Lextreme II
Active Member
I recently acquired a 1995 LS400. Its considered the 2nd generation LS400. I was reading the repair manual. I didn't know the 1995 have OBDII. Interesting isnt it?
Obdii
- Thread starter Lextreme II
- Start date
The 1UZFE EGR Delete Kit is available for sale here.
I don't know what to say to that. It is flat out not true. The part about it being a nightmare. That tuning strategy is true of the original TCCS in the 80's also. You have to meat the terms of Vf, or the fuel trim will change. That is a good thing, by the way. And when you max the Vf and set a code, fail safe is employed. Which is not limp home by the way. A known good value is substituted.
Huh? Open loop is determined by engine temperature and operating condition, such as load and TPS input. Long term fuel trim comes from the oxygen sensor input, not open loop.
You get changes to the fuel trim because the lambda sensor sees an enrichment problem, and wants to keep the catalytic converter in its operating range, namely 14.7:1 AFR.
http://www.autoshop101.com/forms/h44.pdf
Page 5 of 7, although the whole article is worth reading.
Huh? You think it sucks that you can individually point out a dead cylinder, instead of guessing and going to a leak down tester? Are you kidding me? It saves so much time, and having the serial data so easily attained is great idea.
Lextreme II
Active Member
The reason I say that because I thought OBDII started 1998, but I guess Toyota is little head of its time.
turboandrew
Member
Actually I think the first required year was 1996. California might be different (earlier). Many 1995 cars starting getting OBDII I guess becuase it best suited the car company's schedule for roll-out.
The worlds first OBD-II compliant engine was the 3.0L 1mz-fe Toyota v6.
OBD-II is a nightmare if you don't employ a tuning strategy to keep the long-term fuel trim in check when doing major modifications.
The primary reason OBD-II sucks is because the LTFT is required to operate in open-loop mode. In previous OBD-I Toyota engines. All you have to do is force open-loop anytime you want to make a gross fuel change to the stock ECU.
In OBD-II what happens is that you run closed loop & get continuingly lean fuel changes. The LTFT then carries over into open loop & you get progressively leaner as time goes on in a continuing cycle.
Especially in NA-FI engines. As you garner boost in closed-loop.
Also interesting to note is that all of the early OBD-II engines retain OBD-I secondary systems, so they have the OBD-I diagnostics equipment present. Altho the OBD-II ECU's themselves will not respond to OBD-I diagnostic requests.
Later OBD-I systems do have limited serial data output, it just requires the correct Vetronix scanner to read the data.
Having been a tech, I hold the exact opposite opinion. OBD-II is more inconvienant to troubleshoot on. There's alot more to troubleshoot. Modern OBD-II from Toyota has more than 1300 codes. Of which when it comes to engine performance/problems... You really only need the 40 or so codes in OBD-I that only trip when there's actually a problem. You also don't have all the super sensative second & third level systems to throw dummy lights.
Read the list of codes on the OBD-I systems you encounter. Then start scanning the OBD-II codes. Most of them quickly become redundant, and irrelevant.
OBD-II is a nightmare if you don't employ a tuning strategy to keep the long-term fuel trim in check when doing major modifications.
The primary reason OBD-II sucks is because the LTFT is required to operate in open-loop mode. In previous OBD-I Toyota engines. All you have to do is force open-loop anytime you want to make a gross fuel change to the stock ECU.
In OBD-II what happens is that you run closed loop & get continuingly lean fuel changes. The LTFT then carries over into open loop & you get progressively leaner as time goes on in a continuing cycle.
Especially in NA-FI engines. As you garner boost in closed-loop.
Also interesting to note is that all of the early OBD-II engines retain OBD-I secondary systems, so they have the OBD-I diagnostics equipment present. Altho the OBD-II ECU's themselves will not respond to OBD-I diagnostic requests.
Later OBD-I systems do have limited serial data output, it just requires the correct Vetronix scanner to read the data.
Having been a tech, I hold the exact opposite opinion. OBD-II is more inconvienant to troubleshoot on. There's alot more to troubleshoot. Modern OBD-II from Toyota has more than 1300 codes. Of which when it comes to engine performance/problems... You really only need the 40 or so codes in OBD-I that only trip when there's actually a problem. You also don't have all the super sensative second & third level systems to throw dummy lights.
Read the list of codes on the OBD-I systems you encounter. Then start scanning the OBD-II codes. Most of them quickly become redundant, and irrelevant.
I don't know what to say to that. It is flat out not true. The part about it being a nightmare. That tuning strategy is true of the original TCCS in the 80's also. You have to meat the terms of Vf, or the fuel trim will change. That is a good thing, by the way. And when you max the Vf and set a code, fail safe is employed. Which is not limp home by the way. A known good value is substituted.
Huh? Open loop is determined by engine temperature and operating condition, such as load and TPS input. Long term fuel trim comes from the oxygen sensor input, not open loop.
You get changes to the fuel trim because the lambda sensor sees an enrichment problem, and wants to keep the catalytic converter in its operating range, namely 14.7:1 AFR.
http://www.autoshop101.com/forms/h44.pdf
Page 5 of 7, although the whole article is worth reading.
Huh? You think it sucks that you can individually point out a dead cylinder, instead of guessing and going to a leak down tester? Are you kidding me? It saves so much time, and having the serial data so easily attained is great idea.
drifty325i
New Member
So if im running a 1996 1uzfe with an aftermarket computer, obd-11 will mean nothing to me? because the aftermarket takes completly over the tune right? 
drifty325i
New Member
Its a full stand alone link ecu. So as far as im aware it controls the lot
Long-term fuel trim is 100% perminant. ALL fueling data is run through the stored LTFT. If you're long term fuel trim has adjusted itself to -5.2% while crusiign around in closed loop. That -5.2% is applied regardless of what is going on. If you go WOT at 6000rpm. That -5.2% LTFT is STILL being applied to the fuel calculation!
The STFT feed-back is disabled in open loop. LTFT is ALWAYS PRESENT.
I can't say it a fourth time. My head will explode.
http://www.autoshop101.com/forms/h44.pdf
An old T-Ten training manual. Please Refferance the paragraph LONG FT I will not tell you you're wrong a fourth time. I'll just hit you in the head with a chair, or a rotting trout.
The full training manual would be avalible here.
http://phatg20.net/modules.php?name=Downloads&d_op=getit&lid=368
The STFT feed-back is disabled in open loop. LTFT is ALWAYS PRESENT.
I can't say it a fourth time. My head will explode.
http://www.autoshop101.com/forms/h44.pdf
An old T-Ten training manual. Please Refferance the paragraph LONG FT I will not tell you you're wrong a fourth time. I'll just hit you in the head with a chair, or a rotting trout.
The full training manual would be avalible here.
http://phatg20.net/modules.php?name=Downloads&d_op=getit&lid=368
I have already been through those courses. Thanks anyway. I didn't misstate anything, but I did not read correctly what you wrote.
I took that as you are saying that open loop is entered because of long term fuel trim. That is what it looks like you said. What about the rest of my post?
You wan't me to read the link on an out dated but still correct page I already posted from?
I took that as you are saying that open loop is entered because of long term fuel trim. That is what it looks like you said. What about the rest of my post?
You wan't me to read the link on an out dated but still correct page I already posted from?
Nope. Just aslong as people realize that you'll average 10-15% stft correction being applied to the ltft while cruising because of how easy it is to enter boost cruising on most turbo setups.
Because of that, you'll almost universally have a -10% ltft (10% lean) after a relatively short amount of time.
You have your typical yahoo shop, or unknowledgeable street tuner. Who thinks the engine should be tuned @ 12.5:1 regardless of what it is. Then afew weeks later you step on the gas & suddenly you're wizzing piston & rings because you're trying to run 13.75:1 & leaner @ WOT on boost.
OBD-II honestly isn't hard to work with, you just HAVE TO KNOW what you're doing. An 90% of the people, even tuning knowledgeable people can not come up with strategies to deal with the closed loop LTFT leaning.
Which is why NA-FI, or big NA. It's much easier to run pre OBD-II. In general, you can get away with highway robbery using a high-end piggyback to virtually give yourself near fully programable management by forcing open loop anytime you want.
AFA troubleshooting, if you can do one, man you can do the other lol! Bridge TE1 & E1. It'll flash the codes.
Because of that, you'll almost universally have a -10% ltft (10% lean) after a relatively short amount of time.
You have your typical yahoo shop, or unknowledgeable street tuner. Who thinks the engine should be tuned @ 12.5:1 regardless of what it is. Then afew weeks later you step on the gas & suddenly you're wizzing piston & rings because you're trying to run 13.75:1 & leaner @ WOT on boost.
OBD-II honestly isn't hard to work with, you just HAVE TO KNOW what you're doing. An 90% of the people, even tuning knowledgeable people can not come up with strategies to deal with the closed loop LTFT leaning.
Which is why NA-FI, or big NA. It's much easier to run pre OBD-II. In general, you can get away with highway robbery using a high-end piggyback to virtually give yourself near fully programable management by forcing open loop anytime you want.
AFA troubleshooting, if you can do one, man you can do the other lol! Bridge TE1 & E1. It'll flash the codes.
You should not see major changes in FT in general. LTFT is changed only if STFT corrections are constantly +/- it's limit. Also, LTFT is done in load cells so low throttle FT corrections will have no effect on anything but low throttle. Seeing 15% or more in total fuel trim is a red flag. Besides when making major modifications, you are so off the base values that you should have full control of fuel and ignition in the first place.
So... what do you guys think of the CAN system?
So... what do you guys think of the CAN system?
