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Go Back   TDIClub Forums > VW TDI Discussion Areas > TDI Power Enhancements

TDI Power Enhancements Discussions about increasing the power of your TDI engine. i.e. chips, injectors, powerboxes, clutches, etc. Handling, suspensions, wheels, type discussion should be put into the "Upgrades (non TDI Engine related)" forum. Non TDI vehicle related postings will be moved or removed. Please note the Performance Disclaimer.

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Old December 6th, 2005, 17:34   #1
cathalferris
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Join Date: Jun 2005
Location: Limerick, Ireland
Fuel Economy: 580 miles/62litres
Default Wiring pinout for MAP sensor

On the combined MAP/AIT (manifold pressure/air intake temperature)

pic:

there is a 4-pin connector. I want to double-check that it is the yellow-green and the yellow-blue that are to be bridged.

I found a nice link that describes a similar sensor, but the wire colours are not the same.

I don't want to guess this.

Thanks.
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2002 Audi A4 variant PD100@140+, 245ft-lb. Otherwise stock.
1998 Passat variant (sold), AHU, GT15, @120 bhp (VAG-COM butt-dyno), Boost sensor cap, boostvalve at 1.2bar. 203,000 miles. Based in Limerick, Ireland.
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Old December 7th, 2005, 08:40   #2
cathalferris
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bump?
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2002 Audi A4 variant PD100@140+, 245ft-lb. Otherwise stock.
1998 Passat variant (sold), AHU, GT15, @120 bhp (VAG-COM butt-dyno), Boost sensor cap, boostvalve at 1.2bar. 203,000 miles. Based in Limerick, Ireland.
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Old December 7th, 2005, 15:09   #3
cathalferris
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Yep it was the yellow-green and the yellow-blue wires that are the MAP sensor leads. Now for some fun and games with sensor output modulation
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2002 Audi A4 variant PD100@140+, 245ft-lb. Otherwise stock.
1998 Passat variant (sold), AHU, GT15, @120 bhp (VAG-COM butt-dyno), Boost sensor cap, boostvalve at 1.2bar. 203,000 miles. Based in Limerick, Ireland.
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Old December 8th, 2005, 01:51   #4
Cheshire Cat
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despite the massive responce, please keep us posted, cheers Nic
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Old December 9th, 2005, 11:37   #5
cathalferris
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Default Success!

Alright!

I now have a MAP that is reporting to the ECU the way that I want it to. It reports as normal for the low boost conditions, but it will only report a constant medium value once the real values go above what would previously have caused a code to be thrown and limp mode engaged.

Monitoring vag-com controller 1 (engine) block 11, I can now see that at idle, the MAP reports the exact same that it always did. However, once the actual MAP pressure goes above a certain limit (1350mbar for a 2.7v zener diode and 300 ohm resistor) the MAP sensor only reports that clamped pressure of 1350mbar. I have a dawes device controlling the higher pressure region the way that I want it to - spike to an indicated 1.15 bar on my boost gauge dropping back to 1.05 bar constant. I think I'll play with the dawes device to get it to hold at 1.15 constant - the spikes are so short and so small that I'm not worried about them.

My circuit is so simple. I have from the yellow-green wire, a 2.7v 0.5W zener diode with the band towards the sensor, in series with a current limiting resistor of about 300ohm, connected to ground. No connection of anything to the yellow-blue sensor wire.

I'll be trying different values for the zener diode when my electronics shop gets them in stock, I think the ideal value will be either with a 3.0v zener or else with a 3.3v zener. I'll have to experiment and see, but I have a feeling that the engine will limp mode on me with the 3.3v because at high revs it'll be showing 150mbar too high from the sensor when compared to the requested at 4300rpm.

My turbo pressure control piping is like this:
Banto bolt on the gt15
Short tube from there to the tee for my gauge
Short tube from there to the tee for the dawes device.
Longish tube from there to the N75.
I have the second connector from the dawes device put in close to the wastegate controller.

I'm happy with the way that this works, and it looks like I'll be able to make it switchable also.
I have to go and mount the menagerie of cables and free-hanging components down onto a little breadboard in a little tidy plastic box to hide in the dashboard.

I'm all ready now to have those pp520 injectors in and performing without smoke! I'll have some pics up soon, but the wire work is certainly not pretty and I'm not proud of how it looks. I could go and get the proper VAG connectors and splice in correctly, but that would take a while for them to come in.

I'll have to be careful though, as masking the higher MAP values from the ECU removes one safeguard from the system. The ECU cannot know if there is an overboost condition... so if the N75 fails or a pressure control pipe comes loose, it could be a bad day. I'll just have to monitor the boost gauge religiously.



I've driven with this in for 200 miles today in various traffic conditions comparing to the output from the vag-com to the boost gauge. I'm not throwing any codes, but I can feel the little loss in horsepower from putting that little bit more energy into the turbo than before.

My reference links include:
MAP reference
and various threads here on MAP clamping.

My way will not cause a CEL because of differences in the idle values reported, and I think that it would also be applicable to those that are unchipped with the newer two-pin MAP sensors (chips will need to see the higher MAP).

What do you lot think?
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2002 Audi A4 variant PD100@140+, 245ft-lb. Otherwise stock.
1998 Passat variant (sold), AHU, GT15, @120 bhp (VAG-COM butt-dyno), Boost sensor cap, boostvalve at 1.2bar. 203,000 miles. Based in Limerick, Ireland.
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Old December 14th, 2005, 15:41   #6
belinassu
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hi, my engine (tdi 1.4 3cyl) has a GT15 also...
i tried to rise the boost using the 130TDI MAP (3 bar range instead of 2,5)
and it seems to be better from 1800 rpm
but it lose power before this rotation speed
and i needed the fuel sensor trick (with a 180ohm resistence)...

i'll work on the MAF signal next step..

Last edited by belinassu; December 14th, 2005 at 15:47.
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Old December 15th, 2005, 13:28   #7
cathalferris
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I couldn't use the 3 bar sensor, as I have the combined temp/pressure sensor.

I presume the fuel sensor trick is to change the fuel temperature reported to the ECU? Can you see the effects with a vag-com? Do you get lots of smoke at WOT at higher revs?

For nice info for the MAF sensors, look at http://www.geocities.com/tech4tdi/

I got me a 3.0v zener this evening, I'll play with that tomorrow, and I'll try to get a little circuit soldered up to make it all tidy.
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2002 Audi A4 variant PD100@140+, 245ft-lb. Otherwise stock.
1998 Passat variant (sold), AHU, GT15, @120 bhp (VAG-COM butt-dyno), Boost sensor cap, boostvalve at 1.2bar. 203,000 miles. Based in Limerick, Ireland.
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Old December 15th, 2005, 22:24   #8
mojogoes
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Why don't you all just go back to a mechanical pump no ecu and have done ??
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Old December 16th, 2005, 10:51   #9
cathalferris
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Quote:
Originally Posted by mojogoes
Why don't you all just go back to a mechanical pump no ecu and have done ??


Because it's nice to play and to find out how it all works and how it tweaks!

Having electronic control of the system is much better for me, as I can then play with settings via the laptop instead of having to go digging with the spanners. Doing this whole sensor modulation with the boost control system is an experiment for me, to see what-if, and to stay working within the constraints of the engine limits.

Playing with the sensors in the manner I have implemented means that I retain full ECU control on idle and part-throttle, and gives me the headroom to do more without going down the chip route. I will be getting RC3 within the next few months, but it is nice to know that the limp modes can be bypassed safely for the meantime.

By the way, that 3.0v zener makes the ECU see a max value of 1490 mbar as seen on block 11 in Vag-com, and the boost gauge reads 1.2 bar max. I have to wait for the local Maplins to get the next-higher steps of diode next week to get the MAP sensor to match the lowest value of requested boost.

Diagrams and a write-up in a new thread to follow when I get the whole thing sorted, and verified.
Watch this space!
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2002 Audi A4 variant PD100@140+, 245ft-lb. Otherwise stock.
1998 Passat variant (sold), AHU, GT15, @120 bhp (VAG-COM butt-dyno), Boost sensor cap, boostvalve at 1.2bar. 203,000 miles. Based in Limerick, Ireland.
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