Pierburg valve bypass

Twinturbo

Junior Member
Messages
101
Hi everyone
New owner of a 3200gt auto from Australia , owned for about 3 weeks now and boy oh boy these Italians can really make an odd car despite being serviced regulary by maserati it has had endless problems since electrically, I'm quite knowledgable in DIY so I'm keen to sort this sexy beast out but a real curiousity for me is my powerband it makes a small torque surge to 7-8psi around 2-3krpm then plateau till around 5-6krpm when it hits 14psi although smooth this is a very odd way to deliver power and I'm brainstorming whether or not bypassin the pier burg valve could deliver the full 15psi in 1 linear turbo surge like all other parallel turbo setups.... Anyone have info on whether this can be done or first hand experience in the bypass mod?
Kind regards
Bjorn
 

Contigo

Sponsor
Messages
18,376
It could be the boost valve which needs cleaning (electrical connectors) if it is flat or something related to the pedal potentiometer/throttle body.

Are there any codes stored in the ECU? Engine light comes on or is on? Need to get the codes to really get to the bottom of it. There are so many things which could cause the problem which you describe.
 

Twinturbo

Junior Member
Messages
101
It could be the boost valve which needs cleaning (electrical connectors) if it is flat or something related to the pedal potentiometer/throttle body.

Are there any codes stored in the ECU? Engine light comes on or is on? Need to get the codes to really get to the bottom of it. There are so many things which could cause the problem which you describe.

No error codes, just an odd powerband , since this vehicle has no boost gauge are there anyone who has studied the nature of delivery? It's like the waste gates are set at 7-8psi spring then the pierburg pulses out to 14psi 5-6krpm , I dont have error codes comming up just curious bout the way and why they would deliver overboost so high up in revs unless my valve is malfunctioning like u suggest, do u get 1 solid turbo surge or staged like I seem to get??
Regards Bjorn
 

Contigo

Sponsor
Messages
18,376
You get a shove in the back like you wouldn't believe when a 3200 is running right. Remove the electrical connector from underneath the Pierburg valve and give it a good clean with electrical contact cleaner.
 

Twinturbo

Junior Member
Messages
101
Update on my boost curiousity study, so I bypassed the pierburg valve to see what the waste gates are set at oem and it does indeed to be 8psi , so the function of the pierburg valve is to bleed extra air from the waste gates to .95bar or around 14psi around 5krpm instead of just giving all the boost in one surge early on at 2.5-3k rpm why though?smoothness ? Traction safety?
I did a test and bled air with a controller to 12psi and it all came on at 2.5-3krpm and indeed felt faster than stock and at a lower boost and still gave a nice cam Surge later on in the upper rev range while keeping boost rock steady at 12psi , that's 2-3 psi lower than stock but cause boost came on early it felt faster than the staged delivery.
My question to fellow modifying enthusiasts is have any of u boosted the turbos in a parallel mode past oem boost pressures bypassing the pierburg valve or is it always done through ecu chips and kept in the "slower" imo staged configuration? Any opinions /advice on this topic very welcome critism included
Regards Bjorn
 

Tamariini

Junior Member
Messages
102
well this topic was an interesting find! I have been researching boost behaviour on my 3200 GTA and have found it rather strange also to be honest :conf:

Because of that i have also been planning to bypass pierburg valve...

Any opinions how to repair my boost control system since i don't have steady boost while driving WOT and boost is fluctuating and you can really feel it on power delivery.

I took log on the boost while accelerating from 30km/h to 170km/h and here is the result, what can be wrong? No vacuum leaks:
 

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urquattrogus

Member
Messages
838
One day someone will fit an aftermarket ecu to a 3200 and take it to a good mapper.

In the process scrapping the original drive by wire throttle solution.

Then we will know what these cars are really capable of! And with greater reliability to boot if done well.
 

highlander

Member
Messages
5,214
One day someone will fit an aftermarket ecu to a 3200 and take it to a good mapper.

In the process scrapping the original drive by wire throttle solution.

Then we will know what these cars are really capable of! And with greater reliability to boot if done well.

I know diddly squat about the dark workings of electronics, but would love to see this happening although I doubt we ever will.
 

davy83

Member
Messages
2,809
I believe if you read some of the press on this car two things come up regularly. One is that Ferrari were pressing Maserati to keep the power down so it did not eclipse the Ferrari's. I am not sure I believe this but its a good story and there are many tales of valve timing being out from the factory and also cars with the valve timing set up properly running on rolling roads with 410-420 BHP.
The other theme with the early cars was that the boost came on too suddenly and was difficult to handle and there was a perceived impression the car was difficult to drive and possibly dangerous and this I think resulted in the later cars having a much more staged turbo delivery and also considerable tweaking with the fly by wire code to make it more drivable. I have a facelift car with the mods and the ECU control of the engine is positively bizzarre in places, it will often run the revs up to get the turbos to kick in and then back off despite what you do with the go pedal, it also hangs onto gears in sport mode and clearly does some fairly radical interpretation between your foot and the engine. So the staged boost delivery would have been introduced to make the car more drivable, and more stylish? It was never intended to be an out and out racer and so the engine is almost certainly not set up for maximum power, its not really what the cars about. I suspect the Maserati view of this is that the power should be enough to give you the desired experience! Personally i like the car the way it is, but like others might be interested in seeing what the engine could do, because I think it can do more!
The boost graphs don't look that bad to me? Are you expecting better consistency than this?

Update on my boost curiousity study, so I bypassed the pierburg valve to see what the waste gates are set at oem and it does indeed to be 8psi , so the function of the pierburg valve is to bleed extra air from the waste gates to .95bar or around 14psi around 5krpm instead of just giving all the boost in one surge early on at 2.5-3k rpm why though?smoothness ? Traction safety?
I did a test and bled air with a controller to 12psi and it all came on at 2.5-3krpm and indeed felt faster than stock and at a lower boost and still gave a nice cam Surge later on in the upper rev range while keeping boost rock steady at 12psi , that's 2-3 psi lower than stock but cause boost came on early it felt faster than the staged delivery.
My question to fellow modifying enthusiasts is have any of u boosted the turbos in a parallel mode past oem boost pressures bypassing the pierburg valve or is it always done through ecu chips and kept in the "slower" imo staged configuration? Any opinions /advice on this topic very welcome critism included
Regards Bjorn
 

zagatoes30

Member
Messages
20,759
The guys who look after my 155 Q4, spent lots of timing playing about with various methods of managing the boost control using the standard ECU and various controllers with some success. However they could never get consistent delivery until we went down the custom map route with electronically controlled boost valves, this pairing got it running a smooth 300BHP on 0.9 bar/ The engine is currently being rebuilt with all modifications designed to work together which will hopefully allow it to safely run more boost and therefore more power.

Learnings have been that piece meal upgrades can release more go but to get serious improvements a wider scope of upgrades need to be planned in.
 

Tamariini

Junior Member
Messages
102
One day someone will fit an aftermarket ecu to a 3200 and take it to a good mapper.

In the process scrapping the original drive by wire throttle solution.

Then we will know what these cars are really capable of! And with greater reliability to boot if done well.

This has been done many times already i think?

One example https://www.youtube.com/watch?v=jDIaRbMCi6A

That is close to what i would want on my cars (My 75 V6 Turbo is very close) power delivery.

But now i want to have boost delivery which stays even and is not constantly going up'n down between 8 and 16psi....
 

Tamariini

Junior Member
Messages
102
well this topic was an interesting find! I have been researching boost behaviour on my 3200 GTA and have found it rather strange also to be honest :conf:

Because of that i have also been planning to bypass pierburg valve...

Any opinions how to repair my boost control system since i don't have steady boost while driving WOT and boost is fluctuating and you can really feel it on power delivery.

I took log on the boost while accelerating from 30km/h to 170km/h and here is the result, what can be wrong? No vacuum leaks:

Answering to myself if someone is having similar problems. The fault was on the pierburg valve hosing, apparently hose from turbine to valve is pinched from somewhere since air is not flowing through very well and i cannot pull hose off behind the timing gear.

I installed new hoses and test drive i went. Pull is even now and i logged boost similarly like i did before and here is the result:
Screenshot_20180428-184935.jpg
Boost is still fluctuating but only between 11 and 12 psi which is very good i think!

Next question, What should the stock boost be? I have found several different "opinions" from this forum and others, variating from 11psi to 16psi but does someone has a fact to tell?
 

lozcb

Member
Messages
12,300
Update on my boost curiousity study, so I bypassed the pierburg valve to see what the waste gates are set at oem and it does indeed to be 8psi , so the function of the pierburg valve is to bleed extra air from the waste gates to .95bar or around 14psi around 5krpm instead of just giving all the boost in one surge early on at 2.5-3k rpm why though?smoothness ? Traction safety?
I did a test and bled air with a controller to 12psi and it all came on at 2.5-3krpm and indeed felt faster than stock and at a lower boost and still gave a nice cam Surge later on in the upper rev range while keeping boost rock steady at 12psi , that's 2-3 psi lower than stock but cause boost came on early it felt faster than the staged delivery.
My question to fellow modifying enthusiasts is have any of u boosted the turbos in a parallel mode past oem boost pressures bypassing the pierburg valve or is it always done through ecu chips and kept in the "slower" imo staged configuration? Any opinions /advice on this topic very welcome critism included
Regards Bjorn
There's a reason most 3200's had rear quarter panel damage , is that turbo kicking in sprightly when accelerating/exiting bends or roundabouts like we have here in the Uk