Hi gee, yes I got a automatic with a remap and after I read your build tread with interest I tried the same, hooked up the vac solenoid but I found the result disappointing, very slow spool up, higher egt’s, so after a couple of days I changed it back, to be honest I couldn’t see the point, I thought the whole idea of manual boost control was, to get rid of the drop in boost to accomodate the egr process, not needed after blocking egr! I know they turned off the egr valve in the remap but also the vac sol?
Anyway, thank you for sharing your knowledge in your build tread, you’re a legend!

 

Thanks for the feedback. That is interesting, my spoolup is still fast and smooth, I hit 21.5psi by 1700rpm.

 

Hey gee, do you see any advantage in going back to ECU control of the turbo on your truck?
I would try it but I cant remember how to hook it up again.

 

As said below I found my cruising boost to be around 1psi lower on average and the boost responded smoother (vnt dancing to conditions), running my WM means that the slightly lower cruise boost makes my WM tank last longer, so I don't use my needle valve any more to compensate.

 

I reconnected the VNT to ECU control, I was surprised to find it much better than I thought, only early results so far, about 80km, some highway some in town and no towing yet.
Spool up was not quite as quick, but quick enough I recon, boost at cruising speed a little lower than before, about about 14/15psi, and EGT a little higher, with manual control I had it at 16/17psi.
Spool up is smoother than before and no surge like I used to get.
I did notice the boost drop when cruising down the highway, more pronounced at light or almost trailing throttle, didn't seem to cause to much of a problem yet.
This got me thinking, I want to get the remap fine tuned on a dyno, I wonder if anyone has done that with the ECU in control of the VNT?

 

I don't think so, to my knowledge I'm the first to go back and try it.

 

There are a couple of shops over here that tune and leave the factory solenoid in control of the whole show, and have been for years.
I have never liked the Dawes/tillix and it would seem that you are all just finding out why.

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There are a couple of shops over here that tune and leave the factory solenoid in control of the whole show, and have been for years.
I have never liked the Dawes/tillix and it would seem that you are all just finding out why.

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Not sure about all, I still have no issues with mine after all these years. What is it you refer to when you say that?

 

I don't now about that Max, before the remap the troll used to drive like crap with the ECU in full control, it would over boost and go into limp mode, on the highway the boost drop would cause the EGT to rise quite a bit.

 

Absobloodylutely, the DI system was notoriously damn unreliable once we started playing with EGR/exhaust/etc/etc, that was why many of us had no choice but to scrap any ECU control of the VNT (CRD was a totally different kettle of fish, but I still came across a few strange ones).

It has only been since the recent advent of the DI remap (not cosidering the option of using expensive chips and sometimes mutlple chips and sometimes other electronic devices as well) that I had been able to revisit the vac sol as a cheap, and so far successful, alternative.

 

Just had a go at this, but only got slow spool with low boost 12psi max. Am I right in thinking boost side of dawes stays connected as before, solenoid hose#1 to vac supply under IC, hose#2 to vacuum side of dawes (with green damper thingy), and hose#3 to clean air supply? I did not adjust dawes preload...

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Just had a go at this, but only got slow spool with low boost 12psi max. Am I right in thinking boost side of dawes stays connected as before, solenoid hose#1 to vac supply under IC, hose#2 to vacuum side of dawes (with green damper thingy), and hose#3 to clean air supply? I did not adjust dawes preload...

Yes you have it right, with the barbed end pointing upward the top one goes direct to vacuum line, the middle one goes to the Dawes and the lower one goes to a clean air pickup. You could be finding that your ECU is trying to compensate therefore effecting boost.

I recently got hold of another vac sol and tried that, disaster, pulled it apart to clean and lubricate and didn't improve so put my original back in again, my original has been acting up occasionally hence why I wanted a second one to play with. I know from others that it doesn't always work for them, one of the guy's in WA is the only other one I'm aware of that has tried and it worked and I have no idea why, indeed my original one when I installed it chattered like crazy so I had to lubricate that but I didn't pull it apart to do it. That is one reason I've decided to give this UK device with its own Vac Sol a go, should have it soon.

BTW, when I refitted the original vac sol up I had to adjust the Dawes up 2psi to get back to 21.5psi I normally use.

Vac Sol internals.

 

That is interesting! I did flush it out with wd40 but that's it. I'd have another go with it and adjust the dawes if I thought I would get better spool, but I doubt that will happen...

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I have been running the vacSol to control spoolup with the remap for the past few weeks with success. My tillix is still is in place to control max boost.

Spoolup is quite fast and no problems hitting max boost of 19-20psi below 2000rpm.

I found it drives nicer with the vacsol controlling boost, although I did have the needle valve set quite aggressively.

 

That is good to hear, after I first did this I thought I was the only one it was working for, it is funny how some work and others don't. My needle valve is still in place but disconnected, I would be interested to hear if you find any difference in max boost with vacsol connected/disconnected, mine reads 1.5-2psi higher with vacsol disconnected, tried it again the other day and still the same, I suppose it is possible there could be slight leakage through seals and joints in the vacsol????

 

Hi all,
I read all these posts with a lot of attention.
The Dawes / Needle arrangement is definitely far from what a proper electronic control would do, to manage the arm progressively. And Yes, blocking the EGR and replacing the stock exhaust by, say, a 3" stainless steel, brings us far from what our ECU was designed to do. Hence the different routes that many of us have followed.

I also did a lot of ECUTALK acquisitions to try and understand what was going wrong with the ECU, and I believe I did. There are times where the ECU opens the EGR, and some of the exhaust gaz comes back through admission. And the ECU try and compensate for these changes of flows. When EGR is blocked these flows are modified, and the ECU is not aware. So things do not go as nicely as they should.

When you have a look at Nissan Documentation, they explain that the actuator rod opens the VNT progressively ( 0 to 10mm roughly), when vacuum is applied from roughly -500mbar to -200mbar.

When stopped, vacuum is zero. Rod is fully out.
When idle, ECU is trying to get maximum pressure in admission, and -500mbar roughly is applied ( parameter VNT Turbo is 55.9%x 950mbar vacuum pump). Rod is up, and arm striking the stop screw.

When driving, the ECU controls the length of the rod continuously, applying commands to the solenoid, between those values, depending upon the load, throttle, revs, and power requirements.

When you have a needle, it just sets the maximum closure of the VNT you authorise. And this stays the way it is, until the pressure in admission reaches the value at which you have set your dawes. When the dawes opens, you suddenly have the pressure from admission which goes to the control line, and this opens widely the VNT.

If the settings are not right, you get bounces, and all is a matter of compromise, and often you have to reduce the spool-up by opening the Needle ( and therefore reducing the VNT max closure, and reducing the spool-up).

I wrote a post to explain what I did to keep a nice and quick spool-up, and max pressure under control, getting the same kind of vacuum range applied to the actuator.

I closed the needle much more, to increase spool up to suit my use of the PATROL, set the Dawes with a compressor to open at 750mbar, but inserted behind the dawes another Needle, to reduce the flow of pressurized air going into the control line of the actuator when it opens. And I controlled what was going on with a vacuum gauge. I managed this way to get a progressive opening og the VNT whilst the pressure was going up from 750mbar to 1.1 bar ( the limit I had decided not to exceed ).
With this arrangement, all is under control, and you make a proper and 'linear' use of the VNT.

I have also been considering an electric actuator, but this would imply a computer to be connected to several sensors, and a significant amount of software to be written. So I did not embark on this project.

I had to modify the MAF voltage a little ( I had 2.16V at idle) by inserting two Schottky diodes connected in parallel, and the two in serie on pin 35 of the ECU ( MAF input), and this gave me 1.84V at idle, 3.9V max, and no more limp mode.

With this arrangement, my 2000- Manual transmission - no chip - no remap Y61 3.0 Di requires between 8.6 and 9.5l per 100km, and the driving is fantastic.

 

Hi guy’s , add another one that works with vacsol. Will drive around with it connected for a while but all good .

 

Good work Steven, your one of a few, now you will get an idea of how much improved driveability is. I hope your VacSol handles it, mine went haywire after a while and when I replaced it the results were really bad, hence looking at the Digibooster. The interesting thing will be to get out on the highway and do some high speed cruising (especially in cruise control) and see what happens. Keep us informed mate.

 

Thanks Ross, will do some highway drive later on today have to pick up Theo from work.. will let you all know I get on


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Hi all, did about 20-35 kays of driving today mostly local area and 15 kays worth on freeway. Troll went really well . Drivability is amazing with Vac solenoid . Didn’t get any boost drop at all doing 100klms per hour ,there was a bit of traffic that time of day so didn’t get sit on 100k for long periods of time. Drivability has improved greatly with vacsol.

 

Hi guy’s, I’ve posted a video on YouTube of some freeway driving i did a couple days ago, not very good with this kind of stuff so if you look up vacuum solenoid reconnection it will come up .


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EDIT: I embedded the link into your post Steven,
Ross.

 

Well done mate, that looks like it is working perfectly, it will be interesting to see how it reacts at speeds up to 110k, when I first tried this on mine over a year ago and once I got above say 102-3k I saw an intermittent reaction on the boost gauge, mostly you had to be watching the gauge to notice it, nothing serious or life threatening just the ECU apparently looking for a confirmation signal from somewhere then it jumped back to normal in a second or two.

 

Thanks, plan on doing more local driving also will include 110 k speed as well , just need to get better attachments for go pro and do videos in smaller sizes.


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Reconnected Vac sol today car drove really well so far.Will leave connected for now and see how it goes.

 

I had to modify the MAF voltage a little ( I had 2.16V at idle) by inserting two Schottky diodes connected in parallel, and the two in serie on pin 35 of the ECU ( MAF input), and this gave me 1.84V at idle, 3.9V max, and no more limp mode.

Hi Phdv61!
What amperage of schottky diode you use and how did you put it? Can you please illustrate how you did that. Thanks much

 

Vac solenoid reconnect

Now I’m getting confused have full nads remapped by Harley now that you are saying that if you reconnect vac solenoid and remove needle valve keep Dawes valve for max boost the spool up will be a lot smoother to troll will be more fuel efficient

 

Now I’m getting confused have full nads remapped by Harley now that you are saying that if you reconnect vac solenoid and remove needle valve keep Dawes valve for max boost the spool up will be a lot smoother to troll will be more fuel efficient

Basically yes, but what actually happens is that with Dawe4s/Tillix the VNT has full vacuum to it all the time except when you have your needle valve opened, then the vacuum is lowered by an amount governed by the amount you have the valve open. The job of the vacuum solenoid is to control the amount of vacuum going to the VNT so that as boost is required the vacsol allowed a higher vacuum so in normal driving the VNT is dancing to the requirements, without it the VNT is at full stroke all the time. If you look at your ECUTalk you will see a number like 55%T, that is the amount of vacuum the ECU is telling the vacsol to let through, this number moves as you drive, with just a Dawes or Tillix it is at 100%.

As you may have read I have gone a step further and tried the Digibooster which is a non ECU controlled devise that governs a vacsol. I had my genuine vacsol working well, average boost on cruising was a few psi lower and managing the whole thing a little better, but I later had issues with the vacsol, tried a few others and they all reacted differently, this is why some seem to be able to get it to work like I did originally and then again others it does not work for no matter what they do (this is an unknown but I still think worth a try as it costs nothing), this was another reason I thought I would test the Digbooster as an alternative to Dawes and Tillix so far so good, but if you can get your genuine vacsol to react the way it should you will see improved driveability like several others have.

 

Vac solenoid

Just thinking again isn’t it why we have taken full control of the turbo with Dawes and needle valve to stop it grenading.is that the vac solenoid controlled by the ecu sometimes for some strange reason will shut off the the turbo boost when you need more air not fuel into the cylinders.it seems to me we are going backwards. Or is is it with remapped ecu from Harley everything is different I know when he remapped mine he stopped the egr opening and maybe his tuning makes it able to control vac solenoid more efficient.

 

Just thinking again isn’t it why we have taken full control of the turbo with Dawes and needle valve to stop it grenading.is that the vac solenoid controlled by the ecu sometimes for some strange reason will shut off the the turbo boost when you need more air not fuel into the cylinders.it seems to me we are going backwards. Or is is it with remapped ecu from Harley everything is different I know when he remapped mine he stopped the egr opening and maybe his tuning makes it able to control vac solenoid more efficient.

That is exactly why I did not revisit this before I had my remap, I spoke of this much earlier. As said it works for some but has not worked for all, this is due to the convoluted signals within the ECU on the various models, it costs nothing and if it does work for you it has small but appreciable benefits.

 

Ross, Could not help myself. went and hooked up VNT vac solenoid last night with Tillix limiting max B. Doing OK, will report after more driving. I left needle hooked up for simplicity and closed. Same concept as attached(your drawing I think?).
Needle closed to replicate solenoid operation.

Benefit of needle with vac solenoid function, guess would only slow spool up rate if opened?
Any lag due to vac piping length (too long)?
Any benefit having needle as an operational choice option?
Other?

 

Cool, I look forward to your feedback, the biggest issue people for whom this hasn't worked is boost jumping around, this could be for a couple of reasons, but the guys who have made it work seem happy with the result so far.

Yes that is my schematic, I found that long lengths of tubing do affect manual boost control, this can be different for some due to how and where they actually set it up. You can still have the needle if you want, as I see it this would only be for fuel eco on trips where you have the needle in cab and can knock back boost a bit on flatter sections of highway or inner city driving to reduce spoolup.

I don't use a needle valve anymore (still in the car but disconnected) because basically I'm in a constant state of testing, one day it may go back in.

 

Vac solenoid

Do you have to use a dampener when you connect it all back up is it really nessesary because I through out the old one when I put in the needle valve

 

Do you have to use a dampener when you connect it all back up is it really nessesary because I through out the old one when I put in the needle valve

Good to do the caparison using vac solenoid without dampener fitted (same as your manual boost control configuration). Then try w/dampener if too much bounce.

 

Will find out next week head turned up today so I will be a bit busy this week end

 

CRD VNT vac solenoid/Tillix after remap.

Spent the last week doing CRD Comparative Performance with use of VNT Vac solenoid (In lieu of Needle valve) and retained Tillix for boost control.

Eng build 08 CRD stock except installed:

NADS with 3” Exhaust(Muffler/CAT)
ECPT remap/tune
Procharge stage 3(H/F) Turbo_ Max boost 26 psi/AFR 20:1
Jonny Tig cooler(similar CC Ultimate), 4” thru Air Box / 9” K&N Pod Filter (3” from air box to turbo), 4” Fwd facing snorkel/Safari air ram.
VNT Actuator set at 13”Hg. Reduce from 13.5”Hg to make spool a little more aggressive low down.
AFR around 15.5:1 early then flat 20:1 once on full boost (26psi @ 2200rpm).

ECPT dyno result(Tillix/needle) Actuator 13.5"Hg - 136kW / 512 N-m (4th gear) 21Feb19.

OBSERVATIONS

Tillix with VNT vac solenoid provided near same result as experienced with needle controlling spool.
There is a slight improvement in driveability, pwr (UltraGauge measurement) and ECO(only slightly). Need to go fishing up the mountains to see how it runs.
Appears to produce less turbulence in JT cooler (ie: reduced noise level) and there is the presence of very slight compressor surge (dose) when coming off full throttle at gear change. Would be interesting to measure the manifold pressures differential. Maybe the vanes are being better controlled by ECU?

Did a run with only VNT vac solenoid without Tillix. It was notorious, the boost behavior was excessively high and erratic (non-linear) with a high mid range boost spike (hump) and the over boost caused the VDO needle to bash off scale (30+ psi) did not trust it at all. The ProChg H/F turbo just wanted to make boost (I held right back). Replaced Tillix and took control of the situation.

Used VNT solenoid with Tillix and needle as well, but using needle to reduce boost caused EGTs to rise and as I run good boost levels anyway (removed it). Noticed with slightest adjustment of needle with VNT solenoid the boost would drop noticeable quick as compared to when running only Tillix/needle valve.
Best performance gain from my mods(except for ECPT tune) is install of JT cooler and 4” induction.

Disadvantage: No adjustment of spool for off road. Will see how it goes.

Advantages:
Less turbulence noise heard from JT cooler at higher load boost levels.
Slight improvement ECO (200+ kms) 11.0-11.5 l/100km down from 11.5 l/100km – mainly country roads, max 100kph - undulating (hauling) sealed 80%, gravel 15% @13”HG. Be higher in the suburbs or off road.
FYI, my ECO (hwy) with full manual boost control driving home from ECPT(Tuggerah) via Syd (400ks) at 110kph was 12.5 l/100kph and 11.5 cruising country roads (prior to 4” induction - 13.7 l/100 kms).

Conclusion:
Torque behaviour very similar for both VNT solenoid or using Needle valve.
Lugs slightly better with VNT solenoid (gains from 1500rpm). Can do it at lower rpm nom 1200rpm but no spool increase (just holds).

Hauls strong 4&5th gear (100% eng load/512 N-m) from 1500rpm @10 psi and gains to produce 20psi @ 2000RPM and max boost nom 26 psi @ 22-2300rpm. With VNT solenoid/Tillix can pull off from stationary in 2nd gear (level ground) very easily.

EGTs @ cruise (100kph)
30% eng load/boost 8-10 psi (EGT 280 degC).
40-50% eng load/boost 10-12psi (EGT 300 degC).
60% eng load/boost 14-16psi (EGT 325-350 degC).
Can haul on test hill 4th gear 60% eng load 2400RPM can hold 10psi,hit full throttle and straight to 20+psi
Very driveable to date will retain VNT solenoid with Tillix and see how goes. Time will tell.

 

As said in post #1, I too couldn't get the system to function if I let ECU manage all, had to have manual boost control. It sounds like reconnection of vacsol worked for you as it did for me, nothing that leaps out but definitely improved driveability. Still a bit strange that not all can get the same results, the answer still eludes me.

Absolutely the vanes are controlled better, our ECUtalk tells us the percentage of vacuum the vacsol is letting through to the VNT, does your ultra gauge give that measurement?

 

I have the Ultragauge EM plus that provides 76 possible gauges but percentage of vacuum as controlled by vacsol is not supported. The MX version can be programmed to show "Vehicle Manufacturer Proprietary Gauges" (if codes are known). Appreciate your suggestion/advice of way ahead.

Also, Would be interested in you boost behaviour (psi against RPM) in say 4th gear under load from low down (say <1000RPM) up to where max boost is obtained. My stage 3 does well but is slow to bring on boost, next to zero until approx 1500rpm where it produce 5-6 psi. Does lug lower down but only gains well from 1500rpm. The boost will rise at a linear rate to 20psi (2000RPM) and max 26psi (22-2300rpm). As you appreciate the H/F turbo having a larger exhaust wheel takes a bit to spin up, ProChg pushes approx 30% more air as compared to stock turbo at same level of boost.