bryan767

iTrader: (6)

so after driving the car for a few months im starting to get a strange issue. Sometimes my afr's will spike 15-19 and the car will want to shut itself off. iv had it bad where the car wont even turn back on after driving for a hour or more. After letting the car cool down for 20 minutes it starts right back up with normal afr's.

so after a bit of researching i found out the main relay may have gone bad. so in an attempt to see if that was the case, i waited till the car started to act up again. turned the car off, swapped the defroster relay for the main relay which was almost to hot to touch. and the car started right up and ran fine. i later went to toyota and bought a brand new relay. and iv been driving on the car for about a week but im slowly starting to notice the issues again. yesterday it started happening after i coasted down a very long hill with 0 throttle. my afr was maxed at 21.7 because i was not on the gas. after this the car started to be in the 15/16s at idle and i had to smack the gas to bring it back down every other second.

and then this morning, driving to work (10minute drive under 25mph the whole way) it starts acting up again. im entering the parking garage and my afr is reading 15/16s, as well as when i put it in park.

Im considering buying another relay and undoing the 12v mod
i have a aeromotive 340lph
stock 1jzgte
safc
hks fcd < this could also be the problem i think
440cc injectors

i also plan on wiring in a mapecu3 because i kinda think the safc/fcd is playing some role in this.


on the plus side i decided to keep my car, i bought a rear window visor, titanium turbo blanket, freshly rebuilt head, arp head studs and a 2jz headgasket.

bryan767

iTrader: (6)

edit, i was thinking. this usually starts to happen after i coast down a hill with 0 gas. im kind of thinking im blowing my spark plugs out possibly, or my coil packs have gone bad.. or i have ecu leakage. ugh the possibilities.


fixed my a/c yesterday though lol

stockhatch

iTrader: (12)

I think you are on to something regarding the fuel pump. Are you running that fuel pump through the stock fuel pump wiring then? It may just be too much for it at full bore. That's a lot of pump and not a lot of wire(or amperage) on the circuit to feed it. I may run into the same issue with my TT denso, but I hope not

bryan767

iTrader: (6)

Yea stock wiring. I'm not sure if I'll have to redo the wiring. I had a Walbro in it then put the aero in. Now I'm thinking I wired it wrong because they say it runs off reverse polarity and I wired the black to ground and red to power. People say you need to run it red to ground and black to power. I need to do more research

bryan767

iTrader: (6)

Any other thoughts? This is really pissing me off.

cartmill

iTrader: (3)

any problem with a relay (like the EFI relay you're talking about) will be all or nothing, so it won't just "half-way" work. either it clicks on, or it doesnt.
and your stock ECU is what switches the EFI relay on and off anyway.

i'm with stockhatch. check the voltage back at the fuel pump.

GS4_Fiend

iTrader: (22)

just a guess... is there a higher amp fuse that is not intended for? check for high resistance on the wiring, power and ground that is going to that relay. High resistance in a circuit will cause it to run hot.

bryan767

iTrader: (6)

ill check the fuses and get a multimeter on it this weekend.

i dont see why it would just now start happening. the only things (electrical) iv changed since i got the car months ago were the injectors, 340lph aeromotive fuel pump and 12v mod.

my other guess is that the 340 fp is supposivly supposed to be wired backwards (reverse polarity).. i wired it normally red to power / black to ground like the walbros.. but i have yet to find out a solid answer

bryan767

iTrader: (6)

from the aero website

okay so i probably wired it correctly then.

but look what i found!

http://www.supraforums.com/forum/sho...12V-relay-mod&

it was a archived post so it didnt come up in my searchs on the site.. lol

summary:
found a mk4 supra guy having same issue, however its with a secondary relay not his main relay. however ill be redoing the 12v mod using a 75amp relay off of the fuel pump ecu to power the fuel pump. my belief is that the reason why my main relay is over heating is this: when i go into boost/etc i put extra load on the relay and it surges to higher then 30amps as some people have stated. this in turn, turns into heat which also causes resistance in the circuit. adding a relay between the fuel pump and main relay will stop this from happening.


This is the recommended relay to use for 1-3 fuel pumps.. its a little bit over kill for just my one. but id rather be over then under the tolerances!

TYCO BR-5000 75-Amp High Current Relay

then ill be rewiring it like this:




im also swapping heads, taking out the safc and installing a mapecu3 this week. ill report back with my findings

stockhatch

iTrader: (12)

Good luck, sir. I have a good feeling that this will solve your issue.

GS4_Fiend

iTrader: (22)

That makes total sense great find

bryan767

iTrader: (6)

update:

pulled into parking lot after driving for 15 minutes and the car dies, afr was over 18/20 (not moving, something was causing not enough fuel to get to the motor)

-rebuilt head installed (this probably took over 30 hours to do btw)
-put new coil pack connectors on last night and i got a better idle
-new toyota main relay
-waiting for the 75amp relay to be delievered

despite these things it still died on me today pulling into work. my friend whos a mech. told me that my batt terminals could be giving a bad ground to the fuse box, since they wont reallllly tighten down on the battery, i can literally spin it around on the negative side, so ill replace those tonight. in the mean time i start jiggling wires around the battery with the car running after it cooled down (keep in mind. if i let the car cool down for 20 minutes or so itll start back up with no issues and as long as im driving 60mph+ it wont die however at low throttle itll die out on me) nothing happens. so i go and start to remove the pass side ecu foot cover and literally as soon as i move it from its current position just a cm the car tries to die. i found a few pinched wires under there as well as the ecu not being secured.

moved the wires around and secured it down and it seems to be running fine now.

im going to my friends house tonight to resolder the harness since the guy before me used butt connectors to connect the ecu and they look very old and brittle. as well as redoing the battery terminal to one for a speaker system and installing my mapecu3. i have a 75amp relay on order to do the new and improved 12v mod posted on the aussie site here:
http://www.supraforums.com.au/forum/...-pump-mod.html


summary:
found pinched wires under the pass side foot rest as well as brittle looking wires from the safc that someone did a hack job of installing..

bryan767

iTrader: (6)

i never replaced the relay, however i plan to.. i believe my issue was either the coilpack connectors or the pinched wire under the foot rest. the connectors were very brittle and most were not clipped on because they were broken and i think some of the wires my have been touching. and also the safc and hks fcd probably had something to do with the issue. i removed all of that and replaced it with a mapecu3

after replacing i havnt had a problem since.