map sensor short to ground

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Iklein
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map sensor short to ground

Post by Iklein »

Hi guys,
So on the dyno yesterday, using vcds to check funny performance, we got "map sensor error short to ground" after replacing the Map sensor and reset error codes. Anyways got home n started fault finding the map sensor pinouts to ecu and checking for shorts between the 4 wires. I don't get any shorts. I get continuity of all the wires from sensor side to the the ecu side plug. With ecu plugged in..on the map sensor wires I get:
Pin1 - Gnd
Pin2 - +5v
Pin3 - +5v
Pin4 - 0.016 (signal wire I assume)

Is this correct? Is there indeed a wiring problem as tuner says it is?
Should I check voltages on the Map sensor with it plugged in as well and what should I get on the sensor itself?
It is the car is SIG(was busy tuning piggy back), has new Map sensor,new temp sensor..

Thanks
Polo playa 2001 2.0L 8v, headwork,xorst,282Estas,Uniq - 99kw 189nm
Mk1 Golf '85 1.6 sold
Mitshubishi Tredia '85 sold
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panic-mechanic
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Re: map sensor short to ground

Post by panic-mechanic »

A faulty or dead lambda sensor might cause the other error. Just unplug the lambda and see if the map sensor clears without coming back.
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Iklein
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Re: map sensor short to ground

Post by Iklein »

My playa doesn't have lambda panic..
Polo playa 2001 2.0L 8v, headwork,xorst,282Estas,Uniq - 99kw 189nm
Mk1 Golf '85 1.6 sold
Mitshubishi Tredia '85 sold
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panic-mechanic
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Re: map sensor short to ground

Post by panic-mechanic »

Oh dear. When you look in the vagcom at measuring blocks does the manifold pressure show a value?
Stephan van Tonder - Jhb - Putfontein Benoni
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'05 Touareg v10

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Re: map sensor short to ground

Post by -=sT3V3=- »

I used to have the same error come up intermittently, turned out to be a fault map sensor.

Check the pinout from map sensor plug to ecu plug. if there is continuity and no shorts the issue must be map or ecu
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THANAS
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Re: map sensor short to ground

Post by THANAS »

-=sT3V3=- wrote:I used to have the same error come up intermittently, turned out to be a fault map sensor.

Check the pinout from map sensor plug to ecu plug. if there is continuity and no shorts the issue must be map or ecu
Not 101% sure, but I think the short to ground error is triggered by an out of bound signal voltage (voltage too low). On a connected MP9 sensor exposed to atmosphere, I would expect the voltage to be much closer to 5v, or just above what you would get from a pressure reading at WOT. It is also possible to get a brand new, faulty sensor. Try replacing the sensor or swapping in one that you know is working to try isolate the problem.
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chucker02
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Re: map sensor short to ground

Post by chucker02 »

Why is there 2 5v supply's? The map sensor takes the pressure in the manifold aswell as the air temp so I think the one 5v supply should not be there
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2006 Citi Golf 2E, Dictator, 4-2-1

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Rides thread: http://vwclub.co.za/forum/viewtopic.php?f=11&t=183329
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Re: map sensor short to ground

Post by THANAS »

chucker02 wrote:Why is there 2 5v supply's? The map sensor takes the pressure in the manifold aswell as the air temp so I think the one 5v supply should not be there
Image

If you look at the component housing B7 and B8, there are 4 wires, a common ground, 5v supply to MAP, MAP Signal Wire and 5 v supply to Temp sensor. The ECU monitors the current through the 2nd 5V line through the temp sensor to ground and infers temperature. This is based on the calculated resistance in the temperature sensor (basically a thermally variable resistor).
Iklein
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Re: map sensor short to ground

Post by Iklein »

Thanks Thanas, I'll try a swop out with a working one from a friend, unfortunately I don't have vag with me..its a Buddy's and will probably only be able to give more detail over the weekend wrt measuring blocks Panic, . I must mention that mine was completely buggered and here was no stock of the polo map sensor, I was told the smaller golf one is the same and needed bushes to fit manifold, I then went this route. Smaller mk1 map sensor. Apparently its been done many times with no issue, think this is related?
Polo playa 2001 2.0L 8v, headwork,xorst,282Estas,Uniq - 99kw 189nm
Mk1 Golf '85 1.6 sold
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Re: map sensor short to ground

Post by panic-mechanic »

Probably not. Also don't discount that there is a,possible wiring issue with the piggyback.
Stephan van Tonder - Jhb - Putfontein Benoni
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Re: map sensor short to ground

Post by THANAS »

panic-mechanic wrote:Probably not. Also don't discount that there is a,possible wiring issue with the piggyback.
This as well. :iagree:
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chucker02
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Re: map sensor short to ground

Post by chucker02 »

THANAS wrote:
chucker02 wrote:Why is there 2 5v supply's? The map sensor takes the pressure in the manifold aswell as the air temp so I think the one 5v supply should not be there
Image

If you look at the component housing B7 and B8, there are 4 wires, a common ground, 5v supply to MAP, MAP Signal Wire and 5 v supply to Temp sensor. The ECU monitors the current through the 2nd 5V line through the temp sensor to ground and infers temperature. This is based on the calculated resistance in the temperature sensor (basically a thermally variable resistor).
O ok makes sense! Thanks for thr lesson!
Current:

2006 Citi Golf 2E, Dictator, 4-2-1

Ex:
2003 Audi A3 1.8t, Thanas Tuned, FMIC, coilies, DP and exhaust
2007 Citi golf. ADY with Spitronics 60-2, estas 282, 4-2-1, coilies
Rides thread: http://vwclub.co.za/forum/viewtopic.php?f=11&t=183329
2002 Citi golf. ADY carb, estas 282, 4-2-1, GW delarey big brake kit.
Rides thread: http://vwclub.co.za/forum/viewtopic.php?f=11&t=157603
1971 VW beetle
terrance@smartec
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Re: map sensor short to ground

Post by terrance@smartec »

Nice analysis

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Iklein
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Re: map sensor short to ground

Post by Iklein »

Good Morning Gents,

1stly Thanks for all the help and advice, really appreciate it. So I managed to do some fault finding Saturday past.
The tests was done with Vag plugged in, and some hard driving.

Oh and Panic, this is one of those polocup (remap) ecu jobies, I dont seem to get many ecu options or readings, went through about 200 addresses.- Nothing for measurement on the Map Sensor. Unless there's an exact address and I couldn't find it or I'm probably missing something.

-Swopped out ECU with another, and same fault.

-used the bridge plug to put mp9 back as standard, bypassing UniQ, and No fault Code!!, I think then its isolated to Chip and/or its wiring. Although over-fueling the engine responded much better. especially from pull away, which is what I'm struggling with.

-Swopped out Uniq with a buddy (tuned also for 2.0L 282cam but on diff engine) just for testing sake. Did this twice, with the His Chip I drove 3times the distance with no error, the last run was really hard driving and it did pop up. reset fault, put my Chip back and fault comes up with one sprint (bout a 600m stretch).

So it definitely looks like its on the chip side of things. I was told if the Chip is faulty the engine wont start?? Can it just be a certain part of the circuitry of the Chip that's acting up? I find it strange to be either working or Not at all..

I am going to try to trace the chips wiring and check for any abnormalities today.

Thanks Again..
Polo playa 2001 2.0L 8v, headwork,xorst,282Estas,Uniq - 99kw 189nm
Mk1 Golf '85 1.6 sold
Mitshubishi Tredia '85 sold
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Re: map sensor short to ground

Post by -=sT3V3=- »

Cant a 2.0 mapped MP9 handle a 282 cam without the uni-Q?
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THANAS
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Re: map sensor short to ground

Post by THANAS »

Unichip :puke:, I'll take my peasant Dicktator over the Polocup/UniQ combo any day. I do rag Dicktator a lot, but it's a very robust system. Any AFM will be better suited (Not so sure about GoTech, but still).
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Re: map sensor short to ground

Post by panic-mechanic »

Yeah honestly i would much rather than dictator than mp9 and unichip.
I have actually stopped using/tuning unichip a while ago.
Stephan van Tonder - Jhb - Putfontein Benoni
'05 Audi A6 3.0L TDI Avant
'09 Touareg 3l TDI
'13 VW CC 2l tdi (repair project)
'05 Touareg v10

Perfect Power dealer. I do dyno tuning.
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