Misfiring v5 Bora

[Marshthedarsh]

Hi all. Recently picked up a 2000 Volkswagen Bora V5 for a good price, only 95,000km in the clock. 150bhp, 10v version I believe. Drove okay for a bit, but have now diagnosed a misfire on a specific cylinder - no spark from one coil in the coil pack.

Did this by pulling out the leads one by one and seeing if I still got a spark. On the pack, 4 produce a spark - 1 doesn't. This particular coil seemed to have a few cracks as well. Did some research, and signs pointed to the ignition amp. Surprise surprise, it had been re-sealed - and had been soldered inside. With the car running, did some poking inside the ignition amp around the dodgy looking wires and was able to get a spark from A on the pack (cylinder 2 I believe). So I seemed to have found the problem. However when trying to put the cover back on it must have moved the wires and haven't gotten a spark from that coil on the pack since. So I picked up a replacement amplifier, and still had the same issue. Tested the new one with a multimeter and got ohm readings you'd expect, while the old one showed a non-connection.

I have switched around the spark plugs and leads, but still no spark on Coil A (able to get one on the other 4). Therefore it seems that it is the Coil Pack that is the issue, and is not producing a spark from one coil. But I have managed to get a spark from this coil before when playing around with the ignition amp, so is the coil pack good after all? I got some epoxy and sealed up all the cracks - still nothing.

Does anyone know of a way to test whether the problem is the coil pack or amplifier, or even other? After getting a spark - the new ignition amp should have solved it. So either this amp has a fault on that cylinder control as well, or the coil pack has an intermittent fault and will fire under the correct circumstances. Therefore I need a new coil Pack?


Any help is appreciated, cheers :)


I should probably add a few things... When key switches the interior on, the fuel gauge needle moves to where it should be - but the engine temp gauge needle just moves to 50 (the minimum), and does not move at all when driving. Does this indicate a temperature sensor fault? Service light comes on, but overdue for one anyway. Have ordered a Vag-Com scanner, but has still not arrived. Am keen to check the codes and see what I get. Idle is a bit rough, sits around 800, but smooths out over 1500 - though this is an obvious symptom of a misfire. When I did get all 5 firing it was quite smooth. Transmission is a bit rough changing gears (Automatic), though is this just a result of the misfiring?

Currently not driving the car atm, sitting waiting and hoping for an easy fix.

[Marshthedarsh]

UPDATE.

Have worked through the coils systematically looking for sparks on the removed spark plug when only running the power source and one pin (for one cylinder) from the pack. Sounds a bit complicated, but actually quite simple.

Basically, I can get all 5 coils on the pack to spark when each is connected to one cylinder pin coming from the ignition amp into the coil pack, but only from 4 out of 5 of the cylinder pins. This seems to indicate that all 5 coils will create a spark, but the ignition amp itself won't tell one to spark when all plugged in correctly.

So it seems the replacement had the same issue as the original, hopefully the third amp will do the charm...

[Crasher]

Firstly you need to fit a new genuine VW ignition amp, VW part number 071 905 143 and good quality coil (not necessarily genuine) VW part number 071 905 106 and good ones are available from Beru, NGK and Bosch. The aftermarket amplifiers available from Standard, QH and Facet I have found to be utterly useless. They are stupid money here at around £360, I dread to think what one will cost in NZ!

[Marshthedarsh]

Hmmm, now things are really getting strange...

Got another amp, same problem. Decided to test all the coils one by one again, still all sparking. However, what we've now found is that the brown plug on the top that goes into the ignition amp - one wire won't tell any to spark (and controls the coil the misfire is on). This is the opposite to what I found the other day, so it seems that the ignition amp WAS working - and it's just not getting the signal from the ECU.

So could this be a faulty ECU? Or just a bad wire into the amp. Possibly a bad crankshaft and/or camshaft sensor... Considering I was absolutely sure all the wires were working when testing the other day...

[Crasher]

Have you done a code read yet?

[Marshthedarsh]

Not been able to do a code read yet, but trying to get one done ASAP.

I've managed to find that all 6 wires into the amp connect to the ECU, so not a bad wire. Basically I believe the ECU isn't telling one coil to spark when the car is running. Is this a simple case of needing to reset the ECU so it can relearn itself? Or is this a symptom of a bad ECU, and I'll need to swap it out for another...

[Crasher]

If it is the ECU, you cannot just "swap it out" as it is coded to the instruments and a used or new replacement cannot be easily coded in, we usually have to take the car to the VW dealer.

[Marshthedarsh]

New ignition amp, same deal. New coil pack, same deal. No spark on Coil A. Have tried all the permutations of spark plugs and leads - so it pretty much confirms that the amp is not receiving a signal on pin 6 (from the ECU) - and therefore not telling coil A to make a spark. Result: Misfire, only 4/5 cylinders running.

I'm just wondering if there's anything else that can cause a constant misfire like this. I haven't been able to do a full scan - but one of the few faults I got was the ECT (which I assume accounts for the Temperature Gauge on the dash not moving above the minimum of 50). Have bought a new one, and will install it when I get it. I can't seem to see a green one anywhere, so it possibly still has that Black one that always gives in. Have read that if this doesn't work it can cause a misfire, but then so can many things.

Otherwise I'll take it to the VW dealer to get the ECU looked at. From what I've read - it seems that they're able to reprogram it and it will work completely again. Is this the case?

cheers.

[Crasher]

The ECT sensor is in the water housing on the side of the head that also contains the thermostat. Yes the dealer can re-flash the map on that ECU BUT if it is a driver failure the ECU will have to be physically repaired or replaced but to be honest I have never known a coil driver to fail, ever, BUT the system on that engine is unusual even compared to the V6 version plus that amp is very prone to failure so who knows what could happen. This new amplifier, is it a brand new genuine VW dealer supplied part?

[Marshthedarsh]

When I got the car, (I think) it was firing on all 5. When it started misfiring, we opened up the (resealed) amp and a mate had a go at poking some of the wires inside. Managed to get the 5th cylinder firing when poking a dogy wire, but it dropped when we tried to put the lid back on. So at this stage it strongly seemed like the amp. He had a go at re-soldering it, but when we started it again - we saw some sparks jumping across some wires inside the amp. Turned the car off straight away, looks like the wires had been too close together. Though I can't imagine this would kill the ECU and cause it not to spark anymore.

Got a "working" replacement from a euro parts scrapyard and that didn't fix it. Either it had a similar problem, or it wasn't the amp at all.

Got a third one from a guy who knows about these parts. Refurbished in the UK with a 24 month warranty. Same problem. It's possible they all have the same issue on the same control - but I think it's highly unlikely.

It's just a huge, annoying mystery. Thought I'd solved it - but two replacement parts haven't fixed it. But then why did we manage to get all 5 firing one time :s

[Crasher]

I would not trust anything other than a brand new genuine amplifier, not even any of the pattern units available, I have had trouble with these in the past.


we saw some sparks jumping across some wires inside the amp. Turned the car off straight away, looks like the wires had been too close together. Though I can't imagine this would kill the ECU and cause it not to spark anymore.

It is a 5 volt driver, a reverse voltage of whatever it may have been could damage it.

[Marshthedarsh]

Yes sorry, I should have mentioned that both of the replacement ignition amps were genuine VW ones. But they aren't the problem, by switching wires and looking for a spark on the spark plug - all 5 coils will fire from any of the pins on the ignition amp. It's just that (when all plugged in correctly), one pin on the ignition amp isn't getting a signal from the connector on top going into it, so it's like the ECU is only telling 4/5 of the pins to make a spark - therefore the misfire.

I tried resetting the ECU but no change. Is it possible that when I do a code read (and get a "misfire on cylinder X" - as expected) - that a simple resetting of the fault code will fix it?



The ECT sensor is in the water housing on the side of the head that also contains the thermostat.

Got the part, but can't for the life of me seem to find where it goes. Took out the air box to get a better view, but can't really find it. It seems to be on a different place on each variation of engine - and no guides/photos/videos are of my 2.3L. Unsurprisingly the manual for the engine doesn't actually show you where anything is.

I'm sure when I find it it'll be painfully obvious, but right now I am pretty lost.

[Crasher]

It is under the coil pack in the huge plastic water houisng.

[Marshthedarsh]

Cheers mate. Pretty simple - but there's just so much stuff in the way. Think I put everything back correctly...

Turned it on. Revs up to above 1000, engine sounded very powerful. However after a while the revs dropped to 750 and the car went back to how it has been feeling. However temperature gauge is now working again. Climbs slowly and sits at a healthy 90 in the middle. Engine told me to Stop and check the coolant as expected.

Just curious as to why it sounded so healthy when I first started the car - but now back to the misfiring symptoms. I wish I checked to see if I was getting a spark when I first started - but now I'm not.

[Crasher]

Can you find the cars type number on the data sticker or failing that, post/PM me the VIN?

[Marshthedarsh]

Not too sure about the Type Number. VIN is: <removing VIN>

[Crasher]

I will leave the email reminder on my work PC so I can check this tomorrow.

[Crasher]

The car is a type 1J2 3Q3, with an AGZ engine, FDD autobox and left the production line at Wolfsburg in Germany on 4th July 2000. It has a Motronic M3.8.3 ECU, part number 071 906 018 K.

The idle speed should be between 650 and 750 rpm

From what you describe I would be putting an oscilloscope on the wires to 2, 3, 4, 5, 6 going into the amp and out, to make sure I had a signal going in and out respectively.

You say you have no spark on coil A?

This is from the manual.

Ignition coil -N-, -N128-, -N158-, -N163-, -N164-



◆ Marked for H.T. cables:
E = Cylinder 1
A = Cylinder 2
D = Cylinder 3
B = Cylinder 4
C = Cylinder 5


The firing order is 1-2-4-5-3 so E, A, B, C, D.

Then I thought, woaha, hang on, has he got the cylinders going A=1 B=2 C=3 D=4 E=5 and then I thought, nahh, he can't be that daft as the leads are labelled 1-E, 2-A, 3-D, 4-B and 5-C plug/coil end appropriately.

So using this table and the wiring diagram (see below), I get it to mean the following at the coils 6 pin plug T6x from the amp output T6u.

E = Cylinder 1 = N = pin 6
A = Cylinder 2 = N128 = pin 2
D = Cylinder 3 = N158 = pin 5
B = Cylinder 4 = N163 = pin 3
C = Cylinder 5 = N164 = pin 4

For the amp input T6t from the ECU T80 the arrangement numbers are not the same IF the colour cods of the wires stay the same OR if the pins stay the same, the colour codes jumble around and there is not annotation to say which ECU pin is which cylinder or coil driver so I will stick with colour code therefore

E = Cylinder 1 = N = pin 6 to 6 (still) to 78
A = Cylinder 2 = N128 = pin 2 to 5 to 70
D = Cylinder 3 = N158 = pin 5 to 2 to 71
B = Cylinder 4 = N163 = pin 3 to 4 to 77
C = Cylinder 5 = N164 = pin 4 to 3 to 57

So in other words the ECU output would be

Cyl > ECU pin

1 > 78
2 > 70
3 > 71
4 > 77
5 > 57

If I am right!

So when you say


the amp is not receiving a signal on pin 6 (from the ECU)

I presume you mean at pin 6 on the plug going INTO the amp so pin 6 is to pin 78 and is for coil N, cylinder 1.......

Using the wiring diagram I cannot for sure say which signal wire from the ECU triggers which coil amp but it is how I have worked it out, if anyone can find a definitive M3.8.3 T80 pinout diagram to show which pins are for which cylinders it would be a huge help.

N - Ignition coil
N122 - Power end stage
N128 - Ignition coil 2
N158 - Ignition coil 3
N163 - Ignition coil 4
N164 - Ignition coil 5
P - Spark plug connector
Q - Spark plug
T6t - 6 pin connector
T6u - 6 pin connector
T6x - 6 pin connector
10a - 10 pin connector, in the cable channel, left side
85 - Earth connection -1-, in engine compartment wiring loom
A104 - Positive connection -2- (15), in dash panel wiring harness
D52 - Positive connection (15a), in engine compartment wiring loom
G2 Coolant temperature sender (01039)
G40 Hall sender (00515-2113)
G62 Sender for coolant temperature (00522-2312)
220 Control unit for motronic
N79 Heater element (crankcase breather)
N156 Intake manifold change-over valve (01243-4333)
T6l 6 pin connector, brown, on the protective housing, on the water case, left side
T10a 10 pin connector, in the cable channel, left side
T80 80 pin connector
85 Earth connection -1-, in engine compartment wiring loom
220 Earth connection (sender earth), in engine wiring loom
A100 Connection -2- (87), in dash panel wiring harness
A104 Positive connection -2- (15), in dash panel wiring harness
D101 Connection -1-, in engine compartment wiring loom
D102 Connection -2-, in engine compartment wiring loom

http://i222.photobucket.com/albums/dd20/Crasher1964/AGZIGNITIONWIRING_zps00d0cd19.jpg (http://s222.photobucket.com/user/Crasher1964/media/AGZIGNITIONWIRING_zps00d0cd19.jpg.html)

[Marshthedarsh]

Hi mate, sorry but been busy for the last week and didn't realise I'd gotten a reply.

Got a code scanner, and got a few first up.

Engine: 00668
00525 = 02 Sensor - Voltage Low - G39
00635 = Oxygen Sensor Heating Circuit - Ahead of Catalytic Convertor

A/T: 00518 = Throttle Position Sensor - Signal out of range (G69). Also check for loose ECM Power Relay.

SRS: 00532 = Transmission Control Module Relay - Supply Voltage (B+) Malfunction Low Battery of Bad Ground

ABS: 00688

00688 is just the usual battery one if I'm not mistaken.

Cleared them all and when I started up the car the idle was back up to above 1000 for about a min before dropping back to 750. Just like it did when I replaced the ECT.

Went for a short drive, only two that came back were: 00525 = 02 Sensor - Voltage Low - G39
00635 = Oxygen Sensor Heating Circuit - Ahead of Catalytic Convertor

But of course the others may reappear after a while.

So does this mean the 02 sensor needs replacing? Though I don't imagine it's causing the misfire. Still getting prominent sparks on B C D E but nothing from A. All the leads are in the right order.

[Crasher]

The correct VW descriptions for those codes and the variations are

00635 Lambda probe heating in front of catalyst

a) Open circuit/short to earth = Wiring open circuit or short to earth or G39 defective
b) Short to positive = Wire has short to positive

00525 Lambda probe G39

a) No signal = G39 defective or Lambda probe heating defective or Wiring open circuit
b) Short circuit to positive = Short circuit to positive in wiring or G39
c) Short circuit to earth = Short circuit to earth in wiring or G39 or Fuel tank empty

​Your machines descriptions don't match very well. Check fuse 43 but I suspect you need a new pre cat lambda sensor. Fit one, clear the codes and go from there.

[Marshthedarsh]

Took it in to a VW specialist today, and he's not sure what's causing it either. Straight away he noted the horrible idle, said they were all a little rough - but this was too much.

He noted that it seems to only be misfiring at idle, and his vagcom wasn't getting a misfire - only the oxygen sensor, yet he says it will usually come up when you do a check. Car does drive quite nice when warm and in motion, but has a bad idle.

He said that the MAF seemed fine, and it probably wont be the ECU because if it's bad, then the car won't go at all.

Like you Crasher he said the first thing to do was get the pre-cat changed as it was the only code. I'm guessing if it's bad it will improve the idle and mileage, though I'm not sure it's gonna fix the misfire. If it only misfires at idle as he suspects - then does the ECU play any part in the issue?

His workshop is at the bottom of a steep hill - so from a standstill it's a very bumpy and squeaky ride up. No charge for all his troubles though.

[Crasher]

The mixture is set by the ECU at all times using information from, the lambda sensor so if that is FUBAR the ECU will not have a clue what is going on and may under or over fuel and that will make the engine run rough, he could have checked this with a simple tailpipe 4 gas emissions test to check the O2 level.

[Marshthedarsh]

Ordered a new Bosch Pre-Cat. Before getting the installation sorted, I went and scanned the codes again: still getting 00525 - but 00635 has been replaced with 00553. I believe that's relating to the MAF, and the code has come out of nowhere. Only two codes I get, and when I clear them they both come back after a short while.

When the car is idling and I unplug the MAF - there's a little judder but the car goes back to how it was when plugged in. Same when I plug it back in, so the car reacts to it plugging and unplugging - but each side of this the idle and engine is consistent.

I've read that the MAF could be bad if it runs better unplugged, but it just runs the same. Does that code mean the MAF neads cleaning/replacing - or is it strange that this code has appeared out of nowhere and 00635 has disappeared.

I'd still think the O2 sensor is bad though. Exhaust has a light chug chug, and is pushing out big puffs of invisible air.

Mileage I'm getting is pretty horrible too. Onboard display just changes all the time according to how hard I push the gas vs how far I'm going - but seems to settle at 4ish km per L every now and then = 10 MPG.

I'm only driving around backstreets to see how it goes, but from last "Please Refuel" to current "Please Refuel" - 13L got me about 50km.

[Crasher]

Stop unplugging the AMM and code 00553 should stay away! I have been trying (in vain) to stop people doing this for years. Unplugging it and what happens means nothing.......

[Marshthedarsh]

Cheers for that. I don't make a habit out of playing with the MAF - so the code must have come from when the guy was playing with it. Code hasn't come back.


UPDATE - So I bought a cheap Used ECU - and when I plugged it in I now get all 5 coils sparking. So I'm pretty sure we've found the problem.

Of course the car only starts for a second because of the immo - but it certainly sounds so much better than it did with the old ECU. All electronics working.

So is the process to get a new Transponder chip as simple as it would be to get a spare key? Or do we have to go through the Dealer because the ECU has been switched... Cheers.

[Crasher]

Here we have a mobile chap come round and do this for us in his van, if you do not have this facility it may be easier to take the car to a VW dealer and ask them to code it in.

[Marshthedarsh]

Managed to plug in VAG COM and reset the Immo to 00 so it matches the current key. Immobiliser light no longer flashing and car starts up just fine with present key. Will go for a proper drive in the morning and assess the 02 sensor then.

Cheers for all your help Crasher :D


For anyone reading this in the future for help:

Car had a dodgy Ignition Amp, that was the problem - so get a replacement. We made it worse by playing inside the Amp which damaged the ECU - and it only ran on 4 cylinders instead of 5.

What solved our additional problem was another ECU, then reset the code with VAG COM so the key matches.

[Crasher]

Re-matching the ECU like that hardly ever works for me, I can remember one was a Golf 4 1.6 AKL but later stuff, no chance. Admittedly it is not something I try very often as we hardly ever have to chnage ECU's.

[BravoMalaga]

Hello Crasher,
I own the same engine in a golf 2.3 and I am "glad" to see I am having exactly same troubles than you. How did you fix it?
I thought it was going to be the ignitions coils and I just order it before reading your post.
Will I need to change the ecu and program the ECU?
Thanks a million for your help

[Crasher]

What is the cars year and engine type code?

[BravoMalaga]

What is the cars year and engine type code?
Hello. Year 1999. Engine code agz. Golf mk4 2.3 v5 150 cv.

[Crasher]

The AGZ has a single coil pack so it could be plugs, leads or coil pack but the most common problem on the AGZ is failure of the ignition amplifier which is on the bulkhead.

[BravoMalaga]

The AGZ has a single coil pack so it could be plugs, leads or coil pack but the most common problem on the AGZ is failure of the ignition amplifier which is on the bulkhead.

Thanks Crasher.
I checked sparks, plugs and leads and i am 100% sure they are ok.
I already ordered the coil pack so crossing fingers before spending more money.
And what about the ecu problems???
Thanks
Ignacio

[Crasher]

In my experience the chap from New Zealand who started this thread is the only instance of this problem I have ever heard of, ECU failure is extremely rare.

[BravoMalaga]

The AGZ has a single coil pack so it could be plugs, leads or coil pack but the most common problem on the AGZ is failure of the ignition amplifier which is on the bulkhead.

Thanks. Can you pls confirm that part number is 071 905 143 ?

[Crasher]

Yes.

[BravoMalaga]

Yes.
Hello Crasher,
I changed the single ignition coil and same result.
So I wil take a look of the ignition amplifier you said.
Could you tell me where is it located? I attached a photo in case help
Thanks a lot.

[Crasher]

It is on the bulkhead.

[BravoMalaga]

Thanks Crasher!!! I managed to take the piece out and I opened it. It has a bad conexion I have to fix and hopefully I will have my car running this weekend.

Can I ask you something? I am thinking in buying a second hand Audit S6. As an expert, what do you know about this engine? I have read many good things. It have almost 124K miles km so price is good but I am not sure what to do. Any idea what I have to focus on in order to avoid spend too much money in the future?
I normally take a look of pad, rotors, abs, wheels, sound, oild leaks, wagcom errors, garages invoices, maintance book, external, internal aspect ....

[Crasher]

Which S6? There are lots of different versions.

[BravoMalaga]

Hello,
Sorry. I missed your mesage. It is the 2007 one avant 450CV. After reading a lot I will not buy it. They have problems with the carbon and that mean to clean the valves every 15.000 K spendint to much time.

Regarding the golf v5, I bought a facet ignition module and it worked just for 10 km then the car started to work with 4 cilinder again. I went to the engine and smelled bad.

I have a copuple of questiuons if you can please help me.

1. Do you think I have a problem with the alternator or is just the facet piece that is as bad as you said previously.

2. I read also it could be the crankshaft sensor?? The thing is that all the problems started after I almost broke the timing belt because of the plastics under the belt were loosen.

The official shop from VW is asking me 458 EUR plus taxes here in Spain. I am thinking in selling the car honestly...

What do you think???

[Crasher]

The aftermarket amplifiers available from Standard, QH and Facet I have found to be utterly useless


Timing belt? It is chain. As I said, Facet aftermarket amplifiers are crap

[Fourteen]

Hi Crasher

Sorry to go back to this issue again, My Bora 2000 AGZ is doing the same, Now what i want to know is, In each of the 6 Pins on the input harness to the amp, how many pin should contain power from the ECU, On mine only one that i found alive with 12V, the rest there is no voltage.