Where has all the power gone ??

[arran_m]

Hi all,

I have recently had a few power problems with my 97 1.9 tdi, it started when going over 2500rpm the power would just dip and not return until the ignition was turned.

I put it into the garage but the computer would not talk to the car so they physically had a look and checked things manually, my turbo was replaced a couple of months ago so doubt its that but they have told me that they need to send the ECU away to be tested as they think the problem lies here.

Is this likely as having looked a lot of things are listed to check but ECU I have not seen mentioned.

Any help would be appreciated

Arran

[scotty33]

Hi

I think ECU problems are quite rare, the symptoms you describe can be caused by too much or too little boost pressure. Either way, the ECU goes into 'limp mode' which resets when the ignition is turned off.

look for leaking large bore hoses on the intake/intercooler system.

Also check the small bore hoses that connect to the turbo wastegate or vnt actuator.

The 90 hp cars need positive (i.e. boost) pressure to operate the wastegate

The 110hp cars I think use vacuum to operate the VNT mechanism which provides boost pressure. Either way a leak causes failure and limp mode.

Could you get a Vag com cable and scan it yourself? Would probably cost less than sending the ECU away and you would be set up for next time there is a problem?

[arran_m]

Hi,

Thanks for the info, I have ordered some hose to replace the vacuum hoses so will be trying that before sending the ECU off to be tested.

I don't know why but VW and the AA have had problems with no communication betweek the 16 pin socket and their own computer systems for diagnosis so I assume that it doesn't work regardless of me getting the VAGCOM cable

[TimboUK]

My mate works at a garage, he tried 2 diagnostic units (first one was a really expensive Snap-On system) that did not manage to communicate. The second was a cheapy one that was supposed to work on all VAG cars. The last resort was a big mobile Bosch "laptop" that got straight in :)

Until he tried the Bosch (as apparantly the ECU is Bosch) I was also thinking the ECU port was faulty!

[martin15s]

My 2000 110bhp diesel had this problem this past week - changed the vacuum hoses around the turbo, N75 and MAF and all is well.

[scotty33]

Is the car 90 or 110 hp?

[martin15s]

110hp - as in my post

[arran_m]

Hi,

Its a 110bhp and I have tested the MAF which is working so waiting to fit the new hose, where abouts is the N75??

Thanks

[adamss24]

Hi,

Thanks for the info, I have ordered some hose to replace the vacuum hoses so will be trying that before sending the ECU off to be tested.

I don't know why but VW and the AA have had problems with no communication betweek the 16 pin socket and their own computer systems for diagnosis so I assume that it doesn't work regardless of me getting the VAGCOM cable
Do you have an aftermarket stereo fitted ? It might be that the K line is shorted to positive especialy if you are using certain DIN adaptors... If it's a 90 Bhp engine, the problem may lay within the ECU as the MAP sensor(boost sensor aka trust sensor) is embeded into the ECU and it will have a small vacuum pipe conected to it. Make shure that pipe is not blocked with crud or full of oil ! If its a 110 bhp, check for vacuum leaks, perished pipes, sticky VNT mechanism, faulty VNT actuator, not tight jubilee clips on boost pipes and faulty MAFs...

[arran_m]

Thanks for all the info although a lot of it has just gone straight over my head, will change the pipes and check the clips are tight but as for the other things will just have to leave it to the garage to sort as Im not that technically minded just wanted an opinion on the ECU diagnosis.

Thanks again

[grpassat]

I had a power loss problem , that was intermittenet loss of turbo boost at around 2200 rpm on a 2001 130hp passat. not sure if this helps, but they replaced an electronic switch in turbo boost on the waste gate. Not sure exactly what was done as it was in italy, but it did fix the problem and apparently this didn't manifest itself on the ECU. The tech had seen the problem before.