(I also have this on the VW caddy forum)

 

Is anyone here a knowledge base on the 1.9D (AEF) engine in the Caddy/Pick Up? I am desperate for some help please!

My plans were always to transplant a more powwrful engine into the car, but before that thought I'd spend some time checking that I am in fact getting the best from the 1.9D that is there now. Following a small job on a squashed intake box gasket, I discovered what seems to me an excessive amount of carbon in the in the tubes. So I spent the weekend taking off and giving the head an old fashioned de-coke. All back together tonight and is it running better? Possibly. I certainly notice it being free-er - or is this psychological?

Now to engine management. Here are some notes:
1. Engine starts first hit when cold (I have a high torque starter motor)
2. Huge rattle on start up from cold that ceases after a minute or three - I suspect hydraulic tappets.
3. Engine starting when hot is terrible. Really bad sometimes. I have fitted a delay timer to temp sender that fools the engine in thinking it is cold on start up. It now starts first hit when hot...
4. Accelerating in first gear produces terrible diesel knock throughout the revs. Not as pronounced when the engine is hot.
5. Accelarating half way up the revs in second also diesel knocking, then tails off.
6. Pulling in 3rd and 4th gear, the engine is marvellous. Only some spasmodic diesel knocking when it is a no load pull, eg down hill.
7. On a good road, I can push the truck up to 120kph without too much effort. 130 I believe is top speed, yes?

I have replaced the temp sender twice - the last time with one from VW Dealer Parts at an exorbitant price...

Two things here strike me:
a. Info is not getting to the distributer pump reagrding the heat of the engine and what it needs in way of starting.
b. Info is not getting to the distributer pump advance mechanism as to when torque is required and not required.
Am I correct?

Now the question. What is wrong?
In may previous thread, #Incaddy suggested that cam belt timing could be an issue in misbehaving AEFs - hoping you read this post, based on the above info, could this be a problem on mine?

I have read somewhere that the AEF in the Caddy does not have an ECU as such, but some other device, yes? There must be something that tells the distruter pump what to do, that translates signals from various senders, yes? What is this device and where is it? Is it known to fail? How about the pump, can this give trouble or is it bomb proof?

I think I also read somewhere, but cannot find it now, that there is a possibility that a circuit that the temperature sender fails in something and causes the hot start problem. Is this so? If so, where and what?

I have the same hot start issue (not the diesel knock issues) so very interested to hear any solutions.

 

I have changed the temp sensors and have not had any change in the behavior.

It seems that any experts there might have been on the AEF engine have moved onto pastures new. I have the same enquiry out on the VW forums as well without success.

 

I did read somewhere that our engine controllers had some issues in relaying information from the temp sender to the pump, but cannot find the reference, nor indeed any other. 

 

Regarding your hot start problems. There could be a work around but first you need to ascertain they will work. Try removing the four pin connector from the temp sender. Tape it up and run it like this for a few days. It will mean that your glowplug light will come on at every start and you must wait for it to go out before starting. It will also mean that you do not have a temp gauge, so only do this if you do not have overheating problems. This test forces the engine to think it is cold at every start and makes the necessary adjustments.

 

If this solves the issue, then the ways to continue, yet have a temerature gauge, it is necessary to break one of the wires to the sender and insert either a manual on/off switch or an automatic timer that cuts out this wire for a few seconds prior to starting.

 

Of the four wires going to the sender, two are for the temp gauge and the other two are for the engine control signal. It is one of the latter two that you need to intercept.