Overfuelling - 1996 Kafer / Beetle 1600i Mexican

[MexiBugUK]

Hi,
Sorry, I can read some German (lived in Gutersloh 2 years) but not too good.

Anyway, My 1996 mexican 1600i is using a lot of fuel - 20 MPG. and the emissions are too high. It has failed the MOT. Pre CAT the emissions are within the limits set by VW.

I have had a new Lambda sensor, new temp sensor and rolling road diagnostic check. Still no good.
Could a dead catalytic converter cause the overfuelling? I think not.
It is more likely the excess fuel has damaged the CAT.
How can I test the cold start system? I have been told that could be sticking and causing the problem.
I am considering replacing the injection system with carbs, coil and 009 distributor. Can this be done on this engine?

Are there any suppliers of Catalytic converters for this car in Germany? Can get in UK (i hope)but £500.
I am not a mechanic, but have worked on 4 older Beetles and built a kit car through to SVA standard so I know my way round the toolbox.
I would appreciate any help, Thanks

Ian - MexiBugUK

[phade]

Hiya Ian,

The first thing you will need is a VAG 1551/1552, VAS 5051/5052/5053 or a VAG-COM with the correct mexican beetle plug on it. Alternatively you can make up your own lead by following my instructions on Manfred's 1600i website (the mexican beetle plug end in this case are three flat-bladed pins insulated with heatshrink).

The VAG 1551/1552, VAS 5051/5052/5053, VAG-COM or an equivalent hand held scanner is available on eBay. The 16 pin OBD II (JEDEC J1962F) female socket is available from S K Pang Electronics.

I suspect that the following are faulty (which have caused several errors to be stored in the ECU's fault memory):-

- Ignition transformer (available from GSF, etc).
- ECU Relay (Relay 30, available from any VW dealer)

Have a look at my parts cross reference list to see what other VWs and Audis those parts will fit. You will need that information when you order parts from GSF.

In general a faulty ignition transformer and/or a faulty ECU (voltage control) relay will cause the following faults to be stored in the ECU's fault memory:-

- Lambda signal too high (G39)
- Throttle potentiometer (G69) - No Malfunction Detected, intermittant
- Internal Control Module (ECU) Memory Error, No Signal
- Intake Manifold Pressure Sensor (G71) - Open or Shorted to B+
- Supply Voltage B+ - No Malfunction Detected, intermittant

Once you have got a new ignition transformer, ECU relay (relay 30) and a diagnostics kit, you should then be able to read the ECU's fault code memory and erase them. This will then get the ECU out of emergency mode (referred to as "Notlauf" on the 1600i website) and your car will run a lot better. The fuel economy should also improve significantly.

As far as the cat convertor goes, the only thing to really look for is rattling or severe rust. If either is the case then the cat should be renewed. These are available from the following:-

http://1600i.de/

http://www.vw-classicparts.de/

partsvw@hotmail.com - Antonio Trejo (beware of UK VAT and import duty !!!)

If you wish to order parts from the VW Classic Parts Center, you will need the part number for the cat convertor, which is listed in my parts cross reference list on the 1600i website, but try Manfred first since it may be cheaper to get one from him.

If you are within the Kent or Surrey area, let me know and I'll see when (if possible) I could diagnose your car and advise you from there.

Also I think putting carbs on your engine would be a mistake., it involves the changing the following:-

- Air filter unit (with thermostat and warm air flap vacuum unit)
- Vacuum advance distributor
- Cylinder heads
- Fuel tank (either modified or replaced)
- Fuel pump (I'm not sure where you can mount a mechanical on one of those engines)
- Fuel lines - replace to 5mm

The end result of installing carburettor bits on your engine would be worse fuel economy compared to a fuel injection engine (30 MPG if you are very lucky !!).

A typical mexican beetle 1600i engine usually will do about 40 MPG (depending on driving conditions).

Let me know how you get on and good luck with your car.

Cheers,

Phil

[MexiBugUK]

Phil,

Thanks for the advice. I assumed the ECU would have been looked at - but i now remember the garage didn't have the diagnostics to read it and considered sending it away for reading and reset.

I am struggling to order the correct adaptor from SK Pang. Is it the 2x2 adaptor? Obviously nothing is standard in the UK for this car. Is it easier to buy the female socket and make up your own lead?

Will resetting the ECU affect the final emissions.? The test done at MOT was as follows: CO at idle too high 1st fast idle 4,095 (limit 0.3), CO at 2nd idle 2.005 (limit 0.3) and at slow idle 4.697.
Lambda test after second fast idle was too low: 0.946 (lowest should be 0.97) Could be the CAT as well?

Someone on another forum suggested the injectors could be worn and dribbling causing excessive fuel and raised emissions?

[Guido]

it is not the 2x2 Adaptor,

The right plug you can see here:

http://www.1600i.de/1600i-diagnose/iso9141-interface/diagnosekit.html

and an adaptor to normal OBD2 here:

http://www.1600i.de/sell/spare-parts/spare-parts.html

[phade]

Hiya Ian,

I would doubt that the injectors would be the cause of high emissions. A leaking injector would normally result in a strong smell of petrol from within the engine bay and you would see fuel around the injectors (they are the small black things next to the spark plugs). Leaking fuel injectors and fuel hoses are however dangerous since they can cause an engine fire.

Guido is right, it is definately not the 2x2 connector, the diagnostics connector is unique to the 1600i mexican beetle and it is located on the front left hand side of the engine compartment, behind the big black round circular connector. A picture of this is on the 1600i website, http://1600i.de/ (or http://www.1600i.de) . You can only get the OBD II connector (purple socket) from S K Pang Electronics.

To make up your own lead (if you cannot get the adaptor from Manfred), you will need the following:-

- A small ABS plastic box (to house the OBD II connector) - Maplin or CPC (Combined Precision Components)
- A female OBD II socket (JEDEC J1962F) - S K Pang Electronics
- Adhesive heatshrink (6mm or 3mm 3:1) - Maplin or CPC
- Three thin flat steel (or a metal you can solder onto) pins - Local hardware store
- 3 core cable (eg. mains cable), approx 1m to 2m in length - Local electircal / hardware store, Maplin or CPC

Insert the wires (with the pins attached to them) to the OBD II socket. When wiring up the OBD II connector make absolutely sure that you have put the wires into the correct pins !!! You will not be able to get the pins back out again once you have put them into the socket.

Now cut out a hole in the side of the ABS box to fit the OBD II socket, this may stick out a bit (just make sure that you can connect the VAGCOM lead to it afterwards !!!). Glue the connector to the ABS box using JB Weld or similar.

Next drill a hole to allow the 3 core cable to pass through it. Insert the 3 core cable through the hole and join the OBD II connector's wires to the wires on the 3 core cable. Make sure that you use the adhesive heatshrink to insulate these cables !!! Make sure that you tie a knot (or use a strong cable tie) in the 3 core cable to prevent the cable from being pulled out.

Now strip back the other end of the 3 core cable (I would suggest about 50 mm or so) and solder the 3 flat-bladed pins to the wires of the cable. Use adhesive heatshrink to insulate these wires but make sure that the bare ends of the flat-bladed pins will fit the 1600i diagnostics socket !!!

Your home made adaptor should then be ready for use.

Good luck with your car,

Phil

[MexiBugUK]

OK I had a long Saturday making up the cable, and messing with software.
Eventually everything was in place and the ECU showed three fault codes (only 3).
The Lambda sensor (now replaced), the Temp Sensor (again replaced) and the air flow sensor (I disconnected it to check it was functioning). I have reset the codes, run the engine and checked the ECU again. No fault codes!
It previously had a stutter as the throttle was released - that has gone. I obviously cannot recheck the CO and Lambda readings. I am replacing the plugs today and checking all leads, earth straps and inlet / outlet for leaks.

Could not get the ignition transformer - GSF talked me out of an alternative (no misfires) they said it wouldn't be the fault. At this moment in time I have not sourced a relay, but looking at the test results, it has not shown a fault.

I will update any findings. This site has been a great source of information. Manfred supplied a CD with the sensor I got from him - some really good information.

[phade]

Hiya Ian,

You can easily get the following from your local VW dealer and GSF:-

- Relay 30, VW dealer (costs about £10)

- Ignition transformer, GSF (mk 3 polo fuel injection, etc - 3 pin).

It seems like that the engine oil temperature sensor was causing your car to intermittantly cut out (that's what my one did).

If your car intermittantly cuts out again, check the hall sender on the distributor. This can be done by wiggling the 3 pin socket (on the distributor, not the cable) whilst the engine is running. If the engine misfires or runs unevenly when you do this then the distributor will need to be replaced (you cannot get the hall sender out of the distributor, I have already tried that one !!).

The lambda probe can be checked with VAGCOM by using 08 Read Value Measuring Blocks, group 001 or 002 (I cannot remember which one). You will need to look for the lambda probe voltage column (this should be fluctuating between 0V and 1V).

Another method of checking the fuel pressure regulator (this can be another cause of misfiring) and the fuel pump delivery rate is to use a fuel injection pressure gauge. I have documented this on the 1600i website.

Good luck with your car and it's MOT retest,

Best of luck,

Phil

[MexiBugUK]

Ok, I have now had two weeks working on this problem. What I have done so far:
Replaced parts -
Lambda sensor
Temp sensor
ignition module
ECU relay
HT / plug leads
plugs
dizzy cap
air filter
exhaust gaskets
oil filter
oil (semi synthetic - for the hydraulic tappets)*
Other work:
cleared all DTC / fault codes on the ECU, removed exhaust system, to replace the gaskets (discovered a few small leaks) and replaced some missing nuts on the manifold!
Static timing (as described on http://www.1600i.de). Breather system flushed out. - I discovered oil vapour was passing through the air filter into the idle stabilisation valve - obviously this should only have air passing through it.

This now raises the question of why oil is being forced up into the air filter? Back pressure? Could this be the end product of a knackered CAT?

Anyway, whilst stood scratching my head a neighbour enquired about the problem. When I explained he produced one of the old 'Gunson Gas Tester' kits. Great. So according to the antique eqpt, the CO is now down to a fluctuating 0.5 - 1%. Much better than the 4.6% at the test station.

i am now in a predicament. Do I return the car to the MOT tester to see if the antique is producing over the top results -(the car is running well!) and if it fails go for the CAT then. Or, do I replace the CAT as part of my glossary of replaced parts / work completed / money WELL spent?

Something I haven't mentioned is the milky residue building up in the oil filler tube. When i first go the car it had been stood unused for a while, so I thought the problem was short journey syndrome. Then I was told synthetic oil has a tendancy to do this, but it should rectify itself with an oil change and regular use - no it hasn't. I am presuming the condensation forming in the engine is finding its way into the oil filler and reacting with the oil there, this would also explain the oil/water transfer into the air filter box and into the tubing to the idle stabilisation valve?

Again - back pressure through the engine from a blocked / broken CAT?
Refurb my old CAT- £215 + delivery collection
New CAT from Germany - 320 Euro's
New CAT from VWHeritage - £ 470 ..

I have stuck with it. I cannot convert to carbs, it is a 96 car and anything used in the UK after 1992 has to have a CAT and tested as such.
Plus the list of parts to convert the beast was longer than the one I have produced above.

Sorry for the novel, but it may help someone else in the same position as Mexican Beetles get older, and parts and knowledge are so scarse.

So What do you think about:
The milky oil
Back pressure
and the CAT?

[phade]

Hiya Ian,

Are you referring to a yellow-ish sludge in the oil fillter cap and up the oil filler tube (as well as inside the air filter box)? If that is the case, all you will need to do is to clear out that muck. My car does that fairly regularly but it doesn't cause any problems and has done it since brand new. It may also be a good idea to use engine flush when you car is due for it's next oil change.

Regarding oil, I would only recommend using 15W40 mineral oil. Synthetic (or even part synthetic oil) has an unfortunate habit of weeping past oil seals and gaskets (as I found out) which can be a problem. Since I went back to 15W40 standard mineral oil nearly all of the oil leaks disappeared.

It seems to me that the cat convertor could be on it's way out (0.5% to 1% is a lot higher than the 0.3% maximum limit for an MOT). However, the Gunson Gastester isn't very accurate at all in this case (it's accuracy is typically +- 0.5% CO) which would make the CO reading you observed fairly meaningless.

I would take it back to the MOT and see if it passes on the emissions (an MOT approved gas tester such as the Crypton is silly money even on eBay). If it doesn't then the cat should be replaced. I wouldn't bother with VW Heritage since they take forever to get one, I would get it from any of the following instead:-

- Manfred Graf (http://1600i.de)

- VW Classic Parts Center (http://www.vwclassic-parts.de)

- Antonio Trejo (vwparts@hotmail.com)

A blocked cat would cause the engine to have severe lack of power (even when it isn't under load) and would be very noticable, a broken cat would result in excessive emissions.

Good luck with your car,

Phil

[MexiBugUK]

OK it passed the MOT with flying colours - eventually.

However, it now stalls at traffic lights / coming to a halt, revs drop very low, and she stalls. I had adjusted the throttle as per the website, slight gap then close up. I have now had to run it up a bit just to keep it running when warm.
Any ideas? Obviously this is not a major problem now, I have 12 months to mess until the next test.

[phade]

Hiya Ian,

Have you tried Basic Settings (VAG commands 01 - Engine, 04 - Basic Setting, 000 - Group 0) after you had adjusted the throttle cable?

I have also just noticed in my fuel injection booklet that "Basic Settings" can only be performed under the following conditions:-

- Engine oil temperature less than 44 degrees C (column 3)

- Throttle valve potientiometer value between 11 and 112 (column 8 )

- Engine speed value above 128 (column 9)

I have managed to do basic settings on my car when the engine was warm and at idle speed without any problems.

Let me know how you get on.

Cheers,

Phil