wait.... IHI... how did u get it to 8? different computer? You coudlent get an aftermarket tac working either!!!??
Is there a way to change rev limiter?
- Thread starter PorterzSupra
- Start date
Yeah, well don't even think about 8K with a stock bottom end.
The stock rods don't like whipping the heavy stock pistons around like that. They have a tendancy to stretch and spit rod bearings at anything over 7K.
I wouldn't even approach 7K without ARP rod bolts.
The stock rods don't like whipping the heavy stock pistons around like that. They have a tendancy to stretch and spit rod bearings at anything over 7K.
I wouldn't even approach 7K without ARP rod bolts.
IHI-RHC7 said:
Ok thanks. A bit of confusion though. When I said "fuel cut" I was refering to what Toyots calls fuel cut, as mentioned in the link for testing posted by Grim above. Are you saying that test cuts spark or is it a test to simulate the other fuel cut often mentioned here caused by excess airflow? And when that happens what is cut, injection or spark?
This is interesting because I have a lot of information on the ecu and this isn't mentioned. I'll have to check this out on my TCCS tester. I can simulated any condition with it, just that I never got around to setting up either of these tests.
You know, I'm not sure if it's fuel or spark Gary, but I know that it is very different from FCO. FCO in an overboost situation actually turns the car off for a moment. This is a progressive bounce, so I'd think that it's spark based on the behavior...
It's possible the software is written to make the fuel cut test mentioned a simulation of the airflow FCO and not the rev limiter but I'll test both and find out. The fact that you jumper the idle contact and float the TPS input to test rpm cut leads me to belive it might be associated with rev limiting (as Grim stated) and not airflow FCO. We'll know soon, as well as what's cut in both conditions, as I hate mysteries. Btw, my compliments for your expertise.
JJ, That fuel cut is for emissions. It shuts off the fuel when the engine is revving down with the throttle plate closed. Look at the test carefully, with the IDL contact forced closed, the fuel cut occurs above 1600 rpm. You don't notice it when you are driving, but if you are slowing down with the throttle closed above 1600 rpm the engine is effectively turned off! It has nothing to do with the FCO that everyone talks about at high boost.
I kinda suspected that based on the test setup. It's why I said earlier I was of the opinion the test was to verify something else and the name of the test is somewhat ambiguous. But since Grim is a pretty sharp guy I wasn't gonna chisel my belief in stone. Injection cut on decel is common to most cars and the Supra is no different. The injection cut on decel and the dashpot work together to limit HCs. It's why the TPS and dashpot need to be setup right.
The confusion for me was over what that test was verifying. Clearly it's looking at rpm with with the TPS floating but the IDL shorting part was throwing me. Now that I think about it what you say makes perfect sense.
I'm here to learn too. Doesn't happen often but when it does I'll certainly accept it. Besides, I've crammed so much other technical stuff into my head over the years I can't remember everything
Now I just need to verify some things (both on the car and on my simulator) to satisfiy my curiousity. As I've said, forums are good but I've learned sometimes the info is either inaccurate or not the whole story. One must trust, but verify. Save me the trouble by telling me what gets cut on both excess Kf and revs. Is it injection or spark? I'd think it would be spark for the rev limiter but that's just a guess.
The confusion for me was over what that test was verifying. Clearly it's looking at rpm with with the TPS floating but the IDL shorting part was throwing me. Now that I think about it what you say makes perfect sense.
I'm here to learn too. Doesn't happen often but when it does I'll certainly accept it. Besides, I've crammed so much other technical stuff into my head over the years I can't remember everything
Now I just need to verify some things (both on the car and on my simulator) to satisfiy my curiousity. As I've said, forums are good but I've learned sometimes the info is either inaccurate or not the whole story. One must trust, but verify. Save me the trouble by telling me what gets cut on both excess Kf and revs. Is it injection or spark? I'd think it would be spark for the rev limiter but that's just a guess.
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Here' cram so more technical info into your head.
http://www.supramania.com/forums/showpost.php?p=180719&postcount=18
It's about stroker motors, but it covers piston speeds fairly well. After reading it you can decide how high you want to rev that puppy.
http://www.supramania.com/forums/showpost.php?p=180719&postcount=18
It's about stroker motors, but it covers piston speeds fairly well. After reading it you can decide how high you want to rev that puppy.
I meant technical other than car stuff. Cars don't tax me all that much. Although there is a lot to know they're not rocket science. I'm not gonna rev mine anywhere near that, let Porter blow his up if he wants. My interest is on the software in the ecu and it's idiosyncracies as even the factory documentation is lacking. Look at the oil pressure input for example. Took some digging to find out what that does.
For those electronically inclined the ecu uses an 8051 MPU. It's an old Intel 8 bit processor with internal eprom. The code is standard 8051 assembly language and can be read using any 8051 emulator or prom programmer. Someone said it was encypted but I didn't find that to be the case. Actually, I could be wrong but I know of no way to encrypt 8051 assembly langauge and still use it in that device.
For those electronically inclined the ecu uses an 8051 MPU. It's an old Intel 8 bit processor with internal eprom. The code is standard 8051 assembly language and can be read using any 8051 emulator or prom programmer. Someone said it was encypted but I didn't find that to be the case. Actually, I could be wrong but I know of no way to encrypt 8051 assembly langauge and still use it in that device.
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3p141592654's explanation sounds more likely than mine, I hadn't thought of the decel condition until he mentioned it. Though there is still the question of why it would turn on and off at certain RPM, that's a pretty good fit for what the engine does just above redline...
JJ, the cut happens above redline, though I'm not sure by how much, I'm usually to busy watching the track to keep any attenention on the tach, especially if I'm running WOT in first gear. First gear is snaky at best, and the later gears usually give me enough time to shift before it cuts.
This is nothing like the cutoff that you get if the stock ecu thinks too much air is flowing through the engine, that is MUCH more severe, this is a much smoother bounce.
Anyhow, keep us posted when you figure it out.
JJ, the cut happens above redline, though I'm not sure by how much, I'm usually to busy watching the track to keep any attenention on the tach, especially if I'm running WOT in first gear. First gear is snaky at best, and the later gears usually give me enough time to shift before it cuts.
This is nothing like the cutoff that you get if the stock ecu thinks too much air is flowing through the engine, that is MUCH more severe, this is a much smoother bounce.
Anyhow, keep us posted when you figure it out.
Yeah Grim, I bet the last thing you're looking at is the tach
3p's explanation does make sense. His looking at how the test is "rigged" and combining it with what he knows of the ecu shows good critical thinking skills. I usually think along the same lines but since I can't remember the last time you were off on something I decide I'd better hedge my bet.
I'll check it out and let you know. The factory TCCS checker (the one that goes inline with the ecu) works better as a monitor than a checker although it does do some simulation. I homebrewed another one that does more simulation than monitoring. I can use it either on the car or off so it shouldn't be a problem to dummy the ecu for whatever conditons I want and see how it responds. I want to verifiy this rev limiter thing and see what it cuts but I have a feeling Jake is right, it's gonna be spark. I'll also see what excessive airflow cuts.
Gotta go to work soon and that means I'll be gone for a while but as soon as I get back I'll do it. Been a while since I played with the ecu so it'll be interesting. I'll also review all my TCCS books, it's been a while since I read them so I've probably forgotten the details.
3p's explanation does make sense. His looking at how the test is "rigged" and combining it with what he knows of the ecu shows good critical thinking skills. I usually think along the same lines but since I can't remember the last time you were off on something I decide I'd better hedge my bet.
I'll check it out and let you know. The factory TCCS checker (the one that goes inline with the ecu) works better as a monitor than a checker although it does do some simulation. I homebrewed another one that does more simulation than monitoring. I can use it either on the car or off so it shouldn't be a problem to dummy the ecu for whatever conditons I want and see how it responds. I want to verifiy this rev limiter thing and see what it cuts but I have a feeling Jake is right, it's gonna be spark. I'll also see what excessive airflow cuts.
Gotta go to work soon and that means I'll be gone for a while but as soon as I get back I'll do it. Been a while since I played with the ecu so it'll be interesting. I'll also review all my TCCS books, it's been a while since I read them so I've probably forgotten the details.
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LOL - I may be correct a good portion of the time, but I'm nowhere near infallible! And I absolutely don't mind being corrected, or worry about a good debate, years in management has taught me how to keep personality and real-world issues separate.
After all, I spend my days explaining to testers how to tell coders that they have made mistakes... hopefully without having to soothe injured egos on the development team for weeks afterwards.
After all, I spend my days explaining to testers how to tell coders that they have made mistakes... hopefully without having to soothe injured egos on the development team for weeks afterwards.
jetjock said:
I had heard it was encrypted too, so I never bothered to mess with one.
Now I need to built a test bench
Hey Grim, you know the old saying: "If it was easy, they wouldn't call it code".
Supracentral: The 8051 has limited on board eprom (2k I think but don't quote me) and I recall there is more in the form of separate prom in the stock ecu. Been a long time zince I've been inside one though. It's all in 8051 assembly. The problem is (unlike a paper copy of the source code) there are no comments. You'd have to learn the 8051 insruction set and analyze it from there. Doable but a daunting task, at least for someone with my level of progamming skill. I was more a hardware guy.
Maybe it could be recompiled and the comments added, I don't know. It's been a long time since I messed with that stuff. I could be wrong but I'm guessing there are very few programmers who work with assembly these days unless it's for small imbedded control applications.
Supracentral: The 8051 has limited on board eprom (2k I think but don't quote me) and I recall there is more in the form of separate prom in the stock ecu. Been a long time zince I've been inside one though. It's all in 8051 assembly. The problem is (unlike a paper copy of the source code) there are no comments. You'd have to learn the 8051 insruction set and analyze it from there. Doable but a daunting task, at least for someone with my level of progamming skill. I was more a hardware guy.
Maybe it could be recompiled and the comments added, I don't know. It's been a long time since I messed with that stuff. I could be wrong but I'm guessing there are very few programmers who work with assembly these days unless it's for small imbedded control applications.
As I recall, the 8051 actually came with 4k of storage, which would turn into a fair bit of code, but shouldn't be impossible to figure out.
I have a bunch of old decompilers for reverse engineering code... they don't produce the prettiest looking output, but it be possible to decipher with some work. If one of you guys manages to pull the assembler off I can dig into my old tools, see if we could make some sense of it.
As I recall, Reg Reimer pointed out that it was encrypted, however, I'm always tempted to take facts like that with a grain of salt considering that it was in his interest to make people want to buy the techtom upgrades. So... making the stock ECU seem more difficult wouldn't be much of a stretch. Perhaps he just thought that compiled == encrypted?
PS: I know of no way to encrypt assembler for the 8051 either, unless you are using external memory to store your code and another chip to de-encrypt it before running it... seems like an awful lot of work that would be mostly pointless.
I have a bunch of old decompilers for reverse engineering code... they don't produce the prettiest looking output, but it be possible to decipher with some work. If one of you guys manages to pull the assembler off I can dig into my old tools, see if we could make some sense of it.
As I recall, Reg Reimer pointed out that it was encrypted, however, I'm always tempted to take facts like that with a grain of salt considering that it was in his interest to make people want to buy the techtom upgrades. So... making the stock ECU seem more difficult wouldn't be much of a stretch. Perhaps he just thought that compiled == encrypted?
PS: I know of no way to encrypt assembler for the 8051 either, unless you are using external memory to store your code and another chip to de-encrypt it before running it... seems like an awful lot of work that would be mostly pointless.
You're right Grim, made me look up the data sheet. 4K it is. And the 8751 has eprom, the 8051 has rom.
Unfortunately I've completely screwed the pooch on this one and everything I wrote was wrong. I just opened up my original ecu (I run the spare) and it doesn't have any member of the MCS 51 family in it. The ecu for my other 80s era car does though. It's been so long I'd mixed then up in my rapidly fading memory. Doh! Sorry about that. For all I know Reg is right as I don't recognize the controller Toyo used but as you said, it would seem pointless.
Unfortunately I've completely screwed the pooch on this one and everything I wrote was wrong. I just opened up my original ecu (I run the spare) and it doesn't have any member of the MCS 51 family in it. The ecu for my other 80s era car does though. It's been so long I'd mixed then up in my rapidly fading memory. Doh! Sorry about that. For all I know Reg is right as I don't recognize the controller Toyo used but as you said, it would seem pointless.