Recently my car faces a new problem, when I start the engine the motor RPM's are fluctuating (engine sounds very rough, engine is rocking and RPM's are just up and down) for say approx 1 minute.[/align]After engaging the trottle the engine is still rough (within this period), but then after a short period everything is O.k again and the engine drives just fine even at low Idle R.P.M.[/align][/align]This is only happening when the engine is cold.[/align][/align]I changed the sparks, oil exchange, replaced the gasoline filter, but nothing solved the issue.[/align][/align]Would somebody be able to tell me what the problem is?[/align][/align]Thanks in advance[/align][/align]Alltwin[/align][/align][/align]

 

I would try cleaning the throttle body and see if that fixes it.

 

Thank you for your suggestion!![/align][/align]Could you please be more specific on what to clean on the trottle body?[/align][/align]I can remove it but what then, should I polish it or should I remove the electroncis?[/align][/align]Please advise[/align][/align]And Thanks already[/align][/align][/align]Alltwin[/align]

 

Just clean the chamber with carb or brake cleaner. Just clean where the air flows through.

 

Hi, from my experince this could also be air leak on input side, in mine it was the manifold gasket. Fulctuation was result of computer trying to find optimal mix. check vacum hoses, elbows and tube from air filter to engine for cracks.
br tapsa

 

Hi Thank you for your suggestion.[/align][/align]As feedback I tried to clean with the Throttle body cleaner as suggested earlier, but that did not change anything.[/align][/align]However I do know that one of the rubber tubes is detoriating (your hand really turn balck when you toucg them).[/align][/align]I will check.[/align][/align][/align]Could be the "Idle valve controller", the one close to the radiator and directly connected to the manifold?[/align]Is there a way to check this "Idle valve controller".[/align][/align]Appreciate your suggestions[/align][/align]Alltwin[/align]

 

It is is a 98 it will have an idle motor and you can try cleaning that as well.
Check all smaller hoses for cranks since they are going like you explained.

 

Hi,[/align][/align]What do you mean by Idle motor? my car is from 2002 (V70 Station)[/align][/align]I checked all these small tubes coming from the air filter enclosure.[/align]One going directly to the motor and one is going to a kind of pressure regulator, both tubes are O.K.[/align][/align]What else could I do, more suggestions to solve this problem?[/align][/align]The weird thing is we have a board computer on the car, but this one does not generate any message.[/align][/align]Alltwin[/align]

 

OK since it is a 2002 it doesn't have an idle motor.
You didn't specify year.

 

When were the plugs last changed? Also, I'm not that familiar with the motor...does it have some sort of throttle position sensor?

 

I had a similar problem with my idle and the cause was a leak in the big air intake hose between the air cleaner and the throttle body. You could try making up a solution of soapy water, spray your air hoses, and look for blowing bubbles. If you find bubbles, you've found your leak.

 

Plugs have been changed one month ago, as well the gasoline filter.[/align][/align]I suppose it has a throttle valve detector at the side, should I open it and check if I find something irregular?[/align][/align]Thanks[/align][/align]Alltwin[/align]

 

Dear All,[/align][/align]I tried to capture the problem using our camera with sound and uploaded the movie on Youtube.[/align][/align]Please check and let me know if you know what the problem could be.[/align][/align]http://ca.youtube.com/my_videos_edit...sq%3D%26dm%3D2[/align][/align][/align]Sincerely[/align][/align]Alltwin[/align]

 

Sorry the link above does not really work[/align][/align]Please search Youtube for "Volvo V70 engine problem" it will pop op in the listing[/align][/align]Alltwin[/align] [/align][/align]This link should work[/align]http://ca.youtube.com/watch?v=LwQb9WA13Po[/align]

 

Does it happen every start up or only after sitting a while?

 

Basically only during a cold start.[/align][/align]If the engine is warm, after start the engine runs perfect.[/align][/align]It is really puzzling me, what could it be?[/align][/align]Alltwin[/align]

 

I wonder if the fuel pressure is bleeding back when it sits for a while causing the stumble when cold started.

 

Hi[/align][/align]That's a great suggestion!![/align][/align]Were to look, how to check?[/align][/align]Please advice[/align][/align]Sincerely[/align][/align]Alltwin[/align]

 

Best way to check is to get a fuel pressure guage and connect it. Then start the car and let it run for a second and make sure you have good pressure. Then turn it off and let it sit for an hour or 2. It should hold pretty good pressure. If it drops to 0 then you know it is bleeding down.

 

Hi [/align][/align]Thanks!! I tried to do something else, at least trying to prove you are right w.r.t bleeding the pressure.[/align][/align]I assumed that the presssure was gone, so I turned the ignition key just until the car should start.[/align][/align]The fuel pump should come in when the pressure is too low, correct?[/align][/align]So I did this and then I noticed a lot or rattling under the hood, which stopped after approx 1-2 minutes.[/align][/align]I waited a little bit longer and tried to start-> yes the car was running normal from the very beginning >wow.[/align][/align]So now the question what could it be this rattling underneath the hood causing a fuel pressure drop??[/align]and were would it be located under the hood?[/align][/align]Please advice[/align][/align]Alltwin[/align][/align][/align]