AGG Cold starting problem

Helo from a new member. Fiited a new starter motor to my 8v anniversary started on the the button for first day or so. Went for a long drive and then stalled at a set of lights and difficult to start as if engine flooded. Got runing again after a few minute break then stalled at a junction. Left the car parked up for a few hours. Very difficult to start; engine turning over but not firing taking 10 to 20 secs to finally start up but seemed flooded. Nursed it home but next morning very difficult to start and only fired when foot to floor.
Over the last few months have fitted new crank sensor and temp sensor. No fault codes showing. Check temp readings on air temp sensor against diagnostics and readings the same. Where would you reccommend I start to cure my problem. I have a Hitachi air mass sensor date stamped 1996 could this need replacing? Had the plugs out and they are black sooty so seems mixture runing too rich? Ant ideas or sugegstions very much appreciated. Use a Skyes & Pickard fault finding kit with VAG module.

Look forward to your replies really dont want to replace my car love the Mk 3 Anniversary too much but want to cure the niggling electrical faults so joned your club oh and I have been reading every conceivable forum on the web and not found anything related to poor starting on AGG mostly read about intermittent stalling etc hope soemone can help and I apologise for long winded message x

I would suggest you first of all replace the ECU relay, this is at postion 3 on the fuse box (top row, third from the left) and has the number 30 printed on top. This is available from VW under part number 165 906 381 and costs just over £11.

crasher cheers bud

I did that first thig this morning along with 167 relay and reset the TB in the usual way of disconnecting the battery - No change stil very difficult to start. So I have got some carb cleaner and set about cleaning TB, temp sensor and air mass sensor along with cleaning air pipe and oil breather. There is a split in the oil breather pipe at the block end but I doubt this would affect the starting performance or am I miss judged. Will now have to see in the morning if this had had any effect as the engine is hot and starts easily on first fire of 3 seconds. Fingers crossed. Im on 140k so I suspect I will end up changing even more parts lol!!! The idle is spot on at 900 revs now and does not fluctuate at all. The TB was a little caked up but I did clean this about 6 months ago. Keep in touch crasher and I will update in the morning and advise if all of this has cured. Regards:beerchug:

Disconnecting the battery deletes the adaptations and does not reset the throttle body, this can only be done with diagnostic equipment in Basic adjustment mode 04, group 001.

Hello crasher

Went out this morning and the problem is still there. Approx 5 - 7 attempts at starting turning the starter over for 10 secs bursts with foot to the floor. A few spits of trying to fire then finally she goes. There after starts everytime ok during the day.

Do you think its more to do with the throttle body? Air mass sensor? where do you suggest i next look at or test. I am not flushed with cash so dont want to go on a massive spending spree or to take to a garage as expereince shows they are hopeless at fault finding.

Speak soon

Crasher just thought of something I have noticed but not given any thought to. About 4 months ago I fitted a new temp sensor to the block bought from GSF. I have noticed recently even when on the motorway and giving it some gas it did budge much from mid 70 degrees. Been out just around town no more than 3 miles and its up dead on vertical i.e. 90 degs. Maybe the sensor is faulty batch. Would this affect starting first time in the morning? I have ordered a cable for my computer so I can download and use vag-com as Ihave been using the pickard module which doesnt allow you to program anything just read of data in engine. Let me know your thoughts. I have found sometimes buying stuff from gsf is nt a good idea and better to buy from vag genuine parts would I be right ?

The temp dipping when cruising at speed is more a stuck open thermostat to me, over cooling basically. That starting problem doesn’t suggest either throttle body or AMM but they can act up if the accelerator is depressed for starting. How does it start if you do not touch the pedal? I think we are stuck until you have a VAG-COM cable and you can read some measuring block info. I would be interested to see what temp the ECU was seeing when you are trying to start it and the ECU voltage.

Crasher thanks for that as I will have to wait until the usb cable comes is first thing tomoz I will try and start her with the thermo cable disconnected and see whether it will fire i.e. not getting a temp sensor no doubt we will speak later in the week..................you must love being a mechanic if when youget home youare sorting other peoples cars out..........in closing I am most grateful for all you contribution no doubt it will get easier when I have VAG_COM enjoy the rest of the weekend dude

Don’t try stating the car with the sensor disconnected until you have checked for fault codes as that will store one, but I think you have checked with that other tester haven’t you? Sometimes I love being a mechanic, sometimes I hate it, just like anyone else and their job I suppose. What I do like is helping people trying to fix problems others can’t. A large proportion of my work is sorting really difficult problems that have stumped others and I do a lot of work for other local garages who have given up but don’t want to tell their customer, it puts you under a hell of a lot of pressure to succeed but I don’t always win. I had to give up on an Arosa yesterday as the garage who brought it in only allowed me an hour to track down a communications error between the engine ECU and air bag ECU plus a lambda fault. I sorted the lambda fault but the comms error had me beat in the time allowed, very frustrating.

Summary to my probme aided by the maestro Crasher..........new coil pack; The old one once removed has two hairline cracks in the body casing. To summarise this is all I had to change but in the last 6 months on a 14 yr old car and 140k miles I have also replaced the following:

Dissy and associated electrical parts (Beru)
plugs & leads NGK & Beru
Crack sensor non genuine
Water temp sensor VAG genuine blue replacement
30 Relay VAG genuine
Starter motor Recon unit by BOSCH from Unipart/Autoparts

My summary of problem was difficult starting from cold which developed into difficult starting at all times whether engine cold or hot. Intermittent stalling at low revs (traffic lights and roundabouts) with loss of power as well.

Crusher is a true gentleman, scolar and all round good guy