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Now with 0JZ
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Discussion Starter · #1 ·
So, in an attempt to fix all of the fuel issues in this car, I installed my LC-1 the other day, and wired it up to my ECU, bypassing the old, dead O2 sensor. The car idles, and cruises great now, but WOT is a different story...

I finally got my serial pcmcia card for my laptop, so that I can actually connect to the LC-1 and get some readings. The car's normal in closed loop mode, hovering right around 14.7. When I floor it, it goes rich..... really rich..... 7.8:1 rich.

I dont know about you, but that seems like a LOT of fuel. What do you think could be the problem? I think thatit might be the fuel pressure, as the pump was replaced before I got the car, and I dont really trust the shop that did it. They were Nissan guys, and hadn't seen a 1JZ before.

I amost finished installing a Megasquirt system into the car this evening to control the fuel, so I think instead of trying to find the source of the problem, I'm just going to tweak the injectors some.

BTW, do you think I will get some significant power gains once the A/F is more around 12:1?
 

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Well I am not familiar with the LC-1 wideband's but from what I can understand your basicly putting the NB output from the LC-1 controller to the stock ecu??? I am not 100% sure this will work on the 1jz application, it could have different switch over points and ect. what I would do is buy a stock 02 sensor, put a second bung in your downpipe for the LC-1 o2 sensor and monitor what it is doing.

BTW what are you using for a tach signal on your megasquirt..... I was planning on going the megasquirt route but have decided to ditch that setup to go back to stock turbos and electronics just to get the car running and driving. I wasnt able to generate a "usable" tach singal from the stock crank and cam angle sensors, its is posible to do but I broke my laptop and wasnt realy happy with having to play around with the MS too much longer so I ditched it.... I would like to hear how it goes on your car though, its def. and interesting setup if you can get it opperating 100% but that will take some time forsure.
 

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Discussion Starter · #3 ·
Well, the NB O2 only comes into play during idling, and cruising, and in those situatons, the car is running perfectly. The LC-1 has two outputs with fully programmable curves. One is currently programmed to mimic the stock NB sensor.

And, to get a little off-topic, the RPM signal was the only the only thing that I couldn't get working properly with MS. I was trying to use the ignition success signal from the ignitor, I think it's IGT, which in theory should provide a nice 5v square wave with the RPM. The signal's there, I just had problems running it to both the ECU, and MS at the same time. MS would pull the signal down to the point where the ECU would stall the motor.
 

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hmmm ic...... see I was planning on running sequensial ignition with my setup so I had to run 2 triggers (crank angle and rear cam angle) I know it is posible to do as it has been done before. If you want I can send you the info I have on how to do this but it will require ditching your stock ecu ...... you could always make a field harness so that you can play with the megasquirt and then if you cant figure it out just plug the stock ECU back in and drive.
 

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what fuel pump are you running? Is it a Walbro or a TT pump?

also are you running an after market fp regulator?

there are many factors that can cause you to run that rich... another thing you can check, is besure your TPS is working properly.
 

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Discussion Starter · #7 ·
I'm not sure of the fuel pump. I know it was replaced, and I would assume it was some sort of aftermarket fuel pump. I would have to go find the recipt with the work done, it may have the type of pump on it.

I've had issues with the TPS, I will have to check to make sure it's working properly. I adjusted it by accident, causing my idle to hunt up and down, which I've since fixed to a stable idle.
 

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i dont think it has to do with the fuel pump. the pump will only flow the allowed pressure that the fuel pressure regulator will allow. the car will run rich on open loop beacue open loop the PMC is trying to figure out how to keep that motor running as best as it can untill the o2 sensor reaches about 600F. after that the car sould go into closed loop. where the PCM has set standards for the motor to run. TPS, and MAF sensor should be checked. also are you running an aftermarket blow off valve? is your timeing off causeing your valve over-lap to be longer than what it should be? are your valves seated properly.
 

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Discussion Starter · #9 ·
The O2 sensor should not come into play at WOT regardless of temperature. The O2 sensor is really only used for fuel economy at idle and cruise. The O2 can't read anything accurately outside of stoic measurements. That's when the engine should use predetermined measurements like TPS, MAP (not MAF, I'm sure that was a typo), Knock RPM, etc when under load.

No, I'm not using an aftermarket BOV. Timing has not been checked, there's 60K miles on the engine, and I would guess the original timing belt. It very well could have stretched. I have a new belt to put in, which I was going to do when I put my new cams in, but I think I may just take off the timing cover, and make sure everything is lined up on tuesday.
 
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annoyingrob said:
The O2 sensor should not come into play at WOT regardless of temperature. The O2 sensor is really only used for fuel economy at idle and cruise. The O2 can't read anything accurately outside of stoic measurements. That's when the engine should use predetermined measurements like TPS, MAP (not MAF, I'm sure that was a typo), Knock RPM, etc when under load.

No, I'm not using an aftermarket BOV. Timing has not been checked, there's 60K miles on the engine, and I would guess the original timing belt. It very well could have stretched. I have a new belt to put in, which I was going to do when I put my new cams in, but I think I may just take off the timing cover, and make sure everything is lined up on tuesday.
Agreed upon by me

open loop is a part of the engine water temp circuit not the O2,
O2 mesures timming some knocking fuel ratio its more of an exhaust temp monitor if your car is running to hot on the O2 sensor it thinks your car is detonating it will dump fuel retard timming

open/closed loop look at your water temp circuit cuz if your water temp is warm then it will not run open loop

for fuel on open loop check out your cold start injector and the rest of your fuel system & water temp circuit
 
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dunno if there is one it would be on the inside of the plenum i have not had any major issues so have not needed to hunt down this problem on a 1jz i kind of had a similar problem on the 5m in my mkii it turned out to be the pulsation dampner was leaking through that little screw on the top of it.
 

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Discussion Starter · #13 ·
Evilempire1.3JZ-GTE said:
Agreed upon by me

open loop is a part of the engine water temp circuit not the O2,
Really? I was under the impression that "open loop" meant that the engine was not relying upon the o2 sensor for fuel corrections. What is the correct term for this then?


Anyways, I pulled off the timing cover, aligned the engine to TDC, and checked the cams. They are dead on. It's not a timing issue. Would an aftermarket fuel pump be able to change the base fuel pressure with the stock regulator? If so this still may be a fuel pressure issue. What's an easy way to check the fuel pressure on these cars? Is there an easy place to conect a gauge?
 

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annoyingrob said:
Really? I was under the impression that "open loop" meant that the engine was not relying upon the o2 sensor for fuel corrections. What is the correct term for this this?
That whats its doing. the PCM wont take into consideration of the 02 untill closed loop.
 

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Discussion Starter · #15 ·
AJbiff said:
That whats its doing. the PCM wont take into consideration of the 02 untill closed loop.

Ok, if this were the case, I would not be getting nice 14.7:1 A/F ratios at idle and cruise like I am right now right? (verified with my LC-1 and laptop)
 

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Discussion Starter · #16 ·
Also, I'm not sure it's related....

Lately, my ISC has been stuck open. I did take appart, and the 1 way valve is still working fine, so it doesn't seem to be a boost leak. More importantly, my heater doesn't work anymore. I used to get tons of heat from this car. I could start the car, and crank the heater, and it was blowing warm almost immediately. Now, no heat at all. It's not important now, but winter is coming, and it will be cooling down outside. I'm not sure, it may just be the climate controls, they do messed up things from time to time, like not changing which vents are operating, or not lighting up.
 
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