AUA 1.4 misfire cylinder 2 - trim readings

tuizner

tuizner

A2OC Donor
2000MY 1.4 AUA

I have the misfire on cylinder 2 at idle. Leads, plugs, EGR changed and compression good in all.

just flushed oil and added wynns tappet cleaner.

Will do a leakdown soon and a vacuum leak probably at garage.

Just run some diagnostics during misfire but reading the data isnt yet my forte. Below shows a couple of runs. Is this clear to anyone? Garage is the next call but am actually intersted in trying to learn.

Definatey rich at idle - can smell it

rpm is hunting by 50rpm even at say 2000rpm.

also the fuel light just came on (but no DTCs) - fuel pump or filter?



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Awaiting delivery of a Ross tech hex tool next week.

Is the NGK sensor the preferred one or ?
 
Hi there

In short yes, that is the consensus generally. I would wait until you can scan with VCDS as it seems to give the most reliable results on A2s given their age. I agree with Mac that the pre cat lambda may be a likely suspect given it does most of the heavy lifting in terms of fuel mix. I would also check carefully for leaks on the air intake side. Certainly worth eliminating the cheap or low cost items before changing a lambda

J
 
2 VCDS scans showing plenty misfiring on 2. Cards on the table - I am very much learning here. Does this show anything obvious? which measurements would be good to look at?

Did a leak down test on warm engine and all looks good

Also got the fuel light on the dash a couple of times and the last time the accelerator did not operate the throttle until waited a few minutes and restarted... would this point to something?

finally - can hear a 300Hz-ish tapping sound in the right front wheel well - possibly the ACF (although its not vibrating on touch). measured the evap valve resistance and is within tolerance.

thanks for listening
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Hi there

Well you certainly have a misfire on 2, actually all the time. I guess it will be more noticeable at tick over. Looking back to your initial post if it was me I’d be thinking ignition coil next. There have been a number of posts on the forum with similar issues. Hairline cracks on coil packs seem to come up. From memory I think Bosch seem to be a preferred maker. I would favour this over going for a Lambda at this point.

On your second point are you saying the throttle stopped working when you had a fuel warning come up? Are they related, well maybe, the common element is the ECU. Worth inspecting/cleaning all the connectors as a no cost starting point.

J
 
Hi,
I'm learning too. I'll look through the VCDS Lable file in the morning, see which Groups and Blocks might help. I'm also not a 1.4 Petrol expert, so forgive this question, does your engine have individual coils, or the single four way one, on earlier cars?
Mac.
 
It's a 2000 model with a single coil but that has been changed. Throttle cleaned (was clean anyway). Plugs changed. Leads swapped. New EGR. Compression is great. cylinder Leak is great (<20%). injectors swapped over (but I will replace #2 again just to be sure). I can't see anything crazy on the lambda data but am no expert.

The fuel light occasionally coming on plus the humming makes me wonder if it's a fuelling issue. And yes the second time the fuel light came on and I started the engine - the throttle did not respond to the pedal input - nothing when floored. Is it fly by wire?

Also engine really shakes on idle ( but smooth on revs). I did read about a new rear engine mount solving someone's issues. Not sure how but also a cheap option to try.

The wife wants me to send the car back (only had it 10 days) but it's now got under my skin and I will solve this :)
 
tuizner said:
It's a 2000 model with a single coil but that has been changed.
Click to expand...

to what?

When I had terminal misfires (particularly cylinder 2 but then generally) it became clear the original single coil pack was cracked to hell around the potting compound on the casing rear and in the plastic of at least one spark plug connector. (worth noting that I replaced all four (non-identical!) plugs and cables with Bosch ones just after buying the car 2 years previously as well as throttle body and EGR to get it running consistently). I obtained a chinese coilpack copy overnight from Amazon that instantly gave smooth running - for about 10 minutes whereupon the output to spark plug 1 failed completely so it went back to be replaced by a Bosch that I was able to get 3 days later that has run perfectly ever since - so skimping on the coil with a cheap pattern part can result in undesirable experiences. I have been told that the coil pack outputs issue sparks in pairs so it should not be possible for only one output to fail, but that was my experience with the cheap one (I was watching the misfire counters so could see what was what).

Secondly the pre cat Lambda needs to be in good shape and preferably an original NGK / NTK ; the garage fitted a generic (after the first MOT in our hands showed the original cat had been goosed by a failed original lambda) that had questionable performance (fuel consumption not great ever) and certainly before Christmas last year there were regular earthing errors coming up on diagnostics. A new NTK V1-LZA11 (1825) with the correct 5-wire connector supplied in place out of the box was fitted and the car has been transformed - 15% uptick on economy at least under all conditions and no spurious engine light errors since that happened periodically on and off over the previous years of ownership.

Yes, the lambda (and a Bosch coil) aren't nearly as cheap as some of the alternatives but they completely transformed the running.
 
tuizner said:
It's a 2000 model with a single coil but that has been changed. Throttle cleaned (was clean anyway). Plugs changed. Leads swapped. New EGR. Compression is great. cylinder Leak is great (<20%). injectors swapped over (but I will replace #2 again just to be sure). I can't see anything crazy on the lambda data but am no expert.

The fuel light occasionally coming on plus the humming makes me wonder if it's a fuelling issue. And yes the second time the fuel light came on and I started the engine - the throttle did not respond to the pedal input - nothing when floored. Is it fly by wire?

Also engine really shakes on idle ( but smooth on revs). I did read about a new rear engine mount solving someone's issues. Not sure how but also a cheap option to try.

The wife wants me to send the car back (only had it 10 days) but it's now got under my skin and I will solve this :)
Click to expand...
What do you mean by fuel light?
EML or Low Fuel?
I'm with @Robin_Cox good advice. Coil packs do seem to be a weak area, in general. What brand is the one fitted?
Mac.

Mac.
 
Idle speculation, just wondering if the early single coil pack cars could be converted to the later separate variety. The schematic only shows the later.
Mac.
 
PlasticMac said:
Idle speculation, just wondering if the early single coil pack cars could be converted to the later separate variety. The schematic only shows the later.
Mac.
Click to expand...
My thinking is, no HT leads to cause problems, and troubleshooting is made easier, as you can swap over coil packs.
Mac.
 
Robin_Cox said:
to what?

When I had terminal misfires (particularly cylinder 2 but then generally) it became clear the original single coil pack was cracked to hell around the potting compound on the casing rear and in the plastic of at least one spark plug connector. (worth noting that I replaced all four (non-identical!) plugs and cables with Bosch ones just after buying the car 2 years previously as well as throttle body and EGR to get it running consistently). I obtained a chinese coilpack copy overnight from Amazon that instantly gave smooth running - for about 10 minutes whereupon the output to spark plug 1 failed completely so it went back to be replaced by a Bosch that I was able to get 3 days later that has run perfectly ever since - so skimping on the coil with a cheap pattern part can result in undesirable experiences. I have been told that the coil pack outputs issue sparks in pairs so it should not be possible for only one output to fail, but that was my experience with the cheap one (I was watching the misfire counters so could see what was what).

Secondly the pre cat Lambda needs to be in good shape and preferably an original NGK / NTK ; the garage fitted a generic (after the first MOT in our hands showed the original cat had been goosed by a failed original lambda) that had questionable performance (fuel consumption not great ever) and certainly before Christmas last year there were regular earthing errors coming up on diagnostics. A new NTK V1-LZA11 (1825) with the correct 5-wire connector supplied in place out of the box was fitted and the car has been transformed - 15% uptick on economy at least under all conditions and no spurious engine light errors since that happened periodically on and off over the previous years of ownership.

Yes, the lambda (and a Bosch coil) aren't nearly as cheap as some of the alternatives but they completely transformed the running.
Click to expand...
Original TEMIC unit (no cracks) replaced with an NGK coil and NGK plugs. Misfire occurs when engine is warm (3-5 minutes after start).
 
Check out the wiring between the ECU and the coil pack, as this wiring is cylinder specific. I can't find wiring for single coil pack, but likely to be the same as for the multiple coil pack version, (J220 is the ECU).
Here's the wire colours for each cylinder:

Screenshot 2023-07-19 15.34.13.png


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Suggest you take a look at the Engine Readiness, State, Group 100, to see if there's anything the ECU is unhappy with.
Block 1 Readiness Bits:
1xxxxxxx - Exhaust Gas Recirculation (EGR)
x1xxxxxx - Sensor heater
xx1xxxxx - Oxygen sensors
xxx1xxxx - A/C system
xxxx1xxx - Secondary Air Injection (AIR) system
xxxxx1xx - Activated charcoal system
xxxxxx1x - Catalytic converter heater
xxxxxxx1 - Catalytic converter

Block 2 Coolant Temperature
x-1xxxxx Complete distance

Block 3 Time Since Engine Start

Block 4 OBD-Status
1-xxxxxx - MIL warning lamp on
x-x1xxxx - At least one malfunction detected
x-xx--1x - Heating cycle ended
x-xx--x1 - Heating cycle not possible

For now, I'm thinking the Fuel level indicator is not related to the engine problem.

Mac.
 
OK apart from cat heater?

also to note the activated charcoal solenoid is constantly on/off at that 2-300Hz. taking the charcoal line off you can feel the constant vacuum switching.

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tuizner said:
OK apart from cat heater?

also to note the activated charcoal solenoid is constantly on/off at that 2-300Hz. taking the charcoal line off you can feel the constant vacuum switching.

View attachment 110766
Click to expand...

Ignoring A/C system, it's Secondary Air Injection System, (SAI), and Activated Charcoal System from Block 1, and from Block 4, the EML light should be on, and the Heater is faulty, not sure if that's the lambda heater, or Cat heater.
If you don't have an EML light, then something is dodgy has, (probably), been done, does it come on with ignition on, but not started? Should do.

The Activated Charcoal Solenoid is a DC device, so if it's buzzing, it is most likely faulty. Change it I reckon.
Check pipe work around the SAI for leaks. Should hear it run on startup, along with raised revs, for a short time, (less than a minute on my TT).
But if the EML has been blanked, then your Wife's on the right track, talk to the seller. It shouldn't have passed an MoT, if the EML doesn't come on at first turn of the ignition.
Mac.
 
Group 041

Block 1 Resistance,Bank 1 Sensor 1
Block 2 Heater Condition
Block 3 Resistance,Bank 1 Sensor 2
Block 4 Heater Condition

Mac.
 
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