VW TDI forum, Audi, Porsche, and Chevy Cruze Diesel forum banner

1 - 6 of 6 Posts

·
Registered
Joined
·
10 Posts
Discussion Starter #1
Hey you guys (and girls) :bowdown

I´m a new member from Denmark, 36 years of age and living in the northern part of Denmark with my wife and our 3 kids. I have a degree in electronics and acoustics and my "car/auto" skills are what I would describe as "Learning by doing and a lot of googling"
The car pool consists of my wife´s belowed VW Bora 2.0 from 2002 with 268.000 km covered so far, my sunday/summer car, a mk1 Golf GTI from 1981 with a "in the shed" build 16v engine with Weber Alpha throttle bodies and all the usual suspension mods. And finally my daily driver a mk3 Golf GTI TDI with a 110bhp AFN engine, that lately has been causing me sleepless nights.
My first problem was one day driving home from work the engine started to loose power gradually untill the car went into "limp" mode. I have a 70km drive to and from work, and this happened after the first 15km of the trip, damn it´s a long way home when the engine is only reving 1400´ish rpm.
Well got home and connected my VCDS, and did a readout of the fault codes in the ecu :panic:

Here we go :

9 Faults Found:

01265 - Exhaust Gas Recirculation Valve (N18)
31-10 - Open or Short to Ground - Intermittent

01262 - Solenoid Valve for Boost Pressure Control (N75)
31-10 - Open or Short to Ground - Intermittent

00527 - Intake Manifold Temperature Sensor (G72)
30-10 - Open or Short to Plus - Intermittent

00539 - Fuel Temperature Sensor (G81)
30-10 - Open or Short to Plus - Intermittent

00522 - Engine Coolant Temperature Sensor (G62)
30-10 - Open or Short to Plus - Intermittent

00553 - Mass Air Flow Sensor (G70)
28-10 - Short to Plus - Intermittent

00777 - Accelerator Position Sensor (G79)
27-10 - Implausible Signal - Intermittent

00741 - Brake Pedal Monitoring
27-10 - Implausible Signal - Intermittent

00765 - Modulating Piston Movement Sensor (G149)

After alot of saying the F-word and a lot of other things I managed to do some measuring on my wiring loom and found that the part of the loom that runs behind the airbox was melted probably due to the wires rubbing against the edge of the airbox and the chassis resulting in the insulation being damaged. I repaired all the wires, checked all the sensors, did a reset of the fault list in the ecu and then I was down to these faults :

00527 - Intake Manifold Temperature Sensor (G72)
30-10 - Open or Short to Plus - Intermittent

00539 - Fuel Temperature Sensor (G81)
30-10 - Open or Short to Plus - Intermittent

00522 - Engine Coolant Temperature Sensor (G62)
30-10 - Open or Short to Plus - Intermittent

00777 - Accelerator Position Sensor (G79)
27-10 - Implausible Signal - Intermittent

00741 - Brake Pedal Monitoring
27-10 - Implausible Signal - Intermittent

I manually checked these sensors again, all measured out fine, then I checked and measured the wires from sensor connectors to the ecu, these were also fine, hmmm....... I then had a look at the wiring diagram again and found out that all of the sensor that had faults all had the same ground connection to the ecu, but the wiring seemed fine so I took the ecu apart and discovered that the pin were ground 220 was connected was melted just before the pin was attached to the pcb in the ecu. So the current must have been pretty high :eek
I repaired the pin, reset the ecu faults, and all was fine............Yes :nana2:

And now, 1½ month later a new problem, damn....

Car wouldn´t start, lot´s of juice on the battery, no cracnking, after numerous tries the starter finally gave in and started cranking but barely turning the engine. The engine started after a couple of tries.
Then I started my trip to work and found the car with no power at all, had my VCDS in the car and connected it up. No faults in ECU memory, but my boost pressure was very low, around 0,6 bar @ 2000-3000rpm (7 psi). I put the car in neutral and kicked the accelerator a couple of times, the final time I did this something happened when the engine went over 4000rpm, it felt like power was restored, and the engine had a lot better throttle response (in neutral still). I tried to doo a couple of runs from low to high rpm, some power was definetly restored, but the engine was still slower than usual. Had a look in VCDS again and the MAF reading was stuck at 550mg/str.
Stopped again pulled og the connector to the MAF, no change in reading or engine response/power.

Do any of you clever guys have any ideas what happened to my car, and any procedure for checking the MAF "hot wire" on a mk3 TDI engine code AFN. I have found a lot of write-up´s for the mk4 MAF, but none for the mk3.....:bowdown

Best Regards and power to the "do it yourself people"

Anders Fiedel
 

·
Premium Member
Joined
·
23,902 Posts
The best way is to look at MAF requested vs. MAF actual. Yes, there's a writeup in the mk4 FAQ but some other things which could cause low MAF readings: EGR open, clogged exhaust, bad wiring.

Does your car have a variable vane turbo or regular wastegate turbo? I suspect that it has a regular turbo. The variable turbos had problems with the vanes and actuator sticking.

Something else mk3 TDI in the US were affected by - there's a hose inside the ECU that goes to a boost sensor. In your case it's probably not bad because it normally throws a code of internal ECU fault http://www.myturbodiesel.com/1000q/a3b4/ecu-hose-chip-tdi-65535.htm
 

·
Registered
Joined
·
10 Posts
Discussion Starter #3
The hose inside the ECU is ok, my turbo is a VNT type, when I compare MAF requested and MAF actual, the requested value is looking right (following engine speed/throttle) but the MAF actual is stuck at 550mg/str.
 

·
Premium Member
Joined
·
5,942 Posts
Might be worth making sure your ecu is nice and dry too with that list. I'm not sure where yours sits on the mk3 golf but I've seen a few soaked giving grief including my own.:)
 

·
Registered
Joined
·
10 Posts
Discussion Starter #5
Might be worth making sure your ecu is nice and dry too with that list. I'm not sure where yours sits on the mk3 golf but I've seen a few soaked giving grief including my own.:)
If you read through the post you will find that these faults have been corrected :D
New problem has arrived, but maybe I should move this to another group in the forum ?

Regards
 
1 - 6 of 6 Posts
Top