Nistune Forums

Matt, i've found my map sensor and reconnected it. Does the MAP Sensor/ Boost Pressure Sensor flag need to be reactivated? or does it just need a physical connection?

Reactivate the boost sensor DTC codes as they are connected. If you are going over 18psi then increase max voltage to 5120 (the boost sensor does not report this high) to avoid CEL on high boost

I've also reconnected the boost sensor back on my own personal vehicle (R34) to monitor the problem this week.

I've been spending several weeks now with logic analyser and emulators connected to the R34 ECU and replaying the problem to locate the section of code which is doing this. Managed to trace the path of ECU code from reading the MAF sensor, boost sensor to doing the calculations. It is quite complex and I'm still figuring it out. Factory service manual does not cover this

So far I've worked out that with the boost sensor disconnected, when there is a drop (even small drop of say 20ms) with the TPS the NEO ECU will quickly decrease the TP from the current value down until 129 and hold it there for a short time and then it will gradually recover. The idea is to handle throttle response using both TPS/boost sensor inputs.

Such a large drop does not occur when the boost sensor is connected. I assume there would be a small drop in TP (and fueling) until it reaches the expected reported boost from the sensor

My next test is to slowly increase boost levels the ECU sees from 2.7 volts (0psi boost) to limit the drop of TP

Where K constant is increased (and also scales are increased) then the drop becomes larger (so say TP is currently 230, it will drop to 129 and can end up in the middle of the map).

With using factory TP load scaling to a maximum of 160 last column (overboost) and 144 the second last column, the drop from 144 to 129 would be less significant with default factory scaling setup.

Further testing shows that TP will keep dropping until the current boost level. So if the boost level is 0psi or less (ie 2.7 volts) then it will drop to 132

However if the boost level is higher, then it will compensate accordingly. More details here:
http://www.nistune.com/mantis/view.php?id=173

One workaround for no boost sensor is to set max boost voltage to 5100mv and wire the boost sensor input at 5V (but not higher otherwise you will get a fault code, and this will result in the TP drop)

Ok, so just plugging it in won't work? Feeding the input 5v will though?

Next issue i have come across is my VCT doesn't work. I can activate it via active testing, but it won't activate in gear/clutch in/rev. I went to unplug my neutral switch to test it disconnected and it was already disconnected. Its a factory auto converted to manual, could this have any bearing on VCT not activating?

Sounds like you dont have a speed signal going into it? Speed must be over 0km/h for VCT to work. Check this

The TP cut will drop until it reaches the measured boost level. So if the sensor is disconnected electrically (0.0V) or at vacuum hose (2.7) then it will drop TP down to 132

If the sensor signal is 'faked' at 5V (and max boost sensor set to 5120mV) then the TP will not drop

The boost sensor signal is used in conjunction with the TPS input for transient throttle enrichment adjustment, whilst the VE map (TPS vs RPM) is used for steady state throttle enrichment adjustment

I was testing with a fellow Stagea owner, Who could activate VCT by depressing the clutch, putting it in gear, and blipping the throttle, VCT would illuminate in Consult View. I could not replicate this, and thought it might have had something to do with the neutral switch not being connected when i did the manual conversion (as i could not find the wire at the time) but if im not seeing Neutral SW illuminate in Consult View it shouldnt matter. Potentially the vehicle not being up to temp (we dropped VCT Min temp to 50 deg but unsure if it got upto temp in the 2 mins it was running).

I will test to see if it is my speed sensor (I did have an issue where the connecting screw had fallen out of the back of the cluster, and was giving me a speed sensor CEL, but i fixed that and tested connection back to ECU, which was good, and no more CEL).

As for the boost sensor, i will use the LM2596 set to 5V and set Max boost sensor to 5120mV. Would you like me to take a log of it?

Im definately getting a speed signal (Speedometer in consult view is working). Tried dropping the VCT min temp to 0, and putted up the street and VCT would not activate. Does the ECU need to see the neutral switch on/off? or just off and speed input?

From some of the code I've seen the neutral switch plays a factor in VCT going on / off.

You can take a log of it and I'll look through it. The 5V reg sounds fine for fooling the boost signal input

I took some logs, and it turns out VCT is activating, but the problem is, not when it should be. As i understand, VCT activates just above idle when requisite parameters are met, then switches off at the set rpm. After going through the logs i noticed VCT would activate at varying RPM, Speed and throttle position, so nothing consistent there. What i did notice was it would always kick in when TP(load) would hit 14350 and above, and deactivate once it dropped below. After doing a bit of reading, TP(load) is in reference to airflow vs RPM? and is adjusted via K Constant. Will the K Constant number be causing the issue because its not seeing the right load to activate VCT perhaps?

The VCT is controlled based on:

Coolant temperature 70-119 degC
TP (load) from 56 (TP index = TP/256)
RPM until 5400rpm and then it will cut (and then recover below 5400rpm)
Speed > 0 km/h

You are right, adjusting K constant will affect the positioning of TP and where the VCT is enabled after idle

Yes TP comes from MAF / RPM * K constant (this is covered in our training slides)

Right click your fuel map to show the current VCT area (this is covered in the manual btw) to show TP position

Your K constant should be adjusted so the ECU operates in the factory TP range (ie factory TP scales) if you have feature pack, so it doesn't move far from factory TP load range

Log of this also would be helpful

Matt wrote:The VCT is controlled based on:

Coolant temperature 70-119 degC
TP (load) from 56 (TP index = TP/256)
RPM until 5400rpm and then it will cut (and then recover below 5400rpm)
Speed > 0 km/h

You are right, adjusting K constant will affect the positioning of TP and where the VCT is enabled after idle

Yes TP comes from MAF / RPM * K constant (this is covered in our training slides)

Right click your fuel map to show the current VCT area (this is covered in the manual btw) to show TP position

Your K constant should be adjusted so the ECU operates in the factory TP range (ie factory TP scales) if you have feature pack, so it doesn't move far from factory TP load range

Log of this also would be helpful

Thanks for the replies. My K constant is 400, Base image is 497. It looks like my fuel map maxes out, or even goes off the map. I will try and make sense of the training slides and reread the manual.
Ive attached a log of 1st to 3rd gear, which seems to be where VCT activates latest. Im yet to go back and see Clint at Profile (because ive had no time) but hopefully this week and i will see what he says based on your suggestions

Your maximum TP index reached was at 10.546 in the log. where it reached 181 but your maps (from the first page in this thread went upto 160)

So the scaling is good going upto 160, but the K constant needs to be lowered a smidge (say 10%) and then add 10% TIM to add the fueling in (which lowering K took out) then recheck cruise mixtures

Okay that fuel map is strange... it is very 'pointy' which seems to indicate the tuner had to add a crap load of fuel in top end. I am suspecting you have fuel pressure issues which are being masked. Please check fuel pressure on full boost as you may have a lazy fuel pump

VCT is operating perfectly, It kind of goes into the area and then back out again as you change gear. You can see once you highlight that area it going in and out as you scroll through the log in playback

Matt wrote: Okay that fuel map is strange... it is very 'pointy' which seems to indicate the tuner had to add a crap load of fuel in top end. I am suspecting you have fuel pressure issues which are being masked. Please check fuel pressure on full boost as you may have a lazy fuel pump

VCT is operating perfectly, It kind of goes into the area and then back out again as you change gear. You can see once you highlight that area it going in and out as you scroll through the log in playback

Fuel wise, this would be using the flex maps i assume, as i had E flex in there at the moment, not sure if that would effect that? Clint had his flow gauge on the car when he was tuning it. Its running a Walbro 485, but using the standard FPR so i would have thought that would have been ok?

As for the VCT, im still a bit confused. I thought it should activate just above idle if all required boxes are ticked. Im basing this off what other Stagea chums have said, and also what i have read ( i know this is to be taken with a grain of salt), mine doesnt seem to activate below 2300ish under WOT, or even more if just cruising, but the delayed activation seems more evident in 1st and 2nd gear. Im going to go see Clint, but i just want to approach him with as much info as i can (without being too dickish) and work out what we can do.

Your VCT activates once the load hits the 5th column across. This is more than just off idle. If you want it to activate lower, then reduce the TP enable point

This is load enabled (not RPM enabled) so keep this in mind that 2300rpm doesn't actually mean anything from the ECU point of view, but how much airflow is measured before it activates

It is more evident in lower gears since there is not as much load. He can simply lower the VCT TP load enable if you need it to activate sooner (on load, not RPM)

If that is what Clint needed to map in (and you have correct idle fuel pressure, and increasing 1 psi fuel pressure for 1 psi boost) then that is fine. Normally I see a flatter fuel map, so just an observation