147JTD pre-cat removed

Today I was removing the pre-cat from my 147JTD 8v, according to recommendations of our friend kgb... One week before the main-cat was removed, to. Sound of the engine on the high revs is with some turbine note now. Everything is OK (no any failure light in the board computer screen) and Alfa go very well. The picture bellow shows the removed pre-cat and replacement pipe.

Next step is the new ("semisport") backbox and finaly one good remap.
Cheers. Dusan.

Was there any noticable power/performance gains removing the pre-cat rather than just the noise at higher revs?

Cheers,

Mark

Hello Mark_JTD
Maybe it is only the suggestion but I think that my 147JTD 8v now goes in low revs easily than before. Although dyno test is only way for verifying of BHP and Nm gain, it is well known that removing of both cats boost performance, in case of turbo diesel engine. Back-pressure is unwelcome and harmful for turbo diesel exhaust system.
I have not extra noise in high revs (it is diesel), already the mentioned turbine note (something like whistle), but sound is significantly quieter in compare to petrol engine without catalyst. Only the sound from the engine (front of car) is usually audible. The exhaust noise is like before (diesel silent and deep sound).
Best regards
Dusan

Thanks Dusan for the info. I'll maybe take a look at doing this myself

Cheers,

Mark

Turbo will generally spool a lot quicker without the cats in as it can clear exhaust gasses faster

The only problem you might experience after the remap and usually after installing also the BMC-CDA!! is the solenoid valve that controls the vanes of the turbo. It costs about 60-Euro.

Good thing to do is to spray some WD40 on the....missing my words here...the thing that looks like vacuum reservoir on the turbo...and that controls the vanes....maybe a picture will better explain it.

Do NOT spay WD40 on the turbo itself.

Thanks for your opinions dear colleagues... It is so motivating for me in my tuning efforts!
I have some questions for you:
● What is your opinion about of preliminary essential activities before remap of my Alfa (for example: injector cleaning, MAF sensor check, solenoid valve check, etc)...
● Which BMC-CDA is enough good for 147JTD: 70-130 or 85-150? Where would be located the cold air induction pipe input?

Thank you in advance for your answers and best wishes,
Dusan.

Anyone got a photo of the solonoid valve or the exact location?

Cheers,

Mark

For the 147 or for the 156

For the 147 it is located on the back of the Air filter box.

On the 156 I think it is on the radiator.

Just follow the small rubbber pipe from the turbo actuator.

I know the one you mean now, yup it's in the middle at the bottom of the rad on the 156.

What exactly does the valve do and how does it fail?!

Sorry for hijacking your thread a bit Dusan.

Thanks in advance.

Mark

It is Ok. I am interested about right location of solenoid valve, too.
I am still waiting yours response about pre-remap activities.
Best regards. Dusan.

Originally Posted by Mark_JTD

I know the one you mean now, yup it's in the middle at the bottom of the rad on the 156.

What exactly does the valve do and how does it fail?!

Sorry for hijacking your thread a bit Dusan.

Thanks in advance.

Mark

That solenoid is actually an electric "Motor" that controls how much vacuum is going to the turbo actuator which controls the vanes....which controls the turbo boost.

The solenoid with time becomes "lazy" if I can say that....it can not quickly enough move the vanes on the Turbo so that the pressure doesn't rise about the trash hold level which is given value in the map in the ECU.

For example when you accelerate hard...in the first few seconds the ECU uses its overboost map...so the Turbo pressure can go to 1.7Bars (2.7 with atmospheric one) then it has to lower to hold boost level...lets say 1.5BAr...and has to stay there....

When the Solenoid valve is "lazy"....when you press hard the pedal the boost level goes to 2.5BAR (3.5bar atmoshp) instead of 1.7Bar....the car goes like crazy but then...you get the limp home mode...Error on the menu screen as the Turbo can not lower its boost to pressures below 1.56Bar IN TIme to the normal 1.5 which is giving in the map.

If you drive normally you won't get the problem....but it usually appears while overtaking..which is dangerous...Keep in mind that if you get such error...just press the gas pedal to the floor...otherwise the ECU will cut the fuel supply and you are in a bad situation. The ECU will "reset" itself the moment you change gear...basically the moment when you release the pressure from the turbo...

You can search for an very old thread started by me.... JTD overboost problems with BMC-CDA fitted or something like that, to see the actual numbers.

Vise versa if you have anywhere on the vacuum pipe that goes to the solenoid valve, the turbo won't be able to raise its pressure and the car will become very slow and the ECU will put it into limp home mode.

In my experience 80+ % of overboosting problems with the VNT turbo JTDs....meaning anything other then the 105hp version on the 156/145 and 136bhp version....are coming from that valve.

Other 10% is from sticky vanes...then you need to open the turbo and clean it...not a very hard job...but it has to be done very nicely...if you don't clean it well you will still get the problem.

Another 5% is from a non closing EGR valve on full power...which lets exhaust gases again into the inlet manifold and raises the pressure which is detected by the MAP sensor. On almost all JTDs it is better the close that valve at all times....it is needed only for Emission levels anyways.

If I find the video clip of the cut turbo with moving vanes which I made from this year's Geneva Motor Show I will post it here.

Originally Posted by dusan

It is Ok. I am interested about right location of solenoid valve, too.
I am still waiting yours response about pre-remap activities.
Best regards. Dusan.

Pre-remap activities.

It is good to diagnose the car with someone who really knows what he is doing....EGR valve operation, high pressure fuel pump, MAF sensor, any errors on the car. Very common ones on old JTD cars are P0191 usually a problem with the regulating valve on the high pressure pump about 160Euro. P0235 overboosting....

Check all the turbo pipes.

Check your brakes...especially your brake pads...there is a lot of turkish low quality staff in our region that can cause huge problems!!!

Good thing is to change the anti-freeze and clean the water radiotor, also the intercooler.

You can change the brake fluid to racing one...like Motul RBF600 Dot4.

Basically your has to be in excellent condition....that is your safety!!!

You don't have to worry much about the engine...that engine can last for 1 600km without oil pressure...

Thank you kgb very much, your contribution for tuning ideas is valuable and very friendly . I will go in local garage and check all things according to your recommendation. Tomorrow (Saturday) in BataSportAuspuff company should be making the backbox with oval endpipe. I will send pictures of new backbox as soon as possible.
Cheers and best regards
Dusan