[Mk2] [Turbo] Uni chip removal and over boost

[afennell]

If you remove a uni chip and boost module, and your car has an upgraded intercooler, de-cat, mongoose. Will the car boost higher then standard.

I know with the supras if you remove the cars you need something to control the boost.

[Martin F]

have you not already got a boost controller?

if not then the boost will run as standard with maybe an extra bit off boost in 3,4,5 but nothing to worry about..

if you have a boost controller then you should turn it down to standard and then turn the boost up a bit at a time until you have the desired boost,
if you have a rev 3 ecu then it can handle more boost with no problems,I run mine at 1.2 bar

[afennell]

Thanks,

I have the boost module fitted to the uni-chip. Thinking of removing it as i have an intermittent problem, leaving me with no boost control.

What cotroller do you use, are all your other electronics standard?

[Martin F]

the boost module from the unichip just lets you get a better map for the chip but does not control the boost..If you haven't got a boost controller then your car was mapped on standard boost..i`d check your pipe that goes from the turbo to the actuator for a valve just in case there is a mbc as unichips get much off there power increases from upping the boost.

Also take note from which wire goes where when removing the chip incase you would like to use it again.

electrics standard apart from colder spark plugs and new cap,arm and leads
I'm using an Alexi avcr but had a mbc before and am reverting back too another one as i found it too work better for my requirements

[terrabyte-computing]

the boost module from the unichip just lets you get a better map for the chip but does not control the boost..

The above statement is correct for Rev 1&2 but on a Rev3 the unichip can control the boost using the factory system

[Martin F]

The above statement is correct for Rev 1&2 but on a Rev3 the unichip can control the boost using the factory system

ok, didnt know that

sorry

[Slarty]

the boost module from the unichip just lets you get a better map for the chip but does not control the boost..

The above statement is correct for Rev 1&2 but on a Rev3 the unichip can control the boost using the factory system

Hmm.....I'm sure it doesn't, as I've just removed (and have in front of me) a unichip and boost "module" from my Rev3. There is NO way it could possibly control boost in any way shape or form.

It was tee'd into the FPS (fuel pressure sensor) and it only has one port. The only way it could possibly work is if it was used as a replacement for the VSV, which given that it was being used to monitor boost, I struggle to accept. Coupled with the fact that if it were to be used as a VSV, it would need an exhaust port of some description to vent the excess boost, which it does not have.

There may be another unit that you can get for unichips, and if that is the case, I stand corrected.

[afennell]

Mine is plugged in the same way, in the map sensor.

Could it change the info given to the ecu so it does not open the waste gate?

Can somebody please say for definate as I would be alot happier about pulling it out if i will still be boosting around 18psi.

[Martin F]

if your boosting to 18 psi then you have too have a manual boost controller connected to your actuator, and as your running a rev 3 then the ecu is capable off running that boost without the unichip...any pics

[Slarty]

Could it change the info given to the ecu so it does not open the waste gate?

In a word, no. Certainly from what I've seen at least.

The boost is controlled soley by the wastegate actuator. The unichip does not (again in my experience) control this in any way.

I'd say your best bet is to do what I did.

Remove the unichip, run a single pipe from the turbo to the actuator (with the VSV blanked off) and see what boost you get.

With the unichip in place, I had extreme overboost, up to 1.2-1.3 bar. This was with no form of boost controller at all. I initially put this down to an overly free flowing exhaust system (3" D/P and 3" exhaust) but having put the cat back in for the MOT, I still had the overboost problem. Once Luke had removed the unichip I had rock solid 0.7-0.8 bar boost. I can only assume that the unichip had a "bad" map on it that caused the overboost.

Soon cured that with an MBC

[Martin F]

With the unichip in place, I had extreme overboost, up to 1.2-1.3 bar. This was with no form of boost controller at all. I initially put this down to an overly free flowing exhaust system (3" D/P and 3" exhaust) but having put the cat back in for the MOT, I still had the overboost problem. Once Luke had removed the unichip I had rock solid 0.7-0.8 bar boost. I can only assume that the unichip had a "bad" map on it that caused the overboost

it`s all a bit confusing
so how did your turbo go from 13psi to 18psi with just the unichip but no boost controller....
any one any ideas?

[Slarty]

hehe, ok, here's my take on it.

Mechanically, the boost is restricted by the actuator pressure. The spring is set to X psi, and as such will not allow more than that amount of boost.

However, there are other ways in which the turbo will overspeed, and hence cause boost creep (boost creep is simply where the exhaust turbine spins faster that you want it to).

If the "map" is set such that the fueling and ignition allows for a far hotter and latter burn than is set by the standard ECU, the "hot & late" exhaust gases will prompt the exhaust turbine to spin faster than normal. This results in the turbo generating more boost than it normally (with the standrad ECU) would.

I can only state that my car was running actuator pressure only, and with the unichip would overboost to 1.2-1.3bar, but as soon as it was removed, it held a steady 0.7-0.8 (the slight diffence being me reading the gauge under full throttle!!) bar.

[Andy K]

The Unichip and boost module DOES control boost on rev3's if it's been installed properly.

The unit called the 'boost module' is a module that provides 2 functions, it firstly functions as a map sensor allowing the mapper to map past ranges not covered by the rev1/2 map sensor.

the second function it does it to control/drive the factory VSV, thus controlling boost. The unichip by itself does not have enough power to drive the VSV directly so the boost module is a device driver that that sinks enough current to operate the VSV.

The 'boost module' comes in another flavor without the pipe for the integral map sensor. devices such as these are used to drive WI or another injector using one of the unichips other outputs.


Ok, your problem, if the mapper has mapped the boost for a certain set of engine conditions and then you change them, by fitting coolers, induction and exhausts etc, then the boost will rise and effectivly needs to be remapped to bring it back down. this occures because the unichip /boost contol module (BCM) control is open loop. Unichip fitting is best after any breathing/cooling mods.

If you remove the unichip correctly ( you can't just rip it out)and reset timing etc, you should be back to stock boost. But first I'd check leaks in pipes that go to the VSV.

Slarty, the reason you are on low boost I guess is because your on spring actuator pressure only and no bleed by the vsv. this could be because the unichip has been removed incorrectly.

On rev 3's the best solution is to have a unichip WITHOUT the boost module fitted, controlling ig advance and fuelling with ref from the stock map sensor that'll go up to 20psi.

then use a ebc (great because it is closed loop)or man bleed valve to control whatever boost you require. Then you can wind it down with extra breathing mods.

HTH

Andy

[Slarty]

Slarty, the reason you are on low boost I guess is because your on spring actuator pressure only and no bleed by the vsv. this could be because the unichip has been removed incorrectly.

Andy, this falls short on one point (which I must admit I hadn't previously noted)

My car is running a, oh I don't know, call it a stage 0 turbo. This means that it is running an actuator with only one port, not two as per a VSV set up. This means that with the unichip fitted (which by reciepts it was) the unichip had no way of controlling boost. It was simply under actuator pressure. But it still acheived higher than actuator pressure?

As I stated earlier, I don't know the ins and outs of unichips, so it "may" be possible that they control boost in an otherwise method, I can and will only coment on my previous set up.