Ignition point sensor - 2.0 16v 9A

[sam2.0 10]

Just had my codes read and this is the only one that's come up.

 

2112 - ignition point sensor

 

After a bit of searching this seems to also be called "ignition reference sensor", which is the cable attached to the 4th HT lead.

 

The issue with the car is it sometimes fires on 3 cylinders, more so when its cold. So far I've changed the dizzy cap, rotor arm, HT leads, single coil. I have also turned the ignition point sensor around, apparently it can only go on 1 way.

 

So, could the cable be knackered? The engine doesn't seem to care if the cable is plugged in or not.

 

Any other ideas?

[Jim 2]

I always found my 16V didn't seem to care about it being connected either but it's there to detect knock (I think) for fuelling so probably quite important to have it fitted. They're still available from Volkswagen (I bought one about 18 months ago) but they're not cheap.. about £60 IIRC.

[bmwcompact 10]

Sorry I cant help with possible misfiring issues-intermittent problems are always so frustrating to solve-and it may be a fuel problem since you say its more likely when cold.

As far as the ref sensor is concerned I second Jims statement that the car will run whether it functions or not so thats unlikely to be your problem. I had my car several months before I found and then connected this sensor. The car has 2 knock sensors so thats not the function of the ignition sensor. It tells the ECU when ignition has occurred on cylinder 4. The ecu controls when the spark occurs in terms of advance/retard (largely down to the Hall sender in the distributor) and how much fuel to put in dependent on speed, load and temp. I think the ignition ref sensor is there to confirm to the ecu that the appropriate advance/retard has taken place-its a feedback loop for the ecu. I am no auto electrical expert so someone out there may say Im wrong!

[sam2.0 10]

Fuel filter replaced and still no joy.

 

It works fine when its warm, but lumpy (3 cylinders) when its cold. To me that sounds like a temp sensor not working. Suggestions?

[Jim 2]

There is a coolant sensor for the ECU in the side of the block.. I believe it's the one labelled here as the thermotime sensor. May also be worth replacing the ECU temp sensor next to it! They're both under the coolant flange...

 

[sam2.0 10]

Do you know part numbers? Its a 9A Engine...

[davidwort 0]

is it really running on 3 cylinders or just running lumpy generally? You can check the resistance that the temp sensors have is a progressive curve by removing from the car and heating/cooling in hot water and testing with a multimeter, I have the graph of correct range in an old passat haynes manual. It could be that the cold start enrichment isn't working correctly (5th injector/cold start valve) but that should only really spray (controlled by thermotimeswitch on head) for a few secs in warm weather.

 

Injector spray pattern test at idle (i.e. closed metering head flap) would be interesting, with fuel atomisation worse on a cold engine a poor injector spray pattern can lead to poor combustion on one or more cylinders when cold. Easy enough to remove the fuel pump relay, bridge the terminals and use the battery neg lead as a switch to power the pump on and off, pull the injectors and spray into bottles observing if the spray pattern is a nice cone or not.

[sam2.0 10]

Sounds like 3 cylinders and has very little power. Once the car is above 70oC it seems mostly fine with the odd dip back to lumpy mode. Once fully warm it'll drive fine through all the rev band and gears.

[davidwort 0]

over the years I've seen/heard/read various problems with the 16v and idling,

I'll try to recall them:

vacuum leaks on vac hoses under inlet

split boots on inlet system (vac leaks again)

throttle switches not functionning (so idle circuit not triggered), can be down to microswitches or wiring

old or ropey pattern lambda sensors

broken/faulty temperature sensors

old worn injectors,bad patterns, or leaking when they should shut off

metering head tweaks to try to fix the symptoms of the above (i.e. messing with CO screw under orange tamper cap)

more recently water in the air filter???

dodgy hall senders or wiring to.

oil in distributor

ignition timing out (new cambelts fitted one tooth out)

general headgasket issues

standard rotor arm, cap, plug lead issues

[bmwcompact 10]

Re temp sensors. I have just been through this with my 9A engine. Sensor 5 above is only for the gauge. Sensor 4 thermo time is not fitted on a 9A. Sensor 3 gives the ECU its temp info-this is part no 026 906 161: you can get it from vwheritage for £14-90 inc vat and postage (Its a Meyle quality part- the original was Bosch 0 280 130 040 which is not easy to find). However for what its worth I dont think this is your problem.

[sam2.0 10]

Thanks, for £10 it may be worth trying anyway.

[sam2.0 10]

Fixed! Figured I should update this incase anyone else has the same issue.

 

It was the damn spark plugs. I'd ruled them out as I had tested them by grounding them one by one, they all sparked. But, I figured it was worth replacing them anyway.

 

Just done an oil change too, so its good to go now.

 

Thanks for the help guys.