Hello, I have Volvo S40 with the engine type B4194 T2, 147kW/200hP, 1999, and I need info about idle problem.

When I start the engine in the morning it start normally, good and work for a few seconds ok and then, it happen more often when it's cold out side, idle "fall" down, some how lose strength and rpm fall. I have to hold the throttle and to pump somehow with throttle and it start to work normally after a few minutes .

When I was on annual technical inspection of the car before registration they check exhaust gasses and they told me that I have more air in exhaust than I should have....they told me that I have a hole on exhaust pipe and to check with mechanic. I did it but he found nothing..

Also I noticed that the engine have the same symptoms after I refill the fuel. It run normally and as I fill up the fuel, after few minutes the car have the same symptoms like in the morning when it loose the power on the gas. After a few minutes everything's is back to normal.
I read in the manual and its written that if the cup is not close correctly it could have some symptoms like that. I check several time, cup is ok....

There is no lights-on dash board like engine service or similar.

It would mean a lot to me if someone who recognises the symptoms or is a mechanic for this cars would contact me.
I would like to mention that I have been to an authorised Volvo service center twice but without a solution, I live in Malta and the quality and knowledge of the mechanic is at an incredibly low level and that is zero responsibility....its shame that they represent Volvo at all...

Thank you

Srdjan Jevremovic
srdjanj14@gmail.com
Viber/WhatsApp +38163 1775558

 

There is a possible tie in between the gas tank and the lean condition. Your car has an "evap" system that is designed to recover fuel vapors from the gas tank into a carbon filter then opens a "purge valve" which allows the engine's vacuum to pull in the vapors to be burned. This design requires a vacuum line to run from up by the radiator all the way back to the gas tank. If that line tears or if the gas cap is loose or the filler is torn etc, air can get sucked in (the tank is supposed to be a sealed system) causing a vacuum leak. With all that said, I'd expect a CEL fault code to be set to tell you whether theirs a small or large evap leak so the starting point is to have an OBD2 scanner to check for any stored fault codes. Note that air leaks can occur in almost any of the vacuum lines as well as in the turbo air tubing so a full visual inspection of the hoses and boots is a first step. After that, you can use something like carb cleaner and spray around the tubing, injectors, intake gaskets etc to see if anything gets sucked in and bumps the idle. Exhaust leaks can mess up the O2 sensor's reading too - most common is the "flex pipe" section of the exhaust (that metal mesh section) can tear and produce a leak (you should hear it and can feel puffs of exhaust) that can set off a CEL for the front O2 "lambda" sensor. Note that small leaks mostly impact idle since when the car is running the volume of metered air can "out run" a smaller air leak.

 

Thank you, I'm so impressed with quick replay. On the other forums... they never replay, and I have that problem for a while.
I will check everything and I'll get back here to share the info for all the other.

Thank you

Srdjan