52 replies to this topic

[james4563]

Should I be worried that my boost gauge has twice logged a peak of 1.7bar? I'm not sure how long of a period is spent at that level, when I try to replicate it I cant get it to happen. Normally peak is around 1.55bar if I go WOT.

 

Actuator is set very low, like 10psi.

 

Not sure what would be causing that to happen. Hoses all seem to be attached and in good order.

[Duncan VXR]

What map / setup is the car? 25psi is a bit too much Imo. Cant remember off the top of my he's what stg4 is but sure its 21ish peak Could be wrong as its some time since I had my one DG

[james4563]

It's a courtney stage4. But wasn't mapped during my ownership so I don't know exactly what they mapped it at.

 

My understanding is that it should run around 1.4 -> 1.5 bar. Which as you've mentioned is about 21 psi, and for the most part it does run that. My boost gauge logs peak boost until I reset it, and one two occasions over the last week I've viewed the peak to see it's logged at 1.7bar.

 

Courtney did say to me on the phone that peak boost on a stage4 should be around 21psi.

I'll have to keep an eye on it, maybe the boost solenoid is on it's way out or needs a clean. Can't hurt to try that.

 

 

Edited by james4563, 31 October 2017 - 08:08 PM.

[SteveA]

Has to pipe that fixes onto the top of the actuator popped off?

[james4563]

This has just got even worse. My boost gauge just logged 1.87bar which is WAY to much. Yesterday I have replaced both BCS and set the wastage as loose as it goes. It's just holding the flap closed no more preload than that. All pipes look good. New maf was fitted as well What else can cause this. I don't want to drive it like this, too dangerous.

[Nev]

A useful thing you can do is to buy and install a small video camera pointing at the actuator. Take it for a drive and then look at the video to see how much the actuator is opening the waste-gate. It might be that your actuator diaphragm is split and consequently only part opening... this test will rule it out with just a few minutes work.

 

I bought one from eBay for £5 and it is tiny (size of a 1/2 a finger) and I have used it for diagnostics quite a few times.

 

Another thing that strikes me, is that your gauge could be going out of tolerance... try buying and using another boost gauge (diff manufacturer/type ideally).

Edited by Nev, 20 November 2017 - 08:44 AM.

[james4563]

Cheers Nev I'll check that out. Do you have a link to which one you bought. Sounds like a useful diagnosis tool. After I posted I did actually see a post in here from Courtney that said they run 25psi peak overboost on stage 4 vxt. Maybe it's just the cold weather? 25 psi is 1.7 bar. Will phone then up in a bit and double check.

[Nev]

I bought my video camera 4 or so years ago, so I expect newer models are out. It was just some cheapy Chinese jobby, but surprisingly effective at looking at various things operating whilst you drive. Mine came with an assortment of useful clips and mounts.

 

Cold (denser) air will certainly contribute to higher power due to higher cylinder pressures if unchecked, however the pre-turbo EBP should remain (almost) the same, as the wastegate control is based on absolute pressure as measured by the MAP (Manifold Absolute Pressure) sensor. However there is the exception of the waste-gate diaphragm which uses the analogue ambient pressure as a reference, which does make the boost control somewhat relative (to ambient atmos pressure).

 

Anyway, a 1.75 Bar boost is too much and likely causes your fuel adjustment tabs to max out (and thus run lean).

 

 

 

Edited by Nev, 20 November 2017 - 09:40 AM.

[siztenboots]

if its the actuator , and I have been getting more feedback about problems with the turbosmart ones , but in general a actuator with spring or diaphragm problems gives poor linear control of position.

 

problem is they are not exactly a cheap part and labour costs, to just swap out to chase a fault

 

[james4563]

I spoke with Courtney and they said that it might have been mapped at 25 psi peak overboost, if the fueling was there. They want me to give them the previous owners name so they check check on their Dyno records and see exactly what was done. I need to check my log book and then ill see what they find out. Which actuator is recommended then? The standard OEM VXR one? I'm going to check the static break later but I'm pretty sure it'll be right.

[Nev]

Wow, Courtenay maps now allow 25 PSI over-boost? That can't help the torque spike!

 

Pretty sure when I had their stage 4 map 8 years ago, that mine held a steady 18 or 19 PSI and maybe spiked to 21 PSI. Maybe your old car's owner asked for "everything it's got" (AKA "find me a ditch") map!

Edited by Nev, 20 November 2017 - 10:43 AM.

[james4563]

Could be. They said it might peak as high as 25psi and then by 5500 rpm it should drop to about 14/15 psi. Seems a bit of a strange boost curve. It does feel like it's got a bit of a power spike 😂

[Nev]

The boost curve is "strange" as it's only a tiny turbo and the maps after "stage 2" push it out of it's sweet spot on the efficiency map. The compressor is too small to provide enough air flow for beyond 5500 RPM, hence why your power dies off at around there.

 

Edited by Nev, 20 November 2017 - 12:03 PM.

[siztenboots]

unfortunately posting images on the forum is such a tedious time confusing process these days, thanks to photobucket.

 

the picture below shows p11cov's car with a turbosmart actuator  and stage 4 Courtenay ( dotted line ) and my own TeamVXRacing software ( solid line )

 

both are running an identical "engine load" profile , the figures are uncorrected at the wheels , so allow ~15% losses to obtain flywheel

 

the top end performance is I think held back by the standard manifold , it works well on a Zafira towing a caravan

 

too much actuator preload , poor fine control , bad actuator linear response = variable boost

 

 

[james4563]

I had actually seen that picture before. What gear was that run in? My car made makes boost earlier than that, Courtney said it probably wheel span on the Dyno and gave a false reading but it actually appears to do the same on the road. It makes peak boost around, if not before 3k. How much do you charge for that map? It might be easier to just get it remapped by you as I mentioned before.

[james4563]

I've spoken to John at Courtney today and he very helpfully looked up the cars mapping session from the previous owner. It was mapped with high torque as the target requested from previous owner. The max overboost on Courtneys Dyno while mapping was 24-25psi ( 25 = 1.72bar ). However it won't and shouldn't sustain that for any length of time, John actually said that by 5500 rpm it was running just over 1 bar. He advised to test in 4th gear from 40mph. Which actually logs 1.8bar plus, I feel like it'll just keep on going up if I don't lift. Soon as I see it getting high I lift off of course. If I do a pull in 3rd from 40 then it'll reach about 1.45bar but instead of then dropping of it just seems to hold it flat at 1.45bar. Something really weird going on with this car. Anyone got any further ideas? I can't understand why it's make so much boost in 4th. Especially with all the new sensors. I did a test using odb and torque android app too, which rather worryingly logged 33psi peak... Lol. Does it need an ECU reset to take into account the new sensors....? The only other sensor I can think of that relates to boost control would be the MAP sensor, could this cause overboost if the ECU is calling for more boost because of an incorrect reading from the MAP sensor?? Going to blow up at this rate... 😂

[Nev]

Hmmm, I think a change of the MAP sensor is in order. Also change your boost gauge, it could easily be over-reading and you might be worrying about nothing.

 

In the end talking about these things doesn't resolve them, you have to just keep observing and changing things. If it were me, in order of expense/hassle:

 

1. Fit new boost gauge. Cost £10.

2. Buy video camera, mount over actuator, check wastegate is opening fully.

3. Buy + fit new (not a copy part) MAP sensor.

 

 

 

Edited by Nev, 21 November 2017 - 09:09 AM.

[CHILL Gone DUTCH]

Maybe there was is issue with original sensors at time of mapping, and now you have installed new it's changed the characteristics

[Nev]

Maybe there was is issue with original sensors at time of mapping, and now you have installed new it's changed the characteristics

 

Good point.

 

Though asking CS to map for full torque sounds like the basis of the problem. Far better would be to put a better flowing inlet manifold on and a bigger turbo compressor wheel for the extra power (without any extra boost/torque mapped in) IMO.  

Edited by Nev, 21 November 2017 - 09:22 AM.

[james4563]

Maybe there was is issue with original sensors at time of mapping, and now you have installed new it's changed the characteristics

I had wondered this. Unfortunately the only way to sort that is to take it to Courtney to have them look at the map car. It looking more likely I'll have to make the trip.