1jz misfire

8

83mk2cody

New Member
Oct 20, 2009
8
0
0
Dallas, TX
So I finally got my motor in and running but it runs like complete shit and misfires in at least 2 cylinders.
First off here is my setup:
90 Toyota Cressida (MX83)
Stock JZX81 motor, auto tranny and ECU
JZA70 wiring harness
stock twins with an open Y-pipe
stock injectors
Aeromotive FPR with fuel pressure set to 45psi at idle
Walbro 255

First thing I did was swap my entire ignition system with my brothers motor (JZX90) and bought new NGK Iridium spark plugs gapped at .030, and that did nothing but Im getting good spark. Next I had a spare fuel rail laying around so I cleaned and Ohm'd all 6 injectors, there at 14 Ohm's. Also before I installed the fuel rail I made sure each injector had a good spray pattern, but I didn't have them flow tested. I made sure the first 4 injectors were firing with a noid light. I did a compression test and the lowest was #2 @139 psi and the highest was #4 @ 150 and the rest were around 145. I've sent my ECU to drift motion and had the capacitors replaced. I swapped my MAP and TPS from my bro's car, and bought a new ECT sensor. I've triple checked my timing and its dead on. I have the CEL light hooked up and it doesn't have any codes for me.

So do you guys have any input on what I might try next? I'm planning on Ohm'ing out my harness and making sure its pinned right. I'm getting closer to thinking that its my ECU but I cant seem to find any JZX81/JZA70 ECU's out there right now so I might save my pennies and get a standalone, but I dont want to spend the money on a standalone and it still run like shit.

Anyway here's a video of it running, I disconnect the MAP sensor then fuck around with the throttle until I take it to WOT and it just falls on its face

http://www.youtube.com/watch?v=ToBAO_aahmo


Any input is appreciated!
Cody
 
525gte

525gte

New Member
Sep 19, 2011
450
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0
hoquiam
Make sure the tps is calibrated .. also ck out the coils for cracks. I would also get rid of the iriduim plugs and go get the stock ngk plug part number I belive is 4644 that came in it gap at. 24 to 26.
 
mjsn1

mjsn1

New Member
Oct 18, 2009
284
0
0
Qatif
the problem is because of the plugs. I tried iridium plugs and it started misfiring, swaped them with new ngk's and it ran normally.
 
8

83mk2cody

New Member
Oct 20, 2009
8
0
0
Dallas, TX
Where did you buy the plugs at? I tried "vatozone" but all they really had were the Iridiums. I'll stop by Oreilly's and pick up another set tonight and see what happens.

I'm pretty sure the TPS is calibrated because I've swapped it with one off my brothers motor and his runs fine, but I can check the resistance and make sure there isnt a dead spot in it.
 
8

83mk2cody

New Member
Oct 20, 2009
8
0
0
Dallas, TX
I just opened up my ECU to double check and make sure the boards were clean. There was a small spot maybe the size of a quarter of fluid from one of the caps so I cleaned the board with brake clean. Hooked the bitch up and it runs like a champ! I'll still go and buy some new plugs and re-gap them, but thanks for the input.

Cody
 
8

83mk2cody

New Member
Oct 20, 2009
8
0
0
Dallas, TX
should I just replace the one that had the fluid around it? Ive already sent it to Aaron at drift motion and had them replaced. I'll run it for a few days and open it back up and check the board and see if there is any new fluid that leaked out of it and if so I'll replace it.
 
hvyman

hvyman

Dang Dude! No Way Man.
Staff member
Apr 17, 2007
12,568
1
0
Fullerton,CA
If already leaked it need to be replace. Can cause more damage.

Just look at the cap and go to a electronics store. Should say something like 100uf 10v. Just match that up. If you can find the same with the v then get one with a little higher.
 
525gte

525gte

New Member
Sep 19, 2011
450
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hoquiam
If u can't find the plugs in a 7 heat range witch is part number4644.. you can get a the same plug in a 6 heat.. ill have that part number later its on my bench
 
8

83mk2cody

New Member
Oct 20, 2009
8
0
0
Dallas, TX
It started missing again so I cleaned the ECU one more time and it idled good but it cut out during boost. I ran to radio shack and bought a 22uF 35v capacitor and replaced it but it looks like there still is a little bit of damage to the board right around the capacitor. It idles good and I drove it up and down my alley but once I got back it started missing again :( I also found out I'm stuck in 1st gear and it wont shift, fucking automatic...
 
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