Audi A4 2.0 TDI Rough idle

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Re: Audi A4 2.0 TDI Rough idle

Postby STC » Thu Aug 18, 2016 11:57 pm

you only have control on duty cycle and not frequency right?
Isn't frequency an issue? Just asking...


Yes & No !!

Frequency will not be too much of an issue when you are activating something directly as our IMV, DRV or any electric motor or solenoid as in this case. Just be cautious of going above 90 / 95% duty as the component may or may not like that for any period of time

It could be tricky if there is a PCB and circuitry between the motor & the connector that we can access to control it. I think some fans are like that where the duty from the ECU is in milliamps, is then measured and the electronics in the fan ECU will then do the magic and control the fan. The Circuitry may get fussy about the Frequency.

Can it do any harm to put a faster / slower frequency to it ?? Assuming the Voltage is Correct (ie not push 12v into a 5v circuit) ?? Can anyone here answer that ?

I have not tried it ?

Have a good look on ebay for PWM Motor Controllers, they are available in varying frequencies.

For the £8 it costs this is a well built tool, good quality and has heaps of Diagnostic Value. Don't forget it has no value on its own, you will need some Correct Wattage and Ohm Resistors or a good decade box to keep the ECU happy when you have the components unplugged and this substituted in.

If you get stuck I can post some links.
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Re: Audi A4 2.0 TDI Rough idle

Postby Fanstiintza » Sun Mar 19, 2017 2:46 pm

Hi. I have the same problem with a similar car and nobody knows what's the problem. i been in 3 garages and change 3 injectors but the problem is still there. Can you tell me what is DRV means? Thank you
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Re: Audi A4 2.0 TDI Rough idle

Postby STC » Mon Mar 20, 2017 5:20 pm

i been in 3 garages and change 3 injectors but the problem is still there.


Why is it that the Injectors are always first in the firing line ???


tell me what is DRV means


I believe it is a German (Bosch) Acronym. In English it refers to the "Fuel Rail Pressure Regulator / Valve.

As far as I know these come complete with the Rail and Pressure Sensor at the other end and cost about £1000 Shiny English Pounds. A bitter pill to swallow but worthwhile if it fixes it.

The Drama starts when it does not fix it ?? You cannot diagnose a fault based on another mans findings on a similar car.
You need to find someone that has the correct tooling and knowledge to devise and follow a methodical test plan.

You could post your location and ask for a recommendation here - but that's your choice.
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Re: Audi A4 2.0 TDI Rough idle

Postby Fanstiintza » Thu Mar 23, 2017 10:50 am

I change the valve with a friend, it cost me 165 pounds...not to expensive after I spend more then 1000 for 3 injectors. The car is back to normal.
I live in Birmingham if you know any good garage for the future. Thank you
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Re: Audi A4 2.0 TDI Rough idle

Postby STC » Thu Mar 23, 2017 10:41 pm

Good to hear you got a fix :D :D

Not wishing to rain on your parade but please bear in mind that the new regulator should be adapted/calibrated to your vehicle with a diagnostic tool for it to function absolutely correctly in the long term.

not to expensive after I spend more then 1000 for 3 injectors.

It is a shame that our "colleagues" in the garage trade continue to Rubbish our reputation. Read below and I am sure you will never have those problems again. Tell your friends if you are served well.

May I ask ? Did you check the Qualifications of the Technician that Diagnosed the fault. For instance http://www.imiregister.org.uk/search?fh ... Birmingham

I live in Birmingham if you know any good garage for the future. Thank you


Have a chat with Geoff Dyed at https://www.eveshamgarage.co.uk/diagnostics.php

(He taught me - at Masters Level - if that holds any weight for you)
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Re: Audi A4 2.0 TDI Rough idle

Postby nelnun » Thu Nov 02, 2017 1:14 am

dieseljohnny wrote:Disconnecting inlet metering valve while running seems to have no effect at idle and but does under full throttle,no load condition.
(...)the vehicle will idle the same with the air mass meter and/or egr valve disconnected and the actual air mass value displayed was a plausible one taking into engine rpm variation.
Is it trying to establish if Egr valve is stuck open or opening itself?

Hi johnny, hi all :D

I'm new here and I'm facing a similar issue!
Some questions, if you disconnect the EGR valve or air mass, there is no change on the idle?

I have a 2010 Tiguan, engine CBBB (170cv) and the symptoms are, from cold, when I start driving with a very light acceleration (around 1500rpm) the engine seems to slightly hesitate, like misfire, but nothing that I can call rough idle. The problem is when I stop the engine, after a cold start and driving it for 2 or 3m, then when I star the engine back, now is has a very rough idle and very bad smell from the exhaust. When I start to driving with this rough idle, it kangaroos till around 2000rpm with a hard injection sound, like a very old diesel van! After that 2000/2200 rpm acceleration, it is back to normal. When warm, it is always normal, this happens only when cold!

I’ve made some tests. Fuel rail pressure is always fluctuating between 220 and 280bar. When it is in the the rough idle, if a disconnect the EGR solenoid, EGR valve or Air mass, it detects a fault on EGR system, deactivates the EGR and idle is back to normal. When I connect back the EGR solenoid, the rough idle reappears. It is not EGR valve problem because I’ve already replaced it last year:S
If I disconnect the IMV, nothing different happens. If I disconnect rail pressure sensor, still behaving the same but with a little different injection sound.
I've already replaced lambda sonde and no difference!

Any ideia?

Thanks
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Re: Audi A4 2.0 TDI Rough idle

Postby grunf1976 » Tue Nov 14, 2017 1:46 am

Hi,
had the same problem on 2011 passat. It took me a while to diagnose and it turned out that injectors were the problem.Had them done and it solved the problem.
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Re: Audi A4 2.0 TDI Rough idle

Postby ob1diagnostics » Wed Nov 15, 2017 2:38 am

Hi nelnun, what brand of egr did u use when you replaced it last year?
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Re: Audi A4 2.0 TDI Rough idle

Postby nelnun » Fri Dec 08, 2017 7:18 pm

ob1diagnostics wrote:Hi nelnun, what brand of egr did u use when you replaced it last year?


Hi, the new one is Valeo, like the original one, but it was not bought on VW, the only visible diference is the VWAG logo missing on the valve body. I've replaced it because of a fault code on it with engine working in safe mode (power loss), but the issue still persists in the same way.

Well, in fact, this issue is present since I bought the car, 4,5 years ago (car is 8 years old), but the cold hesitation with a very light acceleration (in a horizontal street, like shopping park) is getting a slightly worse.

I've already spent a lot of hours testing and reading, but I'm still in the same place where I've started!

Last things done:
- Lambda sonde replaced;
- Mass air flow sensor replaced;
- Ultrasonic injectors clean
It stills the same!

When it is with rought idle (cold start, drive for 3/4m, stop and restart engine) if I disconnect and open slightly the intake pipe just after the MAF, the ECU thinks that air flow has dropped and closes a bit the egr valve (lets say that egr valve duty cicle increases from around 45% to 55%) and idle is back to normal, thats why I tought that the problem would be related to the MAF and replaced it!
This rought idle always happen when engine is turned on with an engine temperature around 40ºC!

Some testes done so far:
Temperatures just after cold start. Turbo gases (dark blue) rises till 120ºC in a few seconds and stabilizes there for some minutes (is it normal to stabilize in 120º for so long?):
Temps.jpg
Temps


After 3m driving, before shut down, EGR spec is 310mg/str. After restart, EGR drops to 295mg/str after 3s and is when the engine start to failing at idle (and the injection quantity increases):
Temps_2.jpg


I'll post latter my injections reads aswell
Last edited by nelnun on Sat Dec 09, 2017 4:27 pm, edited 1 time in total.
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Re: Audi A4 2.0 TDI Rough idle

Postby nelnun » Fri Dec 08, 2017 7:20 pm

grunf1976 wrote:Hi,
had the same problem on 2011 passat. It took me a while to diagnose and it turned out that injectors were the problem.Had them done and it solved the problem.

What do you mean exactly with "same problem" please? Did you replace them all, or just the faulty ones?

Thanks
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