don't care how much more it takes to get it right........I love this damn car.....i'll let ya'll know what happens thanks for the info!!!!!!!!!!111 :wink:
 

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Natro,

What year is your car?
What year car did the AFM's come from? 82 is unique. 83-85 should all be interchangeable.

Has the AFM idle bypass screw been exposed and adjusted?
If you don't know what I'm referring to, see a pic I put up at this address: http://photos.yahoo.com/bc/deanjanderson
Look in the album called "Modifications to Supras", picture number 7.

Here's what I'm thinking....
If the AFM idle bypass screw has been turned to allow a lot of air to get through, then perhaps enough is getting through the AFM to run the car at idle without opening the AFM flapper door. This could mean that the AFM will signal the fuel pump to shut off since the flapper door is closed.

Another simple way to test for proper fuel pump signal coming from AFM is to remove air filter, put key in ignition, turn to on position (without starting the car), then use your finger to barely open the flapper door. When you push it open about a quarter inch, you should hear the fuel pump start up. You'll hear the fuel running through the lines in the engine compartment pretty easily. If you have to push it open a lot, something is wrong with the AFM.

Hope that helps.
 

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Discussion Starter #13
no help

Replaced ecu, tps, idle control valve.....from junk yard, all good parts....still the same damn thing, I am at a loss.............
 

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Discussion Starter #15
figured it out

Finally, the truth shall reveal itself.......With my turbo setup, I used a air plenum from an 87 7mgte...its the aluminum air intake hose that says 300 on it. I used some couplings from the 5mge air intake system and I suppose the were just dry-rotted.....but there was a huge rip on the bottom part of one of the coupling.....I couldn't see this to save my life....oh well....thank god its fixed......thanks to all for the suggestions......I have some additional parts for the 5mge that I got from the salvage yard,,,,,if anyone is interested let me know and I 'll hook yo ass up..Here is what I have,

ECU.......from 83 5mge Automatic Transmission
ECU.......from 85 5mge Manual Transmission
TPS.....From 85 5mge
Ignitor box.....from 5mge
Idle speed control valve.....from 5mge

All these products work fine......I just used them to help narrow down my problem.........let me know what yall need...............I'll send out quick like [email protected]
 

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What else controls the fuel pump turning on/off. My fuel pump is randomly not coming on when i try and start the car. I replaced the fuel pump last weekend thinking its was starting to go out. Two days later car would not start again. That evening car started up fine. It will only ramdomly not start. I have checked all the fuses in the engine compartment and driver kick pannel. If i short the fuel pump check connector you can hear it running but the ramdom times the car wont start it will not. Turning the key on/off, on/off will get the fuel pump to start running again but it will take anywhere from 2 key turns to 50 or more. When the fuel pump is running correctly and the car is starting i can take the air filter off and slightly open (1/4 inch or less) the air flow meter vane/door and hear the fuel pump running. Can the air flow meter start to slowly go out and not work periodically? Would it be a good idea to remove the top cover and inspect the inside? Is there any relays i need to check that the manual (chiltons) does not cover? Let me know guys. I am not worried about screwing anything up. I know tons about my car but have not had this problem before.
 

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sounds like you have either a bad relay, or a bad wire somewhere. the wire to the fuel pump might be coroded in a spot and sometimes making contact and sometimes not.
 

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Where is this relay?

Also i do know that the 2 wires going into the top of the fuel pump looked fine. I would like to check the relay then trace the fuel pump wires if need be.
 
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