Tdi MAP sensor and Limp mode

[chuffingaudi]

My trusty A4 110 Tdi has developed a curious problem.

Whilst under partial load at about 3000 rpm the engine fades to about half power (Limp mode). I've had the engine checked and apparently the MAP sensor has thrown up a fault code. Restarting the engine cures the problem temporarily until the next time.

Could anyone please tell me where the MAP sensor lives? Some say its under the ECU in the black box under the wiper blade mechanism. Other say its underneath the black pipe running over the top of the engine. The Haynes manual makes no mention of it at all!

And where's the best place to get a new one?

[ini]

Facelift versions 98ish onwards, have a map sensor (combined pressure & temp) located next to the intercooler.

If it is a pre-facelift A4 (no DIS/trip computer) the map sensor is located on the circuit board inside the ECU, it has a small tube feeding pressure from the top boost pipe. They have a separate temp sensor on the top boost pipe.

The later type are available at most part suppliers, and come in different pressure BAR ratings, and 2 different probe diameters (early & late).

The early board mounted Bosch type, are a little harder to source.

[chuffingaudi]

Thanks for the information. I have taken the top off and have indeed found a pipe trailing off to the fire wall, and a sensor on the right hand side (from drivers seat) in the black cast pipe running across the top and back of the engine.

I pulled off the small vacuum pipe and blew down it, ending up with a mouthful of black, what looked like degraded rubber. This pipe does not appear to be holding pressure. I will open up the black box that sits behind the firewall and try to see if there is anything visible wrong and possibly change the pipe and publish the result.

[ini]

The small section of tubing inside the metal ECU body can also degrade (joins board mounted MAP to ecu body)

[chuffingaudi]

Many thanks for the tip! Ok! Took the top off the box lifted the board up and found the unit the pipe plugs into. The pipe looked a bit perished, so replaced with new and blown through to clear all the debris. Put it all back together and went off up the road and hey presto! no difference.

Therefore assuming it can only be the unit on the board I went to the local breakers. Sharp intake of breath. " that will be £100 mate and we havent seen one in ages".

I have since read on this site you can replace the MAP sensor with diodes and other things for perfomance tuning. Is this a viable option? or should I keep going through the breakers and hope a complete board will turn up! If so would a 1.9tdi passat board do the same job or are they completely different?

[ini]

All of the earlier 110 TDI engines use the BOSCH '0273003210' 2.5bar board mounted map sensor.

All automotive MAP sensors use a 0-5volt range, so any 3pin 2.5bar (250kPa) MAP will work.

You could also use the later type intercooler/boost pipe mounted map (4pin)but you would have to drill into a boost pipe to mount it, and plug it in at the ECU end.

Pin 2 on the later 4pin type is Temperature output voltage.

An alternative is the ECU mounted VMAP sensor, as it is adjustable from 2.5bar - 4bar in 100mbar increments.

[chuffingaudi]

Ini, many thanks for these gems of information. I have googled the parts and see i have some options to go at now. I will try to obtain the part and solder it in myself. Though I probably wont take the performance route as she has done 130000 and I dont want to blow her up!!! If I remove the board from the car and it loses its power supply will it be damaged? I dont have VAGCOM and the manual says it has an immobiliser built in yet I cant find any info on this in the paperwork supplied with the car!

[ini]

If you remove the ecu to change the MAP sensor it is simply a matter of plugging it back in.

You only have to reintroduce it to the intruments/car if you are installing a new/different ECU.

[chuffingaudi]

Many thanks ini, will let you know the result when I have located and installed the part.

[AutoTDI]

The Haynes manual makes no mention of it at all!


Fuel system - diesel 4B.7, Air intake charge pressure/temperature sensor. Paras 23,24 refers. Photo ref 8.23

Have just checked my sensor; there are only two wires connected, so trying to work out whether these are for pressure or temp, surely can't be both? My car is a 97MY A4 1.9TDI(110) AFN engine.

Co-incidentally, have done VAG-COM scan and these faults have come up:

00575 - Intake Manifold Pressure
17-00 - Control Difference
00519 - Intake Manifold Pressure Sensor (G71)
- 28-00 - Short to B+

The engine runs normally, so I'm not sure what's happening here.

The car has recently had its MOT and passed OK. Before the MOT, I did a scan with VAG-COM and there were no fault codes. I wonder if the MOT emissions test might have produced the fault codes?

[charliemouse]

Just had the same proble with mine (after a new MAF and pump too...)

Fitte new MAP sensor, all is well. They are £55 for a BOSCH from GSF of £42 from Andrew page for a Facet. (AP were £72 for BOSCH).

Bought and fitted German not Italian!

So now to fit the new dampers, brakes, front bumper, tyres...

Buy a £600 car, get a £600 car:o

Nik

[chuffingaudi]

Many thanks for the advice guys. I havent yet attempted the MAP sensor as it looks a bit daunting and I will have to allow for a bit of time off in case it all goes wrong.

The dampers on the rear the Advant have gone too (Rear end bounces all over the place and the rear wheels skip on rough surfaces) so Ive ordered a complete set of remanufactured gas ones from ebay from bestellung@sitzkonsole.com for a grand total of £71 delivered. ( I know too cheap to be true, but I checked them out against a previous buyer and he recommended them) I will keep you posted when I ve fitted them to see if theyre any good. Cheers!

[charliemouse]

Chuffing,

Just all 4 dampers on mine. Genuine Sachs/Boge from GSF £29.50 + VAT so exactly the same as Ebay. They are full units too not inserts. Very good now they are on.

The Map sensor takes about 1 minute to fit. Clear the code using a £20 hand code reader (my car didn't start running right until the code was cleared).
Reall no need for time off - you could do it on your way to work in GSF carpark!

Nik

[ini]

I also used to get these fault codes on my 110.

00575 - Intake Manifold Pressure
17-00 - Control Difference
00519 - Intake Manifold Pressure Sensor (G71)
- 28-00 - Short to B+

The car would limp at 3000rpm under load in higher gears.

The problem would vanish for several weeks, every time i towed a trailer long distances.

I always assumed it was the VNT mechanism sticking or CAT blockage, and the extended period of high exhaust temperature was burning off any carbon/crud buildup.

The car would work very well for several weeks afterwards, and be much more powerful and smooth.

[AutoTDI]

I cleared the fault codes with VAG-COM and they haven't come back - at least they weren't there the last time I looked. As I stated before, performance has been OK throughout, regardless of fault codes, so I'm mystified as to what's going on. Intermittant fault maybe?

I've just done another VAG-COM check and the following has come up:

00575 Intake Manifold Pressure
17-10 Control Difference Intermittent

So there does appear to be an intermittent fault somewhere. The plumbing looks OK, so can I assume the MAP sensor is faulty? Engine still performs OK.

[AutoTDI]

I think I really must replace the MAP sensor now. Mr White Van left me dawdling at the traffic lights and I couldn't catch him even using kick-down. Or maybe his van was chipped, but I doubt it.

[Teflon]

Had all the same problems and codes on an A6.

MAF checked, MAP replaced, fuel filter replaced, crankcase pressure valve replaced, hoses checked, etc. Mine is definately a sticking turbo VNT, confirmed by disconnecting the control rod and furtling around with it.

Turbo is coming off for decoking next week. Wish me luck.

[AutoTDI]

Today, my car decided to cure itself. Mr White Van would have stood no chance! So this just confirms my suspicions about the dodgy MAP sensor. Thinking back to yesterday's humiliation, the auto box didn't want to change up from 1st gear. Presumably this would be consistent with a loss of power and torque?

[chuffingaudi]

Further information on the MAP sensor fitted to my 1997 110 TDI. This model has the MAP sensor fitted to a circuit board behind the firewall and is fed by a tube from the manifold.

I originally changed the tube to eliminate air leaks and blockages from the list of possibilities that could cause limp mode and the MAP fault code, but this did not cure the problem. Prior to changing the MAP sensor I took the lid off the box to try and find part nos etc and noticed the sensor capsule was full of the same gunk that was in the original tube. Since cleaning the gunk out, it has not gone into limp mode and it has been around 4 weeks now. The power when approaching 3000rpm can waver and feel a bit like it is about to go into limp mode occsasionally, but so far it has not, so I may still have to replace the MAP sensor at some point.

I hope this helps!

[EmmettC]

An alternative is the ECU mounted VMAP sensor, as it is adjustable from 2.5bar - 4bar in 100mbar increments.

Where can you get one of these map sensors?

Thanks

Emmett

[avspider]

Where can you get one of these map sensors?

Thanks

Emmett


Any chance of some info on these, as i'm having problems with mine, and i believe it's a circuit board mounted one. :o And worried about changing it:o

[EmmettC]

Would the change from a 2.5 bar to a 3.0 bar manifold air pressure sensor increase the power much on the car? Would there be any other adjustments required in order for the engine to handle the pressure boost?

Just if i was to go for the vmap sensor would it be foolish to take the jump up to 3.0 bar, or is it better to be safe and stick with the 2.5 bar?

Thanks

Emmett

[ini]

Using a 3bar MAP sensor, when the ECU is still calibrated to use the standard 2.5bar unit, will result in higher boost pressure throughout the rev's.

When the turbo is actually producing 18psi, the MAP sensor is only reporting 15psi as interpreted by the ECU etc (0-5v range is stretched), and the management system will increase the boost.

Although with a little extra fueling this can provide a relatively cheap power increase, it is not the correct way to do it.

The idea of fitting a higher bar rated MAP, is so that the ECU can be calibrated to see and manage higher psi's accurately on a modded car.

Without altering the ECU parameters a higher bar MAP could result in surge, very high spikes, limp mode from too great a difference between MAP & MAF readings, and turbo damage.

[vg9]

Hi all

New to the forum and I just wanted to run by an issue I have with my Audi 1.9 tdi A4 avant reg 98.

I use to have a rattling noise in my exhaust in the middle box and then that went away. After a month or so the car felt it was loosing power (struggling to speed up) I was informed that this is due to the exhaust being blocked. Also no faults showed up on the diagnostic machine.

Then the other day the car started to blow smoke and the glow plugs and oil started flashing (checked oil this was fine). This happened on and off sometimes it would not blow smoke and somtimes it would not start at all.

After checking the exhaust I was adviced that the exhaust was blocked as the exhaust was not hot at all from the middle box onwards (especially after runnig the car) .So the exhaust was changed (middle and back) . No change at all.

Car was plugged in on the diagnistic machine.

5 faults recognised

00522 029
Intake manifold pressure
regulating diff
sporadic fault.

00522 035
Coolant temp sensor
short circuit to earth
sporadic fault

00765 035
Modulating psiton movement sender-G149
sporadic fault

01268 035
metring control-n146

00553 031
air mass meter -g70
open/short circuit to earth


also when the car runs for a while and you switch it off the fan stays on for a while.

after this we had the coolant temp sensor changed and had no joy. we were adviced that we need to change the intake manifold pressure sensor and check the coolant pipe.


Please can you advice as the car is still blowing smoke, doesn't pick up speed and now doesn't start up sometime. This has happened all within 2 days except for the picking up speed which is being gone on for 3 months.

Advice will be greatly appreciated on this matter.

regards
VG9 :confused:

[mrjolly]

Did You Check That The Cat Was'nt Blocked Or Brocken Up Inside. This Is A Fairly Common Faliure. If There Is A Hint Of The Idea The Exhaust Is Blocked It Is The First Thing I Would Check.

[vg9]

quite right, I had the same concerns first the rattling noise in the exhaust and then no noise and a block so this is why I had to change the middle and back box as it was blocked. The area where it was blocked you could acutually hold the pipe without it feeling hot.

but changing the blocked exhaust has not resolved any of the other issues as mentioned earlier .

any ideas ???

[EmmettC]

Hi folks, just a quick question about my 97 audi tdi

When there is fault codes on the car, such as MAP and MAF sensor fault codes, can these be cleared shutting power off to the ECU for an extended period by disconnecting the battery??

Or is it necessary to get the fault codes wiped by vag-com or something similar?

I'm just curious as i've replaced the MAF sensor but the power still dies and goes to limp mode after around 3000 rpm, although not as frequently as it used to.

Thanks

Emmett

[EmmettC]

Further information on the MAP sensor fitted to my 1997 110 TDI. This model has the MAP sensor fitted to a circuit board behind the firewall and is fed by a tube from the manifold.

I originally changed the tube to eliminate air leaks and blockages from the list of possibilities that could cause limp mode and the MAP fault code, but this did not cure the problem. Prior to changing the MAP sensor I took the lid off the box to try and find part nos etc and noticed the sensor capsule was full of the same gunk that was in the original tube. Since cleaning the gunk out, it has not gone into limp mode and it has been around 4 weeks now. The power when approaching 3000rpm can waver and feel a bit like it is about to go into limp mode occsasionally, but so far it has not, so I may still have to replace the MAP sensor at some point.

I hope this helps!

Hi Folks,

i just got the ECU open on mine and had a look at the MAP sensor, i disconnected the pipe running to the sensor and sucked on it to see if there was any dirt in it, but i could suck air through it pretty easily and could hear hissing as air was being dragged in somwhere else. Does this indicate a leak?? Or is a valve working somwhere letting air in?

I'd need a second person to find out exactly where the leak is coming from.

I this is a leak, i think this would cause the car to go to limp mode at 3000 rpm, am i right?

Thanks

Emmett

[vg9]

Hi

Just a quick update referring to my question I had posted on my 98 1.9tdi. I had the temp sensor, map and air flow meter changed. The car is still blowing smoke and sometimes not starting. It was put onto the machine again and it is showing as a diesel pump fault.

Any suggestions ?????

cheers
VG9

[chuffingaudi]

This MAP sensor problem lingers on still. I found this quote on the DIYNOT website and thought I would add it in case it was helpful. It appears this ECU MAP sensors is a common problem.

"I had the same fault code on my Audi A4 Tdi with AFN engine.
Like yourself I'd tried everything from MAF sensors, N75 valve, VAG specialists and Audi themselves. A replacement MAF sensor did help
to some degree but I still lost boost albeit less frequently.

The biggest problem with these engine management systems is that the MAP sensor is built into the ECU. You'll see that a vacume pipe is connected directly to the ECU. After a lot of use this pipe can suck hot oil into the ECU and spray it over the MAP sensor and into the rest if the ECU. It doesn't take and electrical engineer to know that this is a very bad thing indeed http://www.diynot.com/forums/images/smiles/icon_sad.gif

I never managed to resolve the issue but AMD in Bucks (VAG tuner) let me know that the above was a common problem and as the MAP sensor is integral to the ECU - it's not an expensive fix. In the end I sold my Audi on without fixing the issue after 50k miles of driving.

I now own a Honda and never plan on buying a European car again!"

Following the advice of INI I have found a 2.5bar MAP and Temp sensor (Bosch no. 0281002177) from a scrap Golf TDI and plan to rob it together with the plug and as much of the wiring loom as possible and wire it into the ECU in place of the board mounted one. I have the datasheet for the ECU mounted one (bosch 0273003210) anyone got any ideas on the pin out for the 0281002177

[ini]

This page gives the pinout for the 4 pin 0281002177.

http://www.geocities.com/tech4tdi/pages/map.html

You only need pins 1, 3 and 4 for pressure, if you keep your original charge temp sensor.

Are you going to mount it on the top boost pipe, or rig up some tube fed pressure setup?

[chuffingaudi]

Ini, thanks for your help yet again.

I now have the 2.5bar MAP sensor and the wiring plug and some loom out of a scrap Golf Tdi for £10. I did consider buying the boost pipe as well as it had the fitting for the sensor already made but decided against this as it would take as long to adapt the odd shaped golf boost pipe as it would to drill and tap my existing A4 boost pipe. I am thinking I will position it just after the intercooler as they do on the later A4's, I guess this will keep it away from the turbulence close to the induction manifold. This would seem to be a good neat solution and would allow easy maintenance should the sensor ever fail again. I will let you know how I get on.

[chuffingaudi]

An update on this issue.

The ECU board mounted MAP sensor in my car finally failed signified by permanent Limp Mode and a puff of black smoke on start up accompanied by high idle speed.

Following the advice of ini I have replaced the board mounted MAP sensor and extended the wiring to the new replacement MAP sensor mounted in the black pressure pipe leading to the manifold. The results are:

1. Instant Cure for the limp mode and start up issue.
2. Increase of around 4mpg.
3. A vast saving over anything I have been quoted to repair this problem.

Resolving the problem this way, saved an expensive repair to an increasingly rare ECU board and provided a cheap an easy sensor to replace should it fail again.

I have attached a sheet on how I did this in the hope that it may be of use!

My thanks to INI for his invaluable advice.