1986 2.1 Auto Sleeper Over fueling when cold ** UPDATE**

[Sunnyside]

hi Guys,
My name is Frank and a new memeber.
I have just bought ( ie on Monday )a 1986 2.1 fuel injected Camper T25 (T3) and she runs great when warm. But if you dont get her to start first thing in the morning she floods. Some times she will splutter for a few second and them die . Definitely flooded.
Things checked so far are Coolant temp sensor,which ironically was new! plugs, leads, cap and arm, timing, air leaks ( although tht might help the flooding problem not hinder)
Has anyone got some ideas.

I am trying hard to work out what part the Idle control module can play in cold starting and if it was to fail would it make the engine very very rich??

HELP PLEASE

Thanks in advance,
Frank

[Aidan]

Over fuelling is possibly fuel regulator or injector or ecu related, rather than idle system which is allowing extra air in, check there's vacuum getting from the plenum chamber to the disi and fuel regulator and check the vacuum connection from throttle body to disi. On ignition ON fuel pump should run for a short bit, couple of seconds, you should hear it run, to presurise the injection system and then when you go to start position a signal goes to ecu to say starting, ECU checks the temp2 sender and temp1 sender (in AFM) and fuels acoordingly and disi/hallsender/tci make spark and ignition
if pump isn't switching off then pressure will be high and will overfuel and if regulator not getting vacuum it will overfuel
what's the resistance of temp 2 at cold ?
how good are the earth clusters in the engine bay ?

[Sunnyside]

Over fuelling is possibly fuel regulator or injector or ecu related, rather than idle system which is allowing extra air in, check there's vacuum getting from the plenum chamber to the disi and fuel regulator and check the vacuum connection from throttle body to disi. On ignition ON fuel pump should run for a short bit, couple of seconds, you should hear it run, to presurise the injection system and then when you go to start position a signal goes to ecu to say starting, ECU checks the temp2 sender and temp1 sender (in AFM) and fuels acoordingly and disi/hallsender/tci make spark and ignition
if pump isn't switching off then pressure will be high and will overfuel and if regulator not getting vacuum it will overfuel
what's the resistance of temp 2 at cold ?
how good are the earth clusters in the engine bay ?

Hi Aidan,
Thanks for the reply.
The CTS2 has been replaced today just in case. It reads about 2.5K @ 11 degC.
The strange thing is, if you start the van from cold and let it warm up or even just drive away its fine. Its if you start it, then stop or stall then restarting causes the engine to flood or at best build its self up from a flooding misfire to eventual run if you floor the throttle.
It starts fine once the engine has been running for 10 minutes. You wouldn't even know there was a problem.
The idle control unit is working, as once the van has warmed up, it does control the idle speed and if you pull the connector off the top of the valve the idle speed changes..

Also, I have taken the CTS2 out of CCT and put in a 2.5k potentiometer in cct with the DME/ECU. If you attempt to start the van from cold with the resistance artificially a bit lower. 1k for eg it start much better. Its why we bought a VW part numbered new sensor as we thought the one in the engine was duff. It wasnt a VW part number and TBH putting a new one in has helped a little as the old one was reading 4.6k at 11 degC. Funny thing was you could see it was brand new so some one has been chasing this problem before I bought the van. By using the pot and telling the ecu the coolant is at 1k ohm did dramatically improved the starting of the van and it didn't smell like it was attempting to burn excess raw fuel.
I am now suspecting either a weeping injector or an injector which had a poor spray pattern. Thats the next port of call tomorrow .
As you have mentioned I will be checking the fuel pressure but , once the van is up to temp it runs quite lean with no real signs of over fueling?? its really weird.
What do you think.
Thanks,
Frank

[Sunnyside]

OK

CTS2 replaced
Intake temp sensor OK
Fuel pressure OK
Injectors tested OK
Idle control unit OK
Earth connections OK
Airflow meter OK
Coild, cap arm & leads OK
Plugs checked....but ............they are the 3 electrode type and I dont think it should have this type

Starts first time from cold absolutely fine, but floods if a second attempt is made whilst cold.
Once engine is warmed up its absolutely fine

Does anyone have experience of the 3 electrode spark plugs
Frank

[LittleMissSunshine]

Hiya from me!

[Sunnyside]

Hiya from me!

Hello

[1664]

Plugs checked....but ............they are the 3 electrode type and I dont think it should have this type

Funnily enough I replaced my plugs at the weekend - I have over fuelling/flooding issues too which turned the old plugs black. Same as you - fine once it's warmed up but nail biting up until then as it can just flood and grind to a halt with no warning and won't start again. I turned the mixture screw down by half a turn; clutching at straws really. Unfortunately, I'm a complete duffer at all this so I'm hanging on for more clement weather then I'm stripping the lot out and cleaning/checking everything according to the VW Digijet training manual pdf (includes Digifant I think); also have the Vanagon Manual and the Haynes.

Anyway, checked in the Haynes Manual for plug types which listed Bosch and Champion plugs. These depend on what colour sticker you have on your coil. My local motor factor didn't stock either but looked up a NGK equivalent. When I opened them they were a three grounded tips affair so I checked on t'internet and they were indeed a replacement. Fitted them Saturday and drove to Dubfreeze and back (100 miles round trip) and they work although that's hardly a test of time.

http://www.sparkplug-crossreference.com/" onclick="window.open(this.href);return false;

[Sunnyside]

Plugs checked....but ............they are the 3 electrode type and I dont think it should have this type

Funnily enough I replaced my plugs at the weekend - I have over fuelling/flooding issues too which turned the old plugs black. Same as you - fine once it's warmed up but nail biting up until then as it can just flood and grind to a halt with no warning and won't start again. I turned the mixture screw down by half a turn; clutching at straws really. Unfortunately, I'm a complete duffer at all this so I'm hanging on for more clement weather then I'm stripping the lot out and cleaning/checking everything according to the VW Digijet training manual pdf (includes Digifant I think); also have the Vanagon Manual and the Haynes.

Anyway, checked in the Haynes Manual for plug types which listed Bosch and Champion plugs. These depend on what colour sticker you have on your coil. My local motor factor didn't stock either but looked up a NGK equivalent. When I opened them they were a three grounded tips affair so I checked on t'internet and they were indeed a replacement. Fitted them Saturday and drove to Dubfreeze and back (100 miles round trip) and they work although that's hardly a test of time.

http://www.sparkplug-crossreference.com/" onclick="window.open(this.href);return false;

Hi 1664,

Do you think its cured the cold starting issues
We have exhausted every avenue now apart from fitting non standard different plugs. They are as you say black if the engine fails to start. Apart from fitting a push button to alter the CTS2 reading if it floods to weaken the mixture for a few seconds I cant see a way of stopping it flooding. Strangle it starts great first time when cold and every time when warm. Its just a second cold start and there on that is the problem. The smoke out the exhaust is chocking and pure rich fuel .

[1664]

Do you think its cured the cold starting issues

What? Changing the plugs or just turning the mixture screw down? Whichever you mean, I very much doubt it.

I don't know what the CTS2 is, like I say I'm a duffer and will have to crawl through the manuals when the weather improves. I must admit, I don't get any smoke - well, not that I've noticed at any rate. Mine always starts no problem but can flood and stop anytime after that up until it's warm but only occassionally. I don't tend to attempt second cold starts as once I'm moving I tend to drive to a meet or show as it's not a 'daily drive'.

[icosahedron]

Throttle switch set correctly?

I've had my DJ engine since new. Was never happy with cold starting with a slight misfire at first, the smell of petrol and a little smoke on occasion. A second start after stalling was also very difficult. VW at the time assured me it was normal. Anyway, years ago I changed the curve of the temp2 sensor by adding a resistor in parallel and another in serial. They cancel each other out when the engine is up to temperature and only affects cold starting. Never had any issues with cold starting since then and assumed that mine was perhaps just a little odd. Can check the values if interested when not so dark and wet.

There is no way to adjust the mixture. Screw on throttle body is for adjusting idling speed and CO setting on AFM is best left alone.

[1664]

Screw on throttle body is for adjusting idling speed

Oh.Well it didn't make any discernable difference to that. I didn't fancy touching the CO

[Sunnyside]

Throttle switch set correctly?

I've had my DJ engine since new. Was never happy with cold starting with a slight misfire at first, the smell of petrol and a little smoke on occasion. A second start after stalling was also very difficult. VW at the time assured me it was normal. Anyway, years ago I changed the curve of the temp2 sensor by adding a resistor in parallel and another in serial. They cancel each other out when the engine is up to temperature and only affects cold starting. Never had any issues with cold starting since then and assumed that mine was perhaps just a little odd. Can check the values if interested when not so dark and wet.

There is no way to adjust the mixture. Screw on throttle body is for adjusting idling speed and CO setting on AFM is best left alone.

Hi thanks for the reply.
CTS2 2.5k ota at 11deg.
Funnily enought I was thinking about reducing the cold start resistance by using a resistor as well. I used a Pot and experimented and sure enough with a reading of 1k it starts OK still a little hesitant but OK Unfortunately as soon as the engine warms up the original cTS2 has got to be put back is cct.

Could you please post or PM me the details you did with the 2 resistors. That would be a very very big help

[icosahedron]

I found the spreadsheet that I used for my calculations. After experimenting I settled on using a 3300 ohm resistor in parallel with temp2 and a 12 ohm in serial with this combination. I measured the temp2 resistance when warm at 215 ohm. A 3300 ohm resistor in parallel brings it down to 202 ohm with the 12 ohm bringing it back up to 214 ohm. I used standard 0.25W carbon resistors and made up a cable harness with male and female junior timer connectors that contain them and making it easy to return to standard.

My van has been in daily use for the past 13 years. Since the modification I've never had cold start issues even in sub zero temperatures. I've also since acquired a spare fuel injection system and have never found evidence that something is amiss with my original system.

I'd be very interested to know if this improves your situation.

[Sunnyside]

I found the spreadsheet that I used for my calculations. After experimenting I settled on using a 3300 ohm resistor in parallel with temp2 and a 12 ohm in serial with this combination. I measured the temp2 resistance when warm at 215 ohm. A 3300 ohm resistor in parallel brings it down to 202 ohm with the 12 ohm bringing it back up to 214 ohm. I used standard 0.25W carbon resistors and made up a cable harness with male and female junior timer connectors that contain them and making it easy to return to standard.

My van has been in daily use for the past 13 years. Since the modification I've never had cold start issues even in sub zero temperatures. I've also since acquired a spare fuel injection system and have never found evidence that something is amiss with my original system.

I'd be very interested to know if this improves your situation.

Now that's some serious info thanks a bunch. I dont just mean about the resistor values but the fact you have had a similar problem and you cured it.
I am going to source a resistor and try just that.
I
will post my findings after a period of time testing. Which due to the nature of the problem means the engine has to be cold , once warmed up slightly it starts fine.
Thanks for now,

[tonytech]

Have you checked the resistance of temp2 at the ECU end of the cable?
and checked that the contacts are clean and tight?

T