Crank Shaft Trigger Wheel ? HELP

[jgscott]

I have a US Ver. 97 SC400 with a few mods and am running a Zex Nitrious kit. I am in the process of making some other changes and am using a Unichip ECU.

I talked to Unichip today and need to know if the 97 SC400 1uzfe has a 24 tooth or 34 tooth Crank sensor Trigger wheel. Anyone know ? Or know where I can get a picture of it ?

 

[Lextreme II]

Scott,

Welcome to our forum. I took it out once and forgot the teeth number. I can double check that later this week. I am sure some other would know. I attached a Crank trigger wheel.

 

[jgscott]

Thanks Lex. I have been here a number of times and think this is the best Lexus site there is. Now Unichip wants to know something like is it 24 - 12 with a 2 spaces at TDC. If you look at yours do you have any idea what thats about and want they want ? Thanks.

 

[cribbj]

With a non-VVTi motor the physical trigger wheel has 12 teeth. No "missing" teeth; it uses a cam trigger to signal the #1 TDC event (well nearly TDC) rather than missing teeth on the crank wheel.

Then in '98 with the VVTi motor, Toyota changed to a 34-2 (34 teeth with 2 missing) arrangement, but still kept the cam sensor. Apparently with these motors, they are now needing finer resolution than the 12 tooth wheel was providing.

Be careful to clarify whether the UniChip is asking for how many "physical" teeth are on the crank trigger, or how many for the complete 4 stroke, 720 degree engine cycle? Many aftermarket ECU's want to know how many crank trigger teeth are in the "engine cycle", so it's double the number of physical teeth on the wheel.

The images and descriptions below show the two systems. The upper description is for the earlier system, and beginning with the paragraph marked 3), they're talking about the '98 VVTi motor. It's a bit confusing below because I uploaded two different pics from the Toyota docs, but they're appearing without a "break" between them.

John

 

[Toysrme]

Ditto. I'm not 100% sure for a 1uz-fe, but all toyota i6 & v6's that are OBD-II have 36 teeth triggers. The spec is 36 teeth 2 of which are missing. Depending on how their information is setup it would either be 36-2 or 34-2. Depends on their software.
Are you *sure* you want a unichip? Emanage Ultimate does more & is end-suser programmable. SMT-7 is cheaper & does even more. I mean who wants to pay for a unichip & have no ability to program it...

Basic e-mange & smt6, or smt5's do as much & still cost less.

 

[WeasyS2S]

According to the toyota spec manuels that i have read in 2002 ALL post 1996 toyotas were equiped with 36-2 as mentioned by toysrme

Unichip is a one off tune....its good if the setup your going with is what your going to be with for the life of ownership....if you change anything...say...cams..:shrug: ...then you need to take it BACK to the dealer to get it tuned vs whipping out a laptop and tuning.

And as mentioned the greddy emanage is good, the smt7 cheaper and better...if you want basic tuning with some basic features then smt6 is great

 

[cribbj]

From the Toyota NCF documentation for the 1997 LS400 engine, that I cut & pasted in my first post, Toyota was still using the 12 tooth wheel for the 1UZ in '97, and only changed it in '98 as a result of the change to VVTi. OBDII had nothing to do with the change.

BTW, my '97 OBDII Supra with the 2JZ motor also has a 12 tooth crank trigger wheel, however I understand the '98's and newer with VVTi changed to a 36-2 or 34-2 type.

Scott, one way to determine what you actually have, if you have any doubt about all this, is to get a multimeter that has a frequency counter function, and put it on the crank wheel signal coming in to your ECU and see what the frequency is at say 1000 RPM. Then you can easily calculate how many teeth are on the wheel according to this:

F/RPM/60 = T

Where F is the frequency you see on the counter and T is the number of teeth on your wheel.

John

 

[Red Supra]

Assuming me are talking about USDM toyota engines

1UZ
to 1997 12 tooth trigger wheel
98 and up (first year for vvt) 36-2 trigger wheel

Toyota 2JZ-GTE
1993-1998 12 tooth crank trigger wheel

Toyota/Lexus 2JZ-GE
to 1995 crank sync taken from distributor
1996-on 36-2 trigger wheel

 

[WeasyS2S]

does those above mentioned 1uzs (97 and what not) have distributors? If so all toyota disti engines were 12

 

[jgscott]

Hey thanks guys. 12 is the correct #. WOW what a site !