Tdi Loss Of Power (again) - Resettable

[wytonpjs]

Final view - just a tad gunked up then!

[GSMGuy]

Peter, mine looked like that the last time I had it out... gave it a quick squirt with cintact cleaner (all I had to hand) but ni change... I wonder if as stated the thing is "gunked" up... Maybe there is oil in the sensor airway, and it causes a delayed reaction from the pressure sensor - by which time you are overboosting, and it kills the boost??

 

I've thought it could be the T-MAP for a bit now, did you get a price on yours?

 

Mike

[wytonpjs]

Mike - no price, I'm just going to go for it as this is beginning to bug me! Hopefully, if one of the factors has one I'll be able to try it without buying if my cunning plan works. Will update you tomorrow.

 

I've been racking my brains about what the TMAP sensor actually is. Methinks it is too small to be an actual pressure sensor and I'm wondering whether it is some kind of thermistor, ie a device whose resistance varies with temp. From playing with VAG_COM tonight I know that the ECU is being fed an absolute air pressure figure from another sensor (G93 if I recall correctly from the screen) so this may not be a pressure sensor but a crude flowrate device working on a calculated pressure from the temperature rise induced via the compressor element of the turbine. Anyway, to stop blathering on if the thermistor skin goes porous, its resistance will change (ie drift) from its baseline and this will also vary as it gets hotter in the airflow :angry: It's a thought anyway!

 

Peter

[GSMGuy]

Peter, apparently T-MAP says it all... Temperature and Manifold Absolute Pressure sensor......

 

PS you can get me on MSN if you have it... mike@kitchendream.co.uk

 

Mike

[Masked Marauder]

 

Until you get rid of that damn engine breather it will continue to gunk up until kingdom come.

You can reduce/turn off the EGR with VAG-COM and apparently that helps stop it all going to glue.

[wytonpjs]

Hi - no news on whether we have got a TMap sensor so far but the day is young :rolleyes:

 

Have been playing with the VAG ELSA Win electronic manual: 2 interesting results.

 

Firstly, max boost at 3000 rpm under driven load should be in the range 1700-2200 mbar. Bit of a performance variation here! If too low, check solenoid valve for charge pressure control (N75) or check vacuum hoses. Otherwise, renew diesel direct injection system control unit (J248) :huh: Don't like the sound of the last! Split between requested and actual boost is supposed to be no more than +/- 50 mbar, ie 100 mbar total split.

 

For the TMap test where the boost pressure is in error, call up block 10 on VAG-COM engine test, disconnect the TMAP sensor and observe zone 3 display. It must briefly fall to 400 mbar and then assume the same value as the elevation sender (zone 2). If it does this, change the TMAP :D If it doesn't make this spec and the wiring checks out, renew the diesel direct injection control unit (J248) :(

 

Full text of TMAP test should follow:

TMapTest.rtf

[wytonpjs]

Update :D

 

Done the TMAP test as described in my last post and RESULT - Duff TMAP sensor :D :D :D (please see graph below)

 

It did almost exactly as it said in the manual, dropping to 340 mbar before rising to match and equal the atmos reading. Interesting, that it was not too constant prior to unplugging it as well. Anyway - it is HISTORY :D

 

Problem is my local crew could not come up with one at any of the factors. Local Bosch main agent could get one at

[seatkid]

I think you misinterpet the pinglish instruxtions.

 

By your interpretation, no matter what the result, there is always a fault...... :rolleyes:

[GSMGuy]

I knew it!!!! Gonna get myself one tomorrow!!!!! Thanks for all the input Peter and SKid etc... Bloody Fraud...

[Guest vr6galaxy]

 

Until you get rid of that damn engine breather it will continue to gunk up until kingdom come.

You can reduce/turn off the EGR with VAG-COM and apparently that helps stop it all going to glue.

I wonder if it's worth while actually blocking off the EGR? on the Delica it's a known modification involving a blanking plate or a cheaper version is to drop a ball bearing into one of valves vacuume lines and stop the valve functioning :rolleyes: this helps stop the old TDI black smoke on start up and helps pass the MOT immisions tests :huh:

[GSMGuy]

Peter - Any chance of a copy of that cd??????

 

 

Mike

[GSMGuy]

Short update... Been to Fraud this morning, they want

[gregers]

u failed to add its was 120kmph :) naughty naughty

[GSMGuy]

Peter - did you replace your TMAP? An update?

 

Mike

[paulmpaciorek]

So Mike.

 

Is you car running as it should be now since you cleaned out the T-map ???

 

 

Paul

 

p.s...where is the t map ...might clean mine for the hell of it !!! :lol:

[GSMGuy]

Yes, and no... Ran fine for a couple of days, and then same - took out sensor and cleaned it again, and been fine since yesterday....

 

Mike

[seatkid]

Sounds as if you need to take off the piping and give it a thoroughly good clean out.

 

Whats your mileage?

 

So do you think its inferior oil, byproduct of chipping, the way you drive or a worn engine that gives you the gunk?

 

Does it burn any oil? (getting in thru EGR or Turbo leakage).

 

Did you put the mini air filter back?

[GSMGuy]

Car only done 41k, full history, don't think its anything to do with the chip, as it only increases fuelling and not boost... I drive my car quite hard, no tootling for moi!!! It doesn't use any oil - I think it just may be duff... Will get a new one ordered - when I find a good price.... Anyone do better than the

[wytonpjs]

Sorry Guys for delay in posting - under the weather and THUMB! On Friday a new TMAP was waiting for me (still don't know cost until my local crew settle up their invoices). Anyway, popped it on (2 minute job) and reran VAG-COM to look at pressure plots. Exactly the same form and shape as before - increasing split and significant diversion at 3000 rpm. Much DEPRESSION.

 

Anyway, took it for a spin on Sat morning with laptop hooked up and daughter mointoring/controlling for me. I recollect that the VAG manuals said peak boost at 3000 rpm in 5th gear should be of the order of 2200 mbar. On the driveway under no load I was getting nowhere near that level of boost. To cut a long story short, the plot as we were driving was a revealation - actual was faithfully following demand with only minor variations except where there was obvious turbo-lag eg, after accelerating hard you suddenly lift off the right foot and the turbo will obviously overshoot. I won't post the full plot - there is over 20 mins of recording as I drove up and down the A14. Trouble was, if you think about it, 3000 rpm in 5th gear equals 90 mph and the best I could achieve between traffic and the speed cameras was less than this (sorry officer but I cannot positively confirm........).

 

Conclusions? My fault was different from GSMGuy's in that the turbo only cut-out on hot days after towing a caravan for nearly an hour (with the air-con on) - it has never happened under normal driving. I suspect that I have replaced a perfectly serviceable TMAP with another serviceable item after allowing myself to get too hung-up over VAG-COM. It has it uses (eg fault codes) but the problem comes when you start to diagnose things with only limited info. It will be difficult to replicate the conditions under which my snag arose in the near future - I just cannot spare the time (and she who is to be obeyed is getting grumpy).

 

To complete the post for anyone else looking at these parameters, the ECU max demand was 2200 and my average peak measured was in the order of 2200 - 2300, HOWEVER, I have measure instantaneous peaks of 2600 but these were always on the overun.

 

Peter

[paulmpaciorek]

Is the T-map sensor also know as the "thrust" sensor ???

[GSMGuy]

Peter, fancy lending me your "pefectly good" TMAP......

 

 

Mike

[seatkid]

Is the T-map sensor also know as the "thrust" sensor ???

No that's attached to the girlfriend....... :lol:

[wytonpjs]

Mike - have to go to Bristol tomorrow at 06.30 (and I HATE early starts). Will try to get it in the post together with the manual as discussed soonest.

 

Peter

[GSMGuy]

Peter, you are a star - at least it will allow me to definately eliminate or otherwise the TMAP - I'll send it back the following day - Oh and SeatAlhambra, will get your old MAF off to you this week... Mant thanks to you both - will keep you all updated..

 

Mike

[paulmpaciorek]

Mike

Did you try Peter's T Map ??? If so is that problem now sorted ???

 

 

 

Paul