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Cold Start Problem

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Old 12-30-2010, 06:29 AM
  #1
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Default Cold Start Problem

Hi fellows,

I have strange problem, which kills me for a long time. I own Audi A4 (B5) year 1996, engine ADP 1.6. My problem is when the car stayed for 2 hours or more in winter and for 6 hours or more in summer the car won’t start from firs time, it starts from second. After the car starts from second try, every next start is O.K until 6 hours in summer and 2 hours in winter cooling time.

Why does it happen?

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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Old 01-02-2011, 05:49 AM
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had a similar problem ths winter,(a4 1998 1.8 se)an absolute pig to start when cold up to 20 mins, once started and warm ok every time,problem was water temperature gauge/sensor,location was back of the engine infront of bulkhead,part was £13,the shop said there was two types blue and green,really easy to change,only a plastic clip holds it in ,dont loose the rubber seal unless you get a new one with part.been ok since even at -12.hope this helps.
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Old 01-03-2011, 11:43 AM
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Hi wizace,

Thank you for reply. The problem on my car is only on the first ignition, second, third etc. are O.K. Only the first one is problematic.

And can you help me with my fuel pressure problem, because I don't know where to start from?
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Old 02-11-2011, 09:38 AM
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Up!
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Old 02-11-2011, 09:40 AM
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Replaced fuel pressure regulator, but still got the problem!
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Old 02-11-2011, 10:16 AM
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Originally Posted by Nikolay_Zhelev View Post
Replaced fuel pressure regulator, but still got the problem!
How old is the battery??
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Old 02-11-2011, 02:24 PM
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Hi Reggie,

The battery is 2,5 years old and the voltage after one night stay is 11.7 V. It's not the best battery, but I've try to charge it on the car for one night and in the morning, the start was the same - first ignition die, on the second - no problem.
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Old 02-11-2011, 05:03 PM
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Originally Posted by Nikolay_Zhelev View Post
Hi Reggie,

The battery is 2,5 years old and the voltage after one night stay is 11.7 V. It's not the best battery, but I've try to charge it on the car for one night and in the morning, the start was the same - first ignition die, on the second - no problem.
Would be great if you could try a different battery - if only temporary for one time. Did you try starting it with the charger still hooked up???
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Old 02-11-2011, 05:35 PM
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I agree^^^^^a weak battery will produce that symptom. But so will a bad coolarnt temp sensor. The ECU needs to know the engine is cold. Then it will make the mixture much richer for the cold start.
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Old 02-11-2011, 06:06 PM
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Originally Posted by Nikolay_Zhelev View Post
Up!
Gratuitous bumping sucks. Knock that **** off.
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