Turbo Direct To Actuator - Still Getting Over Boost - Whats Your Guess

[rockafellqeinstien]

Hi guys, just wanted confirmation on an issue I am having.

I think I am over boosting when temperature is less than about 30 degc. I say I think, because the car (fg) is throwing a p0236 code. now this isnt exactly an over boost code, its saying the Map sensor is out of range. it can throw this code at anything above 18psi (which is my target boost).

So if it was over boosting it could still throw this code but there is a chance that it is the map sensor causing my grief. So I did a leak test on the I/C and piping and besides a few little issues it was fine.

The tune is requesting max duty cycle where its over boosting (waste gate fully open), so I thought maybe the solinoide or actuator is causing a problem. I put a regulated air supplly to the actuator and it opens - doesnt seem to open a lot at 12 psi (its a 12psi garret actuator) but as you dial the presure up to 20psi it opens more. it still continues its travel until about 25 psi. Do you think that if you were able to bring that last bit of travel back from 25 psi to a more usual 18psi, would that help control (I dont think it would really add much flow)

then to eliminate the solenoid I connected the actuator direct to the turbo. my understanding is that this will hold the flapper shut until 12 psi at which point it will start to open the flapper as boost goes beyond 12 psi (comming directly from the turbo.)

Went for a spin and nothing seemed to change. still over boosted and same fault code. although on the boost gauge(using anroid app off the obd port) there was no change in the turbo boost rate of increase around the 12psi point. I would have thougt that at 12 psi where the waste gate would start to open, the rate of boost increase would have slowed - but it didnt. So I am thinking (always dangerous) that the enlarged W/G port is still to small (cant bleed enough exhaust before it hits the turbine) or its a faulty map sensor.

I am working with the tuner of the car, but I live a fair way from him and if its something simple, well that helps everyone (saved a lot of hastle previously with self diagnosis - mainly related to boost leaks.

I also have a afr meter wide band and it is showing higher readings than I would like at the overboost point.

also, would I be corect in thinking you can not tune out over boost if the waste gate is simply too small.

thanks for any help

(specs) gtx turbo xforce 3" sysytem with 4" dump id1000 surge tank and pump valve springs 4" turbo side intake PW stage 3 cooler and pipes

Edited 20/01/13 07:29 AM by rockafellqeinstien

[ratter]

you are correct in assuming you can not tune out an overboost situation because of hardware used and a wastegate that is too small, but the tune can alter the settings to stop an overboost code and/or limp mode from being set

[Maggotmouse]

I just recently got a tune and they could not get over 12lb, they maxed out the boost side of the edit (I dont know) they thought maybe the actuator, which is brand new when I got the wastegate ported and flapper, got a compressor wacked 12 lb down the actuator and it opened, fliped off the arm and check pre load, all good, when on boost could hear a whine, boost leak, removed all the intercooler lines and used hair spray lol on the joins, (as seen on you tube) and 24 hours later went for a drive and F me, did a few wide open runs and backed off when the gauge hit 21lb, so I'm booked in for a re tune on thursday, hoping this has fixed it

[Ralph Wiggum]

  On 20/01/2013 at 7:29 AM, ratter said:

you are correct in assuming you can not tune out an overboost situation because of hardware used and a wastegate that is too small, but the tune can alter the settings to stop an overboost code and/or limp mode from being set

^this + whats your preload on the actuator like? it should not take 25lb's to get fill travel out of it. Sounds like some of the travel is bein eaten up by excess preload

[rockafellqeinstien]

Thanks for that, Not sure on the pre load, I was going to try and remove the arm from the waste gate and have a play but I dont think I can do it while the turbo still on the car - I reackon I'd have no chance of getting the circlip off while its all conected - curse my large hands..

and pulling the turbo out doesnt sound like a fun way to spend my one day off a week

[getuted]

This probably wont help but ill say it anyway, Putting shop air on an waste gate actuator can give misleading indications as to when the waste gate actually opens when driving. I found this out when swapping my actuator for a new stock BA one. I checked it with a regulated shop air and it didn't start to move until 10 psi. Stock boost is around 5 psi what going to happen if I install this one. I installed it anyway and bypassed the boost controller ( compressor straight to actuator) to be safe and went for a drive. I only managed to get 4 psi of boost, creeping to 5psi at high rpm. Puzzled I did some thinking and worked out I forgot to take into account that the exhaust gas is pushing on the flapper valve as well as the actuator, hence the reason I was only getting 4-5 psi and not the 10psi or more I was expecting.

[45T-XR]

You can circlip trick in car, just unbolt the dump off the turbo and move it to one side then use cable ties to tie it up to the exh manifold. Then apply compressed air to the actuator gently and it pushes the flapper open and extends past the turbine housing, a seal pick works well to pull the circlip off then you can pull the rod off the flapper and reduce the preload... It does definaayely sound like a preload issue. My 12lb actuator I have on the gtx I just fitted has around 7.5-8psi cracking pressure and is fully open at around 12psi, ive got around 80% wastegate duty for 19psi boost uptop.

[Madwhip]

How did you get on with this rockafellqeinstien? was it all in the preload?