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ECU Question for the Technically Inclined...today experiment
hello ppl
This is an experiment i always wanted to do, since the Tuned ECU which hpro123 was reffering too, in his previous post, belongs to me.
So today, i bought a simple crystal 8,860 and replaced the one of my STOCK ECU.
I am sure you all ask "what happened"?
well this is what happened.
1) Idle rpm moved from the 850 rpm of the stock ECU to 950!! This gave a solution to the loppy idle of my JWT s4 camshafts.
2) Rev limiter MOVED from 7700 RPM to almost 8400 RPM!!!!
I drove the car for about 50 miles and the only "effect" of changing the crystal is a minimal loss of power from 6600 to 6900. Of course i hadnt the time to dyno my car with the stock and the changed crystal, but i will do that in the near future!!!
My guess is simple, by changing the ECU frequancy(from 8.000 to 8.860) somehow increases advance timming and fuel equally(ps 8%) at WOT. Maybe the excess advance timming is responsible for the butt loss of power i felt afterwards.( i will give dynocharts with both crystal frequancies as soon as i can).
I was very sceptical for sharing this piece of info with you, cause some companies like JWT may loose profitabillity and wont be able to continue supporting nissan tuning parts.
from the other hand, i have heard so many ppl asking how to move or remove their rev limiters , or how to get rid of the loppy idle of "big" cams without spending 600 bucks.(New crystal is 1 dollar!!!)
so i guss we are big men now and we all take responsibillity of our decisions.
thanks for reading my post, and i hope someone can enlight me about that
I was always wondering if something like this would actually work withoiut having some adverse side effects, but could never settle on a replacement crystal frequency. Sounds like a good learning experience so far, but the dyno charts will really be an indicator to what's really going on. Kudos for having the guts to go through with such an experiment.
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96 SE-R: SR20VE - bolt-ons
97 SE-R: GtiR - getting there - need $$$
03 Altima SE V6: alarm+remote start/Pioneer TV+DVD/MB Quart comps/US Amps TU-4360/Stinger blocks, Expert RCA's, and 0 gauge wiring/rest of system going in shortly
I would be interested in doing something like this, but would like to see some dyno #s... Also, do you have pics and steps on how to replace the freq. crystal?
Hmmm i would like to see some pics of how-to's. It seems that a good gain come out of this with few side effects, but maybe with dyno tuning you can fix the bugs....
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joSE-R, I was Born to drive this Machine!
Alex, this is a very interesting subject. If you have access to a dyno, you can do a lot more than changing this crystal. I have not poked around inside the sr20 ecu, but I would think that certain resistors could be replaced to create the same type of changes. Even better, improve upon the changes you have already made.
Much thanks to Alex29 for giving this a shot, and sharing the knowledge. Very curious just like anyone else in seeing the actual #'s, and curves most of all. But a piece of advice, I work in the used part industry(aka a junk yard)and can find any needed parts hopefuly-as in an ecu. Figured the least i could do is offer any help i can since im chomping on the bit to seee the changes, and try this one myself.
i just came home from a short trip to my parents house, 200 miles away from Athens.
Everything concerning bad effects or driveability problems of my NX simply do not exist.
The car performs very nicely, no problems at all. Just what i sayed in my original msg.
Idle moves to 950, and rev limiter to 8.350 rpm( i hitted 8100 rpm 2-3 times with 1-2 gear and by moving the next gear higher in rpm the accelaration is avesome.
The replace of the crystal is very simple and straighforward.
i will post some pics and i will try to take dyno sheets as soon as possible.
yeap, the idea of changing some parts of the hardware of the ECU , like crystal resistors etc , seems cool, as long as someone knows the effects of the certain piece of the hardware.
thank you very much for the responces.
i havent seen a b14 ecu so i cant answer your question my friend.
But if you take your ECU out, take some pics and send them maybe i can give you an answer.
Today i found something very very interesting.
I have SAFCII and i like to watch all parameteres of the engine. Today as i was comparing the Knocking values of the stock ECU with the "crystal" ECU, i found out that the Knocking values of the "crystal" ECU are much lower!!!
That means that my original guess for excessive advance timming may be totally wrong. I now believe that the loss of power is due to a luck of advance timming. i will try to add 2-3 more deggrees from the distributor, to see what will happen.
A very respective tuner friend, told me that in suzuki swift gtis, they used to change the crystal of the ECU too, and the car responded exactly like ours , high idle and moved rev limiter. When i mentioned about the knocking readings, he told me that at swifts after changing the crystal, they added 2-3 degrees of timming cause the different frequancy of the crystal "tricked" the ecu thinking the revs are lower, thus giving lover advance timming from the maps!!!
i will try advance timming by 2 degrees tonight and tell you how it feels.
that would be my guess as to what is happening also, i wonder about a b14...since the computer is getting a lower knock reading from the sensor, that wouldn't be what is retarding your timing, the set map from the ecu doesn't correspond to the actual rpms that you are at...with a swapped crystal and an e-manage, i think that you would have alot more to play with...timing and a/f changes are available on the e-manage, and the higher rev limiter would be a great thing to have because that is the only thing you can't change on the e-manage that i wouldn't mind fooling with, just careful with the valve float w/o upgraded valve train...keep me updated
Due to valve float danger, i replaced the crystal again today, with something not so "aggressive". From 8.860 i moved down to 8.440(stock is 8.000).
Results are exactly as i was expecting too.
1) Now idle is at 900 rpm
2) Rev limiter at 8000 rpm.
But most important, i cant feel any power loss anywhere in the curve.
Most likely, next week i will have dyno sheets for you ppl.
if it works , it will be great for ppl with camshafts, as the raise of idle speed gets rid of loppy idle and higher rev limiter gives the advantage for the next gear to pull harder(higher rpm).
finally to my knowledge no aftermarket piggyback machine like SAFC OR E-manage could alter this two important parameters.
