Cold start problems
#1
11-28-2010, 09:43 AM
Cold start problems
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 is Bulgarian, my mother language.
I will be happy to advice and assistance on your side.
Best Regards
Nikolay Zhelev
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 is Bulgarian, my mother language.
I will be happy to advice and assistance on your side.
Best Regards
Nikolay Zhelev
Last edited by Nikolay_Zhelev; 11-28-2010 at 09:46 AM.
#2
12-30-2010, 11:44 AM
Hi folks,
Today I suspected my fuel pressure regulator and decide to do fuel pressure test. The data I've collected from the test is as follows:
Fuel pressure regulator vacuum hose ON.
Warm engine at idle: 2.25 bars
High RPM: 3 bars
Engine OFF, after 10 min.: 2.75 bars.
My AutoData software gives following information about fuel pressure:
Vacuum ON:
Engine at IDLE: 3.5 bars.
Engine OFF, after 10 min.: 2.75 bars at least.
Why my pressure is different and why the difference is almost 1 bar?
Where should I look for this problem?
Today I suspected my fuel pressure regulator and decide to do fuel pressure test. The data I've collected from the test is as follows:
Fuel pressure regulator vacuum hose ON.
Warm engine at idle: 2.25 bars
High RPM: 3 bars
Engine OFF, after 10 min.: 2.75 bars.
My AutoData software gives following information about fuel pressure:
Vacuum ON:
Engine at IDLE: 3.5 bars.
Engine OFF, after 10 min.: 2.75 bars at least.
Why my pressure is different and why the difference is almost 1 bar?
Where should I look for this problem?
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