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Thread: Beyond FSM questions about how to tune the SR20DE

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Posts: 1-7 of 7
2009-12-27 05:06:33
#1
Beyond FSM questions about how to tune the SR20DE
Q1 I've read that before on this forum the crank pulley can seperate, but I don't understand how this is possible or why a metal pulley would consist of 2 parts. Would somebody please explain this to me?

My readings are like this

[ ] | | | | | ----- p

[ ] = big white mark

| = little marks

p = Where the pin is at and the only setting the car runs proper on (with correct AAC, MAF and working TPS. To confuse things even more, neutral switch is broken now (was intermittent for a while) and temp valve opens about 10 degrees Celcius too early. (replacing the AAC for a good one made the temp valve problem clear).

(- = to show pin is pretty off, forum cut's extra spaces)

However, I do have a steady reading on the pulley so I seem to not need a working neutral switch for timing mode.

Also, from day one I got a timing gun, pin showed where I drew it. But I kept advancing it and the dizzy housing is on a scale 0 (retarded all the way) to 100 on 85.

Q2 Where would my timing be at right now? And does the running rich (sparks show this finally (bad AAC actually was the wrong AAC for this engine) allow me to advance the timing a bit too much?

Advancing it further makes the engine sound like a run away (is this called hunting in English?) So I got the Datascan, timing gun, but no proper readings.

Q3 Is there another possibility why I don't get proper readings? If not, can I swap the crank pulley withous losing distribution chain setting?

Q4 Sparks show signs of pig rich, is it true that the broken neutral switch makes the car run too rich when in gear?

Lambda is fine. WOT is what it should be now (I went from fast but defects to less defects and poor performance to fast again but seems to surge here and there which probably is the temp valve and TPS closed signal is random between 0,20 - 0,26 Volt so I had to set it to 0,20 Volt. Sorry for the long story,

Q5 How do I get my throttle closed signal appear with TPS Voltage 0,5 Volt like FSM kept saying (I worked trought the whole EF & EC today) instead of 0,20 Volt?

So, I probably am not on the 15 degrees stated in FSM, but well beyond that, but FSM also says make sure car under no load @ 2000 rpm has timing > 25, No matter what I do, even advancing it to 100%, I'm stuck on 24 degrees.

Q6 How is it possible I can't get past 24 degrees?

Please advice me to help me understand the ECU and sensors.

Q7 Is there a way to learn what is going on in the standard ECU? For me it's still a (partial) black box, which sets me back sometimes.

Thank you!
2009-12-27 05:12:15
#2
Originally Posted by richardwbb
Q1 I've read that before on this forum the crank pulley can seperate, but I don't understand how this is possible or why a metal pulley would consist of 2 parts. Would somebody please explain this to me?
I'll tackle this one for now.

The crank pulley consists of three parts. The outer metal pulley ring, the inner metal mount, and the thick, ring section of rubber completely separating both metal parts from each other.

It looks sort of like this on our cars, but not exactly.


If the rubber deteriorates badly enough the outer pulley section can rotate independently of the inner mount and the timing marks will no longer reflect the actual position of the crank shaft.

If you'd like to know why cars are equipped with harmonic dampeners to begin with, here is the best tech article I've read on the subject: ATI - The Dangers of Power Pulleys & Understanding the Harmonic Damper
2009-12-27 05:18:25
#3
Originally Posted by richardwbb
Q2 Where would my timing be at right now?
15 degrees before top-dead-center (unless you have a GTi-R motor).
2009-12-27 05:22:48
#4
Originally Posted by richardwbb
Q3 Is there another possibility why I don't get proper readings? If not, can I swap the crank pulley withous losing distribution chain setting?
You need to stop labeling your questions if you're going to sometimes ask more than one question each label. =P

To answer your second question in the quote; yes you can replace the crank shaft pulley with another one without worrying about disturbing the timing chain, mechanical timing (valve timing) or ignition timing (distributor setting). You will be fine.
Take care when removing the crank pulley though. There are many wrong ways to do it, and some can crack your oil pump.
2009-12-29 02:56:58
#5
Thank you very much Ben!

I yet have to pull one 1 pulley (airco I don't want) and maybe replace crank pulley, just to see what timing i'm at and maybe look in to underdrive pulleys, but not sure if that is a good mod on a stock SR20DE.

I also would like to learn more about the oilpump, because I got erratic oil pressure (hammering valves) and cleaning the engine might help, but if I replace oil pump, would a SR20VE pump fit right in?

Anyone that knows the answer on:
Q5 How do I get my throttle closed signal appear with TPS Voltage 0,5 Volt like FSM kept saying (I worked trought the whole EF & EC today) instead of 0,20 Volt?

please?
2009-12-29 04:17:28
#6
Originally Posted by richardwbb
if I replace oil pump, would a SR20VE pump fit right in?
Yes, but you will need the VE oil pick-up tube, a VE crank pulley, and the Gspec spacer. Or instead of the spacer you could get a VE oil pump drive collar. Or instead of the VE crank pulley and spacer I think you can modify the DE pulley to work but that gets complicated.

See here: http://www.sr20-forum.com/howtos/24618-how-crank-pulley-oil-pump-spacer-all-common-combinations-explained.html
2009-12-30 01:25:33
#7
So I fixed the thermostat (what I called temp valve in my first post). Changing the MAF made duty cycle fall from 3.5 to 2.5 already and I still don't know what an acceptable duty cycle is for my car so I had high hopes. But the car kept the mileage just as bad.

While several ppl told me to replace the thermostat as a precaution on this 3rd Nx I bought (first one was a rust bucket, second one was totaled for me) I now understand why. I yet have to test fuel economy but duty cycle dropped to 1.8 and now I only have to replace the neutral switch.

As for the pulley, I guess I'm better of first replacing it with a original second hand, getting the proper tools and skills.

However, I'm still interested in a VE and I learned replacing the head also I will need a programmable computer, injectors, rewire cabling etc. For my DD that means I can't drive it. So I better get a second car first.

I've read about your findings on fitting the VE pump, and that is just a bit too much for me. I might be able to pull it off, but the route I face to get the VE head working, is too long for me and too costly.

Now I'm looking in to getting a SR20VE, but this also has issues to fit in the Nx2000?
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