12 replies to this topic

[Mazzy]

I've been having the part throttle boost issue recently. When on part throttle round town car will dump boost, judder and make the turkey sound. Good news is that it's pretty much 95% resolved. First I replaced my OE recirculation diverter valve with an alloy version (forge copy) from eBay, popped in the yellow spring as car is a CS stage 4 and it's what is recommended for non standard tubbys, went for a drive and it was a little better/smoother but issue was still their. Next I checked all the vac hoses, I found one of the pipes was a little loose on the black vac box, I had some silicone hose at hand and decided to bypass the box completely after doing some reading on the astra vxr forum etc. I plumbed the silicone hose to go straight from inlet manifold to a T piece and then to the FPR and back to the DV. I left the black box in place and the solenoid still plugged in. Went for a drive and the part throttle issue was 95% cured!! It did still do it but very rarely and it was much more subtle, I was infact provoking it for a 10 mile trip and it only happened twice. Still not sure why but it might be the solenoid on the turbo that needs replacing? Either way I can live with it if it's not the solenoid. Will change that next just to see if it cures completely... Issue I have now is Boost Pressure... I did a run/log using Torque App and the peak boost level running through 3rd gear is 29-30PSI. Car was mapped and setup by CS. Why would they have set the actuator to this? Shall I wind it back? What level?

Edited by Mazzy, 28 December 2015 - 12:50 AM.

[Mazzy]

I'm still to try data logging using a proper diagnostic machine. Will try this tomorrow rrow if the weather is good. Have a feeling the torque app isn't so accurate for boost.

[Nev]

Issue I have now is Boost Pressure... I did a run/log using Torque App and the peak boost level running through 3rd gear is 29-30PSI.

Car was mapped and setup by CS. Why would they have set the actuator to this? Shall I wind it back? What level?

 

30 PSI is very very high, something is badly wrong. I'd try and fix that before driving hard or your turbo will not like it. As you say, the first thing to look at is the wastegate getting stuck shut for some reason, may be mechanical (actuator too tight or penny valve getting stuck shut) or might be due to a faulty solonoid (mounted on the turbo housing) or its associated vacuum pipework.

 

GL.
 

Edited by Nev, 28 December 2015 - 09:38 AM.

[stu8v]

Is that gauge or absolute pressure for a start?

[TFD]

What Nev said. 30psi is WAY to high. Either a solonoid or wastegateproblem. @30psi you also should notice a different drive since there's alot more boost. Then theres the bov spring. If you suddenly have use a softer one while all was well some time before, then something is wrong. Softer spring indicates less boost, harder spring more boost. Dont know if yellow is softer (Forgewise it is..) but that would indicate less boost or less vacuum after closed throttle. Pressuretest the system for leaks. Meassure correct boostpressure. Bypass the solonoid to see if boost dropps e.a. is the correct stock boost the actuator is set for. Dont know if bypassing the silonoid gives a code.. Good luck

[siztenboots]

I would back off the wastegate actuator preload a bit , I think chances are you have a solenoid that could need cleaning out , or the actuator needs replacing. The uprated actuators CS sell don't seem to be very robust /  suffer from heat.

 

[stu8v]

Before you do anything put a proper pressure gauge on. It could save you loads of messing about.

[mbes2]

Is that gauge or absolute pressure for a start?

Yep this.. wouldn't trust the psi from your app, even opcom captures the same.. which is 2x boost + xx something added (can't remember what tho) Best you check your boost gauge for a true reading.

[siztenboots]

what you might see in opcom is engine load , 

 

For example, load of 120 , the formula is 120+30 *10=1500mbar, or 0.5 bar boost. *

 

 

* corrected to atmospheric conditions and altitude by ecu

[Mazzy]

Ok, thanks all for the advice guys. Will hook up a gauge to the same vac line and check again. The app is doing a calculation and it does seem wrong. Does the boost solenoid on the turbo come part of the vxr unit as I have old owner receipts for the parts but can't see one for the solenoid. Are part numbers same as the stock turbo solenoid?

[siztenboots]

yes, wastegate actuator and control solenoid is part of turbo unit when replaced , but not the recirc solenoid.

 

give them a good clean through with brake cleaner spraycan

[Mazzy]

Right, update... I plumbed in a boost gauge into the fpr & dvr vacuum circuit and went out for a run. 2nd gear and 3rd runs. Figure below: PSI figures are approx as gauge is in bar: 2nd gear run, peak 1.3bar (19psi) then holds 1.2bar (17psi). 3rd gear run, peak 1.5 bar (22psi) then holds 1.4bar (20psi). So all is OK. The app was giving calculated figures from somewhere and were incorrect. New problem has developed since, onway back home my abs light came on and started flickering fast, airbag light came on (red symbol) and battery light constant. Stereo turned off and back on again, the mileage display backlight kept going off and on but not so rapidly. Is this an alternator issue? I did have my phone charger plugged into the cig lighter and noticed it smelt a little, the cig lighter still works as does the charger. All electrics seem to be working ok since coming back home, have checked fuses, not checked relays (not sure how to other than to swap them with one another?). Only the battery light stays on and the airbag one and abs flickering every now and then. Any clues? Hope its just a relay.

Edited by Mazzy, 29 December 2015 - 05:43 PM.

[stu8v]

Good news regarding the boost issue. Check the output from the alternator with a multimeter.