Yak's Time Attack Nissan 200SX S13

[Yak]

Bit late but Ill start a project thread about my Time Attack competition car. Sister car, in Team Apex to SM's S13.



Competed last year using the car which was already fairly well modified but was not running a huge amount of power. Some where around 250BHP using a GT28R turbo on the original engine and a remapped ECU.

Over the winter... or as it turned out over the spring this year it had a bit of a transformation. The new engine was finally built Spec includes Apex rods, Wisco forged pistons, Tomei Poncams, Balanced (ish) bottom end, SR20DE throttle body, RC 1000cc injectors. All this now controlled but a VEMS ECU.

When the engine was spec'd it was hoped that it would brake 400BHP. It was taken down to Norris Designs and mapped on and engine dyno there and while we were a bit disappointed by the 375Bhp and 1.75Bar looking at the graph it was a nice smooth torque curve.

The new engine didn't make it in for the first round at Donnington due to not having enough time to get it installed.

Got it in and running for the 2nd round at Knockhill but only running actuator pressure as we could not get the VEMS boost controller to work. As it turns out this had not been set up on the engine dyno as they are used an independent boost controller  Very frustrating as I was quicker than a lot of cars in the corners but got killed in a straight line

3rd round at Silverstone and that car started suffering trigger issue (which had shown up at the end of the qualifying session at Knockhil but Id worked out what it was at the time). The car started missing quite badly to the point in qualifying going over the start / finish line at Silver stone I dipped the clutch and the engine stalled! Which meant I went into Copse corner with no server or power steering 
Eventually i think we have tracked the problem down to the CAS with the custom trigger disk in. I now have 2 but neither of them seem to work 100% I think they are over heating on track and then miss reading.
On a positive not I had finally got the boost controller to do something but it only set up in Force Duty mode. While this gave me more boost it also seemed to spike quite badly so Ive turned the % back down a bit.

4th round Id swapped back to the older CAS even though this has miss behaved before and I had badly bent the disk taking it apart in testing before the event it gave no errors compared to the new CAS with the newer thicker disk. Unfortunately due to having to drive to the event at Oulton Park I think it started to over heat again and it started missing again the in warm up session. I was so worried it would miss just as I was on the limit going over Clay Hill and send me into a spin! 
As it turned out this was the least on my worries. I must had opened the bonnet to try and get the engine bay temps down. But being out in the paddock in the wind and rain I must had not left the bonnet fully up.
Having repaired the rear window demister I went back out in the next session... forgetting to put the bonnet back down properly. Just starting my first flying lap and it flew open smashing it and the windscreen.   

[Yak]

But though the map it self in the VEMS seems good I'm still having issues getting the engine running as well as Id like it too.
My current issues are: -

1)Boost control
Now I finally have the solenoid working using force duty is there a guide to setting it up properly? I can get it up to ~1.75 Bar but it seem rather unstable and prone to spiking. I would like to be able to get it smoother and not come in with a big spike. I'm guessing the boost controller can be more sophisticated but I don't get what all the settings mean.

2) Hot Idle
When the car is really warm (track session, sitting in traffic) it will not idle. When cold it idles really quite smoothly but when hot it will hunt and then drop the revs to the point it will cut out. Makes driving it when hot very difficult. I have compared the idle setting to the settings in SMs VEMS install and they are all the same. The only real difference I can see between the installs is SMs MAP sensor is in the engine bay while mine is part of the ECU.
Could it be the length of boost hose from the manifold to the sensor causing issues (the boost gage is tapped into the line too at the mo)
Or could it be the MAT sensor getting heat soak. I have left it idling when it warms up and the MAT is reading up to >50c as it starts hunting and cutting out.
Or is the MAT right and its just breathing in that hot air and this is causing it to cut? Need for better cold air feeds to the filter?

3) The CAS trigger errors
Im guessing this is something specific to the CA but it seems the trigger issues I have are down to the CAS. As then Ive swapped between them the symptoms change. Some times they are fine mostly on the road, apart from testing the old CAS after silverstone when it keep over heating and stopping the car.
The issues seem heat related but it is just im rebuilding the CAS units wrong? Should I get another disk and CAS and have another go?

[rob@vems.co.uk]

Hi mate, thanks for putting the project up.
Boost control - the best description for the setup of that boost control is when you press F1 when its setup window is open.  If you are getting strange spikes then take a look at the Connection option 1 for the boost solenoid in the User Guide:
http://www.vems.hu/wiki/index.php?page=MembersPage%2FPhatBob%2FUserGuide
It works more as an adjustable bleed valve:


Hot Idle - James's 1JZ Skyline also does something similar when hot, which is strange.  I am wondering if its the Idle Air Controller fighting with the Inlet Air temp retard.  You could try going into Settings->Constants and disabling the MAT dependent retard option Be careful the MAT retard is a safety feature which helps lower the chances of detonation so only do this at idle, dont race with it turned off.

CAS Issues - There are a good number of those CAS disks being used without a problem.  It could be that you have been unlucky with that spare one, or you might be doing something frightful with them during assembly   Chances are that there was a problem with that second one as its behaviour was worse than the original.  If someone in the SXOC can give you a spare, get it sent to me, I'll put the thing together and send it on to you.

[Yak]

Boost control - the best description for the setup of that boost control is when you press F1 when its setup window is open. 

Ah I was looking for help on the "Boost Controller Settings" window. If I hit F1 on there I just get a generic help page about "User-Defined Data Editor"

On the "Boost Alternate Setting" window I get this

Choose Alternate boostcontrol = enabled
Start with 48mS period if you dont know that your solenoid wants different
Force duty = disabled to fill in all settings
actuator off below this pressure = 95-110 kpa, 110 for small turbo
boostcontrol target offset, 100 is recommended here. to get TPS scaling working properly
For Low and High Reference settings, read the end of this screen for method
Control Method, Ref-DC + Ctrl recommended
Low Limit, 20 recommended, distance from target the system starts to regulate
Dot Multiplier = 0 recommended to start with, if you have slow boost buildup close to target, raise this
Output channel setup as usual, Activated output = raised boost, if your solenoid acts differently, invert the output

To get this control system up and running, we need to find Low and High boost reference pressure and Duty
A good method to set these up is to force duty cycle using the Force Duty option, then try to find the lowest duty setting that raises boost above your wastegate spring setting
Do this by entering a duty in High Ref Duty setting, and test drive it. Be careful and remember to set a high boost fuelcut in basic settings
Then repeat the same for the highest pressure you would like, then enter these values in High+Low Ref duty + MAP settings, and you are ready to tune your boost target table<br>

Which looks like its been truncated as it doesn't seem to explain all the setting. Have I got a dodgy help file?

To swap to option 1 solenoid set up, what would I use as an restricter?

[Yak]

Hot Idle - James's 1JZ Skyline also does something similar when hot, which is strange.  I am wondering if its the Idle Air Controller fighting with the Inlet Air temp retard.  You could try going into Settings->Constants and disabling the MAT dependent retard option Be careful the MAT retard is a safety feature which helps lower the chances of detonation so only do this at idle, dont race with it turned off.

OK, Ill give that a try when I get the car back. Im presuming it is a safety feature that retards the timing when the charge temp gets really high? Any idea what temp this activates or is it a calculated value?
Ive got a datalog of a cold start up to the point it starts having issues. Would that show up in the log?

CAS Issues - There are a good number of those CAS disks being used without a problem.  It could be that you have been unlucky with that spare one, or you might be doing something frightful with them during assembly   Chances are that there was a problem with that second one as its behaviour was worse than the original.  If someone in the SXOC can give you a spare, get it sent to me, I'll put the thing together and send it on to you.

I was wandering if this would be a possibility that you could put one together for me. See if its my CAS disassembly / reassembly skills that are a bit lacking. I think I should be able to source another CAS.

[rob@vems.co.uk]

The MAT retard starts at 40degC inlet temps.

There are a large number of factors with the RPM oscillation, that PID controller can be a real sod to get working nicely.  We had fun with Paz's original install because he had no IACV on his throttle bodies, so to stop the car stalling we put 35deg advance down in the bottom left cell on the ignition map - each time the engine went to stall it would hit the advance spike and rev up again.  It was a nasty way of doing things but he didnt care as he wasn't thinking about using it on the road (where it would be horrible).
As a simple anti-stall device it seemed quite good.

One of the differences between yours and Kevs could possibly be as simple as the position of the throttle stop - if your IACV is working harder to control the idle speed because the throttle is better shut than his then the tune of the PID is going to be more obvious.

The problem is the number of variables that you have: IAC control, Ignition advance control, position of the throttle plate, condition of the IACV, vacuum at idle (are there differences in cam timing?), ignition advance at idle.

It would be interesting to see what RPM yours and Kevs sit at with the Idle Advance Controller disabled, even better would be to do the comparison with the IACV out of the scenario - I cant remember if the valve remains closed or open when its disconnected.  Eitherway matching the RPM, Lambda, and ignition advance at tickover with as many of the variables removed from the equation would be a great way to start tuning your idle characteristics.

[Yak]

The MAT retard starts at 40degC inlet temps.

Humm well that may be having an effect as Ive seem temps well over 50degC when it misbehaving.

[Yak]

Well turning off the MAT retard didn't stop the idle issues when the inlet temps were over 40c.

But now ive even more fun problem. I went out to set up the alternative boost control settings on Thursday. When to try and find the lowest setting and was surprised to find how high I had to set the solenoid duty to make and effect. Then went to find the high duty setting for full boost and had to turn the duty up more than I have had to before.
I was just about to call it a day as the lap top kept turning it self off as it was getting too hot but on that run the car developed a constant miss fire on boost. Not like the occasional miss fire I have had with the miss reading CASs. It seemed to go away when the car had cooled but then on the drive over to TotB it was back again.

I turned the boost controller off on the way there but as soon as the car made over about at bar off boost it was back again.
Swapped plugs, coil packs, between various CASs and the PTU but nothing seem to make much difference so the few limited runs I did have I effective had a 4000 rev limit (Ive checked at a standstill that the rev limit still is at 7400).

Going to wire the CAS independently of the OE loom and replace the fuel pump but it a hard one to track down as it only shows up under load.
Drove the car back from TotB as well as it ever has... well as well as you can drive a red hold stripped out car that wont idle, with a twin plate clutch, loooong first gear in miles on stop start traffic! LOL

[rob@vems.co.uk]

Okay so we need to do some more tuning at idle then.
First up I think we'll need to try some flyback diodes across your IACV and the boost solenoid, these should make things cleaner.
Then we'll see whats happening with the hot idle - which you'll need to datalog.
If you didnt get any diodes in your rescue pack I'll bung some in the post along with the crimps I promised you.

[Yak]

Ermm, what does a flyback diode looks like then?

[rob@vems.co.uk]

Small black electronic components with a white stripe on one end.

I've put two in an envelope anyway.

Rob

[Yak]

Arrived to day

Where do the flyback diodes need to go?

Ive reset up the TPS, wired up the cold start so now it should not be perminatly on. Was too late by then to try firing it up and setting it natual warm idle.

Cant belive Id not realised that the cold idle was perminatly on and that it wasnt attached to the engine when it was mapped. 

[rob@vems.co.uk]

Just drew up this:

Let me know if it makes any sense or not.

[Yak]

Yep that makes sence. Is there any where prefereable in the loom to add them?

[rob@vems.co.uk]

Up by the solenoid is fairly simple.