Mk1 90bhp Tdi Fast Idle And No Power

[Derren71]

Hi there this is the first time i've ever posted a problem with one of my cars have always found problem and fixed it ok, not this time, so here goes. I won a quality 1996 Gal 90bhp with 1Z engine on fleabay a month ago in excellent condition and she was, previous owners seem to have looked after her. To cut a long story short owner said she just needed a Maf meter so after driving car home at 50 mph started investigating fault, bought a vag-com diagnostics and after scan revealed

553 Maf sensor

539 Fuel temp sensor

522 Coolant temp sensor

777 throttle position sensor

527 Intake air temp sensor

All of these have been replaced 3 times I have a bag full of sensors mafs and bulkhead sensors, have removed and cleaned inlet manifold and egr valve, replaced all vacuum pipes bar the one going through bulkhead to ecu (if that's where it goes} looks ok but will change eventually.This is what happens with car; Idles at 1300 rpm hot or cold and sometimes goes higher and lower as if she's scavenging for fuel, has been fully serviced by myself including little white T filter with o ring on top of fuel filter, she pulls like a train up till 2300 rpm in every gear to 60 mph but on long uphill stretches will drop to about 50'ish. Diagnostics will not reset fault codes neither my cheap vag-com or my friends

[cyborg]

First impression is Its an electrical problem earth or split cable some where so check all ground and chasis ground connections look for chafed cables check all doors and boot however...

 

Quotes taken from

http://www.tdiclub.com/TDIFAQ/TDiFAQ-8.html#e1

- Fuel cut-off valve O-ring unseated - especially if the idle speed is intermittently higher than normal. With the engine cover removed, the fuel cut-off valve is located on top of the injection pump just above where the four steel lines go into the end, and has a single wire going to it. Remove this valve (disconnect the wire first!) and make sure the black O-ring is all the way against the body of the valve, then re-assemble.

 

- Vehicles which have modified engine control systems, especially if a chip and a tuning-box are used together, may experience a phenomenon which has been called "warp field collapse": at full load and generally higher engine speeds, the engine will abruptly go into a reduced-power mode. Investigation of trouble codes with a VAG-COM will generally find a code set which is related to the quantity adjuster upper limit. The problem is that too much fuel is being requested! The solution is to back off the requested amount of fuel, generally through de-tuning the tuning box which hopefully has some manual adjustments that can be made.

[seatkid]

Idling at 1300 rpm sounds like a temperature sensor problem - the ECU thinks its cold and increases the idle speed. There are many different sensor variations (different colours) and if you use the wrong sensor it just wont work.

 

The struggling uphill is a classic MAF sensor symptom. It is important to get the correct MAF sensor for your engine variant - every variant uses a different sensor. As it pulls "like a train" to 2300 rpm its sounds as if the turbo + vacuum system is working. Also check your air filter is not blocked or there is a leak in the air pipework after the MAF as they cause the same problem.

 

 

 

You need to get rid of those faults, thats whats holding the ECU back. On the 1Z engine I think the faults should clear automatically when you get good sensor readings, however its possible you need to "clear" them with VAGCOM.

[Derren71]

Thanks to all will look into fuel cut of valve o ring etc. will keep you all updated since leaving engine guard of top and bottom have heard a light hissing noise under load between 1500 and 2000rpm from what sounds like engine bay and click from relay in fuse box when gal starts to struggle, once again, thank you all.

[Derren71]

After reading article from link at tdi club don't think has been modified unless directly wrote onto ecu, also noticed oil in vacuum pipe from turbo wastegate actuator, if weather holds out and not off to Croft sat. will do more check's and test, cheers all.

[Derren71]

hi again in response to advice fuel cut off valve ok replaced o'ring just incase of leak, no aftermarket tuning boxes anywhere all looks untouched, checked what must have been about twenty earth points all round gal looks ok boot wires damaged next to tailgate hinge have been repaired properly all ok, car fully serviced vac pipes all replaced pipe from next to intake air temp senswhich goes to ecu looks ok and is not vacuum pipe must read air temp or pressure or something at ecu. Just can't seem to find fault, is gal running in safe mode ??? VW said they would tell me the exact fault for

[zorgman]

if the fault is still there it wont clear and is marked as active or perm only the memory can be cleared, sounds to me like the tube inside the ecu has gone it turns "claggy" and sticks together ive change 2 of the pipes to cure limp modes. the ecu is behind the clocks and is held in by 2 torx then unclip cables slide ecu back and wangle it out, open ecu and the pipe is there connected to the map sensor. worth a try as youve tried the norm tests

[Steve Williams]

Hi Have the same problem with mine after the brake light switch packed up, Same codes down to  T, did you get the problem sorted ?????