Celica Forums General Discussion Exterior Playing with crystals in 2ZZ-GE engine ECU

Based on a topic posted a week or so ago wherein someone had eliminated their fuel cut-off in a 2002 GT engine, I decided to tackle the ecu in my 2002 GTS (which has the low 7800 rpm cut-off). Here's how it went:

Based on the original article, I replaced both of the 16 MHz (#1 and #2 in the photo) crystals with 18 MHz. I went out for a drive and to my delight discovered that the 7800 rpm fuel cut-off was gone, or at least high enough that I didn't want to go there. Unfortunately, on the next trip through the tachometer I realized the VVTL-i kick in went up about 1000 rpm to 7200; sort of defeating the purpose of the higher redline. This made me think that perhaps one crystal controls fuel-cut off and the other, valve lift threshold.

I next put the original 16 MHz crystal back in position 2, leaving the 18 MHz in position 1. This caused both the fuel cut-off and valve lift rpms to go back to the original 7800 and 6200 resrectively. i.e. no different from having the two stock 16 MHz crystals.

I then swapped the 16 and 18 (16 in position 1 and 18 in position 2). The fuel cut-off was again gone and the valve lift started at 7200 rpm. Again, pointless.

Both of the original crystals (16 MHz) are now back in the ecu and my fuel cut-off is still 7800. If anyone else has discovered how to get rid of the fuel cut-off while retaining the same VVTL-i threshold in the GTS engine I'd like to hear about it.

...and before you respond "buy an APEXi Power FC", I'm saving up for one as a Christmas present to myself. I also already know about swapping in a 2000/01 ecu and oxygen sensor. The motivation for changing crystals is that they cost $2 apiece and the work takes 10 minutes.

damn, good job!!!

yeah...that was my thread...sorry to hear that it kind of defeated itself with the swap...and good luck with everything else...I haven't done it yet to my car...but I'm working on it

wow if you could figure this out, you would be my newest best friend. do those have to be soldered in or what?

Yes, they're easy to solder in. The originals have a bit of glue underneath so I had to de-solder, then gently pry them off.

so, saying this method ends up working, you dont have to swap out the knock sensor? if you make any progress on this, can you shoot me a pm as soon as you do????

I'll let you know if I find out anything.

where do you get the crystals, anyway???

Your friendly neighbourhood electronics store (NOT Radio Shack, they suck). In Canada we have a chain called Active Electronics. Down there you have Future-Active and Digi-Key. I'm not sure if they have actual locations or if they only do online ordering. If I get the valve lift problem worked out, I'll give you a part # for the crystals.

where can i buy this crystal and what do i ask for i live in long island i went to radio shack and they didt know also went to microcenter i have a 2003 gt 5 speed

here is the thread I posted about this whole thing originally...
https://celicahobby.com/ubbthreads/thread.f_1870193510_0_collapsed_5__1.html

you need 18 mhz electronics crystals...read the thread...it should explain...and if you ened more info I can try to dig it up

oh yeah...and with the GT, don't try it unless you have a bult top end...the stock valves and valve springs won't take it...but with a properly built engine you can get past 8,000 rpm and have no problem...there might be no point as there isn't much power on a N/a 1zz past 7,000 rpm, but with a Turbo things can be nuts. The crew at monkey wrench racing has a HUGE Turbo on an MRS and are pushing 385 whp out of a 1zz engine...and they shift at 8,300 rpm!!! I have a built N/A engine, but haven't done this yet because I haven't gotten around to it, and haven't really found much point

damn this is good stuff i need to know asap, if this can be as good as the power fc, were the hell is lucky wen you need him?

^^^ its no where near as good as the power FC...you can tune things with the power FC...when our cars go up in the RPM range they run dangerously lean...with the Apexi PFC you can tune Air/fuel ratio, and the VVTi on our cars, as well as numerous other things...this cheap mod just lets you rev past the factory limits

Wow, this could be the breakthrough . I usually wouldn't fuck with the ECU, but go for it. I have a GT, so poo on me.

good stuff guys...

^^^ yeah, its why I like this site...lots of useful information that I would otherwise be lost to figure out on my own

My work was on the GTS and was fruitless because the valve lift kick in also goes up in rpm. I have no idea what happens with the GT. Try it on your own. It's fun screwing around with the electronics. I was amazed at how hot the ecu runs when I took it out of the warm engine bay. I couldn't even hold it for a couple minutes. Don't be drinking or eating anything when you have the ecu opened up and sitting on the table.