A2 TDI violent shaking

Air leaks in the fuel system often manifest themselves as poor starting, I presume because enough air gets in to disrupt all three injectors. I feel that your tandem pump is working as you can run at full throttle. So whilst I do think it is worth eliminating the air in fuel theory, it's also worth considering the possibility of an intermittently faulty injector.
 
Assuming the same make of tandem pump the a new gasket and new bolts They are stretch bolt so single use

According to Elsawin the bolts are NOT stretch. Instructions are to torque up to 20Nm for the larger bolts and 10Nm for the smaller. No instructions to replace.

RAB
 
According to Elsawin the bolts are NOT stretch. Instructions are to torque up to 20Nm for the larger bolts and 10Nm for the smaller. No instructions to replace.

RAB

That is interesting as when I went to Preston Audi for the gasket I was told in no uncertain terms that the bolts MUST be changed and if I didn’t change them not to come back complaining that the gasket was leaking
I never checked any further than that being honest. The bolts were under £10 so I ordered them with the gasket and fitted the pump without issues

So to each there own
But I tend to agree the torque is so low I cannot see the bolt getting to the stretch point. Maybe just Preston Audi trying to sell me bolts I didn’t need


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You mentioned poor starting reminded me that the engine doesn't start as smoothly as my other car it almost seems like a weak battery for 1st second or so and then starts. Battery has been replaced recently so not battery fault!

Managed to get a friend of a friend to plug in for me and got this.
Couldn't get any more as he was on his was to a job.
Might try and borrow it for a bit if they are willing.



Address 01: Engine (045 906 019 BA)

16:34:32
945 /min Engine Speed (G28)
6.3 mg/str Injection Quantity
6.6°KW Injection Duration (specified)
1.9 °BTDC Injection Start (specified)
6.6°KW Injection Duration (specified)
0.0°KW Torsion Value
0.02 mg/str Injection Quantity Deviation Cyl. 1
-0.92 mg/str Injection Quantity Deviation Cyl. 2
0.89 mg/str Injection Quantity Deviation Cyl. 3

Changes to this at higher revs

1176 /min Engine Speed (G28)
6.6 mg/str Injection Quantity
6.1°KW Injection Duration (specified)
2.2 °BTDC Injection Start (specified)
6.6°KW Injection Duration (specified)
0.0°KW Torsion Value
0.26 mg/str Injection Quantity Deviation Cyl. 1
-0.42 mg/str Injection Quantity Deviation Cyl. 2
0.16 mg/str Injection Quantity Deviation Cyl. 3


Changes to this at even higher revs

1386 /min Engine Speed (G28)
7.1 mg/str Injection Quantity
6.1°KW Injection Duration (specified)
3.1 °BTDC Injection Start (specified)
6.1°KW Injection Duration (specified)
0.0°KW Torsion Value
0.78 mg/str Injection Quantity Deviation Cyl. 1
-0.33 mg/str Injection Quantity Deviation Cyl. 2
0.40 mg/str Injection Quantity Deviation Cyl. 3

Changes to this at even higher revs

1764 /min Engine Speed (G28)
5.2 mg/str Injection Quantity
5.1°KW Injection Duration (specified)
3.4 °BTDC Injection Start (specified)
5.1°KW Injection Duration (specified)
0.0°KW Torsion Value
0.24 mg/str Injection Quantity Deviation Cyl. 1
-0.80 mg/str Injection Quantity Deviation Cyl. 2
0.52 mg/str Injection Quantity Deviation Cyl. 3

Not sure if this shows anything!
 
Thanks RAB.

Could this cause or contribute to my problem? or could these results show as as result of whatever is causing my problem?

Thanks again.
 
If there is a disparity between amounts of fuel injected for each cylinder, then that could be the cause of the problem. It may be down to one badly worn injector. If they've done more than 200k miles, that's quite likely.

RAB
 
Slow start usually just means a poor earth to the starter/body. Add an extra earth, seems to make a big difference.
 
There is a consistent variance on injector 2 but I’ve seen far worse and the engine ran perfectly so whilst it may not be optimal I don’t think that is your issue
A scam when it’s shuddering would be ideal


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The car had started to shudder as I took it out for a warm up while the guy was on his way over, Albeit not as rough as it has been but rough enough to shake the car and that didn't change from cold to warm.

The figures were taken while the car was warm (normal operating temprature) parked on my drive.
 
In that case one thing that does cause this buy never shows up on a scan is a failing injector wiring loom
It as a hard life as it lives in hot then cold engine oil
Worth taking the rocker cover off and taking the connectors off the loom to injector. Clean them and tighten them up
See if this improves it but the long term solution is to change the loom. Only about £60 from Audi/Tps

Paul


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Also worth cleaning the Earth lead as this could also cause problems when running but I feel this unlikely to be the cause of the shaking as if it passes enough current to crank the engine over then it will pass enough to run the engine once started. But beat to clean or fit another earth lead as already stated above to at least eliminate the poor starting issue
You will likely have multiple issues that may or may not all be contributing to the shuddering

Paul


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I will add the additional earth this coming weekend.

Might be able to "permanently borrow" VCDS used earlier as he rarely uses it anymore as he runs his own workshop now and doesn't use it.
Looks like I might have some learning to do soon!

Would it be best to have injectors checked/cleaned or replace them?
 
Another likely bet is the crank sensor then. Again doesn’t show up as fault on a scan until it gets to the point of the engine not running at all
Try disconnecting the cam sensor. It will though a mil light but will run without the cam sensor albeit it will take longer to start as the ecu needs to figure out which piston is on the compression stroke and therefore which injector to fire

If it stops when you disconnect the cam sensor then the crank sensor is suspect. If it runs better then the cam sensor is bad

You can also remove the maf connector. Again a mil light but if it runs better with it disconnected then replace the maf. Ecu will use a default map instead of the maf readings when it is disconnected

Paul


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If you go for injector cleaning and refurb then Darwin diesels are the guys I always use
They know there stuff but not how to charge big bucks
I always use them for injectors

Paul


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When you replaced the loom from the link I gave did the plugs securely connect to each injector and all contacts clean and shiny, especially injector 2? You do appear to have an issue with injector 2 or cylinder 2. You could swap over no 2 injector to see if that cures the issue as from the scan results looks less likely to be air due to the reading only in cyl 2 being dramatically different.
 
Update
Cam sensor disconnected - The car takes a while but eventually starts but runs the same as before.
Crank sensor disconnected - The car wont start/run.
Reconnected everything and cleared faults started car. Run for a few seconds then stopped. Engine speed sensor no signal.
Looks like crank sensor was on its way out but now I've helped it along. I've checked and double checked all contacts and connectors and found nothing obviously wrong. Sadly my 25 year old Fluke78 meter is also not working so I'm unable to check resistance on sensor.
New sensor going in Saturday if arrives in time.
 
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