EML - Code 21

[Banshee]

So I've been getting this a lot of late and want to understand what is the cause of it. It doesn't matter if I used Pump Diesel, SVO or BioDiesel anymore and I've been trying to monitor the cars behaviour to see if I could pick out any patterns but I've come up with nothing so far

Code 21 - Fuel injection timing solenoid/injector needle lift sensor-malfunction

Causes - Wiring, fuel injection timing solenoid, injector needle lift sensor, CKP sensor, air in fuel

So far I've ruled out air in fuel (IP has no leaks, everything is tight no bubbles in fuel lines etc etc)

No1 Injector has been tested and is 100 ohms as expected so not this

So next, how and where do I test the CKP sensor on a Bosch setup and where is the timing solenoid? :nenau

 

[Madmark]

Crank position sensors is on bell housing bud on the top

 

[panelbeater]

unplug ckp at inlet manifold the reading is i think 1000ohm,no need to take it out unless it needs cleaning as metal partials attach to it.rick will know ohms.

 

[Banshee]

Found it all in the workshop manuals

EC-388

It recommends 900 ohms at 25 degrees Celsius.

I'll check the actual sensor out on the bell housing for damage etc however from looking at the diagrams would I be right in saying that the harness for it is the plug right next to the Engine Oil dipstick?

 

[Banshee]

OK so I think I've figured out what has been causing the nuisance 21 code!!!!!!

Went out and as per the workshop manual and a little help from Alex's Pictures :thumb2 I've determined that at stone cold after not being moved for 2 days the sensor reads 990 ohms and after a 15 min run with engine at temperature it reads 1010 ohms, neither values being 900 ohms so I presume that this is the cause.

I'm going to do a bit more reading through some of the previous threads as I seem to remember someone finding a sensor for an Audi A4 :nenau or similar that just needed a spacer and the plug switching over and still got change for a tenner :thumb2

 

[Timbo_1975]

No surprise that the resistance increases slightly when it's hot as that's what wires do. - it's a very small coil of wire...

I would check the connections are clean and secure and that you have a good quality fuel filter that's sealed, no rusty fuel pipes along the chassis and no other air leaks into the fuel system anywhere else.

if the IP case pressure doesn't run to spec due to air, or the reg valve is sticking, the advance / retard piston wont work properly, especially when the ECU is trying to advance the timing during.

 

[Banshee]

No surprise that the resistance increases slightly when it's hot as that's what wires do. - it's a very small coil of wire...

I would check the connections are clean and secure and that you have a good quality fuel filter that's sealed, no rusty fuel pipes along the chassis and no other air leaks into the fuel system anywhere else.

if the IP case pressure doesn't run to spec due to air, or the reg valve is sticking, the advance / retard piston wont work properly, especially when the ECU is trying to advance the timing during.

Sound reply that matey :thumb2

I am going to give the fuel system a full going over when it gets a bit dryer, I plan to check it the length of the car on a list of checks I always do whilst I'm under it carrying out repairs, like measuring things for upcoming jobs etc :thumb2

Fuel Filter is sealed for sure and the feed to the IP is fine with no air bubbles as I've had transparent 8mm Pipe on from the fuel filter to the IP I'm thinking it's the CKP for sure as the engine light seems to come on always just as the engine gets to its normal operating temp (usually just before half way) and once the light has come on a few times now I've had the car just lose power and haven't been able to do above 50mph

Quick flick of the key on/off however and full power is restored until the next time the MIL light comes on however sometimes I retain full power, it's rather odd, just to double check it wasn't another issue I read and clear the fault codes each time and it's always 21 thankfully :bow

 

[Banshee]

Going to grab one of these modify the plug and source a spacer :sly

http://www.ebay.co.uk/itm/AUDI-A3-A...661?pt=LH_DefaultDomain_3&hash=item2a2f472ef5

 

[panelbeater]

i do not think its ckp.

 

[panelbeater]

when i had probs with green t2 rac pulled my ckp out to replace but on doing ohm ck they were same so put old one back,do not want to upset you but you know the trouble i had when i first got it green t2,same symptoms,then you know what it turned out to be.nissan put it on there machine and could not directly say what the problem was either.time showed it up though.

 

[Banshee]

when i had probs with green t2 rac pulled my ckp out to replace but on doing ohm ck they were same so put old one back,do not want to upset you but you know the trouble i had when i first got it green t2,same symptoms,then you know what it turned out to be.nissan put it on there machine and could not directly say what the problem was either.time showed it up though.

Thanks for the reply panelbeater :thumb2 I've been systematically going through diagnosis procedures everything tests OK until I got to the CPS should read 900 ohms and mine is reading 1010 hot so out of tolerance so will be replaced.

I'll suss it :thumb2 Not scared of hard work and parts are parts, just pieces of metal that bolt to pieces of metal, I'll always find replacments and get it fixed

Not worried :kissy

 

[panelbeater]

you better have my moonshine handy then.

 

[solarman216]

being out of tolerance on Ohms is not important, I used another make that was 1500 Ohms and it was fine, what is important is the integrity of the coil, usually they are fine cold but the broken wire separates when hot putting the ECU into limp mode, if the coil stays open circuit when cold it will not start, Rick

 

[Banshee]

being out of tolerance on Ohms is not important, I used another make that was 1500 Ohms and it was fine, what is important is the integrity of the coil, usually they are fine cold but the broken wire separates when hot putting the ECU into limp mode, if the coil stays open circuit when cold it will not start, Rick

It is deffo CPS then as there has been times when I've come to start the car after using it a few hours before and the car just cranks and cranks and has no intention of firing, flick the key off and back on again and it fires first time.

I'd just put it down to immobiliser being weird, It's looking good to be CPS then :bow

 

[Timbo_1975]

It is deffo CPS then as there has been times when I've come to start the car after using it a few hours before and the car just cranks and cranks and has no intention of firing, flick the key off and back on again and it fires first time.

I'd just put it down to immobiliser being weird, It's looking good to be CPS then :bow

Mine occasionally used to do that, I put it down to an immobilizer glitch too though.

 

[Banshee]

Mine occasionally used to do that, I put it down to an immobilizer glitch too though.

It could still well have been that but so much is adding up to it being CPS now though

Sent from my SM-G900F using Tapatalk

 

[Sweety]

Think it was code 21 I got, truck didn't want to rev & the light came on the dash when I floored it & noticed a lot of black smoke coming out of the back turned out to be a blocked fuel filter:doh once changed it ran great again

 

[AlexD333]

I think it was rayf that mentioned the ohms on the later cps vs the older ones might have higher reading, I went down this route for a while but never changed mine.

 

[Banshee]

Just to keep this one alive, I was under the car replacing the UJ's on my rear propshaft the other night and can confirm that there is no issues anywhere along the line with my fuel lines, everything is air tight.

I swapped the filter anyway just to say I did it, old one had hardly caught anything at all, all sealed back together nice and tight and no air leaks still.

The EML is still coming on, so I'm hoping to god that it's the CPS :bow :bow
I've ordered the £12.50 jobbie linked a few posts back, just need to lob the connector off and smack it on. No need for the spacer as I initially thought I needed, after re-reading correctly the spacer is only needed on the Zexel setup on the front of the engine to stop it being eaten up in the engine :thumb2