ABF Fault - Cylinder 1 Recognition Sensor (G145) - Updated findings

Afternoon all,

Was wondering if anyone could possibly help/offer advice on an ABF running problem. Basically I took my ABF'd Digi Mk2 for an MOT yesterday. Had a phonecall about 2 hours later saying it misfired on the ramps during the emissions test, cut out and wouldn't start. Popped round there to have a look, couldn't see anything obvious so towed it home for further investigation.

Didn't appear to have spark so tried a different coil and hey presto it fired up fine. Thought that would be problem solved however I spent a bit more time looking at it today and it appears to be running ok on the original coil again! Scanned it with VAGCOM for errors and it came up with the following fault code:

00740 - Cylinder 1 Recognition Sensor (G145)
03-00 - No Signal

Cleared the codes and it was back again on the next scan. A search on here reveals it could possibly be a distributor fault. Checked the plug was getting power and it is however makes no difference to the running of the car unplugging it.

I was wondering if anyone could shed any further details or other areas to look at before having to fork out for a new dizzy. Hall sensor failure perhaps? I'm not ruling out the crank sensor yet (brand new but a Topran part, not genuine) but was under the impression that flagged a G28 fault.

The car appears to run fine on the drive, same as it did before but I don't want a repeat performance down the MOT station again and unfortunately I can't road test until that's done lol

Cheers!

 

Thanks for the pointers, will have a look over the weekend.

The problem does seem to be when the car is hot so overheating coil is a possibility - picked up a new one this morning to rule it out regardless.

Would imagine the dizzy to a 1 trigger window one rather than 4 - it's the original still, haven't touched it since it came out of the 'beeza other than a new rotor cap.

 

Got today off so had a look this morning. Put a brand new coil on. Car runs fine but there is an audible miss every so often. Got the car up to temp, seemed to carry on running fine, revs cleanly, got the engine really hot, didn't cut out and hot started fine etc

Sorry to sound like a dunce but what should I be doing for continuity test? Just postive probe in one of the connectors listed above and negative to a good earth on the ohms setting? All wiring and pins look to be intact and ok, nothing bent or out of place.

Had a slight variation of the code when scanned - same fault but 03-10 - No Signal - Intermittent this time around.

Really hope it's not the crank sensor lol

 

Replaced the ECU 30 relay today just to rule that out as it's cheap. Rescanned with Vagcom today several times and no fault codes listed whatsoever lol

However, I did manage to replicate the misfiring symptoms the garage mentioned once it was up to temp and hot, misfire got pretty heavy and was on the verge of cutting out. Revs seems to hesitate, bounce and stick around 2k rpm if I rev whilst at idle.

So, checked over the wiring again, all seems to be ok as far as I can tell. By my reckoning I have two choices:

- Replace the crank sensor again for a genny
- Replace the dizzy to rule out the hall sensor

Rather odd it's not showing the fault consistantly now. Gut feeling says go for the crank sensor first but if anyone could advise before I have to fork out it would be appreciated (money is a tad tight at the mo and both items are not cheap!)


Not the best vid but you can kind of hear the miss in this video

 

Thanks RJ,

On inspection yesterday disconnecting the hall sender from the dizzy makes no noticeable difference to the running of the car. I've only been able to replicate the stalling issue since changing the ecu relay but this could just be coinsidence.

Read up a lot last night and lambda is first on the list to check today. Regarding the measuring blocks which number will those readings be under and what readings are deemed to be ok?. Uploaded label files but there are still things unlabelled.

I guess if the crank sensor is failing intermittently it won't always throw up a fault code.

Again cheers for the help in solving these abf issues!

 

Cheers RJ.

Ran the car up to temp again today, very lumpy and misfiring all over the place right from cold all the way to up to hot. G145 code was back again and the car seems to stick at 2k rpm for a few seconds, kind of bouncing almost like a rev limiter before progressing through the rev range. All of the following was checked running on the drive:

Lambda - Unplugging this made no noticeable difference.
Dizzy - Unplugging this made no noticeable difference.
Throttle position was 0.00 degrees at idle so all correct there.

Measuring blocks were as follows:



RJ or anyone elses thoughts appreciated before I splash out on a genuine crank sender

 

G40 = G145 (for Cam angle sensor (CAS)) is located in what is described as a dizzy. The sensor operates on the Hall effect.
Once the cranksensor (CKP) has plausible signal strength and the TCI unit, KL87 and KL15 are in operation, then the rotor will distribution ignition to the leads regardless of a dopey CAS (G40/G145) MAT(G42) or CTS (G62) and so on.

The CAS is sync'd to the missing tooth (one window) of the crank 60-2 trigger wheel thus giving more infomation on the other cylinder positions.
Cylinder recognition is extremely important as it is responsible for determining which cylinder is in a crank angle window for knocking, via stereo knk sensors, individual spark trimming, as well as the phasing of injection beginning and ending times.
During part load operation, on ABF and VR6 engines, the removal of the G40 sensor will cause the engine remove spark timing significantly by default, and cause engine stumbles and hesitation during the drive as the features described above are disabled. As you can imagine fuel distribution is affected as you are likely to run lean on some cylinders, possibley not helped by temperture correction!
Idle and WOT conditions are less affected as they are controlled by separate tables.

I am of the strong opinion, the ECU is not obtaining a return signal from your camshaft sensor (G40) or the "dizzy" on pin 44 of T68 allowing the diagnostics to show this fault.

My suggestion would be to inspect the 3 pin plug on the CAS at terminal "+" for ~5v and on the "-" for earth. Check the pins of the ECU connector T68 at pin 45 (TPS reference voltage) and pin 44 signal return, to ensure they have not worked themselves away from the ECU pin.
This would also explain why pluging and unpluging the CAS makes no difference to diagnostic result.
You may need to purchase a replacement dizzy if all checks out ok.

 

Thanks for that Toyotec, some really detailed information!

I an confirm the CAS (hall sender) plug is getting 5v but will check over the others details tomorrow. Apologies for a simple question but can I ask regarding the ECU connector pins how you know which number is which? I.e is it just a simple case of counting from left to right until coming to pin 44 and 45? Should I be getting 5v at the ECU plug end too?

I checked the pins/plug visually after RJ's comments above but got a bit confused with the continuity testing. I'm not the best with electrics!

Many thanks!

 

There you go!

T68 ABF/ADL female connector.


The ECU has an internal supply rail with +5v dc. The plug/loom just transports this supply.
You have already confirmed the ECU can supply the Hall (+) with 5 Volts. Now you want to ensure the wire lead from the 3 pin hall plug (0) to pin 44 on the T68 connector is intact with a continuity tester.

Set the tester to the lowest resistance, which may also have a buzzer/beeper function.

Open circuited


Closed circuit with beeper in my case.

 

Thanks chaps, really appreciate the help and the images

My multimeter doesn't beep but I'll just put it on the lowest resistance ohm setting. Will report back tomorrow with the findings! Again cheers!

 

Ok had another look this evening. Following the helpful pointers and pictures above the results are:

Stripped the ECU plug covers back and all pins look ok and undamaged.
Pin 45 to the red/black wire on the hall sender plug = 0 so continuity checks out here.
Pin 44 to green/blue wire on hall sender plug = 0 so continuity checks out here too.

With the ignition on I got 11v at the red/black wire on the dizzy plug rather than the 5v I got before!

Car really does run like a dog now even from cold so something is definitely packing up/becoming more apparent.

 

Do you mean the section that runs behind the back of the cylinder head above the manifold to the TPS etc RJ? If so that looks to be original judging by the material wrapped around it so I could strip it all off. I did send that to you though so I'm sure you probably went over it when you worked your magic on the loom

Is there anything else I should be checking with the multimeter?

 

Haha oh right I see lol. I'll take the covering off today to have a look.

Yeah I changed the #30 ECU relay earlier in the week for a new genuine one just to rule it out. Interestingly it seems to have exaggerated the poor running problem once changed.

The two earth ring terminals that go to the side of head are clean and the cylinder head is unpainted. I will double check again though.

So just to be on the same page the wiring checks on continuity all seem to check out ok then and there's no other multimeter tests I should be carrying out?

Thanks again for the help. One day I may get to drive this car lol