ECU rev limit crystal modification.

[flubyux2]

well... i suppose i can see what you mean by our setups being based on airflow. ive normally seen poor throttle tip in response due to lenghtend distance between the AFM and the throttle body, particularly DSM's w/ FMIC setups Subaru's w/ FMIC setups. a hesistation caused by the delay of airflow to the TB results in that momentary rich condition before the motor responds. my DSM had that problem and my friends WRX has this problem. however, on my setup, my overall distance between the TB and the AFM has been reduced. im no longer using the stock manifold, 3000 pipe, or fmic. i wonder if the reduction in distance between the AFM and the TB will alleviate the problem you mentioned.

and ive seen timing take a dump on DSM's before advancing at the onset of WOT. then it advances as the RPM's climb, all the way to redline. but maybe its always momentarily advanced the timing before pulling it back as ive recalled seeing.

 

[turbobob]

The problem here, on our systems, is that it is all based on air FLOW, and not air PRESSURE. A MAF based system can NOT differentiate between 4000rpm and no boost, and 2500rpm with 4psi of boost. (well, assuming the AFM + IAT are the only 2 sensors... Does Toyota have a MAP somewhere tied in, as well? The only one I am aware of, drives the boost gauge only.)

Sure it can, its called "air load"

Take airflow and divide by RPM then divide by VE. (this is how the boost gauge is run)......

Bob

 

[MRSUPRA]

Bringing this back up since its a good topic anyway. Has anyone heard of this company? Looks like they can increase the rev limit, timing, and air/fuel with this "chip". And the price isn't too outragous.

http://www.technosquareinc.com/toyota.htm

 

[drjonez]

IIRC they're a techtom dealer....but i doubt they can do it unless they have remaining stock of the daughterboards. last i heard techtom was out of 'em...

EDIT: they ARE a techtom dealer. which makes it legit....but the daughterboard shortage still applies.

 

[Cya]

My stock motor and ecu can rev to 7,500, it looks like the previous owner cut a wire on the ecu harness. I can look at it and post what wire it is when I get it back from the shop.

Oh and this is on a 88 turbo motor...or I think it is, looks like the motor was replaced as well. Ill have to check vin numbers.

 

[Clifton]

My stock motor and ecu can rev to 7,500, it looks like the previous owner cut a wire on the ecu harness. I can look at it and post what wire it is when I get it back from the shop.

Oh and this is on a 88 turbo motor...or I think it is, looks like the motor was replaced as well. Ill have to check vin numbers.

Is this off the stock tach or something more accurate? Under load or a quick neutral rev?

 

[Doward]

Sure it can, its called "air load"

Take airflow and divide by RPM then divide by VE. (this is how the boost gauge is run)......

Bob

I'm pretty sure the stock system runs a seperate MAP sensor, just for the boost gauge... I don't think it's calculated from the ECU

*edit* Or are you talking about the boost gauge for the MAFT-Pro? I was under the impression it directly read the boost pressure from the MAP sensor there, as well... I suppose this would only apply to the SD based setups, though?

 

[Cya]

Is this off the stock tach or something more accurate? Under load or a quick neutral rev?

Im not sure what you mean by quick rev but I've done that more than once and held it for second or two but it seems like the engine dosen't want to breath any higher. Yes this was in neutral and on the stock tach but I have been around 7,000 while racing though.

 

[drjonez]

Im not sure what you mean by quick rev but I've done that more than once and held it for second or two but it seems like the engine dosen't want to breath any higher. Yes this was in neutral and on the stock tach but I have been around 7,000 while racing though.

the stock tach (along with all other stock gauges) shouldn't be used for any sort of accurate measurement....especially at the limits of their range.

 

[hottscennessey]

the stock tach (along with all other stock gauges) shouldn't be used for any sort of accurate measurement....especially at the limits of their range.

Yup, even my SAFC will tell me I revved to 7.2k, It could have been a number of different causes, but I certainly did not rev that high. You can't always trust your instruments

 

[flubyux2]

why wouldnt you be able to trust the SAFC? its digital, so its closer to raw data than an analog guage. the AFC pulls a tach signal directly from the ignitor... it doesnt have to go thru any other processing like the analog tach does.

 

[Cya]

the stock tach (along with all other stock gauges) shouldn't be used for any sort of accurate measurement....especially at the limits of their range.

that may be true but after you hold it for second or two soundn't it be able to catch up to what ever you are doing? There's a big difference in running 6 and 7 thousand and you can tell that by just listening to the engine.

 

[Cya]

I got my car back today, the wire cut was the knock sensor two wire.

 

[Cya]

Use this afc diagram....keep in mind I dont recommend this if the bottom isn't balanced.

http://www.supramania.com/forums/showthread.php?t=16203

sorry old school, i need to borrow it.

 

[flubyux2]

so youre saying that w/o the KS2 wire connected, its allowing you to rev past 6500 on the pre89 car?

 

[Cya]

im saying thats the only wire cut on my ecu, and since intalling my SAFC and gauging with the far more accurate rpm gauge the highest I got was 6995.

 

[crazysupra2JZ]

so does anybody know where to get a crystal. i figure a 4.5 mhz would be good enough. from what was said earlier a 4.4 would let you go up to around 6,900 rpm i have a spare ecu i want to try this on. i found the crystal and it looks very easy to replace.

 

[CRE]

www.digikey.com

 

[pimptrizkit]

i've always been interested in this, shame no one wants to play with it.


if i figure it out i might post it up, sure it's a risk, but some people just dont care.

i do, but i can moniter timming & fuel.

i'll like to also say i have seen my stock ecu w/ -25% on the main scale w/ maft pro running 22 degree's of timming at 18psi on a 57trim ct26. i have also seen up to 40 degrees while crusing and 10/12 while idling.

 

[amichie]

I have done this on a few 7M-GE cressida ECUs. Does your ecu have two boards or just one? I have seen early model supra ECUS with just a single board.