mcphilimey

Ok then. The problem is that since i've fitted a FMIC and new tubular exhaust manifold the boost has become uncontrolable. I've got a polar performance chip fitted so i should be seeing about 1.1 bar of boost. The car quickly reaches target boost but then as the revs increase the boost just rises until i find my head planted in the windscreen! Below is a list of things i've tried.

1) checked brass restrictor is in the hose on the bottom of the boost soleniod
2) Have cleaned boost soleniod
3) have disconnected boost soleniod and put a manual boost controller on, which set to it lowest boost pressure allows the car to boost to about 0.7 bar but again as the revs increase so does the boost
4) Have connected a new peice of hose from turbo to the actuator. Same result boost holds at 0.7 but rises with revs.
5) pressure tested the actuator and that is not leaking boost away also could see rod moving ok
6) checked wastegate moves freely.

The only im not sure on is that the wastegate has more travel left when the actuator rod is fully out. Is this normal?

I really at my whit's end with it now!!!

swisstonihasher

Hey bloke, well all I can say from my experience when I went down the tubular manifold and FMIC, I had the lot remapped to match the changes - these changes are big! Sounds like you have boost creep big style...one test you can do is disconnect the boost control so car just runs off actuator, see what that does...should produce max .7 bar and thats it.

mcphilimey

yeah tried that, disconnected the boost control and put a hose between the turbo and the actuator. as you say, got a constant 0.7 bar but as the revs increase so does the boost

Gear Head

iTrader: (2)

RE-MAP!

mcphilimey

i'll need a esl board or similar to do that and will set me back £700 odd which i really don't want to do. Don't want to run anymore boost as the motors got a few miles on it. Just want to control the boost i have got

Varboy

What turbo are you running?

I just tried the same, ie hooking up the compressor housing to the actuator. On a TD05 Big 16g I'm reaching 0.75bar at which point it plateus for a couple of seconds and then rises with revs. I managed about 1.18bar in 2nd at about 5800rpm and then ran out of clear space in front of me.

Sounds like we may both have boost creep issues.

At least I have kind of narrowed down the boost control issues to the solenoid.

mcphilimey

what ever the standard turbo on my96 pre facelift is. All i know it's a TD05 not sure what strain. let me know mate if find any more. i'm going to try and presssure test my fmic system over the holidays make sure thats not leaking

Varboy

yeah sure, what diameter vacuum hosing did you use? I'm having difficulty trying to find out.

mcphilimey

think it was 5mm just want ever i had lying about

bighead

iTrader: (1)

you guys need to A: remap the stock ecu, if that is not possible then B: fit a aftermarket ecu and a remap.

mcphilimey

how will a remap help? all that will do is allow you to run at a higher boost level not control it surely

slipstream_uk

iTrader: (1)

bite the bullet mate, just get the esl livemap done and the problem should go away. on the plus side look at the new power / torque you will gain.

mcphilimey

how will remap help control the boost?

Varboy

Though the answer 'Get a remap' is usually true, it's unfortunately used as the stock answer for many an issue without an explanation as to why it will help.

In your case, you've have lowered your charge temps and increased exhaust gas flow (thus enabling more pressure on the turbine). You have created a perfect recipe for creating more boost, I would guess your ECU is chucking loads of fuel in and not controlling the resultant boost adequately.

Varboy

Reduce fuelling to ensure boost target is not exceeded, lower wastegate duty (and numerous other considerations I have probably not accounted for)

mcphilimey

ok fueling i can understand. im using a manual boost controller and still have a problem so wastegate duty isn't relavate. surley if the fueling was wrong then i would of got these probs before fitting the manifold and fmic

Varboy

I'm really not an expert so would advise obtaining professional advice.

As I understand it, by fitting the tubular exhaust manifold, you are making the passage of the exhaust gases easier, thus the gas is travelling quicker, and is exerting more force on the turbine wheel. As the turbine wheel is now spinning faster, so is the compressor wheel which is now bringing in a lot more air which is colder and denser due to the more efficient intercooling of the FMIC.

Your boost solenoid duty cycle is set in your Polar chip at a certain 'Duty' which is probably a lot higher than it now needs to be as it is not expecting so much air coming through. In summary, it not allowing your waste gate to start opening early enough hence the exahust gases are not expelled quickly enough and the cycle repeats (until of course you hit fuel cut).

The issue of the boost continuing to rise when you have bypassed your boost solenoid may (as I said previously) be down to the wastegate not opening fully or more worringly it can't physically flow the additional exhaust gases produced due to increased charge density.

mcphilimey

im having this problem and im not using the ecu boost soleniod. im using a manual controller so this would indicate that is not a cycle duty issue on the soleniod

mcphilimey

im thinking it a wastegate not being able to flow the exhaust gas problem. as the wastegate seems fine and was working ok before the mods

Varboy

So let me get this straight, you have totally bypassed the stock BCS and line runs from the compressor outlet to the actuator with the MBC 'in the middle'?

mcphilimey

thats correct. im running a hose from the turbo housing to the MBC and from that to the actuator. so bypassing any ecu boost control

Varboy

I think I would try and hook up the stock BCS in line with the MBC.

The ECU will then account for lower inlet temperatures and decrease duty cycle accordingly, it will also lower duty if it detects knock. This might resolve the boost spiking.

If you are truly getting boost creep, hooking up the stock BCS wont help.

Varboy

sorry, forget that, I read your original post again...

mcphilimey

now this is strange and must point to boost creep. just been for a drive with the actuator rod DIS-CONNECTED and the car made full boost
1bar at about 5500rpm in 4th gear that surely points to the wastegate not being able to flow the excess exhaust gas.
any ideas

Varboy

Yes, I believe so.

You're in the same boat I am, you'll have to get the wastegate ported.

Varboy

Or get a map so that fuel injector duty drops off sufficiently as boost starts to rise.

mcphilimey

getting the wastegate sorted is the true solution for problem. Mapping just to deal with it isn't really correct way.
I would like other peoples opinions on this please

sl1000

I had exactly the same problem.
I have an td05-18G turbo, and it also had boost creep.
I also did the test with the disconnected waste gate. it made over 1.4 Bar at 7K rpm!
The tuner i got it from did acknowledge the problem and did a porting to the waste gate and it is now completely solved!!

Also there is no way to map around this problem, without destroying all the good work.
Just get the exhaust site off the turbo and get it ported or do it yourself.

mickywrx

iTrader: (29)

Injector duty will rise, as boost pressure rise's surely. More boost = more fuel required?

sl1000

leaning the engine when going on boost????
best way to get nice round holes in your pistons

just get it ported it isn't that big a job