Hi

i was searching around on the org to see if I could find anything on this...I couldn't so I am asking...

I have read many places that you should retard timing by 1 to 2 degrees if running NOS or other boost. On post 95 max's (as far as I know) there are no ECU mods available from JWT to do this. Would it be possible to trick the knock sensor into thinking that the engine is knocking and hence retard timing?

The knock sensor works on an AC signal whose freqency increases as knock is detected. Now I am not sure how controllable this would be but if I could figure a way to simulate this signal and then increase the frequency, it should work right? What happens if I retard too much...just run really rich? maybe burn rings? I think I will put it on an oscilloscope and see what it really looks like. What do you guys think?

If I were to want to return timing to normal I am not sure what to do. Would the oxygen sensors play a part? May have to trick these also. This would be easier to trick.

Hmmm! Anyone know how these ECUs think? Jim Wolf probably does! Probably won't tell, huh?

 

Also crankshaft and camshaft position sensors plays a part....forgot about that...seems like a lot to do!

 

TTT

 

who told you that JWT doesn't do that?

the JWT NOS kit comes with a daughter board that retards timing..

http://www.clubmaxima.com/articles/N...ForParties.php

 

Hi Sprintmax

Thanks. I read this b4....actually I meant post 96 not post '95. i.e. after 96. The thread says 95-96...I have 97.

I am thinking if I phase shift the cranksensor signal and/or camshaft signal it will achieve the same effect. I have a feeling that the daughterboard from JWT does the same thing. Or just delays the output signals to the coils.

If you know of a company that does 97-99 let me know....Was hoping that someone like MSD would do it....guess not for now.

 

you can use that ECU from JWT for 97 maxima's .. just not for 98's and 99's..

i am not sure about your theory.. i will shove this thread to matt.. let him give you ideas

 

Sounds good, its worth a shot.

 

cliff notes?

i don't know if i have enough time to read all that information you posted




<< 5 hours later>>

thanks for that post Matt.. it was informative and straight to the point.. it was a bit long.. but i knew exactly what you were saying and i know what i plan to do

 

This probably won't work. It's my understanding that once knock is detected(or simulated in this case), the ecu will pull back the timing(like you want)But(big but!), the ecu typically pulls back the timing quite a bit. Probably alot more than you would want. You also have abolutely no control as to the amount of timing pull back. I guess you could hook the car up to an Consult or maybe an OBD-II datalogger to see how much the timing is pulled back but it would alot of work for an un accurate way of pulling the timing. Plus if you start sending a knock signal to the sensor too much, it might throw an error code to the edu.

Just a random thought from me.

 

is that a part on only third gen's?

 

Jeff

you are right about the Knock sensor...I had the same thought about how much control I would have. I am thinking more along the lines of the cranksensor now since this tells the ECU where top dead center is. Doing a phase shift on this sensor should trick it into moving TDC position (theoretically). Not sure if the O2 sensors would detect the difference and override or do something about it Perhaps it would just adjust A/F ratio. Hmmm That's why I asked the question about if anyone knew how these ECUs think.

I am going to scope out the crank sensor and see what kind of signal comes off it.

For the daughterboard, does anyone know where this hooks into? DO you plug this into the ECU? Does it pass through signals to the other side. I don't know since I do not have one. If someone knew which signals were being tapped, that would go a long way to determining how the ECU mod works...whether it tricks incoming signals or just delays outgoing signals.

 

Dont forget the CAM position sensor, its part of the problem too.

 

Well the ignition timing is just ignition timing. No air/fuel adjustment related perse.

Intercepting the crank angle sensor singal might be a good way but changing this singal will modify the timing across the board. So if you do something like is(ie... for a turbo) you would only want to to pull back the timing during boost conditions. Which would be the best way so cold start, part throttle and off boost conditions would be normal. Boost dependant fuel pressure control is easily possible to this might. (in theory anyway)

AEM and MSD claim to have stuff available for all applications(including coil on plug direct ignition cars) sooooo I've haven't called them to drill the tech guy about maxima stuff.

 

Hey Jeff, would the method used on VE's to advance timing work on 4th gens? by moving that thing a little bit (crankshaft sensor? ) whatever it is, forgot.. I remember doing this when I had my VE and it worked, but it was pinging with crappy gas, especially at high RPMs.

 

I thought VE's had timing belt?

 

1) You thought wrong.
2) What does that have to do with the discussion you post *****!

 

Big difference.
4-gen timing sensors are not adjustable w/out some type of custom slotting of the sensor bracket.

 

VG's?

i could have sworn i saw DanNY adjusting the timing on a 3rd Gen at LSP Meet

 

Applying retard only during boost conditions would be the easy part. I could use a switching relay and voltage comparators hooked up to a boost gauge to control that.

Is the basic concept good? Phase shifting the signal would be essentially the same as physically moving the sensor. Did that work for the 3rd gens? If so, it should work for us too!

If all this is true, the hardest bit is to build the appropriate phase shifting circuit.

 

You can adjust the base timing on both VG and VEs.

Here's a clue. VGs have timing belts. VEs have timing chains. :P

 

Yeah I think this is fairly sound(but I'm not an expert). This is probably the exact same thing msd,accel,AEM or whomever would have to do if they wanted to change the timing curves on a direct coil on plug ignition. Ether that or get into the ecu codes itself.

 

Do 3rd gens have crank POS, REF and camshaft POS?

Now a degree or two the computer might let slide. But through my experiance with the sensors you may have to tinker with the camshaft sensor too.

 

I take back what I said about the switching relay. It would be better to have progressive retard rather than a sudden shift never know what's going to happen. It would be easy to control manually...by hand, automatically would be a challenge.

I am going to put this little project on hold for a while while I finish up my NOS window switch project. That one is looking very promising right now and I should finish it off before moving on....plus the garage is freaking cold...I hate standing there trying to scope stuff out when it's 20 degrees! Sometimes I wished I lived in CA and not CO.....sometimes....

I am going to read a little more about this subject also ...anyone have any contacts in the Nissan R&D department? Now that would be great!

 

I believe the Ve 3-gens just use a camshaft position sensor for timing.

I don't know why the 4-gens need a cam position and crank position sensor.

 

Not only that, they have two Crankshaft sensors - one for position and one for speed! What a pain in the b..t. It looks more attractive to delay ignition trigger rather than sensors