1998 Polo 6N1 1.6 AEE engine auto sometimes cuts out/stalls, then restarts 80,000 miles.

[shabazmo]

I am struggling trying to fix my mother’s faithful 21 year old Polo which was purchased new and I have looked after for 21 years. The problem started several weeks ago with the engine missing a beat or two, then stalling when stationary, but more recently, it has stated cutting out even when driving. When this happens it subsequently starts first time and all is well. This may happen only once a day if at all. I have carried out the following as a service was due:
Compression test. All cylinders 14.5 to 15 bar
Replaced sparkplugs
Replaced ignition coil
Replaced rotor arm and distributor cap
Replaced fuel filter
Cleaned battery terminals and earth strap from battery to body and gearbox
Throttle body cleaned with carb cleaner as is done every service
Ignition leads were replaced 4 years and 20k miles ago.
Checked timing marks on crank and camshaft because I replaced the belt recently
I have checked the battery, alternator and earthing using a Ring battery tester and all was ok.
I have looked for induction leaks but can’t find any, and of course there is a lot of wiring that could be shorting.

I am not getting any fault codes via VAGCOM, but one did appear after it had stopped on the motorway.
00529 Engine speed signal missing 03-10 No signal intermittent
00653 selector Lever Auto transmission plausibility. 27-10 Implausible signal intermittent

I can’t figure out if I am lacking fuel or sparks because the fault only occurs momentarily. My mind is switching to the MAP sensor, fuel pump or the Hall sender, but would like to get some views before I spend more time on replacing parts.
Thanks in advance

[shabazmo]

Last night I removed the MAP sensor and cleaned it with carb cleaner. It didn't seem dirty, so I dont think this will do anything positive. I also noticed that the wire loom feeding the MAP sensor is attached to a metal guide on the inlet manifold and was squashed at the point the crankcase hose inlet pipe of the air filter casing presses on it. I just thought that this may be where the there was some shorting occurring. I have tried to loosen the squashed wires and tried to spray some moisture repellent into the sleeve.
I drove 16 miles today and the car drove well, but that's quite a small distance to mean anything.

[Crasher]

The AEE distributor was very prone to failure when these engines were more common, it was so bad that the local dealer (pre TPS days) would always keep two on the shelf as it fitted a wide variety of the hydraulic tappet EA111 engines. I checked with TPS and the part LOOKS to be still available as they are indicating three in stock, part number 030 905 237 GX which replaces the original 030 905 205 AB and the nice surprise is that they retail at £76.74 including VAT which is a bargain when you consider the hall sender inside costs £120 and it comes with a genuine Bosch cap and rotor plus a two year warranty. Also the notes on ETKA say it is no longer necessary to return the old one. You will have to put the ECU into basic settings mode and use a timing light to set the ignition timing, it is a fussy process where the engine rpm must lift on its own to about 1400 rpm in basic settings mode and then you can dial the dizzy in, that is if you can see the timing marks!

[shabazmo]

Thanks a million Crasher. Given the cap and rotor was £31 from TPS, this truly is a bargain. I might just buy one anyway. As far as fitting it, I sold my timing light a few years ago and wonder whether vagcom can be used. If not, it will probably have to take a trip to your place. The car will be going to my daughter at Nottingham uni. The distributor is original and 21 years old.

[Crasher]

We have a lot of customers from our two unies and we are used to helping them through. Twenty five years after graduating a couple are still customers, one bringing his car half way across England twice a year for work.

[shabazmo]

I thought I should conclude this post. Since my last post in mid September, we have driven the car for a month now and it probably only twitched twice. I can only assume that the MAP sensor needed cleaning or the wires to the sensor have been relieved of the strain. Thanks Crasher for helping my brain cells work more effectively.

[shabazmo]

Well the fix didn't last long, so I am taking the car to Crasher on the 17th January. Time for an expert to look at it.

[Crasher]

I will have to make sure my rescheduled double hernia opp does not clash.

[shabazmo]

In order to conclude this post, a big thank you to Crasher who took the car in and replaced the distributor (hall sender) and the car has run perfectly for several weeks now. :beerchug: