Sharan running rich

[steve55]

Hi Everyone,
This might be a bit long winded but I could really use some help !

I have a 1996 2.0gl petrol Sharan ady engine which I have run mainly on lpg with no problems for the last 63K miles. (current 148K) Always reliable with instant start up on petrol.Runs very well on lpg.

It recently refused to start and the rac failed to start it either. It was recovered to a local garage as a electrical fault was suspected.

The car was found to be very flooded, cleared and started but was running very rich.(on petrol)

In an attempt to correct the problem, new temp sensor, lambda and MAF was fitted but still high emmisions and running rich. No air leaks were found.

I decided to get a second opinion at a VW specialist garage who found a lambda fault. This was confirmed by my own lpg software.

Another replacement lambda was then fitted by the first garage but no improvement on emmisions.

I returned to the VW specialist garage who changed the lambda yet again for a genuine VW part and put on a new cat. Still No improvement in the emmisions!

Now emmisions on lpg is Ok so will pass the mot but I would prefer to get this problem sorted before It floods and lets me down again or destroys the new cat.

So some questions.
I am told the injection time is unusually high, around 9mSecs and it should be around1.5mSecs.? This would certainly account for running rich.

Is it possible that the ECU has been upset by running on lpg and could the ECU be easily reset or "virginated"? in situ. and what would be the implications of this?

It is possible the ECU has a fault so it would make sense to get it tested but how on earth does it come out? Anyone done this Please.
Found it behind the instrument cluster but it is not obvious how to remove it from under the top support bar.

(and none of this really explains why I broke down in the first place !)

Any help greatly appreciated
Regards
Steve

[Crasher]

What are the current stored codes? Do you have VAG-COM? I would also check the ECU voltage.

[steve55]

Hi Crasher,
I do not have a vag com but as far as I am aware there were no other codes when checked at the garage apart from faulty lambda. This was cleared.

Can you advise where to check the ecu voltage and what should be expected.

I have just read that disconnecting the battery for a few hours will reset the ECU to factory settings.Do you know if this is valid?

Thanks

[Crasher]

The ECU’s received voltage is best checked using something like VAG-COM in Measuring Blocks 08, measuring it with a multimeter is time consuming and open to “cock up” syndrome unless great care is taken with the delicate wiring and connections at the ECU plug. The ECU has a non volatile fault memory but adaptations on an early ECU may be erased by disconnecting the battery. All it is likely to achieve is to make the engine stall and require you to have the throttle body removed, cleaned, re-fitted and readopted to the ECU in Basic Settings 04. It needs someone with a good diagnostic system and knowledge of the data to go thorough the Measuring Block 08 information to look for anything out of spec. You could try replacing the ECU relay to see what happens. This is on the fuse board at position 3 (upper main row, third from the left) and has the number 30 printed on top with the VAG part number 165 906 381 and costs about £12 from VW. The troublesome relays are black cased and usually made in Malaysia or the Philippines. The more reliable type are grey cased and made in Germany or Portugal. When checked with the engine running the ECU voltage should be just under battery voltage and stable.

[steve55]

Thanks again for your assistance and comprehensive reply.Much appreciated.

New development this morning... Deside to change air filter, replace plugs and oil.
Removed oil filter only to find what I think must be the crank sensor wiring just crumble away ! both the outer and inner insulation is so brittle along it's length and includes the plug itself. I am suprised neither of the two garages spotted it.
Am I correct in suspecting this was probably the initial non start problem because the RAC could not get a spark.

would this affect the emissions or am I still looking for something else?

Now struggling to remove it but looks like I can't get a replacement until Tuesday.

Thanks
Steve

Melton Mowbray

[Crasher]

Sometimes the G28 doesn’t register as a fault code, it is quite frustrating. It would cause an emissions problem if it was causing a misfire but then it should come up as an error code. Only fit a genuine VAG supplied or VDO sensor, the ones in yellow boxes from a well known German manufacturer cause huge problems, I refuse point blank to fit them. The only trouble is genuine ones cost four times what a cheap one does.

[steve55]

Hi Crasher,
Fitted new crank sensor, started straight away. Travelled 160 miles on petrol to give it a run and then changed to gas for the return journey.
Running sweet on gas.


Thought this had resolved the initial non start problem but this morning car refused to start.
Have strong spark and smell of fuel.

Will change the ecu relay today if possible as suggested (it is a black one).

Otherwise don't know where else to go with this one ...any more suggestions please.
Thanks
Steve

[Crasher]

Coolant temp sender.