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Nikolay_Zhelev
11-28-2010, 07:18 AM
Hi folks,

For several years I have following problem with the Audi A4 year 1996, engine ADP 1.6. When the car is cold and has passed a period of not less than 5 hours without being started, while trying to ignite, the first time always fails, but second, third, - no problems, it starts, but the first - no. Then when I stop the engine and take another five hours, the first ignition will not be successful again.
Let me explain in detail what happens in this moment of the first cold engine start. When I set the ignition key in contact position I'm waiting for about 5 seconds then I'm starting the engine. The rpm raised to 200-300, maximum of 400 for about 2 seconds, in the coupe you can feel lots of vibrations from the engine, and after 1-2 seconds, the engine stops itself. In an attempt to solve the problem I have done the following procedures: I made a complete computer diagnostics to an authorized service VW / Audi, no errors, all sensors are working correctly, I cleaned up the MAF sensor, cleaned nozzles, replaced fuel, air, coupe and oil filters, measured the fuel pressure rate (the mechanic said that my fuel pump is almost as new). I've made a software adaptation of throttle body using VAG-COM. I've changed Lambda probe, 3 years ago. Several weeks ago I've replace my Throttle Body with used one - second hand.
After all these procedures, the car continues to give the same problem on first ignition. Now when it's cold outside the problem is on almost every ignition in 2-3 hours window.

Because this problem only happens after major stand of the car without being started it is quite difficult to diagnose.

You can see my problem in this video:

http://www.youtube.com/watch?v=nxag2DeLqCA

The language I'm speaking in this video is Bulgarian, my mother language.

I will be happy to advice and assistance on your side.

Best Regards
Nikolay Zhelev

walky_talky20
11-28-2010, 03:21 PM
I think my help may be limited somewhat, as in the US we never got a 1.6 in a B5. Anyway, here a few things I would look at:

- Check coolant temperature in vag-com, before the cold start (and during, if possible)
- Try watching the misfire counter in vag-com to see which cylinder is misfiring
- Try priming the fuel pump 3 times before starting (turn key ON, wait 5 seconds, turn OFF, turn ON, wait 5 secs, etc)
- Try starting with cam sensor unplugged
- Check fuel trims in vag-com

A few questions:
- What happens if you try to pump the throttle while it is stumbling?
- What if you only just "tap" the starter? If the first start attempt is too short and there is no combustion at all, does the second try work fine?
- Do you have to let the car die on it's own before trying again? If you start it cold, it stumbles, and you immediately shut off the key, then restart, what happens?
- Have you replaced the fuel pressure regulator? Or checked it's vacuum line for fuel leaking?

Amorphic
11-28-2010, 05:41 PM
similar to issue i am having. Mine is a leaking fuel injector. could also be a vacuum leak.

Nikolay_Zhelev
11-29-2010, 02:11 AM
Hi walky_talky20,

Thanks for reply! On you questions: when I pump the throttle pedal, the engine stops immediately. When I just tap the starter, the second ignition is fine! On the first ignition I'm letting the car to die on it's own, but I've tried to shut it manually and there is no difference! The second ignition in the both situations is normal. About fuel pressure regulator, I've checked the pressure and It's O.K. The vacuum line is replaced! Still got my problem!

Hi Amorphic

I've checked my fuel injectors, they're fine and no vacuum leaks.

Best Regards
Nikolay Zhelev

Nikolay_Zhelev
01-10-2011, 10:00 AM
Hi,

About my problem, still got it :( Any new ideas?

Nikolay_Zhelev
01-28-2011, 11:54 AM
Hi folks,

Yesterday I've began troubleshooting my problem and something just got my attention. I did the fuel pressure test with the vacuum hose of my fuel pressure regulator and the fuel pressure gauge. The numbers are as follows: Engine IDLE, vacuum on my fuel pressure regulator is ON the pressure is 2.8 bar, when I disconnect the vacuum hose from my fuel pressure regulator the pressure becomes 3.5 bar. When I shut down the engine, and wait about 10 min. the pressure in the system is 2 bar.

By the specification, the pressure should be: Vacuum On: 3.5 bar; Vacuum OFF: 4 bar; Aft 10 min. : 2.5 bar.

Where should be the problem with my pressure?

Nikolay_Zhelev
01-29-2011, 08:20 AM
Okay, today I've measured the fuel pump pressure and it's between 6-7 bar, so the problem is not in my pump.

Nikolay_Zhelev
02-11-2011, 10:37 AM
Up!

Nikolay_Zhelev
02-19-2011, 03:23 AM
I've changed my fuel pressure regulator, with 4 bar. one, but there is no difference in first ignition. Last night, I've noticed, that when I spray my ignition leads with screen wash liquid, while the engine is working, I can see some sparks to light out. This should be bad insulation I think, but my question is, is this related to my problem with the first ignition and could this drop down my thrust?

Nikolay_Zhelev
02-21-2011, 01:02 PM
Up!

jony_easyrider
11-11-2012, 02:54 AM
I've changed my fuel pressure regulator, with 4 bar. one, but there is no difference in first ignition. Last night, I've noticed, that when I spray my ignition leads with screen wash liquid, while the engine is working, I can see some sparks to light out. This should be bad insulation I think, but my question is, is this related to my problem with the first ignition and could this drop down my thrust?

I have also this problem on my Audi A4 1.6 2002

Did you managed to indentify the problem?

Thanks ahead for your answers!

woolveren
11-12-2012, 11:08 AM
Hi,

About my problem, still got it :( Any new ideas?


I have also this problem on my Audi A4 1.6 2002

Did you managed to indentify the problem?

Thanks ahead for your answers!



I've spend a lot of time and money to fix this cold start issue; tried another MAF, checked whole PCV system, replaced temperature sensors, oil sensors,cleaned throttle body etc etc...

The problem I had was exactly similar to what you described, car always fails to start in the first attempt and then all of a sudden it starts in the second try.

And the culprit was COIL PACK.

Believe me, I never had any symptoms of a failing/ failed coil packs and the car ran smoothly. But as a last option, I changed all four coils with new Beru coils from ECStuning and dude, that made a whole lot of difference.

Car now starts in first attempt and I don't even wait for throttle body alignment time after turning ON the ignition which I used to do before when I had the starting problem. The temperature here is almost 0 degree most of the time and the car starts flawlessly in first attempt(3 sec max).

Car is a 1.8t with 250k miles. :)

contrldsub
11-12-2012, 06:44 PM
Up!

if you start the car on the second try let it run and then shut if off, pull the battery for 30-60sec, (have radio code handy) does it go back to no start on the first try and then start on second, third....? if this is the case i would look at testing intake air temp, engine coolant temp and crankshaft position sensors. these three sensors are what the engine uses during a "cold" start. but audi's seem to be smart enough that if one of them is failing it will bypass and supplement a value in order to get the car running.

Best way to test is with an oscilliscope if you can. if you have access to a good scan tool that you can read engine data on you can use that to check IAT and ECT values when the engine is cold and they should be the same, or close. if your IAT reads -40 it is definatly faulty (unless its -40 out).