1.4 16v AFH Kangarooing and Stalling at idle

[Crasher]

The sensor should be disconnected with the engine running, the revs blipped over 3000 rpm twice and this puts the ECU in open loop mode when the lambda control is shut down. I am at home without a manual but I remember the 3F having the same type of inlet air temp sender with blue CO setting blanking cap, is the cap in place?

[jackanyon]

Attempt 2 following those instructions. Engine started, followed by unplugging coolant sensor and then blipping throttle to above 3k twice. Engine ran for around 45 seconds before cutting out. I restarted the engine, and attempted to rev it. It misfired with any amount of throttle and sounded like it was getting choked, there was clearly no combustion happening, just fuel exiting the exhaust in smoke form. My nosey neighbour said he had a very similar issue with a 6n2, which turned out to be the throttle body (food for thought perhaps). The wind has picked up pretty badly, so I've called it quits and gone inside.

I did look for the

inlet air temp sender with blue CO setting blanking cap

however I'm not very familiar with VW's. Could you describe where exactly it is I'm supposed to be looking? If it's any use, the part number for the T/B is 036133064E.

Thank you for your patience!

[Crasher]

You can see the throttle body potentiometer output in measuring blocks and so can see if it is nice and smooth using the VCDS graph output and a smooth foot action and adapting the TB in Basic settings is important... I did get you to check the ignition timing didn’t I? Ignore the blue coolant temp sender part, I was getting wrapped up with a chap who is going a 3F in a Polo 2 MH. I need to sit at the PC and run through ideas in my head like I would on a job, the last customer AFH I had in was at least five years ago and she now has a Golf 6 TDI that we sold her.

[jackanyon]

I've rescanned for codes after limping it my unit (15 miles away, the drive was horrific!). The only codes there were the EGR and EVAP ones, which are to be expected given those parts have been removed. The code for Ignition Output must've been sorted by replacing the coil. I took the throttle body off and gave it a clean. I also did the adaption in basic settings after. It made no difference however.

I unplugged the O2 sensor, and it behaved a bit better. However it didn't throw a code for it, even after restarting the engine a few times. That seems a bit odd to me, is it supposed to throw a code for no O2 sensor?

I attached a spark tester so I could see if it was losing spark as the revs drop. The spark was consistent and looked as you'd expect, even as the revs dropped. I did notice the the actual butterfly jitters around a bit, and it appears to close up as the rpm drops.

I've linked to a 10 second video I took showing both the butterfly and spark tester. The spark tester is connected between the dizzy and coil king lead, hence why its not in any sort of firing order.

[Crasher]

The butterfly closes on the overrun, part of the emissions reduction strategy, it also moves around a lot if the idle is causing it difficultly. How is the ECU provided with its live and earth feed?

[jackanyon]

Right, got it. Another trivial find on my part then!

Theres a thick red power cable (standard 6n I believe), which runs into the car, down to a white plastic bracket which holds multiple coloured plugs. It terminates on the top with a nut. I think the power for the ecu then runs back out into the bulkhead connecting to the ecu. Theres a red cable and a black spliced into the ignition barrel wiring. I presume this goes back to one of the coloured plugs. However I'm not familiar with VW wiring (Give me a Honda any day), so I couldn't tell you exactly where they go.

See the picture, it describes what I mean by white plastic bracket. I took it as I swapped all of the wiring over just incase. Any snipped off wires were done by whoever converted the original donor car, so I can't tell you why they've been cut or what they did. Theres also a black bracket which has the obd port mounted to it, it may have fuses on it also but I can't remember for certain.

IMG_5076.jpg


For the earth, there's a bundle of brown cables which come from the plastic cable sheath which leads to the ecu. These all terminate into a single ring connector, connected directly to the battery.

[Crasher]

The wiring follows the DIN standard protocol. In basic terms red is battery live direct unfused called line 30, black is ignition switched live, unfused called line 15 and brown is permanent earth called line 31.

[jackanyon]

Just had a quick brainstorm about the wiring. I know that the black cable from the ignition barrel has the cigarette lighter (which always has my FM transmitter plugged in) and fan relay spliced in. I imagine it'd help to remove those to see if theres a degree of interference going on.

[Crasher]

At socket 15 I think there should be two blacks, a thin one and a thick one. These are direct from the red internally which is battery direct and unfused. On the carb engined Golf 2 this was a common source of dash fires as the feed went to the coil and the carbs bolted on heater which would short to earth and...

For accessories you should use the black/yellow wire, called the X line and this owners the headlights and the X relay which powers everything else that only works with the ignition on but again this line out is unfused.

The ECU should receive as direct as possible permanent live (line 30) an ignition live (line 15) a direct to battery earth (line 31) and a starter motor active line 50.