ECU rev limit crystal modification.

[GrimJack]

I know what the difference is on the crank - I'm trying to figure out what the difference is inside the ECU.

 

[blackout_89t]

Ang, I have my ecu sitting upstairs in a spare room. (early 1989 ecu).

Send me a message on MSN later to remind me to open it and take some pictures.

 

[chevyeater]

I opened up my stock ecu after I had AEM in hand. It is from a '90 5 speed with 7M crank. Sorry, some of them came out a bit blurry.

Camshafts are definitely something to look into with a raised rev limit. Valvesprings and connecting rods are something to look into as well if you want to raise your rev limiter reliably. I've been thru this with several 7Ms...

 

[CTsupra]

I know what the difference is on the crank - I'm trying to figure out what the difference is inside the ECU.

ahh... whoops. pardon my lack of attention to detail.

 

[SuprAng]

thanks chevyeater hopefully blackout will get pics of his (forgot to remind him in time for tonight) and we can get an 87 to complete all the possible combos then we can look em over to see what needs to be done, hopefull the more electrically inclined people can give us a hand.

Ang

 

[SuprAng]

bbbump more pics would be nice

 

[mullenc525]

Im not interested in this mod for the increased rev limit, mostly I am interested to correct the advance curve when fuel cut is artificially increased.

Can an 89- ecu be used on an 89+ car? I know the HAC is different, is the harness considerably different?

 

[GrimJack]

Different plugs on the ECU.

 

[Zazzn]

This with a emanage blue would be all you need to fix up the timing curves and fuel curves.

Anyways, ang if you don't get the pictures I know Kirk has my old 87 ECU form my 7m... So I can always try to track him down for some pics... I'm pretty sure I know which crystals they are talking about.. I have them all over my RC cars however they are way higher in MHZ... There is a electronics store close by me that has all the parts we'd need then there is a china man close to you that was trying to fix my emanage that could do all the testing to make it work.. I'm 100% sure he could do it. or figure it out at least.

 

[Chris-Supra]

Any update on this ever? I'd really like to up the red-line on my supra now that I have a bigger t4 turbo... 2500-3000rpms of usable power is decent but a little lacking yet.

 

[Chris-Supra]

Anyone?

A part number/more specific description/anything? I'd love to try this -

 

[blackout_89t]

I never did get you those pics...heh, maybe I will have time in the morning.

 

[Chris-Supra]

Cool- because if its as simple as putting in a new ECU crystal. And a good stock valvetrain will rev to 7500, hell even 7000 would be nice. I'm going to try it on my pre-89 ECU.

 

[flubyux2]

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!

 

[xscurry]

From the first pic that chevyeater posted, this is the oscillator or "crystal" circled in red. It looks like a standard 4 pin oscillator, would be easy to change out.

 

[IJ.]

Wouldn't this mod move everything by the percentage change in the crystal? (ie: Fuel Timing and so on)

 

[drjonez]

Wouldn't this mod move everything by the percentage change in the crystal? (ie: Fuel Timing and so on)

you got it. you're changing the ECU's perception of time.....

 

[IJ.]

To me this would be a bad thing unless you knew exactly what would shift and by how far! :nono:

 

[drjonez]

me too....then again, we're.....uhhhhhhhmmmmm.....different.

 

[IJ.]

"How much timing do you pull at 5000 rpm?"

"Ummm It's 5 hz slower"

"Yeah but what does that work out to in real terms?"

"ummm 5 hz"