increase rev limit on stock ecu [Archive] - Toyota CelicaSupra Forums

: increase rev limit on stock ecu



williamb82
11-19-2007, 01:43 PM
was bored at work and brainstorming some things id like to try for a n/a 6m that i might build just for who ha's for my 86, and remembered this mod.

http://www.supramania.com/forums/showthread.php?t=7786&highlight=ecu+crystal

this theoreticlly should work on our ecu's no problem as they are very similar to ehe 4age ecu's the mod origonated from.

the reason im thinking of doing this myself is i am thinkin of making a home made 6m, with the domed 9.2:1 5m pistons, 7m block and 7mgte rods, my p&p 5m head, tri-mil header after i mod it for a 3in collector, 3in exhaust, the gude cams which make power to 7600rpm according to the specs and im going to mod an intake for a larger tb and run 210cc/min injectors etc.. im thinking i can get over 200rwhp this way if the rev limit can be increased to 8k or so. of coarse i still plan to one day do the 6m wit hthe forged rods and high compresion forged pistons and the webers i have etc.. and aim for 250+rwhp. but this will be just for something more fun in the daily driver.

Dangerous Ken
11-19-2007, 02:23 PM
this theoreticlly should work on our ecu's no problem

There's a big problem in changing how the ECU keeps time. :rolleyes:

Ken

williamb82
11-19-2007, 02:58 PM
not really. it works fien on other cars. and it changes it across the board so all the maps are stretched the same. if you dont want to do it thats fine. i personally want to try it, and beleive itll work great. main problem people have had with aftermarket cams on stock ecu is the rev limit cutting in before peak power is realized, this would solve that.

KurtW85
11-19-2007, 03:15 PM
WHAT ARe YOU TALKING ABOUT!!! IT CANT Be DONe!!! ITS PROBLeMATIC!!! YOU ARe GUNNA BLOW YOUR ISH UPPPPPP!!!!??!?!?!?!&#WY%*Y@)*

williamb82
11-19-2007, 05:36 PM
maybe if it was turbo, im talkin n/a, i have never seen an n/a car have an issue with this mod. and if i blow it up so what.wont be the first time ive blown somethin up and prolly not the last either.

BillyM
11-19-2007, 06:04 PM
Fancy idea... I'd like to see it in operation.

--billyM

sarinas_dragons
11-19-2007, 06:19 PM
I have seen it. I've ridden in a car with it. I can't get in touch with the originator of this idea. I posted about it a long time ago and I was a noob and Junkie lit a campfire in my anooos. Maybe it wasn't Junkie, but just another fucker that built ass-fires the same way...with his fiery tongue.

The car is still around, I saw it last year, at least. Remember? I said "......265 hp turbo-hachi shifting at 9 grrrrrrrrrrrrrrr aaaaaaaand!"

sarinas_dragons
11-19-2007, 06:23 PM
If I sent you an ecu with the rev limit you wanted would you test it?

williamb82
11-19-2007, 07:15 PM
yup. has to be an auto ecu at the moment. dont plan to swap the 86 to 5 speed till i get the 6m built i was talkin about, and then id only leave it that way for dyno time i think. i want 8k limit. though if you have a 87-88 7mgte ecu modded for 8k ill test that on the screwed up motor thats in the 84 right now since itll be replaced soon anyway. lol.

sarinas_dragons
11-19-2007, 08:21 PM
No I meant a test standalone.

williamb82
11-19-2007, 09:43 PM
id test it if itl work with the auto. ill be using a megasquirt 2 on my 84. if you want it tested and it wont work on a auto i may go ahead and make the car 5 speed. i got all the parts. prolly wont make much power currently as it is a stock 82 motor goin in with my trd header and hks exhaust and my home made 3in intake pipe. if i can get people to chip in for dyno time i can dyno on stock ecu then get this one tuned up and dyno again with no changes except the standalone and maf getting disconected(as im assuing the standalone would be map based?)

sarinas_dragons
11-19-2007, 11:00 PM
I have this idea to get a few set of pistons to see just how high a static cr we can go.

I think I said 12.5 on pump gas. Depending on the cams.

Auto is fine. I'm going to be full on this through December and January. I will keep you informed of the progress.

williamb82
11-20-2007, 09:11 AM
i cant keep swappin pistons and tryin it out. i dont have the place to d othat plus still tryin to save money. lol. i do have a set of 85mm 12.5:1 comp pistons. problem is they say for 2800cc or 3000 cc. soi dont know if its 12.5:1 on the 5m or 6m. lol.

Tire Shredder
11-20-2007, 01:18 PM
it may stretch the maps across the board. but it does make the ecu slower.

I'd rather have an ecu that responds quicker to changes (it's pretty slow as it is) than one that's slow. for me, it doesn't seem worth the extra couple hundred RPM, not to mention a 6m/7m crank spinning at 7000rpm would give insane piston speed, far more than I'd ever want to subject a car to that isn't a race car.

williamb82
11-20-2007, 02:44 PM
i was hopin for 8krpm's actually. on a daily basis. i still want to try the crystal mod on the stock ecu. i beleive itll work quite well. i expect to have tons of skeptics and naysayers. i remember when i said i was gonna swap a r154 in my mkii, tons of people told me i couldnt do it blah blah blah, now its done all the time and even more crazy swaps have been done, like norbies v160 and im doi na t56 etc... if we dont try new things, thats where the brick walls come in and modding becomes too exspensive at that point for prolly 95% of the members/owners. this would be a cheap mod to allow the engine to actually be able to respond to cams where currently it cuts off the fun too early to realize the power increase. and no, i wouldnt do this for a turbo car, as i dont even recomend turboing a 5m on the stock ecu, ive driven erics 6mgte, the response was horrible compared to my 7mgte. but for n/a this should work fine. works fin for the mr2 guys bumping their redline from 7k to 9+k. its worth a shot and im willing to be the guinea pig so what does it matter to you naysayers?

Dean
11-21-2007, 03:10 PM
I know Dave A looked at the ECU's a long time ago, trying to see the differences between the 82 and the 83-86 versions. I think he was specifically looking at eliminating the rev limiter. I never heard if he came up with any way to do it, so I suppose that means that he didn't. You should probably talk to him anyway, just to check.
I may have a spare 82 ECU from an auto car. If it would be of any use to you, I can look for it.

williamb82
11-21-2007, 04:21 PM
car is an 86 and the 82 harness on the 82 engine i got is hacked. ill ask him, and iirc, it was an 84 ecu, the one that was from my red 84 i first did the 7mgte swap on. i let him have it as i didnt need it. i think i still got my 85 ecu somewhere. and no, i dont think he looked for a way to remove the rev limit at all. was just comparing iirc and maybe see if it could be easily reprogrammed.

84ptype
11-22-2007, 05:21 PM
http://cgi.ebay.com/ebaymotors/1985-Celica-Supra-5mge-ECU-modified-rev-limit-82-83-84_W0QQitemZ260184826703QQihZ016QQcategoryZ33596QQ ssPageNameZWDVWQQrdZ1QQcmdZViewItem

just saw this..dont know much bout your build, but thought id post it up...maybe you can find out where he got it done..

Supra_Newfie
11-22-2007, 06:52 PM
Well if that does work, then we know of a way to change the limiter. So who's going to be the gp to buy and test that????

Grant

williamb82
11-24-2007, 09:19 AM
im not buyin t. it popped up AFTER i posted this thread and supposedly has the mod i was wanting to try, just not as high of a rev limit. seems the guy may be a lurker and thinkin ill jump on that ecu as i just mentioned wanting to do this. ill just contact the guy that does it and pay him to do it for me.

Solo1Supra
11-24-2007, 11:39 AM
That same ECU has been up on eBay before.

williamb82
11-24-2007, 08:16 PM
ive never seen it, but then again never search for 5m parts either.

williamb82
09-14-2008, 03:07 AM
ok, bored tonight and got brainstorming again. im still interested in the crystal mod to raise the revlimit of the stock ecu. anyone have any idea which crystal to change and what cryatal to use? i cant get ahold of the guy that was doing this for the mr2 crowd. im wantning to be able to rev my 6m higher later if i grab some reground cams.

Dean
09-14-2008, 10:35 AM
William,

If you have an 82 ECU to compare to, it will give you some clues. Remember, the 82 ECU has no rev limiter.

Junkie
09-14-2008, 10:42 AM
William, I only see 1 crystal in the ECU. " I've taken apart a couple 85's ". Haven't played with this mod yet myself, though it is on my mind occasionaly.

williamb82
09-14-2008, 11:36 AM
from what i recall the clock speed needs to be lowered 10% for the 8k redline. thats what i want to try. ill also be running some 210 injectors. i beleive i have 1 set left in storage, if nt it isnt hard to get more at the pick and pull.

Carlos Brown
09-14-2008, 01:13 PM
Gentlemen,

Has anyone every seen any of the documentation on the ECU "rev limit?" If yes (or no), what is the magic number? How has it been verified?

Well, I finally managed to get my solid lifters installed and adjusted. My initial settings of 0.0040" and 0.0030" for the exhaust and Intake (respectively) were extremely noisy. They sounded like 4-Porsches lined up. After going back and adjusting the valves to 0.0025" and 0.0020" (respectively), the car now sounds more like 1-Porsche.

Now while I have not had a chance to tune/test and dyno the car yet, I have kind of gone out on a few little drives just to get an impression of any change.

The car appears to be running very strong currently. Once I run the car up into the powerband there is no noticeable drop off in power. Now, while I have routinely bounced the tach up to 7,000 RPM in the past, I can now casually drive the car up to 6,500 RPM and cruise at part throttle. I was looking for any indication of a fuel cut, etc., but nothing... Once I am able to get back to it I will attempt to drive the car beyond 6,500 RPM, up to 7,000 RPM.

I will plan to dyno as soon as I can - I know that Russell is anxious to go as well...

So, for now I can only say that the car is much different - the power seems to be very linear in the upper RPM range.

Until then, let me know where this fuel cut is suppossed to exist...

P.S. I have added a few pics of the motor with the 70mm TB and modified 6M Intake. Notice the absence of the ISCV.

http://www.flickr.com/photos/17514807@N03/2856932136/in/set-72157602874405737/

http://www.flickr.com/photos/17514807@N03/2856100673/in/set-72157602874405737/

Regards,

Carlos

williamb82
09-14-2008, 01:44 PM
where did you get solid lifters? ive often wondered if there would be any gains in shimming the spring for the valve that regulates oil pressure to the lifters to keep them from compressing as much. looks like there would be from what your describing.

Don L.
09-14-2008, 02:20 PM
Wow, nice job on that 6m plenum! Did you enlarge any of the runners going to the head?
What is your opinion of the 70mm TB benefits? Maybe that is giving you some of the upper rpm power gains. Beautiful work.

Don L.

Carlos Brown
09-14-2008, 02:21 PM
William,

I built the lifters myself. Installing these is not be for the faint of heart, I tell you. Due to the varied length of all the valvetrain components, I ended up pulling and installing the cam towers about 2-dozen times before I managed a setting that worked.

Regards,

Carlos

williamb82
09-14-2008, 02:28 PM
i understand the hassle of adjusting them. im guseeing you took the stock lifets apart and ran a set screw inside a plug that would fit inside the lifter assembly to replace the spring, thuse allowing oil flow arounf it to keep the tip lubed but still manage a non compressing lifter? or did to lock them down low and just use shims with holes under them to get the proper height? ill prolly try just increasing the oil pressure in the head for the time being when i put the engine together. should help quite a bit without being a pain to adjust.

Carlos Brown
09-14-2008, 02:55 PM
DonL,

I did enlarge the port runners a little, but not substantially.

As far as driver impressions go, I do not attribute much of the change in performance to the TB/Intake. I have not noticed any of the much talked about "increased throttle response" at tip-in, which is due to the larger butterfly diameter. In fact, until you mentioned it I had not given it much thought at all. With that said, I am sure that all of these parts are working in conjunction with one another.

The car seems to be breathing incredibly. So far it shows no sign of power drop-off after it hits it's power-band. Unlike the performance that I have become accustomed to with the 5MGE, I am not experiencing the upper RPM flat spot... Had I had the time I would have dynoed each part after install...

I think the primary difference in performance is due to the lifters and not the TB/Intake. I have reviewed many dynos, even from forced air turbos, that showed to same basic upper RPM behavior as the NA 5MGE's, so I don't believe that this is simply due to increasing TB size.

Remember, I am still running the same diameter AFM currently. I do have in my possession, however, a 70mm Ford MAF and a Digital Fuel Adjuster (DFA) that I may install before hitting the dyno. I am hoping that by increasing the entire Intake tract to 70mm that I will see increased performance and/or throttle response.

As it stands, I will have to get back to this next weekend, since I will be out of town all week...

P.S. DonL, You may have seen the photos before, but I added the TB/Intake mod pics. I did go back and improve the Intake opening after taking these photos. http://www.flickr.com/photos/17514807@N03/sets/72157602874405737/

William, I built solid welded crossed-drilled blanks that are near the exact required length. I then used 0.001", 0.002", and 0.010" shims to get the height within spec...

I will take a better (closer) photo of the TB/Intake next week

Until then,

Carlos

BillyM
09-14-2008, 03:10 PM
...I built solid welded crossed-drilled blanks that are near the exact required length. I then used 0.001, 0.002, and 0.010" shims to get the height within spec...

Carlos

Sha-WEET! Carlos, I absolutely have to see this piece of art...

--billyM

Dave A.
09-14-2008, 03:24 PM
Gentlemen,
Has anyone ever seen any of the documentation on the ECU "rev limit?" If yes (or no), what is the magic number? How has it been verified?

Regards,

Carlos




I too am curious as to how the rev limit has been documented. What actually happens at the point of over rev? Does the engine just up and quit until the revs drop or does something else happen? I'm also wondering if the so called rev limiter is being mistaken for valve float when the engine is over revved past redline. :wtf:

Junkie
09-14-2008, 03:31 PM
It's not valve float. Though, feels similar. My 85 shut's down in the 6500 rpm range. Aaron "SilverMK2" had the Gude cams in, and the car still quit pulling in that same area "see dyno chart if still available".

Maybe it's an airflow thing, but, I don't believe so. It flat out feels like electronics holding it. IIRC, and Carlo's has probably read more on this than I ... Didn't SDS get a stock cammed 5m to rev to 7k ?

Dave A.
09-14-2008, 03:58 PM
William, I only see 1 crystal in the ECU. " I've taken apart a couple 85's ". Haven't played with this mod yet myself, though it is on my mind occasionaly.

There is only one crystal which is an 8 MHZ crystal. Leave it be and don't mess with it. :-)

Dave A.
09-14-2008, 04:25 PM
Maybe it's an airflow thing, but, I don't believe so. It flat out feels like electronics holding it. IIRC, and Carlo's has probably read more on this than I ... Didn't SDS get a stock cammed 5m to rev to 7k ?


I wonder if the stock ECU just cranks way back on the ignition timing once you hit redline?

williamb82
09-14-2008, 05:43 PM
I too am curious as to how the rev limit has been documented. What actually happens at the point of over rev? Does the engine just up and quit until the revs drop or does something else happen? I'm also wondering if the so called rev limiter is being mistaken for valve float when the engine is over revved past redline. :wtf:


on the 7m's the fuel cuts out. this has been documented, the injectors just stop firing. as for the 5m, not 100% sure but id be willing to bet its the same way.

Carlos Brown
09-14-2008, 05:54 PM
Dave,

I drove my car up to 6,500 RPM and just cruised there, very casually, without the slightest hint of power reduction. And I do mean "drove it up to" 6,500 RPM - this was not the slow wind up over time thing. Now, perhaps at 6,600 RPM the thing will shut down? We shall see!!!

Regards,

Carlos

Dave A.
09-14-2008, 07:56 PM
So you held it steady at 6500 RPM? What gear were you in? :)

Dean
09-14-2008, 08:26 PM
Nice work everyone. Looking forward to getting another piece of the power puzzle here.

Just to add some more info, my 82 race car has been driven by many Mk2 owners and they all say the same thing. "That thing pulls like a freight train right up to redline." Being an 82, it has no rev limiter from the factory. The aftermarket ignition system has an adjustable rev limiter, set to 6900 rpms. The car makes power past 6500 rpms, unlike any other 5M I've ever driven, which noticeably drop off over 5500 rpms.

83 and newer ECU's do have some kind of rev limiter built in, although I'm not sure exactly how they work. I've felt it kick in on my 83 once at the track when I wasn't paying close enough attention to my shifting. I don't know if it cuts fuel or spark. It stopped the fun at around 7000 rpms.

Sean Chung
09-15-2008, 01:17 AM
I have solidly rode the rev limiter at auto-xs before. It is definately an ECU controlled fuel cut, not valve float. It seemed to come in around 6800 or so. I have since switched to a standalone and raised my soft fuel cut to 7000 and hard cut at 7200. With the soft cut set at 7, I have found through datalog that it will bounce to about 7070 or so. At the last event where I got in about 10 laps, I was consistantly hitting rev limit in a certain section and riding if for a few bounces. I could've (and should've) set it a little higher to get more out of it. I think Don has his set even higher and not encountered valve float, as far as I know.

jsn_ayers
09-15-2008, 01:59 AM
The 5m ECU rev limit is all spark induced. In the morning Ill post up The diff in The 5m ecu and the 6m ecu reving as I have both. My 6m revs upto 7200 with no tweeks. There is a big diff. The same engine and same mods my ^m with the 5m ecu reved to 6700 as you all may have seen in my videos.

JT
09-15-2008, 01:08 PM
The 5m ECU rev limit is all spark induced. In the morning Ill post up The diff in The 5m ecu and the 6m ecu reving as I have both. My 6m revs upto 7200 with no tweeks. There is a big diff. The same engine and same mods my ^m with the 5m ecu reved to 6700 as you all may have seen in my videos.

My -84 5m-g had also 7200rpm limit with stock euro-ecu.

jsn_ayers
09-15-2008, 07:40 PM
http://i292.photobucket.com/albums/mm34/jsn_ayers/th_vid014.jpg (http://s292.photobucket.com/albums/mm34/jsn_ayers/?action=view&current=vid014.flv) 1st gear max (42 mph)
(euro ECU) I tried to get the tach in but no passanger seat to mount the camera.
I also posted a old vid of the 5m ecu (6700 rev limit)

Sean Chung
09-15-2008, 10:28 PM
Are you sure it's spark limited? I know that's how the carb guys do it, but they don't have a choice with carbs. EFI engines would damage the cats if you cut spark and keep dumping fuel, and that doesn't sound very OEM like to me. I know for sure my Stinger does it with fuel, and it feels the same as the way the factory rev limit cut in.

Sounds like its time for me to raise it to 7400. I didn't want to push the factory rev limit too hard, but if they set it to 7200 Euro spec then it should be safe.

Chrisfrom1986
09-15-2008, 11:11 PM
Is there a way to set up both a spark and fuel cut? Sure fuel damages a cat, but fuel cut with a turbo too many times, well thats bad.

jsn_ayers
09-15-2008, 11:54 PM
I dont think it cuts spark. Its more like when the old toyota dizzys have too little advance. The old dial adjust type.

Carlos Brown
09-18-2008, 10:56 AM
Gentlemen,

Yes, I did drive and hold the RPM's steady at 6,500. I did not attempt this in 5th gear, but I did run it in 3rd and 4th gears. I am still looking for a stretch of road that I can run the car comfortably in 4th and 5th gears, because the 3.90:1 rear gear has the car quite fast at those RPM's. In 3rd gear I hit 95 MPH (already way over the speed limit), and in 4th gear I jump to 122 MPH.

I will go out and run the car beyond 6,500 RPM to see where the fuel-cut comes in. I may have to settle this on the dyno...

Regards,

Carlos

williamb82
09-18-2008, 03:38 PM
if i can find my old brown 85's ecu in storage, and i think i know where it is, just a pita to get to that box, ill take the auto ecu from my 86 and mod the crystal and then put it in my auto 85. see if it helps it rev higher before shifting. if it does i think itll be a safe bet that it raised the rev limit too and ill try it on the 86 when the engine is ready and has been run for about a week good and hard.

Junkie
09-18-2008, 04:13 PM
I had the opportunity to play with my 85 the other day. Yep, she'll hold 6500 in 2nd and 3rd at least. Starts cutting out, right at 6800. Pulled good to the 6500.

Mind you, this is also a P.O.S. 200k miles engine, that I probably shouldn't be abusing, but, what the hell, I have a couple more :D

williamb82
09-18-2008, 04:43 PM
lmao, ive been there and doen that. lol. still got the free 82 5m i got, but the lifters and cams were so shot i didnt trust the bearings in it. lol. what i regret is i got dirt and water int oteh 7mgte bottom end that had the melted piston, if i hadnt been in a rush and it wasnt raining i could of kept it cleaned up tight and only had to swap the piston and it would be a ok backup shortblock. instead now i need to just buy all new bearings, hone it and tank it and then put it back together for a good spare. lol already got the new rings.

Carlos Brown
09-18-2008, 09:54 PM
Shawn,

I second your finding regarding Rev limit. I ran real close to 7,000 RPM, but I would have to call it a legitimate 6,800 RPM. This was not a straight out "kill the engine" like my Hemi powered Dodge Ram truck. When it cuts out at about 115 MPH, it just flat out shuts down and it takes a few seconds before you can resume driving. The Supra just kind of began sputtering at 6,800 RPM - kind of strange.

I was half tempted to hunt down a Euro-spec ECU, but for 400 RPM it is not worth it. Going stand-alone for another 1,500 RPM is the only way to go.

At least I can still explore the affect that the lifters have on breathing and HP at high RPM's...

Regards,

Carlos

Chrisfrom1986
09-19-2008, 03:56 AM
When it cuts out at about 115 MPH, it just flat out shuts down and it takes a few seconds before you can resume driving. The Supra just kind of began sputtering at 6,800 RPM - kind of strange.

Your truck hit speed cut (the speed governor), the Supra just fuel cut.

Tanya
09-19-2008, 10:38 AM
Hmm. I'm sure Aaron will have no problem with running Amy Li up to redline and over, if possible, with the 6MGE ECU.

We do know that it's not speed limited as was previously assumed, been well over 115mph in the car with that ECU, no cut. I've been up to redline a few times, but never attempted to go over that (probably bc of the stroke and domed pistons, eek)

Anyway, I would assume it would rev limited to around 6800, same as the 5M...

BillyM
09-19-2008, 11:12 AM
...We do know that it's not speed limited as was previously assumed, been well over 1150mph in the car with that ECU...

I gota get me one of those 6m ECU's!

Lol Tanya,

--billyM

Tanya
09-19-2008, 02:38 PM
Ahh... shit >.<

83CelWA
09-19-2008, 02:41 PM
I know I can wrap mine out to 7200rpm then it hits the rev limiter (learned this "burning out" when it was wet).

jsn_ayers
09-19-2008, 02:43 PM
Than your tach is off by 400

83CelWA
09-19-2008, 02:44 PM
Nope, tach is dead on. There are even 2 of them and they both say the same thing.

jsn_ayers
09-19-2008, 02:46 PM
I showed my vid where is yours. JK.

83CelWA
09-19-2008, 02:50 PM
Actually I could make one the next time I decide to have some fun and find a place. I may have also messed wiring up somewhere with the swap and that may be why I can get a little higher rev limit.

Junkie
09-19-2008, 04:08 PM
Your truck hit speed cut (the speed governor), the Supra just fuel cut.


It's NOT fuel cut .... Fuel cut it a jerking sensation, and is VERY BAD. Toyota wouldn't do something as stupid as cut fuel, at RPM. I could just see all the torched piston tops. It's an electronic cut, either timing or spark, or combination of both.

Billy, we are going to talk a bit more about that innovate data logging. That may be the solutuon for figuring out, what, Toyota did.

BillyM
09-19-2008, 05:42 PM
We can monitor RPM, Spark Angle, and Injector Duty Cycle with an LMA-3 or SSI-4.

...let me know when we're going to dig into it, and I'll give all I can.

--billyM

jsn_ayers
09-19-2008, 09:18 PM
Hey Junkie just hook up a timming light up to the coil and bring the gun into the cab so you can see if its spark cut or have someone under your hood when you rev it (not me). I would but forgot to grap my light when a customer picked up his car.
It sure does feel like the timming map falls short at the limit.

williamb82
09-20-2008, 12:55 AM
would be nice to have a timing light hooked up when on the dyno so someone can see if the timing drops when it hits redline.

jsn_ayers
09-20-2008, 02:00 AM
You can mount a laptop cam and the timing light under the hood too see it advance and than drop off or just plain stop. And record the rpms and advance*. Or get a buddy to hold on to the timming light under the hood and have him/her read out the #s when you are driving.

Chrisfrom1986
09-20-2008, 03:01 AM
Or get a buddy to hold on to the timming light under the hood and have him/her read out the #s when you are driving.

Wat :wtf:

BillyM
09-20-2008, 08:11 AM
...get a buddy to hold on to the timming light under the hood and have him/her read out the #s when you are driving.

$10 paypal'd to the person who gets video of this...

--billyM

Dave A.
09-22-2008, 05:34 PM
Well, there's the trunk monkey so why not also have a hood monkey? :zzzzz:

Personally, I wouldn't want to be anywhere under the hood or near the engine when it hits the rev limit in case something lets loose and/or explodes.


See autoshop101.com article 25 "engine controls #2" page 17.


Fuel cut on all six injectors would cause engine RPM to drop very rapidly, thus allowing the engine revs to fall below the fuel cut point almost instantaneously. The drop in RPM happens so quickly that the rapid on/off period of the fuel injectors results in the surge that can be heard in Jason's video. IOW, there is very minimal lag time between the engine fuel cut RPM and the RPM at which the injectors are switched back on ..... which is most likely only just a tad below the fuel cut RPM. The rapid surge in RPM at fuel cut is nice and smooth because of the massive amount of inertia stored in the flywheel rotating at 6500+ RPM.

This is just yet another prime example of how the Japanese engineers really used (and still use) their heads. So much so that it can sometimes (well, most of the time) be almost impossible to decipher what they were thinking when developing any one particular feature or design.

jsn_ayers
09-22-2008, 06:46 PM
Thank you for clearing that up Dave. My friend was willing to hide under the hood for me for that 10 bucks. Ya he's a smart one he still likes removing split rims for 5 bucks a POP.
This fuel cut is hard to determine as my 89 pathfinders fuel cut made it drop to 4000 RPMs Making it a real dawg on missed shifts.

woggin
04-02-2009, 02:10 PM
William,

If you have an 82 ECU to compare to, it will give you some clues. Remember, the 82 ECU has no rev limiter.


ANY updates on this, i know for a fact my 84 running an 82 motor has rev limit..i have hit a few times, even the dyno operator hit it! i have vid for proof.

williamb82
04-02-2009, 03:15 PM
no update, i went standalone on my 7mgte and going carbs on my 6mg. i can set the rev limit to whatever i want.

woggin
04-02-2009, 04:40 PM
awesomax!!! its a joint word, awesome and max, meaning awesome to the maxx, awesomax!! carbs as if in sextuplet carb setup?? or single carb setup!!

williamb82
04-02-2009, 05:13 PM
awesomax!!! its a joint word, awesome and max, meaning awesome to the maxx, awesomax!! carbs as if in sextuplet carb setup?? or single carb setup!!

http://forums.celicasupra.com/showthread.php?t=45225

donkey2
04-02-2009, 10:36 PM
I am of the impression it is ignition. I've hit the rev limiter on my 83 ecu many times and it is definetly 7200, the motor sputters, but no violent cut or harshness like a hard limiter or fuel cut.

Sean Chung
04-04-2009, 02:11 AM
OEM usually uses fuel to limit rpm. Cutting spark on a cat equipped car would be very damaging. The rev limit doesn't hit hard like a fuel cut because it only cuts fuel every other revolution. A fuel cut feels harsh because it cuts all fuel until the rpm drops. Aftermarket ignitions that limit revs with spark are more appropriate for carbed cars that don't have any other way to limit rpm.

Donn29
04-04-2009, 01:17 PM
Not to mention, how much power are you making at redline, NA vs. 5K+ rpm with enough boost to hit FC?

woggin
04-04-2009, 02:04 PM
i think cutting fuel is the dumbest shit ever, massive lean out condition! its easier to cut out spark, even though it can be detrimental to the cat, wat would you rather have, melted pistons, or no cat!

My 82 5mge sounds like ignition cut at limiter! thats why flames erupt from the rear!!

Sean Chung
04-06-2009, 12:32 AM
One of these days I'll datalog a stock (OBDII) Toyota with the factory scantool so we can see how they do it nowadays. I know my car didnt' have a burning cat smell when it had the stock ecu, and I know my aftermarket ecu cuts fuel. Both limiters feel the same when they cut in. It won't melt pistons because it completely cuts fuel for that cycle, which equals no combustion. I could see a problem if you had an injector leaking that didn't close completely, but then you have problems already, and probably shouldn't be bouncing off a rev limiter.

RPT
05-24-2009, 03:21 AM
Ok I have done more than hundreds of this Crystal ECU mod in the pass 10 years. I would like to contribute this inform for the Toyota community. Just change the crystal from 4MHz to 4.5MHZ for 1000rpm increase of rpm in the case of 4AGE it works with all the old world ECU in the world. There you have it directly from RPT your Honda and Mistu Master tuner. If you need any help in Honda ECU programming please email me at autoserverpt@hotmail.com or visit my website search autoserve home page (Sorry no website link here).