Pitzi

I have a problem, since I have fitted a 3" full free flow exhaust and twin downpipe, I have a problem, with spiking boost, it was suggested to me to fit an electronic boost control (the car has a Prodrive ECU) that would allow me to use pump fuel as I could decrease the boost, and it would also cure the spiking. this I have done, but spiking is still there, when the car gets on boost, if the EBC is set to 1.0 bar it will spike up and down to 1,1 bar for a few seconds, creating a yo-yo effect, very disturbing. it was suggested to me to fit a 3-port boost solenoid as the OE solenoid apparently cannot cope with the speed that the boost builds with a de-restricted exhaust?? it was also suggested that I should have a look at the wastegate spring?? but this sounds wrong, beecause I had no such problems before fitting the 3" exhaust. Has anybody had similar problems and what is the solution?? I dont want to spend a lot of cash on parts that do not need replacing, but I cannot live with the car as it is now.

Second problem is that when I run 102RON fuel, I cannot adjust boost to higher than 1,1bar because it feels like the ECU is shutting down the fuel supply or something, as soon as boost goes past 1,1bar the car just seems to hit a brick wall for a split second, any ideas/solutions??



Any help would be greatly appreciated!!

DrEvil

Back to the top - someone will have some ideas to help this new guy

Katana

Try Dawes. Its only 40 quid.

Pitzi

Excuse my ignorance, what exactly is Dawes???

dhorwich

The brick wall is fuel cut... due to over boost you will need a fuel cut defencer to overcome fuel cut... basically it is a safty mechanism to protect the engine..

You will not get over 1.1 bar unless you fit the FCD...

Dan

dhorwich

a dawes is a manual boost controller...

http://www.dawesdevices.com/boost.html

Dan

Katana

Yup, the Dawes is good alright. Try to get an FCD and you'll be laughing. Not only will it stop spikingm it will also make your car run faster.

Pitzi

Thanks for the advice guys, but I have already got a boost controller, but this hasn`t cured the problem

Katana

You've got a dawes or a bleed valve?

Pitzi

I have an EBC that works on the standard boost solenoid(OE 2-port)
You can manually adjust maximum boost from a **** in the dash.

Pitzi

I have read that a 3-port boost solenoid will cure this, anybody tried this mod???

ustolemyname??stevieturbo

iTrader: (1)

What sort of EBC do you have ? The settings on it can cause the yo-yo you describe if they arent correct. If you want to run so close to the boost cut, then it may be necessary to remove it with a FCD or similar device.
I have also seen cars in the past, for no real reason, after fitting a complete exhaust running into a problem where the boost will always be to high, regardless of controller. ( Ive only seen it happen on pre-MY96 TD05 cars )
The only way I could get control over the boost again, was to modify the wastegate port on the turbocharger to allow more ex gasses to bypass the turbine. This involved removing the turbo, and porting the wastegate. It is as std a very sharp turn, and all I did was smooth this out a bit to allow freer exit. Boost control after this was as normal.
Im not sure why only some cars are affected. The first time it happened, i tried phoning not only the supplier of the exhaust, but also the other supposed experts in the UK who work at subarus. None could offer an explanation as to why the car was overboosting and claimed they had never seen it before. It makes me think that some of the tuners around are no more than glorified Kwik fits.

Pitzi

Evilbevil, thanks for the info.
Regarding the fuel cut out, the PPP ECU was only boosting up to 0,9 bar, that is why I fitted an EBC, to be able to run higher boost when using 102RON, I had never experienced tghe fuel cut-out before fitting the EBC.

I was also told that by fitting the EBC, that spiking would be eliminated, clearly this is not the case, funnily enough, I have tried to turn the EBC down, to 0,6 bar which actually means that the boost solenoid is open, and only the wastegate is regulating the boost. The yo-yo effect on boost is still the same, does this means that the ECU is doing this, or does it mean that the actual culprit is the wastgate spring??

Pitzi

Ustolemyname, the overboost and fuel cut off is not what is bugging me the most, what I am trying to get rid of is the yo-yo on boost, its so bad that the car actually feels that its surging when I accelerate. I really dont mind restricting my max boost to 1,1bar, maybe its better for the engine that way, but the surging is what bugs me.

EvilBevel

Have you tried cleaning out the solenoid / pipework / restrictor ?

What happens when you make a direct connection from turbo nipple out to wastegate ? (should see 0.6 bar ish) Still surging ?

Best is to remove EBC, eliminating possible culprits one by one. Always hard to diagnose from a distance, mind.

john banks

I posted in your original thread - any capable EBC with the right settings should easily sort this spiking out so assuming this I would check your wastegate and its actuator.

raybotha

Pitzi , Ray here , hello from South Africa . Just a few of my thoughts . Have you changed your air filter , and have you decatted your uppipe ?? These 2 things caused me probs on my WRX (no PPP) as the MAF packed in and the wires that attach to the EGT also came unstuck when the EGT was screwed back in . I had an EBC (MRT) unit installed at the same time and also experienced surging . Adjusting the sensitivity help zip . Eventually sold the car ..... Now am driving an STI VII and wonder why anything more than adjusting the size of your restrictor is being recommended ? 0.9 bar with a PPP is below the norm as far as I'm aware , perhaps you should take all the gumf off and get the car running good without any extra help form the EBC's etc. I knnow the ECU will help the overboost effect after 200k's or so . It will definitely stop the shock effect of brining the boost back too far then back up to normal again . I strongly recommend sorting the "problem" (surging) out then going for more boost after , its the same method I believe . Just as an experiment why not refit your origional back box , this will tame the over/underboost symptom and verify the extra flow as being the culprit , not some other malfunction as you suspect . Refitting my standard backbox helped me understand the workings of the car better . You will aslo see faster results as there is less to tame .
Hope this helps , e-mail me direct if you want someone to chat to , I hate to see someone throw money in the wrong direction as I have done .

Ray

Pitzi

Evilbevil, the EBC was installed to try and cure the problem, its not the EBC, because the car was exactly the same before. What I have tried is to adjust the EBC atthe lowest setting, which means that the solenoid is open and the car is only boosting what the wastegate is allowing, 0,6 bar. The surging is still the same.

Regarding the boost cut-out at boost levels above 1,1 bar, I will fit a boost cut defender, this should solve that specific problem.
What still intrigues me is the spiking/surging, the surging being the most irritating of the 2

EvilBevel

>>which means that the solenoid is open

Small detail, but it would mean the solenoid is closed really. Hence giving full pressure to wastegate (instead of bleeding off air), hence boosting on wastegate spring strength only (0.6 ish bar)

John, from your reply on the other thread, I gather you think you can't cure this with a different restrictor ?

Did all this Dawes malarchy begin because you couldn't control boost that way ?

Pitzi

Evilbevil, excuse my ignorance!! Although I am a DIY mechanical minded person, this is my first scooby and I have had it for 3 months now, so I am not really familiar with its quirky mechanicals

I love & enjoy this car so much, and I have spent a fortune on engine and cosmetic mods, I would really be happy to sort out this spikin/surging as I am a bit of a perfectionist and it drives me nuts!! Problem is that here in SA, if you go to 3 workshops/specialist each will have their different ideas, that is why I posted here to see if anybody knows what it is.

So far, locally this is what I have been told to do:

1 Fit EBC (done and its done nothing to cure this)
2 Fit 3-port solenoid
3 Fit larger restrictor
4 Wastegate spring/actuator is faulty
5 Fit a boost cut defender

Now, if I am to do all this, it will set me back a fair amount of money!!

EvilBevel

Pitzi, sorry if it looked like a dig, wasn't meant like that at all.

Just some info that may or may not help you to understand your problem better.

I know how it feels when everyone tells you different things...

I would try the restrictor first... it costs nothing.

If that doesn't work, fastening the waste gate rod is a free mod, but take care to not take it too far. I think there's a thread in this section from the last 2 weeks with pics & all (from PD20, sorry forgot the name) on how to do that.

It is perfectly possible to control boost up to 1.2 or even 1.3 bar on a MY99 without any spiking etc... with the standard solenoid. It may involve "fooling" the MAP sensor a bit to both put the fuel cut a bit back and having the ECU back off trying to control boost too much.

That said, if you have the problem at 0.6 bar, it's got nothing to do with the ECU probably, and as John says, might be just the wastegate actuator. See the thread mentioned above on how to experiment with that yourself (but keep it safely)

Again, I once paid 1.000 UKP to fix "overboost" on my T5 ... later on I found I could have done it myself in about 5 minutes

In short: try the cheap options first.

Pitzi

No mate, I didnt take it as a dig!!
I have just checked, my car hasnt got a restrictor, I remember that the person who installed the EBC said that the restrictor is removed when they fit the EBC. Will probably try the wastegate actuator, and see what happens.
Thanks for all the ideas

EvilBevel

Pitzi, as has been said... you are hitting overboost protection, and no boost controller will change that unless you fit another gizmo that will either remove or change the standard 1.1 bar fuel cut protection.

The boost spike is also normal for a PPP with downpipe, and a brass restrictor with a slightly bigger opening will cure this. (very cheap)

The "floating" boost is the soft overboost protection (ECU trying to control boost), the brick wall is the hard fuel cut.

Edited to say that you don't need another solenoid (yet ) to solve your problem.

[Edited by EvilBevel - 8/11/2002 12:07:19 PM]