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Discussion Starter #1
Alright chaps.

Did my tdi conversion a couple of years ago and i've never been able to sort the boost pressure.

Went from ABL to AHU. Fitted Darkside's .220 injectors, a 2.5 intercooler (might change) and had Darkside re-map it. Didn't go so well. They had it all day and when i asked whether or not i should look at getting the next train home the guy at the counter must have took me wrong, got a bit arsey and replied "i should have told you this morning we couldn't remap it and you would have lost your deposit" - bizarre! Then he went on to say, " because we have to remove the ECU every time we need to alter the settings it takes longer (understandable) and really we should tell people the job is two days, but people don't want to pay for that". Never told me when i bought the job!
Anyway, it makes about 130bhp now (hoping to improve overall performance with some hardware changes and another map) but, i have an issue when the wastegate opens. It doesn't hold a steady pressure on the gauge. It was like this before and after the mapping. The needle bounces once the wastegate opens at max pressure, which went from 1 bar standard to 1.5 after the map was done.

Think i've read before that others have had this. I've played around no end with the actuator preload. In fact, prior to getting the tune done, I wound the thing up tight enough to put it in limp mode, but it held steady until going into limp mode. Obviously couldn't dump the pressure. However, no matter how much i keep increasing the spring pressure (shortening the rod) it won't steady the actuator now.

I could replace the actuator. I could do something with the N75. It's been suggested there could be a boost leak. Just after any info if available. I've renewed all the vac/pressure lines.
ANy pointers greatly received. Cheers
 

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Seems to me your turbo is defective, start by getting the turbo checked 1st although i would get a VNT conversion as that would open a whole scope for tuning. If you still want to retain the wastegated setup then there are larger, more potent turbos from some iveco/peugeot vans or even a very nice turbo from mercedes Atego truck- expensive though ! Your nozzles are a touch small, i would go for 0.260 nozzles from Bosio or even larger from Firad or gibonta...but what you got will do for time being ! I dont know your ecu type but some can be flashed trough the OBD port, some only by taking off the 2x PCL chips from the ecu and flashing them in a programmer...what year was the donnor AHU engine and do you know what type o ecu you have msa15 or edc15v ?
 

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Discussion Starter #3
Seems to me your turbo is defective, start by getting the turbo checked 1st although i would get a VNT conversion as that would open a whole scope for tuning. If you still want to retain the wastegated setup then there are larger, more potent turbos from some iveco/peugeot vans or even a very nice turbo from mercedes Atego truck- expensive though ! Your nozzles are a touch small, i would go for 0.260 nozzles from Bosio or even larger from Firad or gibonta...but what you got will do for time being ! I dont know your ecu type but some can be flashed trough the OBD port, some only by taking off the 2x PCL chips from the ecu and flashing them in a programmer...what year was the donnor AHU engine and do you know what type o ecu you have msa15 or edc15v ?
Hi

Thanks for the reply.

So you think my turbo is knackered? Can you describe how it's causing the issue? It provides boost up to the maximum ok, it's just when it hits maximum and the wastegate needs to modulate it that i get the bouncing needle on the boost gauge. The ECU has to be mapped off the van, not via the OBD - at least this is according to Darkside Develpments. I'm fairly certain this is correct. It's a 1996 Golf it came from. Metal type ECU now socketed with the tunable chip.
To be honest, i have it in mind that the injectors are a tad on the large side for the turbo as it's a bit of a smoker. It's done 145,000 miles on the ABL it came off and is leaking a bit too much oil into the inlet so i am now thinking about upgrading. I was wondering about a GT1749 as i have seen that one of these was fitted to a VE engine with the same nozzles i have and was achieving 157BHP without anything else significant done to the hardware (not sure what the torque was) prior to going for some further mods (this is on Darkside Developments website under project cars. A Caddy).
I've spent a lot of money on the nozzles and calibration so they're staying. I've just bought a Passat 130 inlet mainfold to fit and i'm looking into the easiest intercooler upgrade - apparently there was a front mount on a 2.5 T4? Some available from germany on ebay.

One thing about the VNT i have a question on is whether it will work off the current N75 setup i already have? Just hook it up as the wastegate does?
 

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Discussion Starter #4
Another question i have is exhaust mainfold. Will a Golf/Passat manifold fit as i believe i'll need to use it with that particular turbo due to the manifold casting forming the turnine casing. I know some people use the Golf exhaust manifold and turbo when doing the conversion as they don't have the ABL parts, then cut and weld the downpipe accordingly. So i know the bottom slung setup fits the T4 but the GT1749 is a bigger turbo and there are also many variants with the boost outlet facing different ways etc. Looks like a bit of digging will need doing..
 

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Rikki, buy a acdc welder, learn how to weld then you can make anything fit under the bonnet. Your wastegated setup wont work with VNT turbo, you will need the correct n75 solenoid and the map modified to suit the new turbo. Having a chipped ecu is a pain as the map has to be written on a eeprom programmer and most PCL chips are one time only...
 

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As for the intercooler part, a cheap universal kit comes with pretty much all you need in the box, use your imagination to route the pipes and look for inspiration on the web...
 

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Discussion Starter #7
Rikki, buy a acdc welder, learn how to weld then you can make anything fit under the bonnet. Your wastegated setup wont work with VNT turbo, you will need the correct n75 solenoid and the map modified to suit the new turbo. Having a chipped ecu is a pain as the map has to be written on a eeprom programmer and most PCL chips are one time only...
What's the difference between the N75/actuator setup on a wastegate turbo vs a VNT turbo? The ECU is getting manifold pressure feedback and modulating the N75 to achieve the right reading. The actuator is a spring and a diaphram that responds to change in pressure controlled by the N75. On the surface they look the same, they just operate a different lever. Can you explain what's different and why the hose from my actuator won't operate the VNT's actuator?
I'm really just looking for bolt on parts. If a manifold and turbo off a PD will fit then that's the way i'll go with it. Obviously the downpipe will need cutting and welding, which a mate of mine can do.
As for the chipped ECU, it's the only way to change the map, which i'll obviously have to do once different parts are fitted. It's a rewriteable chip and the van has spent a day on a dyno being tuned. Unfortunately the tuner didn't act in the best way on this occasion but that's why i'm where i'm at with considering further upgrades, along with the problem (assumed to be) with the wastegate. You mentioned it was my turbo as the problem?

As for ther intercooler, yes, i'm looking at all of the options for a FMIC and what i'll have to configure with various hoses to connect it. I could go for a generic from just about anywhere and make it fit, a Sprinter, a T5, or the T4 FMIC which i don't believe i've ever heard mentioned on this forum. Looking at the models listed on their ebay page it was only on 102 and 151 versions but it doesn't state if it fits a short nose or long nose, hence my question.
 

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Wastegate works by using boost as reference and vnt actuator uses vacuum...maps in the ecu are not in same location and needs grafting in which in turn changes checksum on ECU... Also you need a vacuum accumulator and a one way valve to stop it from going back to servo...Its not difficult to go vnt especially as VAG has done legwork for you on other models- look at a AFN map and see the N75 values and PID corrections...
 

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Discussion Starter #9
Wastegate works by using boost as reference and vnt actuator uses vacuum...maps in the ecu are not in same location and needs grafting in which in turn changes checksum on ECU... Also you need a vacuum accumulator and a one way valve to stop it from going back to servo...Its not difficult to go vnt especially as VAG has done legwork for you on other models- look at a AFN map and see the N75 values and PID corrections...
Nice one, cheers.
 

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Discussion Starter #11 (Edited)
Just looking at some things you previously mentioned, i guess i need to fit an AFN MSA15 ECU in order to run a VNT? Or is it just a case of programming?
I've now seen there is the possibilty of converting to EDC15, which will allow easier mapping but involves a bit of work. Not sure if that's entirely worth it for that reason.
 

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Getting your car setup for a edc15 will mean easy tuning in future...youre just a flash away and trust me, it takes loads of flashes and log sessions to get a half decent tune- just as many tuners will tell you !

You can also use a AFN flash file on your ecu assuming firmware will allow it to work...If you get an "internal checksum error- permanent " then you most likely bricked the ecu...MSA15 ecu's are very, very old and with boost increase you might want to add a 3 Bar MAP sensor and adjust diagnostic capabilities which are difficult to upgrade on the ecu's with internal MAP sensor... Start by reading a lot and register yourself on ecu-connections forum as nobody will spoon- feed ya the info you crave...Some folk make good money out of unsuspecting prey like yourself...so called tuners !
 
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