Odd Tdi Performance

[GaryM]

I've posted on this subject b4 but never really identified what is up with my Galaxy, since purchase I was never convinced it was performing as it should. And several steps have taken all of which have made it feel better, new air filter, EGR cleaning, Intake manifold cleaning, EGR recalibration etc.

 

Along the way the MAF has always been in the back of my mind, but outright cost has meant that I only wanted to change it if I had too. All posts seem to suggest that if disconnection results in poorer performance then it is OK and hence I thought mine was OK. After managing to purchase on on eBay for

[Guest SHELLMAST1]

hi mine did this changed maf all vac pipes tried every thing endded up going to ford five hours of tests 300 pound bill found the wastegate sticking now and then sprayed plenty of oil on turbo no trouble since

ps ford wanted to change turbo

[GaryM]

Yep that experience and several of my own is exactly the reason I don't want a dealer to look at it even part of me says if nothing else they should have plenty experience :D :blink:

 

I'm convinced it is some form of management issue / sensor. The other think I have noticed is that it takes about 7 seconds of acceleration to show the fault. So this might be why it does not show up in the lower gears so much as you normally shift sooner than this.

 

BTW I have a variable vane turbo so I don't think there is a waste gate and I have checked the vaccum pipes to there.

[GSMGuy]

Gary, I think ALL turbochargers have a wastegate, it's a safety feature to stop you blowing up the motor with too much boost!

 

Mike

[Guest SHELLMAST1]

only in top gear because it happens at 3000 reves it trips into limp home mode turn it off and it resets the computor thats why it would not show up sum times it would rev through 3000 and you where ok if you keeped above but if you slowed down when you reved again hit 3000 and it will trip i thought mine was electrical because you feel it trip its like a click

[Guest neil_wiles]

I have the same problem and it appears that my cause is a faulty pedal position sensor on the throttle as it fails to be registered (or the ECU wont believe that much acceleration is required ) as a true position during the driving cycle and pushes the ecu into limp home mode (sometimes the MIL flashes).

 

By changing the style of your driving eg no massive changes of input on the right foot, check that the engine will continue to accelerate right into the 4000 band and this will confirm the same problem as I have. The solution is to replace the throttle pedal position sensor.

 

 

:P

[GaryM]

I have the same problem and it appears that my cause is a faulty pedal position sensor on the throttle as it fails to be registered (or the ECU wont believe that much acceleration is required ) as a true position during the driving cycle and pushes the ecu into limp home mode (sometimes the MIL flashes).

Intresting... Would that not cause errors to be logged in the ECU? Have you changed the throttle yet?

 

I have access to a scan tool and reset all codes yesterday so that I could see what has been logged recently.

 

As described it is a very definate trip and when it happens I don't loose power as such it just wont go any faster

 

I'll download the codes later when the wife has finished with the car tonight.

[GaryM]

Checked the codes...

 

- knackered front mid left parking sensor, knew about that.

- Inermittant fault with interior motion sensors, knew about that but never investigated it.

- Intermittant adaptation limit surpassed on the key?? Never seen that, guess it thinks there is an issue reading the security code from the key?

- Lower limit exceeded on terminal 30 of the air conn? Seen that b4 too but have ignored it.

 

And the ones of interest...

- MAF Implausible signal, intermittent. This has only appeared with the new MAF but the syptoms are the same with or without out just a whole lot more pronounced.

- Brake switch implausible signal, intermittent. Have had this for a while now and it seems to trigger the MIL light. It is a common issue documented elsewhere here and has been heaps better since I changed the brake switch but what are the other causes?

[Guest seatalhambra]

Can someone give a bit more detail on where to spray oil on wastgate/ turbo, on a cold engine. I know my tdi has the cover and foam on top with bits behind.

[GaryM]

If the layout is the same for all diesels (and I dont see why not) then it is 2/3rd's of the way down the back of the engine and the bulkhead. It is just about reachable from the L/H side. The job is made easeir by removing the plastic top cover and foam sound proofing.

 

 

As you can tell I'm no expert but further reseach confirms that varible vane turbos do not have a wastgate. As the pressure in them is controlled by changing the angle of the vanes inside which is what I think I have on my 115bhp tdi?

[Ivor_E_Tower]

As you can tell I'm no expert but further reseach confirms that varible vane turbos do not have a wastgate. As the pressure in them is controlled by changing the angle of the vanes inside which is what I think I have on my 115bhp tdi?

Variable vanes are ones fitted to the casing to direct the gasses onto the impeller - the vanes on the rotating part of the turbo do not themselves rotate! Not had a look myself, but I would have thought that there would still need to be a wastegate...and yes, the 115 does have variable geometry turbo.

[MrT]

Surely it needs a wastegate to dump the pressure when you lift off to change gear etc?

[GSMGuy]

Gary, I think the brake switch problem may be the cause of your problem... As the TDi has dBW (drive by wire) it is part of the programming that is the brake pedal is pressed, then the power is cut - try sitting with your car running in neutral/park, and accelerate the engine to 2500 rpm - now with your left foot, press the brake pedal, the revs should drop to idle, which is correct..

 

Now, if the brake switch is sending dodgy info whils driving, this may cause the symptoms you describe??

 

Mike

[seatkid]

Gary, I think ALL turbochargers have a wastegate, it's a safety feature to stop you blowing up the motor with too much boost!

No. VGT Turbos have no waste gate, they control boost by changing the direction of flow of exhaust gases internally. see here for a description

 

yes, the 115 does have variable geometry turbo.

No it doesn't, only the 110 Tdi had a VGT.

 

Gary, I think the brake switch problem may be the cause of your problem

Agreed, a intermitent faulty brake switch/wiring (or incorrectly adjusted) could be the cause. Remember this is a dual switch. search the forum for info about adjusting/replacing.

[Ivor_E_Tower]

There's a 100PS version of the 1.9TDI engine (not fitted to Sharalaxies though) - are you sure that the 115 doesn't have VGT?

[Guest thecodfly]

hello been reading all this info brain overload i too have this problem and was wondering where exactly do you spray the oil into the turbo/ wastegate i have a 1.9tdi galaxy not sure of bhp but it has the volkswagen engine in it and it is an r reg if that helps

thanks :lol:

[Guest pnwheels]

I wouldn't waste your time- the turbo has to come off and be dismantled. The vanes of the wastegate get soot and carbon on them. Its about a three hour job and if you take care, pulling the turbo apart should present no problems. On your age of vehicle the engine will be either 90 or 110 bhp. The engine code for the 90 is AHU. Check the sticker behind O/S/R cover(where the jack lives) or the timing belt cover as the 110 doesn't have a wastegate. Have you had the fault codes read? If wastegate is your problem, the boost pressure sensor tells the ecu to reduce fuel to protect the engine. The wastegate can be tested by attaching a lengh of pipe to the vaccum unit and sucking hard. The lever should move about 8-10 mm and spring back when you stop. Hope this helps.

[Guest thecodfly]

:o thanks will try all when the weather warms up slightly

[andrew welsh1958]

have loss of power problems,but only since taking out brake light switch,if i replace both blue and black switch will i have to get car reset or will it just go as normal,(cant afford prices at frauds) thanks for any replies