ECU rev limit crystal modification.

[NashMan]

this is why i bought rebick lc


but you can do this on none force fed car with really no issies and that why i bet yae any thing he just will not do it to supra no more

me and my brother played wiht this idea about 2 year's ago

but it really mess the hole map of the car mess the timing up alot
in end leans the crap out of your car at certon rpm's

(back ground check brother work at ac deco talked to his freidn at toyota found out the con's of doing it) had to pull some big favors

as for the 500 hp on stock ecu that can be done fine cause toyota did nto amke an grives map at all in any way very flex abable tell you start messing wiht cams and such

if ti tuned on dyno properly you will not have issue it just peoepl that try to tune that don't knwo how to tune blow shit up


now after some mad diggy i found out what the rebick lc does it make hole brand new map for the ecu and the timeing is shot down nicely and widen maps

so i am happy that i bough this so i cna over come rev and be safe at the same time

 

[drjonez]

MalloyNX said he was seeing around 20 degrees advance while boosting 23psi. Thats a lot more conservative than I thought it would be. Of course he is still using 550cc injectors.

more conservative? that's a touch high in my book.....

Well I'm no ECU guru, ( I edited my post, sorry for being an ass ). I've seen many people get jumped on by others more knowledgeable than myself, that it was spark cut and not fuel cut. I bought into it, personally, I don't know, some say fuel some say spark. So which ever it is this is me admitting I fall for misinformation too.
Edit: Another reason I thought this was because MSD boxes cut spark for the rev lim.

FCO and rev limit are both fuel cut off. this has been confirmed on a number of levels- the rebic LC eliminates both. how? it has it's own injector drivers. a few users with standalone FUEL computers (i.e. old haltech, etc.) have no FCO or rev limit.

...Those questioning 500rwhp with a stock ECU and not stand alone certainly have a valid point. I know malloynx made it look easy, but how many others have not?

who's questioning 500rwhp on the stock ECU? not me (i've done it). sure it can be done, but the better question is it the WISE thing to do? that's where i'm coming from....

 

[MRSUPRA]

Yes, very unwise on pump gas to run 500rwhp with the stock ECU. But on race gas(good race gas), a lot of safety margin is given to compensate for the potentially high timing.

 

[Clifton]

pics or ban. i also emailed racerjake from his website to see if he could help me identify the crystal in my 89 ecu. im not sure what im looknig for. but ive already done thru-hole soldering on the toyota ECU PCB, so im not afraid of that. im confident in my electrical skills, i just have to find what it is im looking for!

I don't think racerjake will be of any help, atleast not on the 89+ ecu's. I was the first one that had him do an 89' ecu. It didn't raise the limit. I sent it back to him and he tried something else that also didn't change the limit. After that he stopped doing them. I sold all the stock junk and piggybacks and went standalone and couldn't be happier.


For what it's worth Megasquirt and an MS harness can be done for about the same than a lex, safr plus the extra money from selling the cps, ecu, ect.

 

[Doward]

Adam (Dr J, you are Adam, right? ) is right - 20 degrees of timing @ 23 psi is freaking high. (Well, *touch* high to him... about 6-8 degrees high for me )

Really, he's right on all accounts. Yes, you can run 500hp on the stock ecu + piggybacks... is it safe? That's the question.

If anyone has a table of the timing vs airflow of the stock TCCS (*ahem* JJ ) I'd love to see it.

 

[drjonez]

Adam (Dr J, you are Adam, right? ) is right - 20 degrees of timing @ 23 psi is freaking high. (Well, *touch* high to him... about 6-8 degrees high for me )

sometimes.

If anyone has a table of the timing vs airflow of the stock TCCS (*ahem* JJ ) I'd love to see it.

i HIGHLY doubt that it exists outside toyota's super-secret vault....

 

[IJ.]

I thought the same but then read 114 octane so figured he'd be ok.....

Personally I'd pull a bit of timing to keep it safe but I tend to not run my motors on the ragged edge as I use them for long distance now and again and prefer reliability over screwing a few extra ho out of em on the top end.

 

[jimi87-t]

Thanks for setting me stright on the FC guys

So with MAFT pro, what would be a safe level (not on the edge)?

 

[drjonez]

Thanks for setting me stright on the FC guys

So with MAFT pro, what would be a safe level (not on the edge)?

safe level of _____________?

 

[jimi87-t]

safe level of _____________?

Well if 500hp is pushing it, what is "safe", anything sub 500 or what?

 

[drjonez]

i guess that's really up to the user....how comfortable are you pushing it? personally i'd probably draw the line around 400rwhp....since that's 2X stock power output....

 

[shaeff]

there's a LOT of really good information in this thread.

and i'll also admit, that i was under the impression that it was spark cut, not fuel. eh, live and learn, i suppose...

-shaeff

 

[Doward]

You can't base any electronics on a 'safe hp level'.

You can, however, select electronics based on how well you want your vehicle tuned. Ask anyone that's got a GM OBD1 system - you are ALWAYS tweaking little things (we've practically got the OBD1 as a standalone, as far as fuel/timing goes, lol!)

Excellent case in point - my '88 camaro's stock MAF based system let me run a solid 9psi of boost, and I was able to get my timing down, and fuel up by *fudging* the numbers.

When I converted to a '749 Speed Density system, that was DESIGNED for boost - my part throttle response went up a hundred-fold!

The MAFT-pro does a *lot* to overcome the stock limitations... Speed density, for instance, will give you the best possible throttle response.

I'm still not wild about scaling the input of the airflow, but the ability to adjust the timing seperately from it does a lot to quelch my concerns on that matter.

You've got to realize that Toyota did not build a 100% overhead of available airflow - after whatever airflow is equivalent to a CT26 @ ~11.5 psi, Toyota's engineers figured that was enough.

It's our job, as the tweakers/tuners/gear heads, to take things further than the engineers ever thought of going

 

[tubbie]

You can't base any electronics on a 'safe hp level'.

You can, however, select electronics based on how well you want your vehicle tuned....

It's our job, as the tweakers/tuners/gear heads, to take things further than the engineers ever thought of going

:word8kn: :werd:

Well. said....

 

[IJ.]

"Safe" is a relative thing when dealing with a 7M.....

I found what I consider safe for my motor on the dyno and pulled back 5 psi from there.

 

[drjonez]

...It's our job, as the tweakers/tuners/gear heads, to take things further than the engineers ever thought of going

and it's the job of the engineers here to keep you tweakers/tuners/gear heads in line....

 

[NashMan]

If any one wants the Toyota coding i can still get it as in the Reg Reimers way if you plan on doing this aka burn your own chips ect or add on a daughter board but this may be out of most peoples hands.

 

[toyman1987]

I Have the last pre 89 ECU that Jake put the crystal in, It did not work on mine. I have since went AEM and no longer need Stock ECU.
I do not agree on trying to push 500rwhp out of a stock ECU, the only thing I was trying to accomplish was not hitting the rev limiter before the 1-2 shift (automatic) w 430s after I swithched to 373s it was not an issue.

If there is still any interest on this subject, I can take mine apart and see if there are any #s on the crystal he put in.

It will probably be sold on EBAY after I get back from vacation. I noticed no difference in anything after I put it back in, like nothing was changed at all.

When mine didn't work is when He stopped offering it and requested to be removed from forum.

 

[flubyux2]

ive decided i want to bump the rev limit on my STOCK CT powered setup. i want to shift at 7500 because i CAN. i have a motor that will handle it... including the fasteners, oil system, head gasket, portwork, manifold, fuel and such. im not worried about my motor coming apart. you guys let me worry about that.

ive also tuned out cars, including Haltech powered RX7's, AEM powered MKIV's right on down to SAFC powered MK3's. nothing ive touched has blown up. in fact, people have complimented me on my hand tunes. ive even been able to tune the Flames and backfiring out of a single-turbo FD with fuel using a Power FC.... i know how to tune.

now, 23psi and 23 degrees of advance is a Bit high, but ive seen it happen before and never blown shit up. of course, timing numbers are going to differ from application to application. ive seen WRX's run close to 30* of adv, 22-23* adv on DSM's and pumpgas, and 12-13* on big-single MKIV's. so timing numbers are going to change all the time, primarily based on the combustion chamber design which will affect the flame front propagation. so while a WRX could run close to 28* on pumpgas, a DSM can only reach 22* of adv on pumpgas and MKIV's w/ singles only run 12* of adv on pumpgas. so, maybe the 7M can handle low 20's of adv on race gas. i personally would probably strive for a timing dump upon throttle Tip in, down to base timing. and then try to advance 1* for every 700-800rpm, assuming i see no feedback on the knock circuit, all the way till redline. i think that ought to yeild a relatively safe and conservative timing map.

of course, our timing maps are set to acheive specific advance numbers based on RPM's and other parameters. changing the crystal is going to change the ECU's basis of known time units. and this will lead to the ECU doing "things" at the "wrong time". but if the occurance of such events is only off by a few hundred RPM at the MOST, i fail to see how detrimental this could be when im only shooting for 400crank HP.

in no way am i condoning the use of stock electronics for high HP numbers. it can be done, but its a question of how easy and how long will it last. once i get my big turbo on, w/ big fuel, i will go AEM or E6X... since im shooting for big numbers. i know when enough is enough on the stock ECU. im no big fan of lying to the stock ecu... tahts why i dont like fuel control systems that dont have a way to control timing. scaling Airflow on a stock ecu is the biggest slippery-slope in our field.

sounds like No one who has posted yet, has seen positive results by the crystal mod.. at least not what ive read yet.

 

[Doward]

Actually, flubyux - it's been my experience that on initial tip-in, give it a quick spurt of timing (unless you've got a rich tip-in condition, this will exacerbate it), and then proceed to pull it back gives the best tip-in response.

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.)

When you increase the manifold pressure (danger to manifold!) you increase the DENSITY of the air/fuel mixture. A higher density mixture burns at a slower rate, than a standard 14.7psi of absolute pressure (atmospheric pressure here, guys).

I'll draw up a graph if you guys want, later today, illustrating degrees of crank rotation vs cylinder pressure, comparing N/A vs a turbo motor. It's in Corky Bell's Maximum Boost, btw